/* * Written by Doug Lea with assistance from members of JCP JSR-166 * Expert Group and released to the public domain, as explained at * http://creativecommons.org/publicdomain/zero/1.0/ */ // This is based on the 1.79 version. package com.concurrent_ruby.ext.jsr166e; import org.jruby.RubyClass; import org.jruby.RubyNumeric; import org.jruby.RubyObject; import org.jruby.exceptions.RaiseException; import com.concurrent_ruby.ext.jsr166y.ThreadLocalRandom; import org.jruby.runtime.ThreadContext; import org.jruby.runtime.builtin.IRubyObject; import java.util.Arrays; import java.util.Map; import java.util.Set; import java.util.Collection; import java.util.Hashtable; import java.util.HashMap; import java.util.Iterator; import java.util.Enumeration; import java.util.ConcurrentModificationException; import java.util.NoSuchElementException; import java.util.concurrent.ConcurrentMap; import java.util.concurrent.locks.AbstractQueuedSynchronizer; import java.io.Serializable; /** * A hash table supporting full concurrency of retrievals and * high expected concurrency for updates. This class obeys the * same functional specification as {@link java.util.Hashtable}, and * includes versions of methods corresponding to each method of * {@code Hashtable}. However, even though all operations are * thread-safe, retrieval operations do <em>not</em> entail locking, * and there is <em>not</em> any support for locking the entire table * in a way that prevents all access. This class is fully * interoperable with {@code Hashtable} in programs that rely on its * thread safety but not on its synchronization details. * * <p>Retrieval operations (including {@code get}) generally do not * block, so may overlap with update operations (including {@code put} * and {@code remove}). Retrievals reflect the results of the most * recently <em>completed</em> update operations holding upon their * onset. (More formally, an update operation for a given key bears a * <em>happens-before</em> relation with any (non-null) retrieval for * that key reporting the updated value.) For aggregate operations * such as {@code putAll} and {@code clear}, concurrent retrievals may * reflect insertion or removal of only some entries. Similarly, * Iterators and Enumerations return elements reflecting the state of * the hash table at some point at or since the creation of the * iterator/enumeration. They do <em>not</em> throw {@link * ConcurrentModificationException}. However, iterators are designed * to be used by only one thread at a time. Bear in mind that the * results of aggregate status methods including {@code size}, {@code * isEmpty}, and {@code containsValue} are typically useful only when * a map is not undergoing concurrent updates in other threads. * Otherwise the results of these methods reflect transient states * that may be adequate for monitoring or estimation purposes, but not * for program control. * * <p>The table is dynamically expanded when there are too many * collisions (i.e., keys that have distinct hash codes but fall into * the same slot modulo the table size), with the expected average * effect of maintaining roughly two bins per mapping (corresponding * to a 0.75 load factor threshold for resizing). There may be much * variance around this average as mappings are added and removed, but * overall, this maintains a commonly accepted time/space tradeoff for * hash tables. However, resizing this or any other kind of hash * table may be a relatively slow operation. When possible, it is a * good idea to provide a size estimate as an optional {@code * initialCapacity} constructor argument. An additional optional * {@code loadFactor} constructor argument provides a further means of * customizing initial table capacity by specifying the table density * to be used in calculating the amount of space to allocate for the * given number of elements. Also, for compatibility with previous * versions of this class, constructors may optionally specify an * expected {@code concurrencyLevel} as an additional hint for * internal sizing. Note that using many keys with exactly the same * {@code hashCode()} is a sure way to slow down performance of any * hash table. * * <p>A {@link Set} projection of a ConcurrentHashMapV8 may be created * (using {@link #newKeySet()} or {@link #newKeySet(int)}), or viewed * (using {@link #keySet(Object)} when only keys are of interest, and the * mapped values are (perhaps transiently) not used or all take the * same mapping value. * * <p>A ConcurrentHashMapV8 can be used as scalable frequency map (a * form of histogram or multiset) by using {@link LongAdder} values * and initializing via {@link #computeIfAbsent}. For example, to add * a count to a {@code ConcurrentHashMapV8<String,LongAdder> freqs}, you * can use {@code freqs.computeIfAbsent(k -> new * LongAdder()).increment();} * * <p>This class and its views and iterators implement all of the * <em>optional</em> methods of the {@link Map} and {@link Iterator} * interfaces. * * <p>Like {@link Hashtable} but unlike {@link HashMap}, this class * does <em>not</em> allow {@code null} to be used as a key or value. * * <p>ConcurrentHashMapV8s support parallel operations using the {@link * ForkJoinPool#commonPool}. (Tasks that may be used in other contexts * are available in class {@link ForkJoinTasks}). These operations are * designed to be safely, and often sensibly, applied even with maps * that are being concurrently updated by other threads; for example, * when computing a snapshot summary of the values in a shared * registry. There are three kinds of operation, each with four * forms, accepting functions with Keys, Values, Entries, and (Key, * Value) arguments and/or return values. (The first three forms are * also available via the {@link #keySet()}, {@link #values()} and * {@link #entrySet()} views). Because the elements of a * ConcurrentHashMapV8 are not ordered in any particular way, and may be * processed in different orders in different parallel executions, the * correctness of supplied functions should not depend on any * ordering, or on any other objects or values that may transiently * change while computation is in progress; and except for forEach * actions, should ideally be side-effect-free. * * <ul> * <li> forEach: Perform a given action on each element. * A variant form applies a given transformation on each element * before performing the action.</li> * * <li> search: Return the first available non-null result of * applying a given function on each element; skipping further * search when a result is found.</li> * * <li> reduce: Accumulate each element. The supplied reduction * function cannot rely on ordering (more formally, it should be * both associative and commutative). There are five variants: * * <ul> * * <li> Plain reductions. (There is not a form of this method for * (key, value) function arguments since there is no corresponding * return type.)</li> * * <li> Mapped reductions that accumulate the results of a given * function applied to each element.</li> * * <li> Reductions to scalar doubles, longs, and ints, using a * given basis value.</li> * * </li> * </ul> * </ul> * * <p>The concurrency properties of bulk operations follow * from those of ConcurrentHashMapV8: Any non-null result returned * from {@code get(key)} and related access methods bears a * happens-before relation with the associated insertion or * update. The result of any bulk operation reflects the * composition of these per-element relations (but is not * necessarily atomic with respect to the map as a whole unless it * is somehow known to be quiescent). Conversely, because keys * and values in the map are never null, null serves as a reliable * atomic indicator of the current lack of any result. To * maintain this property, null serves as an implicit basis for * all non-scalar reduction operations. For the double, long, and * int versions, the basis should be one that, when combined with * any other value, returns that other value (more formally, it * should be the identity element for the reduction). Most common * reductions have these properties; for example, computing a sum * with basis 0 or a minimum with basis MAX_VALUE. * * <p>Search and transformation functions provided as arguments * should similarly return null to indicate the lack of any result * (in which case it is not used). In the case of mapped * reductions, this also enables transformations to serve as * filters, returning null (or, in the case of primitive * specializations, the identity basis) if the element should not * be combined. You can create compound transformations and * filterings by composing them yourself under this "null means * there is nothing there now" rule before using them in search or * reduce operations. * * <p>Methods accepting and/or returning Entry arguments maintain * key-value associations. They may be useful for example when * finding the key for the greatest value. Note that "plain" Entry * arguments can be supplied using {@code new * AbstractMap.SimpleEntry(k,v)}. * * <p>Bulk operations may complete abruptly, throwing an * exception encountered in the application of a supplied * function. Bear in mind when handling such exceptions that other * concurrently executing functions could also have thrown * exceptions, or would have done so if the first exception had * not occurred. * * <p>Parallel speedups for bulk operations compared to sequential * processing are common but not guaranteed. Operations involving * brief functions on small maps may execute more slowly than * sequential loops if the underlying work to parallelize the * computation is more expensive than the computation itself. * Similarly, parallelization may not lead to much actual parallelism * if all processors are busy performing unrelated tasks. * * <p>All arguments to all task methods must be non-null. * * <p><em>jsr166e note: During transition, this class * uses nested functional interfaces with different names but the * same forms as those expected for JDK8.</em> * * <p>This class is a member of the * <a href="{@docRoot}/../technotes/guides/collections/index.html"> * Java Collections Framework</a>. * * @since 1.5 * @author Doug Lea * @param <K> the type of keys maintained by this map * @param <V> the type of mapped values */ public class ConcurrentHashMapV8<K, V> implements ConcurrentMap<K, V>, Serializable, ConcurrentHashMap<K, V> { private static final long serialVersionUID = 7249069246763182397L; /** * A partitionable iterator. A Spliterator can be traversed * directly, but can also be partitioned (before traversal) by * creating another Spliterator that covers a non-overlapping * portion of the elements, and so may be amenable to parallel * execution. * * <p>This interface exports a subset of expected JDK8 * functionality. * * <p>Sample usage: Here is one (of the several) ways to compute * the sum of the values held in a map using the ForkJoin * framework. As illustrated here, Spliterators are well suited to * designs in which a task repeatedly splits off half its work * into forked subtasks until small enough to process directly, * and then joins these subtasks. Variants of this style can also * be used in completion-based designs. * * <pre> * {@code ConcurrentHashMapV8<String, Long> m = ... * // split as if have 8 * parallelism, for load balance * int n = m.size(); * int p = aForkJoinPool.getParallelism() * 8; * int split = (n < p)? n : p; * long sum = aForkJoinPool.invoke(new SumValues(m.valueSpliterator(), split, null)); * // ... * static class SumValues extends RecursiveTask<Long> { * final Spliterator<Long> s; * final int split; // split while > 1 * final SumValues nextJoin; // records forked subtasks to join * SumValues(Spliterator<Long> s, int depth, SumValues nextJoin) { * this.s = s; this.depth = depth; this.nextJoin = nextJoin; * } * public Long compute() { * long sum = 0; * SumValues subtasks = null; // fork subtasks * for (int s = split >>> 1; s > 0; s >>>= 1) * (subtasks = new SumValues(s.split(), s, subtasks)).fork(); * while (s.hasNext()) // directly process remaining elements * sum += s.next(); * for (SumValues t = subtasks; t != null; t = t.nextJoin) * sum += t.join(); // collect subtask results * return sum; * } * } * }</pre> */ public static interface Spliterator<T> extends Iterator<T> { /** * Returns a Spliterator covering approximately half of the * elements, guaranteed not to overlap with those subsequently * returned by this Spliterator. After invoking this method, * the current Spliterator will <em>not</em> produce any of * the elements of the returned Spliterator, but the two * Spliterators together will produce all of the elements that * would have been produced by this Spliterator had this * method not been called. The exact number of elements * produced by the returned Spliterator is not guaranteed, and * may be zero (i.e., with {@code hasNext()} reporting {@code * false}) if this Spliterator cannot be further split. * * @return a Spliterator covering approximately half of the * elements * @throws IllegalStateException if this Spliterator has * already commenced traversing elements */ Spliterator<T> split(); } /* * Overview: * * The primary design goal of this hash table is to maintain * concurrent readability (typically method get(), but also * iterators and related methods) while minimizing update * contention. Secondary goals are to keep space consumption about * the same or better than java.util.HashMap, and to support high * initial insertion rates on an empty table by many threads. * * Each key-value mapping is held in a Node. Because Node fields * can contain special values, they are defined using plain Object * types. Similarly in turn, all internal methods that use them * work off Object types. And similarly, so do the internal * methods of auxiliary iterator and view classes. All public * generic typed methods relay in/out of these internal methods, * supplying null-checks and casts as needed. This also allows * many of the public methods to be factored into a smaller number * of internal methods (although sadly not so for the five * variants of put-related operations). The validation-based * approach explained below leads to a lot of code sprawl because * retry-control precludes factoring into smaller methods. * * The table is lazily initialized to a power-of-two size upon the * first insertion. Each bin in the table normally contains a * list of Nodes (most often, the list has only zero or one Node). * Table accesses require volatile/atomic reads, writes, and * CASes. Because there is no other way to arrange this without * adding further indirections, we use intrinsics * (sun.misc.Unsafe) operations. The lists of nodes within bins * are always accurately traversable under volatile reads, so long * as lookups check hash code and non-nullness of value before * checking key equality. * * We use the top two bits of Node hash fields for control * purposes -- they are available anyway because of addressing * constraints. As explained further below, these top bits are * used as follows: * 00 - Normal * 01 - Locked * 11 - Locked and may have a thread waiting for lock * 10 - Node is a forwarding node * * The lower 30 bits of each Node's hash field contain a * transformation of the key's hash code, except for forwarding * nodes, for which the lower bits are zero (and so always have * hash field == MOVED). * * Insertion (via put or its variants) of the first node in an * empty bin is performed by just CASing it to the bin. This is * by far the most common case for put operations under most * key/hash distributions. Other update operations (insert, * delete, and replace) require locks. We do not want to waste * the space required to associate a distinct lock object with * each bin, so instead use the first node of a bin list itself as * a lock. Blocking support for these locks relies on the builtin * "synchronized" monitors. However, we also need a tryLock * construction, so we overlay these by using bits of the Node * hash field for lock control (see above), and so normally use * builtin monitors only for blocking and signalling using * wait/notifyAll constructions. See Node.tryAwaitLock. * * Using the first node of a list as a lock does not by itself * suffice though: When a node is locked, any update must first * validate that it is still the first node after locking it, and * retry if not. Because new nodes are always appended to lists, * once a node is first in a bin, it remains first until deleted * or the bin becomes invalidated (upon resizing). However, * operations that only conditionally update may inspect nodes * until the point of update. This is a converse of sorts to the * lazy locking technique described by Herlihy & Shavit. * * The main disadvantage of per-bin locks is that other update * operations on other nodes in a bin list protected by the same * lock can stall, for example when user equals() or mapping * functions take a long time. However, statistically, under * random hash codes, this is not a common problem. Ideally, the * frequency of nodes in bins follows a Poisson distribution * (http://en.wikipedia.org/wiki/Poisson_distribution) with a * parameter of about 0.5 on average, given the resizing threshold * of 0.75, although with a large variance because of resizing * granularity. Ignoring variance, the expected occurrences of * list size k are (exp(-0.5) * pow(0.5, k) / factorial(k)). The * first values are: * * 0: 0.60653066 * 1: 0.30326533 * 2: 0.07581633 * 3: 0.01263606 * 4: 0.00157952 * 5: 0.00015795 * 6: 0.00001316 * 7: 0.00000094 * 8: 0.00000006 * more: less than 1 in ten million * * Lock contention probability for two threads accessing distinct * elements is roughly 1 / (8 * #elements) under random hashes. * * Actual hash code distributions encountered in practice * sometimes deviate significantly from uniform randomness. This * includes the case when N > (1<<30), so some keys MUST collide. * Similarly for dumb or hostile usages in which multiple keys are * designed to have identical hash codes. Also, although we guard * against the worst effects of this (see method spread), sets of * hashes may differ only in bits that do not impact their bin * index for a given power-of-two mask. So we use a secondary * strategy that applies when the number of nodes in a bin exceeds * a threshold, and at least one of the keys implements * Comparable. These TreeBins use a balanced tree to hold nodes * (a specialized form of red-black trees), bounding search time * to O(log N). Each search step in a TreeBin is around twice as * slow as in a regular list, but given that N cannot exceed * (1<<64) (before running out of addresses) this bounds search * steps, lock hold times, etc, to reasonable constants (roughly * 100 nodes inspected per operation worst case) so long as keys * are Comparable (which is very common -- String, Long, etc). * TreeBin nodes (TreeNodes) also maintain the same "next" * traversal pointers as regular nodes, so can be traversed in * iterators in the same way. * * The table is resized when occupancy exceeds a percentage * threshold (nominally, 0.75, but see below). Only a single * thread performs the resize (using field "sizeCtl", to arrange * exclusion), but the table otherwise remains usable for reads * and updates. Resizing proceeds by transferring bins, one by * one, from the table to the next table. Because we are using * power-of-two expansion, the elements from each bin must either * stay at same index, or move with a power of two offset. We * eliminate unnecessary node creation by catching cases where old * nodes can be reused because their next fields won't change. On * average, only about one-sixth of them need cloning when a table * doubles. The nodes they replace will be garbage collectable as * soon as they are no longer referenced by any reader thread that * may be in the midst of concurrently traversing table. Upon * transfer, the old table bin contains only a special forwarding * node (with hash field "MOVED") that contains the next table as * its key. On encountering a forwarding node, access and update * operations restart, using the new table. * * Each bin transfer requires its bin lock. However, unlike other * cases, a transfer can skip a bin if it fails to acquire its * lock, and revisit it later (unless it is a TreeBin). Method * rebuild maintains a buffer of TRANSFER_BUFFER_SIZE bins that * have been skipped because of failure to acquire a lock, and * blocks only if none are available (i.e., only very rarely). * The transfer operation must also ensure that all accessible * bins in both the old and new table are usable by any traversal. * When there are no lock acquisition failures, this is arranged * simply by proceeding from the last bin (table.length - 1) up * towards the first. Upon seeing a forwarding node, traversals * (see class Iter) arrange to move to the new table * without revisiting nodes. However, when any node is skipped * during a transfer, all earlier table bins may have become * visible, so are initialized with a reverse-forwarding node back * to the old table until the new ones are established. (This * sometimes requires transiently locking a forwarding node, which * is possible under the above encoding.) These more expensive * mechanics trigger only when necessary. * * The traversal scheme also applies to partial traversals of * ranges of bins (via an alternate Traverser constructor) * to support partitioned aggregate operations. Also, read-only * operations give up if ever forwarded to a null table, which * provides support for shutdown-style clearing, which is also not * currently implemented. * * Lazy table initialization minimizes footprint until first use, * and also avoids resizings when the first operation is from a * putAll, constructor with map argument, or deserialization. * These cases attempt to override the initial capacity settings, * but harmlessly fail to take effect in cases of races. * * The element count is maintained using a LongAdder, which avoids * contention on updates but can encounter cache thrashing if read * too frequently during concurrent access. To avoid reading so * often, resizing is attempted either when a bin lock is * contended, or upon adding to a bin already holding two or more * nodes (checked before adding in the xIfAbsent methods, after * adding in others). Under uniform hash distributions, the * probability of this occurring at threshold is around 13%, * meaning that only about 1 in 8 puts check threshold (and after * resizing, many fewer do so). But this approximation has high * variance for small table sizes, so we check on any collision * for sizes <= 64. The bulk putAll operation further reduces * contention by only committing count updates upon these size * checks. * * Maintaining API and serialization compatibility with previous * versions of this class introduces several oddities. Mainly: We * leave untouched but unused constructor arguments refering to * concurrencyLevel. We accept a loadFactor constructor argument, * but apply it only to initial table capacity (which is the only * time that we can guarantee to honor it.) We also declare an * unused "Segment" class that is instantiated in minimal form * only when serializing. */ /* ---------------- Constants -------------- */ /** * The largest possible table capacity. This value must be * exactly 1<<30 to stay within Java array allocation and indexing * bounds for power of two table sizes, and is further required * because the top two bits of 32bit hash fields are used for * control purposes. */ private static final int MAXIMUM_CAPACITY = 1 << 30; /** * The default initial table capacity. Must be a power of 2 * (i.e., at least 1) and at most MAXIMUM_CAPACITY. */ private static final int DEFAULT_CAPACITY = 16; /** * The largest possible (non-power of two) array size. * Needed by toArray and related methods. */ static final int MAX_ARRAY_SIZE = Integer.MAX_VALUE - 8; /** * The default concurrency level for this table. Unused but * defined for compatibility with previous versions of this class. */ private static final int DEFAULT_CONCURRENCY_LEVEL = 16; /** * The load factor for this table. Overrides of this value in * constructors affect only the initial table capacity. The * actual floating point value isn't normally used -- it is * simpler to use expressions such as {@code n - (n >>> 2)} for * the associated resizing threshold. */ private static final float LOAD_FACTOR = 0.75f; /** * The buffer size for skipped bins during transfers. The * value is arbitrary but should be large enough to avoid * most locking stalls during resizes. */ private static final int TRANSFER_BUFFER_SIZE = 32; /** * The bin count threshold for using a tree rather than list for a * bin. The value reflects the approximate break-even point for * using tree-based operations. * Note that Doug's version defaults to 8, but when dealing with * Ruby objects it is actually beneficial to avoid TreeNodes * as long as possible as it usually means going into Ruby land. */ private static final int TREE_THRESHOLD = 16; /* * Encodings for special uses of Node hash fields. See above for * explanation. */ static final int MOVED = 0x80000000; // hash field for forwarding nodes static final int LOCKED = 0x40000000; // set/tested only as a bit static final int WAITING = 0xc0000000; // both bits set/tested together static final int HASH_BITS = 0x3fffffff; // usable bits of normal node hash /* ---------------- Fields -------------- */ /** * The array of bins. Lazily initialized upon first insertion. * Size is always a power of two. Accessed directly by iterators. */ transient volatile Node[] table; /** * The counter maintaining number of elements. */ private transient final LongAdder counter; /** * Table initialization and resizing control. When negative, the * table is being initialized or resized. Otherwise, when table is * null, holds the initial table size to use upon creation, or 0 * for default. After initialization, holds the next element count * value upon which to resize the table. */ private transient volatile int sizeCtl; // views private transient KeySetView<K,V> keySet; private transient ValuesView<K,V> values; private transient EntrySetView<K,V> entrySet; /** For serialization compatibility. Null unless serialized; see below */ private Segment<K,V>[] segments; /* ---------------- Table element access -------------- */ /* * Volatile access methods are used for table elements as well as * elements of in-progress next table while resizing. Uses are * null checked by callers, and implicitly bounds-checked, relying * on the invariants that tab arrays have non-zero size, and all * indices are masked with (tab.length - 1) which is never * negative and always less than length. Note that, to be correct * wrt arbitrary concurrency errors by users, bounds checks must * operate on local variables, which accounts for some odd-looking * inline assignments below. */ static final Node tabAt(Node[] tab, int i) { // used by Iter return (Node)UNSAFE.getObjectVolatile(tab, ((long)i<<ASHIFT)+ABASE); } private static final boolean casTabAt(Node[] tab, int i, Node c, Node v) { return UNSAFE.compareAndSwapObject(tab, ((long)i<<ASHIFT)+ABASE, c, v); } private static final void setTabAt(Node[] tab, int i, Node v) { UNSAFE.putObjectVolatile(tab, ((long)i<<ASHIFT)+ABASE, v); } /* ---------------- Nodes -------------- */ /** * Key-value entry. Note that this is never exported out as a * user-visible Map.Entry (see MapEntry below). Nodes with a hash * field of MOVED are special, and do not contain user keys or * values. Otherwise, keys are never null, and null val fields * indicate that a node is in the process of being deleted or * created. For purposes of read-only access, a key may be read * before a val, but can only be used after checking val to be * non-null. */ static class Node { volatile int hash; final Object key; volatile Object val; volatile Node next; Node(int hash, Object key, Object val, Node next) { this.hash = hash; this.key = key; this.val = val; this.next = next; } /** CompareAndSet the hash field */ final boolean casHash(int cmp, int val) { return UNSAFE.compareAndSwapInt(this, hashOffset, cmp, val); } /** The number of spins before blocking for a lock */ static final int MAX_SPINS = Runtime.getRuntime().availableProcessors() > 1 ? 64 : 1; /** * Spins a while if LOCKED bit set and this node is the first * of its bin, and then sets WAITING bits on hash field and * blocks (once) if they are still set. It is OK for this * method to return even if lock is not available upon exit, * which enables these simple single-wait mechanics. * * The corresponding signalling operation is performed within * callers: Upon detecting that WAITING has been set when * unlocking lock (via a failed CAS from non-waiting LOCKED * state), unlockers acquire the sync lock and perform a * notifyAll. * * The initial sanity check on tab and bounds is not currently * necessary in the only usages of this method, but enables * use in other future contexts. */ final void tryAwaitLock(Node[] tab, int i) { if (tab != null && i >= 0 && i < tab.length) { // sanity check int r = ThreadLocalRandom.current().nextInt(); // randomize spins int spins = MAX_SPINS, h; while (tabAt(tab, i) == this && ((h = hash) & LOCKED) != 0) { if (spins >= 0) { r ^= r << 1; r ^= r >>> 3; r ^= r << 10; // xorshift if (r >= 0 && --spins == 0) Thread.yield(); // yield before block } else if (casHash(h, h | WAITING)) { synchronized (this) { if (tabAt(tab, i) == this && (hash & WAITING) == WAITING) { try { wait(); } catch (InterruptedException ie) { Thread.currentThread().interrupt(); } } else notifyAll(); // possibly won race vs signaller } break; } } } } // Unsafe mechanics for casHash private static final sun.misc.Unsafe UNSAFE; private static final long hashOffset; static { try { UNSAFE = getUnsafe(); Class<?> k = Node.class; hashOffset = UNSAFE.objectFieldOffset (k.getDeclaredField("hash")); } catch (Exception e) { throw new Error(e); } } } /* ---------------- TreeBins -------------- */ /** * Nodes for use in TreeBins */ static final class TreeNode extends Node { TreeNode parent; // red-black tree links TreeNode left; TreeNode right; TreeNode prev; // needed to unlink next upon deletion boolean red; TreeNode(int hash, Object key, Object val, Node next, TreeNode parent) { super(hash, key, val, next); this.parent = parent; } } /** * A specialized form of red-black tree for use in bins * whose size exceeds a threshold. * * TreeBins use a special form of comparison for search and * related operations (which is the main reason we cannot use * existing collections such as TreeMaps). TreeBins contain * Comparable elements, but may contain others, as well as * elements that are Comparable but not necessarily Comparable<T> * for the same T, so we cannot invoke compareTo among them. To * handle this, the tree is ordered primarily by hash value, then * by getClass().getName() order, and then by Comparator order * among elements of the same class. On lookup at a node, if * elements are not comparable or compare as 0, both left and * right children may need to be searched in the case of tied hash * values. (This corresponds to the full list search that would be * necessary if all elements were non-Comparable and had tied * hashes.) The red-black balancing code is updated from * pre-jdk-collections * (http://gee.cs.oswego.edu/dl/classes/collections/RBCell.java) * based in turn on Cormen, Leiserson, and Rivest "Introduction to * Algorithms" (CLR). * * TreeBins also maintain a separate locking discipline than * regular bins. Because they are forwarded via special MOVED * nodes at bin heads (which can never change once established), * we cannot use those nodes as locks. Instead, TreeBin * extends AbstractQueuedSynchronizer to support a simple form of * read-write lock. For update operations and table validation, * the exclusive form of lock behaves in the same way as bin-head * locks. However, lookups use shared read-lock mechanics to allow * multiple readers in the absence of writers. Additionally, * these lookups do not ever block: While the lock is not * available, they proceed along the slow traversal path (via * next-pointers) until the lock becomes available or the list is * exhausted, whichever comes first. (These cases are not fast, * but maximize aggregate expected throughput.) The AQS mechanics * for doing this are straightforward. The lock state is held as * AQS getState(). Read counts are negative; the write count (1) * is positive. There are no signalling preferences among readers * and writers. Since we don't need to export full Lock API, we * just override the minimal AQS methods and use them directly. */ static final class TreeBin extends AbstractQueuedSynchronizer { private static final long serialVersionUID = 2249069246763182397L; transient TreeNode root; // root of tree transient TreeNode first; // head of next-pointer list /* AQS overrides */ public final boolean isHeldExclusively() { return getState() > 0; } public final boolean tryAcquire(int ignore) { if (compareAndSetState(0, 1)) { setExclusiveOwnerThread(Thread.currentThread()); return true; } return false; } public final boolean tryRelease(int ignore) { setExclusiveOwnerThread(null); setState(0); return true; } public final int tryAcquireShared(int ignore) { for (int c;;) { if ((c = getState()) > 0) return -1; if (compareAndSetState(c, c -1)) return 1; } } public final boolean tryReleaseShared(int ignore) { int c; do {} while (!compareAndSetState(c = getState(), c + 1)); return c == -1; } /** From CLR */ private void rotateLeft(TreeNode p) { if (p != null) { TreeNode r = p.right, pp, rl; if ((rl = p.right = r.left) != null) rl.parent = p; if ((pp = r.parent = p.parent) == null) root = r; else if (pp.left == p) pp.left = r; else pp.right = r; r.left = p; p.parent = r; } } /** From CLR */ private void rotateRight(TreeNode p) { if (p != null) { TreeNode l = p.left, pp, lr; if ((lr = p.left = l.right) != null) lr.parent = p; if ((pp = l.parent = p.parent) == null) root = l; else if (pp.right == p) pp.right = l; else pp.left = l; l.right = p; p.parent = l; } } @SuppressWarnings("unchecked") final TreeNode getTreeNode (int h, Object k, TreeNode p) { return getTreeNode(h, (RubyObject)k, p); } /** * Returns the TreeNode (or null if not found) for the given key * starting at given root. */ @SuppressWarnings("unchecked") final TreeNode getTreeNode (int h, RubyObject k, TreeNode p) { RubyClass c = k.getMetaClass(); boolean kNotComparable = !k.respondsTo("<=>"); while (p != null) { int dir, ph; RubyObject pk; RubyClass pc; if ((ph = p.hash) == h) { if ((pk = (RubyObject)p.key) == k || k.equals(pk)) return p; if (c != (pc = (RubyClass)pk.getMetaClass()) || kNotComparable || (dir = rubyCompare(k, pk)) == 0) { dir = (c == pc) ? 0 : c.getName().compareTo(pc.getName()); if (dir == 0) { // if still stuck, need to check both sides TreeNode r = null, pl, pr; // try to recurse on the right if ((pr = p.right) != null && h >= pr.hash && (r = getTreeNode(h, k, pr)) != null) return r; // try to continue iterating on the left side else if ((pl = p.left) != null && h <= pl.hash) dir = -1; else // no matching node found return null; } } } else dir = (h < ph) ? -1 : 1; p = (dir > 0) ? p.right : p.left; } return null; } int rubyCompare(RubyObject l, RubyObject r) { ThreadContext context = l.getMetaClass().getRuntime().getCurrentContext(); IRubyObject result; try { result = l.callMethod(context, "<=>", r); } catch (RaiseException e) { // handle objects "lying" about responding to <=>, ie: an Array containing non-comparable keys if (context.runtime.getNoMethodError().isInstance(e.getException())) { return 0; } throw e; } return result.isNil() ? 0 : RubyNumeric.num2int(result.convertToInteger()); } /** * Wrapper for getTreeNode used by CHM.get. Tries to obtain * read-lock to call getTreeNode, but during failure to get * lock, searches along next links. */ final Object getValue(int h, Object k) { Node r = null; int c = getState(); // Must read lock state first for (Node e = first; e != null; e = e.next) { if (c <= 0 && compareAndSetState(c, c - 1)) { try { r = getTreeNode(h, k, root); } finally { releaseShared(0); } break; } else if ((e.hash & HASH_BITS) == h && k.equals(e.key)) { r = e; break; } else c = getState(); } return r == null ? null : r.val; } @SuppressWarnings("unchecked") final TreeNode putTreeNode (int h, Object k, Object v) { return putTreeNode(h, (RubyObject)k, v); } /** * Finds or adds a node. * @return null if added */ @SuppressWarnings("unchecked") final TreeNode putTreeNode (int h, RubyObject k, Object v) { RubyClass c = k.getMetaClass(); boolean kNotComparable = !k.respondsTo("<=>"); TreeNode pp = root, p = null; int dir = 0; while (pp != null) { // find existing node or leaf to insert at int ph; RubyObject pk; RubyClass pc; p = pp; if ((ph = p.hash) == h) { if ((pk = (RubyObject)p.key) == k || k.equals(pk)) return p; if (c != (pc = pk.getMetaClass()) || kNotComparable || (dir = rubyCompare(k, pk)) == 0) { dir = (c == pc) ? 0 : c.getName().compareTo(pc.getName()); if (dir == 0) { // if still stuck, need to check both sides TreeNode r = null, pr; // try to recurse on the right if ((pr = p.right) != null && h >= pr.hash && (r = getTreeNode(h, k, pr)) != null) return r; else // continue descending down the left subtree dir = -1; } } } else dir = (h < ph) ? -1 : 1; pp = (dir > 0) ? p.right : p.left; } TreeNode f = first; TreeNode x = first = new TreeNode(h, (Object)k, v, f, p); if (p == null) root = x; else { // attach and rebalance; adapted from CLR TreeNode xp, xpp; if (f != null) f.prev = x; if (dir <= 0) p.left = x; else p.right = x; x.red = true; while (x != null && (xp = x.parent) != null && xp.red && (xpp = xp.parent) != null) { TreeNode xppl = xpp.left; if (xp == xppl) { TreeNode y = xpp.right; if (y != null && y.red) { y.red = false; xp.red = false; xpp.red = true; x = xpp; } else { if (x == xp.right) { rotateLeft(x = xp); xpp = (xp = x.parent) == null ? null : xp.parent; } if (xp != null) { xp.red = false; if (xpp != null) { xpp.red = true; rotateRight(xpp); } } } } else { TreeNode y = xppl; if (y != null && y.red) { y.red = false; xp.red = false; xpp.red = true; x = xpp; } else { if (x == xp.left) { rotateRight(x = xp); xpp = (xp = x.parent) == null ? null : xp.parent; } if (xp != null) { xp.red = false; if (xpp != null) { xpp.red = true; rotateLeft(xpp); } } } } } TreeNode r = root; if (r != null && r.red) r.red = false; } return null; } /** * Removes the given node, that must be present before this * call. This is messier than typical red-black deletion code * because we cannot swap the contents of an interior node * with a leaf successor that is pinned by "next" pointers * that are accessible independently of lock. So instead we * swap the tree linkages. */ final void deleteTreeNode(TreeNode p) { TreeNode next = (TreeNode)p.next; // unlink traversal pointers TreeNode pred = p.prev; if (pred == null) first = next; else pred.next = next; if (next != null) next.prev = pred; TreeNode replacement; TreeNode pl = p.left; TreeNode pr = p.right; if (pl != null && pr != null) { TreeNode s = pr, sl; while ((sl = s.left) != null) // find successor s = sl; boolean c = s.red; s.red = p.red; p.red = c; // swap colors TreeNode sr = s.right; TreeNode pp = p.parent; if (s == pr) { // p was s's direct parent p.parent = s; s.right = p; } else { TreeNode sp = s.parent; if ((p.parent = sp) != null) { if (s == sp.left) sp.left = p; else sp.right = p; } if ((s.right = pr) != null) pr.parent = s; } p.left = null; if ((p.right = sr) != null) sr.parent = p; if ((s.left = pl) != null) pl.parent = s; if ((s.parent = pp) == null) root = s; else if (p == pp.left) pp.left = s; else pp.right = s; replacement = sr; } else replacement = (pl != null) ? pl : pr; TreeNode pp = p.parent; if (replacement == null) { if (pp == null) { root = null; return; } replacement = p; } else { replacement.parent = pp; if (pp == null) root = replacement; else if (p == pp.left) pp.left = replacement; else pp.right = replacement; p.left = p.right = p.parent = null; } if (!p.red) { // rebalance, from CLR TreeNode x = replacement; while (x != null) { TreeNode xp, xpl; if (x.red || (xp = x.parent) == null) { x.red = false; break; } if (x == (xpl = xp.left)) { TreeNode sib = xp.right; if (sib != null && sib.red) { sib.red = false; xp.red = true; rotateLeft(xp); sib = (xp = x.parent) == null ? null : xp.right; } if (sib == null) x = xp; else { TreeNode sl = sib.left, sr = sib.right; if ((sr == null || !sr.red) && (sl == null || !sl.red)) { sib.red = true; x = xp; } else { if (sr == null || !sr.red) { if (sl != null) sl.red = false; sib.red = true; rotateRight(sib); sib = (xp = x.parent) == null ? null : xp.right; } if (sib != null) { sib.red = (xp == null) ? false : xp.red; if ((sr = sib.right) != null) sr.red = false; } if (xp != null) { xp.red = false; rotateLeft(xp); } x = root; } } } else { // symmetric TreeNode sib = xpl; if (sib != null && sib.red) { sib.red = false; xp.red = true; rotateRight(xp); sib = (xp = x.parent) == null ? null : xp.left; } if (sib == null) x = xp; else { TreeNode sl = sib.left, sr = sib.right; if ((sl == null || !sl.red) && (sr == null || !sr.red)) { sib.red = true; x = xp; } else { if (sl == null || !sl.red) { if (sr != null) sr.red = false; sib.red = true; rotateLeft(sib); sib = (xp = x.parent) == null ? null : xp.left; } if (sib != null) { sib.red = (xp == null) ? false : xp.red; if ((sl = sib.left) != null) sl.red = false; } if (xp != null) { xp.red = false; rotateRight(xp); } x = root; } } } } } if (p == replacement && (pp = p.parent) != null) { if (p == pp.left) // detach pointers pp.left = null; else if (p == pp.right) pp.right = null; p.parent = null; } } } /* ---------------- Collision reduction methods -------------- */ /** * Spreads higher bits to lower, and also forces top 2 bits to 0. * Because the table uses power-of-two masking, sets of hashes * that vary only in bits above the current mask will always * collide. (Among known examples are sets of Float keys holding * consecutive whole numbers in small tables.) To counter this, * we apply a transform that spreads the impact of higher bits * downward. There is a tradeoff between speed, utility, and * quality of bit-spreading. Because many common sets of hashes * are already reasonably distributed across bits (so don't benefit * from spreading), and because we use trees to handle large sets * of collisions in bins, we don't need excessively high quality. */ private static final int spread(int h) { h ^= (h >>> 18) ^ (h >>> 12); return (h ^ (h >>> 10)) & HASH_BITS; } /** * Replaces a list bin with a tree bin. Call only when locked. * Fails to replace if the given key is non-comparable or table * is, or needs, resizing. */ private final void replaceWithTreeBin(Node[] tab, int index, Object key) { if ((key instanceof Comparable) && (tab.length >= MAXIMUM_CAPACITY || counter.sum() < (long)sizeCtl)) { TreeBin t = new TreeBin(); for (Node e = tabAt(tab, index); e != null; e = e.next) t.putTreeNode(e.hash & HASH_BITS, e.key, e.val); setTabAt(tab, index, new Node(MOVED, t, null, null)); } } /* ---------------- Internal access and update methods -------------- */ /** Implementation for get and containsKey */ private final Object internalGet(Object k) { int h = spread(k.hashCode()); retry: for (Node[] tab = table; tab != null;) { Node e, p; Object ek, ev; int eh; // locals to read fields once for (e = tabAt(tab, (tab.length - 1) & h); e != null; e = e.next) { if ((eh = e.hash) == MOVED) { if ((ek = e.key) instanceof TreeBin) // search TreeBin return ((TreeBin)ek).getValue(h, k); else { // restart with new table tab = (Node[])ek; continue retry; } } else if ((eh & HASH_BITS) == h && (ev = e.val) != null && ((ek = e.key) == k || k.equals(ek))) return ev; } break; } return null; } /** * Implementation for the four public remove/replace methods: * Replaces node value with v, conditional upon match of cv if * non-null. If resulting value is null, delete. */ private final Object internalReplace(Object k, Object v, Object cv) { int h = spread(k.hashCode()); Object oldVal = null; for (Node[] tab = table;;) { Node f; int i, fh; Object fk; if (tab == null || (f = tabAt(tab, i = (tab.length - 1) & h)) == null) break; else if ((fh = f.hash) == MOVED) { if ((fk = f.key) instanceof TreeBin) { TreeBin t = (TreeBin)fk; boolean validated = false; boolean deleted = false; t.acquire(0); try { if (tabAt(tab, i) == f) { validated = true; TreeNode p = t.getTreeNode(h, k, t.root); if (p != null) { Object pv = p.val; if (cv == null || cv == pv || cv.equals(pv)) { oldVal = pv; if ((p.val = v) == null) { deleted = true; t.deleteTreeNode(p); } } } } } finally { t.release(0); } if (validated) { if (deleted) counter.add(-1L); break; } } else tab = (Node[])fk; } else if ((fh & HASH_BITS) != h && f.next == null) // precheck break; // rules out possible existence else if ((fh & LOCKED) != 0) { checkForResize(); // try resizing if can't get lock f.tryAwaitLock(tab, i); } else if (f.casHash(fh, fh | LOCKED)) { boolean validated = false; boolean deleted = false; try { if (tabAt(tab, i) == f) { validated = true; for (Node e = f, pred = null;;) { Object ek, ev; if ((e.hash & HASH_BITS) == h && ((ev = e.val) != null) && ((ek = e.key) == k || k.equals(ek))) { if (cv == null || cv == ev || cv.equals(ev)) { oldVal = ev; if ((e.val = v) == null) { deleted = true; Node en = e.next; if (pred != null) pred.next = en; else setTabAt(tab, i, en); } } break; } pred = e; if ((e = e.next) == null) break; } } } finally { if (!f.casHash(fh | LOCKED, fh)) { f.hash = fh; synchronized (f) { f.notifyAll(); }; } } if (validated) { if (deleted) counter.add(-1L); break; } } } return oldVal; } /* * Internal versions of the six insertion methods, each a * little more complicated than the last. All have * the same basic structure as the first (internalPut): * 1. If table uninitialized, create * 2. If bin empty, try to CAS new node * 3. If bin stale, use new table * 4. if bin converted to TreeBin, validate and relay to TreeBin methods * 5. Lock and validate; if valid, scan and add or update * * The others interweave other checks and/or alternative actions: * * Plain put checks for and performs resize after insertion. * * putIfAbsent prescans for mapping without lock (and fails to add * if present), which also makes pre-emptive resize checks worthwhile. * * computeIfAbsent extends form used in putIfAbsent with additional * mechanics to deal with, calls, potential exceptions and null * returns from function call. * * compute uses the same function-call mechanics, but without * the prescans * * merge acts as putIfAbsent in the absent case, but invokes the * update function if present * * putAll attempts to pre-allocate enough table space * and more lazily performs count updates and checks. * * Someday when details settle down a bit more, it might be worth * some factoring to reduce sprawl. */ /** Implementation for put */ private final Object internalPut(Object k, Object v) { int h = spread(k.hashCode()); int count = 0; for (Node[] tab = table;;) { int i; Node f; int fh; Object fk; if (tab == null) tab = initTable(); else if ((f = tabAt(tab, i = (tab.length - 1) & h)) == null) { if (casTabAt(tab, i, null, new Node(h, k, v, null))) break; // no lock when adding to empty bin } else if ((fh = f.hash) == MOVED) { if ((fk = f.key) instanceof TreeBin) { TreeBin t = (TreeBin)fk; Object oldVal = null; t.acquire(0); try { if (tabAt(tab, i) == f) { count = 2; TreeNode p = t.putTreeNode(h, k, v); if (p != null) { oldVal = p.val; p.val = v; } } } finally { t.release(0); } if (count != 0) { if (oldVal != null) return oldVal; break; } } else tab = (Node[])fk; } else if ((fh & LOCKED) != 0) { checkForResize(); f.tryAwaitLock(tab, i); } else if (f.casHash(fh, fh | LOCKED)) { Object oldVal = null; try { // needed in case equals() throws if (tabAt(tab, i) == f) { count = 1; for (Node e = f;; ++count) { Object ek, ev; if ((e.hash & HASH_BITS) == h && (ev = e.val) != null && ((ek = e.key) == k || k.equals(ek))) { oldVal = ev; e.val = v; break; } Node last = e; if ((e = e.next) == null) { last.next = new Node(h, k, v, null); if (count >= TREE_THRESHOLD) replaceWithTreeBin(tab, i, k); break; } } } } finally { // unlock and signal if needed if (!f.casHash(fh | LOCKED, fh)) { f.hash = fh; synchronized (f) { f.notifyAll(); }; } } if (count != 0) { if (oldVal != null) return oldVal; if (tab.length <= 64) count = 2; break; } } } counter.add(1L); if (count > 1) checkForResize(); return null; } /** Implementation for putIfAbsent */ private final Object internalPutIfAbsent(Object k, Object v) { int h = spread(k.hashCode()); int count = 0; for (Node[] tab = table;;) { int i; Node f; int fh; Object fk, fv; if (tab == null) tab = initTable(); else if ((f = tabAt(tab, i = (tab.length - 1) & h)) == null) { if (casTabAt(tab, i, null, new Node(h, k, v, null))) break; } else if ((fh = f.hash) == MOVED) { if ((fk = f.key) instanceof TreeBin) { TreeBin t = (TreeBin)fk; Object oldVal = null; t.acquire(0); try { if (tabAt(tab, i) == f) { count = 2; TreeNode p = t.putTreeNode(h, k, v); if (p != null) oldVal = p.val; } } finally { t.release(0); } if (count != 0) { if (oldVal != null) return oldVal; break; } } else tab = (Node[])fk; } else if ((fh & HASH_BITS) == h && (fv = f.val) != null && ((fk = f.key) == k || k.equals(fk))) return fv; else { Node g = f.next; if (g != null) { // at least 2 nodes -- search and maybe resize for (Node e = g;;) { Object ek, ev; if ((e.hash & HASH_BITS) == h && (ev = e.val) != null && ((ek = e.key) == k || k.equals(ek))) return ev; if ((e = e.next) == null) { checkForResize(); break; } } } if (((fh = f.hash) & LOCKED) != 0) { checkForResize(); f.tryAwaitLock(tab, i); } else if (tabAt(tab, i) == f && f.casHash(fh, fh | LOCKED)) { Object oldVal = null; try { if (tabAt(tab, i) == f) { count = 1; for (Node e = f;; ++count) { Object ek, ev; if ((e.hash & HASH_BITS) == h && (ev = e.val) != null && ((ek = e.key) == k || k.equals(ek))) { oldVal = ev; break; } Node last = e; if ((e = e.next) == null) { last.next = new Node(h, k, v, null); if (count >= TREE_THRESHOLD) replaceWithTreeBin(tab, i, k); break; } } } } finally { if (!f.casHash(fh | LOCKED, fh)) { f.hash = fh; synchronized (f) { f.notifyAll(); }; } } if (count != 0) { if (oldVal != null) return oldVal; if (tab.length <= 64) count = 2; break; } } } } counter.add(1L); if (count > 1) checkForResize(); return null; } /** Implementation for computeIfAbsent */ private final Object internalComputeIfAbsent(K k, Fun<? super K, ?> mf) { int h = spread(k.hashCode()); Object val = null; int count = 0; for (Node[] tab = table;;) { Node f; int i, fh; Object fk, fv; if (tab == null) tab = initTable(); else if ((f = tabAt(tab, i = (tab.length - 1) & h)) == null) { Node node = new Node(fh = h | LOCKED, k, null, null); if (casTabAt(tab, i, null, node)) { count = 1; try { if ((val = mf.apply(k)) != null) node.val = val; } finally { if (val == null) setTabAt(tab, i, null); if (!node.casHash(fh, h)) { node.hash = h; synchronized (node) { node.notifyAll(); }; } } } if (count != 0) break; } else if ((fh = f.hash) == MOVED) { if ((fk = f.key) instanceof TreeBin) { TreeBin t = (TreeBin)fk; boolean added = false; t.acquire(0); try { if (tabAt(tab, i) == f) { count = 1; TreeNode p = t.getTreeNode(h, k, t.root); if (p != null) val = p.val; else if ((val = mf.apply(k)) != null) { added = true; count = 2; t.putTreeNode(h, k, val); } } } finally { t.release(0); } if (count != 0) { if (!added) return val; break; } } else tab = (Node[])fk; } else if ((fh & HASH_BITS) == h && (fv = f.val) != null && ((fk = f.key) == k || k.equals(fk))) return fv; else { Node g = f.next; if (g != null) { for (Node e = g;;) { Object ek, ev; if ((e.hash & HASH_BITS) == h && (ev = e.val) != null && ((ek = e.key) == k || k.equals(ek))) return ev; if ((e = e.next) == null) { checkForResize(); break; } } } if (((fh = f.hash) & LOCKED) != 0) { checkForResize(); f.tryAwaitLock(tab, i); } else if (tabAt(tab, i) == f && f.casHash(fh, fh | LOCKED)) { boolean added = false; try { if (tabAt(tab, i) == f) { count = 1; for (Node e = f;; ++count) { Object ek, ev; if ((e.hash & HASH_BITS) == h && (ev = e.val) != null && ((ek = e.key) == k || k.equals(ek))) { val = ev; break; } Node last = e; if ((e = e.next) == null) { if ((val = mf.apply(k)) != null) { added = true; last.next = new Node(h, k, val, null); if (count >= TREE_THRESHOLD) replaceWithTreeBin(tab, i, k); } break; } } } } finally { if (!f.casHash(fh | LOCKED, fh)) { f.hash = fh; synchronized (f) { f.notifyAll(); }; } } if (count != 0) { if (!added) return val; if (tab.length <= 64) count = 2; break; } } } } if (val != null) { counter.add(1L); if (count > 1) checkForResize(); } return val; } /** Implementation for compute */ @SuppressWarnings("unchecked") private final Object internalCompute (K k, boolean onlyIfPresent, BiFun<? super K, ? super V, ? extends V> mf) { int h = spread(k.hashCode()); Object val = null; int delta = 0; int count = 0; for (Node[] tab = table;;) { Node f; int i, fh; Object fk; if (tab == null) tab = initTable(); else if ((f = tabAt(tab, i = (tab.length - 1) & h)) == null) { if (onlyIfPresent) break; Node node = new Node(fh = h | LOCKED, k, null, null); if (casTabAt(tab, i, null, node)) { try { count = 1; if ((val = mf.apply(k, null)) != null) { node.val = val; delta = 1; } } finally { if (delta == 0) setTabAt(tab, i, null); if (!node.casHash(fh, h)) { node.hash = h; synchronized (node) { node.notifyAll(); }; } } } if (count != 0) break; } else if ((fh = f.hash) == MOVED) { if ((fk = f.key) instanceof TreeBin) { TreeBin t = (TreeBin)fk; t.acquire(0); try { if (tabAt(tab, i) == f) { count = 1; TreeNode p = t.getTreeNode(h, k, t.root); Object pv; if (p == null) { if (onlyIfPresent) break; pv = null; } else pv = p.val; if ((val = mf.apply(k, (V)pv)) != null) { if (p != null) p.val = val; else { count = 2; delta = 1; t.putTreeNode(h, k, val); } } else if (p != null) { delta = -1; t.deleteTreeNode(p); } } } finally { t.release(0); } if (count != 0) break; } else tab = (Node[])fk; } else if ((fh & LOCKED) != 0) { checkForResize(); f.tryAwaitLock(tab, i); } else if (f.casHash(fh, fh | LOCKED)) { try { if (tabAt(tab, i) == f) { count = 1; for (Node e = f, pred = null;; ++count) { Object ek, ev; if ((e.hash & HASH_BITS) == h && (ev = e.val) != null && ((ek = e.key) == k || k.equals(ek))) { val = mf.apply(k, (V)ev); if (val != null) e.val = val; else { delta = -1; Node en = e.next; if (pred != null) pred.next = en; else setTabAt(tab, i, en); } break; } pred = e; if ((e = e.next) == null) { if (!onlyIfPresent && (val = mf.apply(k, null)) != null) { pred.next = new Node(h, k, val, null); delta = 1; if (count >= TREE_THRESHOLD) replaceWithTreeBin(tab, i, k); } break; } } } } finally { if (!f.casHash(fh | LOCKED, fh)) { f.hash = fh; synchronized (f) { f.notifyAll(); }; } } if (count != 0) { if (tab.length <= 64) count = 2; break; } } } if (delta != 0) { counter.add((long)delta); if (count > 1) checkForResize(); } return val; } /** Implementation for merge */ @SuppressWarnings("unchecked") private final Object internalMerge (K k, V v, BiFun<? super V, ? super V, ? extends V> mf) { int h = spread(k.hashCode()); Object val = null; int delta = 0; int count = 0; for (Node[] tab = table;;) { int i; Node f; int fh; Object fk, fv; if (tab == null) tab = initTable(); else if ((f = tabAt(tab, i = (tab.length - 1) & h)) == null) { if (casTabAt(tab, i, null, new Node(h, k, v, null))) { delta = 1; val = v; break; } } else if ((fh = f.hash) == MOVED) { if ((fk = f.key) instanceof TreeBin) { TreeBin t = (TreeBin)fk; t.acquire(0); try { if (tabAt(tab, i) == f) { count = 1; TreeNode p = t.getTreeNode(h, k, t.root); val = (p == null) ? v : mf.apply((V)p.val, v); if (val != null) { if (p != null) p.val = val; else { count = 2; delta = 1; t.putTreeNode(h, k, val); } } else if (p != null) { delta = -1; t.deleteTreeNode(p); } } } finally { t.release(0); } if (count != 0) break; } else tab = (Node[])fk; } else if ((fh & LOCKED) != 0) { checkForResize(); f.tryAwaitLock(tab, i); } else if (f.casHash(fh, fh | LOCKED)) { try { if (tabAt(tab, i) == f) { count = 1; for (Node e = f, pred = null;; ++count) { Object ek, ev; if ((e.hash & HASH_BITS) == h && (ev = e.val) != null && ((ek = e.key) == k || k.equals(ek))) { val = mf.apply((V)ev, v); if (val != null) e.val = val; else { delta = -1; Node en = e.next; if (pred != null) pred.next = en; else setTabAt(tab, i, en); } break; } pred = e; if ((e = e.next) == null) { val = v; pred.next = new Node(h, k, val, null); delta = 1; if (count >= TREE_THRESHOLD) replaceWithTreeBin(tab, i, k); break; } } } } finally { if (!f.casHash(fh | LOCKED, fh)) { f.hash = fh; synchronized (f) { f.notifyAll(); }; } } if (count != 0) { if (tab.length <= 64) count = 2; break; } } } if (delta != 0) { counter.add((long)delta); if (count > 1) checkForResize(); } return val; } /** Implementation for putAll */ private final void internalPutAll(Map<?, ?> m) { tryPresize(m.size()); long delta = 0L; // number of uncommitted additions boolean npe = false; // to throw exception on exit for nulls try { // to clean up counts on other exceptions for (Map.Entry<?, ?> entry : m.entrySet()) { Object k, v; if (entry == null || (k = entry.getKey()) == null || (v = entry.getValue()) == null) { npe = true; break; } int h = spread(k.hashCode()); for (Node[] tab = table;;) { int i; Node f; int fh; Object fk; if (tab == null) tab = initTable(); else if ((f = tabAt(tab, i = (tab.length - 1) & h)) == null){ if (casTabAt(tab, i, null, new Node(h, k, v, null))) { ++delta; break; } } else if ((fh = f.hash) == MOVED) { if ((fk = f.key) instanceof TreeBin) { TreeBin t = (TreeBin)fk; boolean validated = false; t.acquire(0); try { if (tabAt(tab, i) == f) { validated = true; TreeNode p = t.getTreeNode(h, k, t.root); if (p != null) p.val = v; else { t.putTreeNode(h, k, v); ++delta; } } } finally { t.release(0); } if (validated) break; } else tab = (Node[])fk; } else if ((fh & LOCKED) != 0) { counter.add(delta); delta = 0L; checkForResize(); f.tryAwaitLock(tab, i); } else if (f.casHash(fh, fh | LOCKED)) { int count = 0; try { if (tabAt(tab, i) == f) { count = 1; for (Node e = f;; ++count) { Object ek, ev; if ((e.hash & HASH_BITS) == h && (ev = e.val) != null && ((ek = e.key) == k || k.equals(ek))) { e.val = v; break; } Node last = e; if ((e = e.next) == null) { ++delta; last.next = new Node(h, k, v, null); if (count >= TREE_THRESHOLD) replaceWithTreeBin(tab, i, k); break; } } } } finally { if (!f.casHash(fh | LOCKED, fh)) { f.hash = fh; synchronized (f) { f.notifyAll(); }; } } if (count != 0) { if (count > 1) { counter.add(delta); delta = 0L; checkForResize(); } break; } } } } } finally { if (delta != 0) counter.add(delta); } if (npe) throw new NullPointerException(); } /* ---------------- Table Initialization and Resizing -------------- */ /** * Returns a power of two table size for the given desired capacity. * See Hackers Delight, sec 3.2 */ private static final int tableSizeFor(int c) { int n = c - 1; n |= n >>> 1; n |= n >>> 2; n |= n >>> 4; n |= n >>> 8; n |= n >>> 16; return (n < 0) ? 1 : (n >= MAXIMUM_CAPACITY) ? MAXIMUM_CAPACITY : n + 1; } /** * Initializes table, using the size recorded in sizeCtl. */ private final Node[] initTable() { Node[] tab; int sc; while ((tab = table) == null) { if ((sc = sizeCtl) < 0) Thread.yield(); // lost initialization race; just spin else if (UNSAFE.compareAndSwapInt(this, sizeCtlOffset, sc, -1)) { try { if ((tab = table) == null) { int n = (sc > 0) ? sc : DEFAULT_CAPACITY; tab = table = new Node[n]; sc = n - (n >>> 2); } } finally { sizeCtl = sc; } break; } } return tab; } /** * If table is too small and not already resizing, creates next * table and transfers bins. Rechecks occupancy after a transfer * to see if another resize is already needed because resizings * are lagging additions. */ private final void checkForResize() { Node[] tab; int n, sc; while ((tab = table) != null && (n = tab.length) < MAXIMUM_CAPACITY && (sc = sizeCtl) >= 0 && counter.sum() >= (long)sc && UNSAFE.compareAndSwapInt(this, sizeCtlOffset, sc, -1)) { try { if (tab == table) { table = rebuild(tab); sc = (n << 1) - (n >>> 1); } } finally { sizeCtl = sc; } } } /** * Tries to presize table to accommodate the given number of elements. * * @param size number of elements (doesn't need to be perfectly accurate) */ private final void tryPresize(int size) { int c = (size >= (MAXIMUM_CAPACITY >>> 1)) ? MAXIMUM_CAPACITY : tableSizeFor(size + (size >>> 1) + 1); int sc; while ((sc = sizeCtl) >= 0) { Node[] tab = table; int n; if (tab == null || (n = tab.length) == 0) { n = (sc > c) ? sc : c; if (UNSAFE.compareAndSwapInt(this, sizeCtlOffset, sc, -1)) { try { if (table == tab) { table = new Node[n]; sc = n - (n >>> 2); } } finally { sizeCtl = sc; } } } else if (c <= sc || n >= MAXIMUM_CAPACITY) break; else if (UNSAFE.compareAndSwapInt(this, sizeCtlOffset, sc, -1)) { try { if (table == tab) { table = rebuild(tab); sc = (n << 1) - (n >>> 1); } } finally { sizeCtl = sc; } } } } /* * Moves and/or copies the nodes in each bin to new table. See * above for explanation. * * @return the new table */ private static final Node[] rebuild(Node[] tab) { int n = tab.length; Node[] nextTab = new Node[n << 1]; Node fwd = new Node(MOVED, nextTab, null, null); int[] buffer = null; // holds bins to revisit; null until needed Node rev = null; // reverse forwarder; null until needed int nbuffered = 0; // the number of bins in buffer list int bufferIndex = 0; // buffer index of current buffered bin int bin = n - 1; // current non-buffered bin or -1 if none for (int i = bin;;) { // start upwards sweep int fh; Node f; if ((f = tabAt(tab, i)) == null) { if (bin >= 0) { // Unbuffered; no lock needed (or available) if (!casTabAt(tab, i, f, fwd)) continue; } else { // transiently use a locked forwarding node Node g = new Node(MOVED|LOCKED, nextTab, null, null); if (!casTabAt(tab, i, f, g)) continue; setTabAt(nextTab, i, null); setTabAt(nextTab, i + n, null); setTabAt(tab, i, fwd); if (!g.casHash(MOVED|LOCKED, MOVED)) { g.hash = MOVED; synchronized (g) { g.notifyAll(); } } } } else if ((fh = f.hash) == MOVED) { Object fk = f.key; if (fk instanceof TreeBin) { TreeBin t = (TreeBin)fk; boolean validated = false; t.acquire(0); try { if (tabAt(tab, i) == f) { validated = true; splitTreeBin(nextTab, i, t); setTabAt(tab, i, fwd); } } finally { t.release(0); } if (!validated) continue; } } else if ((fh & LOCKED) == 0 && f.casHash(fh, fh|LOCKED)) { boolean validated = false; try { // split to lo and hi lists; copying as needed if (tabAt(tab, i) == f) { validated = true; splitBin(nextTab, i, f); setTabAt(tab, i, fwd); } } finally { if (!f.casHash(fh | LOCKED, fh)) { f.hash = fh; synchronized (f) { f.notifyAll(); }; } } if (!validated) continue; } else { if (buffer == null) // initialize buffer for revisits buffer = new int[TRANSFER_BUFFER_SIZE]; if (bin < 0 && bufferIndex > 0) { int j = buffer[--bufferIndex]; buffer[bufferIndex] = i; i = j; // swap with another bin continue; } if (bin < 0 || nbuffered >= TRANSFER_BUFFER_SIZE) { f.tryAwaitLock(tab, i); continue; // no other options -- block } if (rev == null) // initialize reverse-forwarder rev = new Node(MOVED, tab, null, null); if (tabAt(tab, i) != f || (f.hash & LOCKED) == 0) continue; // recheck before adding to list buffer[nbuffered++] = i; setTabAt(nextTab, i, rev); // install place-holders setTabAt(nextTab, i + n, rev); } if (bin > 0) i = --bin; else if (buffer != null && nbuffered > 0) { bin = -1; i = buffer[bufferIndex = --nbuffered]; } else return nextTab; } } /** * Splits a normal bin with list headed by e into lo and hi parts; * installs in given table. */ private static void splitBin(Node[] nextTab, int i, Node e) { int bit = nextTab.length >>> 1; // bit to split on int runBit = e.hash & bit; Node lastRun = e, lo = null, hi = null; for (Node p = e.next; p != null; p = p.next) { int b = p.hash & bit; if (b != runBit) { runBit = b; lastRun = p; } } if (runBit == 0) lo = lastRun; else hi = lastRun; for (Node p = e; p != lastRun; p = p.next) { int ph = p.hash & HASH_BITS; Object pk = p.key, pv = p.val; if ((ph & bit) == 0) lo = new Node(ph, pk, pv, lo); else hi = new Node(ph, pk, pv, hi); } setTabAt(nextTab, i, lo); setTabAt(nextTab, i + bit, hi); } /** * Splits a tree bin into lo and hi parts; installs in given table. */ private static void splitTreeBin(Node[] nextTab, int i, TreeBin t) { int bit = nextTab.length >>> 1; TreeBin lt = new TreeBin(); TreeBin ht = new TreeBin(); int lc = 0, hc = 0; for (Node e = t.first; e != null; e = e.next) { int h = e.hash & HASH_BITS; Object k = e.key, v = e.val; if ((h & bit) == 0) { ++lc; lt.putTreeNode(h, k, v); } else { ++hc; ht.putTreeNode(h, k, v); } } Node ln, hn; // throw away trees if too small if (lc <= (TREE_THRESHOLD >>> 1)) { ln = null; for (Node p = lt.first; p != null; p = p.next) ln = new Node(p.hash, p.key, p.val, ln); } else ln = new Node(MOVED, lt, null, null); setTabAt(nextTab, i, ln); if (hc <= (TREE_THRESHOLD >>> 1)) { hn = null; for (Node p = ht.first; p != null; p = p.next) hn = new Node(p.hash, p.key, p.val, hn); } else hn = new Node(MOVED, ht, null, null); setTabAt(nextTab, i + bit, hn); } /** * Implementation for clear. Steps through each bin, removing all * nodes. */ private final void internalClear() { long delta = 0L; // negative number of deletions int i = 0; Node[] tab = table; while (tab != null && i < tab.length) { int fh; Object fk; Node f = tabAt(tab, i); if (f == null) ++i; else if ((fh = f.hash) == MOVED) { if ((fk = f.key) instanceof TreeBin) { TreeBin t = (TreeBin)fk; t.acquire(0); try { if (tabAt(tab, i) == f) { for (Node p = t.first; p != null; p = p.next) { if (p.val != null) { // (currently always true) p.val = null; --delta; } } t.first = null; t.root = null; ++i; } } finally { t.release(0); } } else tab = (Node[])fk; } else if ((fh & LOCKED) != 0) { counter.add(delta); // opportunistically update count delta = 0L; f.tryAwaitLock(tab, i); } else if (f.casHash(fh, fh | LOCKED)) { try { if (tabAt(tab, i) == f) { for (Node e = f; e != null; e = e.next) { if (e.val != null) { // (currently always true) e.val = null; --delta; } } setTabAt(tab, i, null); ++i; } } finally { if (!f.casHash(fh | LOCKED, fh)) { f.hash = fh; synchronized (f) { f.notifyAll(); }; } } } } if (delta != 0) counter.add(delta); } /* ----------------Table Traversal -------------- */ /** * Encapsulates traversal for methods such as containsValue; also * serves as a base class for other iterators and bulk tasks. * * At each step, the iterator snapshots the key ("nextKey") and * value ("nextVal") of a valid node (i.e., one that, at point of * snapshot, has a non-null user value). Because val fields can * change (including to null, indicating deletion), field nextVal * might not be accurate at point of use, but still maintains the * weak consistency property of holding a value that was once * valid. To support iterator.remove, the nextKey field is not * updated (nulled out) when the iterator cannot advance. * * Internal traversals directly access these fields, as in: * {@code while (it.advance() != null) { process(it.nextKey); }} * * Exported iterators must track whether the iterator has advanced * (in hasNext vs next) (by setting/checking/nulling field * nextVal), and then extract key, value, or key-value pairs as * return values of next(). * * The iterator visits once each still-valid node that was * reachable upon iterator construction. It might miss some that * were added to a bin after the bin was visited, which is OK wrt * consistency guarantees. Maintaining this property in the face * of possible ongoing resizes requires a fair amount of * bookkeeping state that is difficult to optimize away amidst * volatile accesses. Even so, traversal maintains reasonable * throughput. * * Normally, iteration proceeds bin-by-bin traversing lists. * However, if the table has been resized, then all future steps * must traverse both the bin at the current index as well as at * (index + baseSize); and so on for further resizings. To * paranoically cope with potential sharing by users of iterators * across threads, iteration terminates if a bounds checks fails * for a table read. * * This class extends ForkJoinTask to streamline parallel * iteration in bulk operations (see BulkTask). This adds only an * int of space overhead, which is close enough to negligible in * cases where it is not needed to not worry about it. Because * ForkJoinTask is Serializable, but iterators need not be, we * need to add warning suppressions. */ @SuppressWarnings("serial") static class Traverser<K,V,R> { final ConcurrentHashMapV8<K, V> map; Node next; // the next entry to use K nextKey; // cached key field of next V nextVal; // cached val field of next Node[] tab; // current table; updated if resized int index; // index of bin to use next int baseIndex; // current index of initial table int baseLimit; // index bound for initial table int baseSize; // initial table size /** Creates iterator for all entries in the table. */ Traverser(ConcurrentHashMapV8<K, V> map) { this.map = map; } /** Creates iterator for split() methods */ Traverser(Traverser<K,V,?> it) { ConcurrentHashMapV8<K, V> m; Node[] t; if ((m = this.map = it.map) == null) t = null; else if ((t = it.tab) == null && // force parent tab initialization (t = it.tab = m.table) != null) it.baseLimit = it.baseSize = t.length; this.tab = t; this.baseSize = it.baseSize; it.baseLimit = this.index = this.baseIndex = ((this.baseLimit = it.baseLimit) + it.baseIndex + 1) >>> 1; } /** * Advances next; returns nextVal or null if terminated. * See above for explanation. */ final V advance() { Node e = next; V ev = null; outer: do { if (e != null) // advance past used/skipped node e = e.next; while (e == null) { // get to next non-null bin ConcurrentHashMapV8<K, V> m; Node[] t; int b, i, n; Object ek; // checks must use locals if ((t = tab) != null) n = t.length; else if ((m = map) != null && (t = tab = m.table) != null) n = baseLimit = baseSize = t.length; else break outer; if ((b = baseIndex) >= baseLimit || (i = index) < 0 || i >= n) break outer; if ((e = tabAt(t, i)) != null && e.hash == MOVED) { if ((ek = e.key) instanceof TreeBin) e = ((TreeBin)ek).first; else { tab = (Node[])ek; continue; // restarts due to null val } } // visit upper slots if present index = (i += baseSize) < n ? i : (baseIndex = b + 1); } nextKey = (K) e.key; } while ((ev = (V) e.val) == null); // skip deleted or special nodes next = e; return nextVal = ev; } public final void remove() { Object k = nextKey; if (k == null && (advance() == null || (k = nextKey) == null)) throw new IllegalStateException(); map.internalReplace(k, null, null); } public final boolean hasNext() { return nextVal != null || advance() != null; } public final boolean hasMoreElements() { return hasNext(); } public final void setRawResult(Object x) { } public R getRawResult() { return null; } public boolean exec() { return true; } } /* ---------------- Public operations -------------- */ /** * Creates a new, empty map with the default initial table size (16). */ public ConcurrentHashMapV8() { this.counter = new LongAdder(); } /** * Creates a new, empty map with an initial table size * accommodating the specified number of elements without the need * to dynamically resize. * * @param initialCapacity The implementation performs internal * sizing to accommodate this many elements. * @throws IllegalArgumentException if the initial capacity of * elements is negative */ public ConcurrentHashMapV8(int initialCapacity) { if (initialCapacity < 0) throw new IllegalArgumentException(); int cap = ((initialCapacity >= (MAXIMUM_CAPACITY >>> 1)) ? MAXIMUM_CAPACITY : tableSizeFor(initialCapacity + (initialCapacity >>> 1) + 1)); this.counter = new LongAdder(); this.sizeCtl = cap; } /** * Creates a new map with the same mappings as the given map. * * @param m the map */ public ConcurrentHashMapV8(Map<? extends K, ? extends V> m) { this.counter = new LongAdder(); this.sizeCtl = DEFAULT_CAPACITY; internalPutAll(m); } /** * Creates a new, empty map with an initial table size based on * the given number of elements ({@code initialCapacity}) and * initial table density ({@code loadFactor}). * * @param initialCapacity the initial capacity. The implementation * performs internal sizing to accommodate this many elements, * given the specified load factor. * @param loadFactor the load factor (table density) for * establishing the initial table size * @throws IllegalArgumentException if the initial capacity of * elements is negative or the load factor is nonpositive * * @since 1.6 */ public ConcurrentHashMapV8(int initialCapacity, float loadFactor) { this(initialCapacity, loadFactor, 1); } /** * Creates a new, empty map with an initial table size based on * the given number of elements ({@code initialCapacity}), table * density ({@code loadFactor}), and number of concurrently * updating threads ({@code concurrencyLevel}). * * @param initialCapacity the initial capacity. The implementation * performs internal sizing to accommodate this many elements, * given the specified load factor. * @param loadFactor the load factor (table density) for * establishing the initial table size * @param concurrencyLevel the estimated number of concurrently * updating threads. The implementation may use this value as * a sizing hint. * @throws IllegalArgumentException if the initial capacity is * negative or the load factor or concurrencyLevel are * nonpositive */ public ConcurrentHashMapV8(int initialCapacity, float loadFactor, int concurrencyLevel) { if (!(loadFactor > 0.0f) || initialCapacity < 0 || concurrencyLevel <= 0) throw new IllegalArgumentException(); if (initialCapacity < concurrencyLevel) // Use at least as many bins initialCapacity = concurrencyLevel; // as estimated threads long size = (long)(1.0 + (long)initialCapacity / loadFactor); int cap = (size >= (long)MAXIMUM_CAPACITY) ? MAXIMUM_CAPACITY : tableSizeFor((int)size); this.counter = new LongAdder(); this.sizeCtl = cap; } /** * Creates a new {@link Set} backed by a ConcurrentHashMapV8 * from the given type to {@code Boolean.TRUE}. * * @return the new set */ public static <K> KeySetView<K,Boolean> newKeySet() { return new KeySetView<K,Boolean>(new ConcurrentHashMapV8<K,Boolean>(), Boolean.TRUE); } /** * Creates a new {@link Set} backed by a ConcurrentHashMapV8 * from the given type to {@code Boolean.TRUE}. * * @param initialCapacity The implementation performs internal * sizing to accommodate this many elements. * @throws IllegalArgumentException if the initial capacity of * elements is negative * @return the new set */ public static <K> KeySetView<K,Boolean> newKeySet(int initialCapacity) { return new KeySetView<K,Boolean>(new ConcurrentHashMapV8<K,Boolean>(initialCapacity), Boolean.TRUE); } /** * {@inheritDoc} */ public boolean isEmpty() { return counter.sum() <= 0L; // ignore transient negative values } /** * {@inheritDoc} */ public int size() { long n = counter.sum(); return ((n < 0L) ? 0 : (n > (long)Integer.MAX_VALUE) ? Integer.MAX_VALUE : (int)n); } /** * Returns the number of mappings. This method should be used * instead of {@link #size} because a ConcurrentHashMapV8 may * contain more mappings than can be represented as an int. The * value returned is a snapshot; the actual count may differ if * there are ongoing concurrent insertions or removals. * * @return the number of mappings */ public long mappingCount() { long n = counter.sum(); return (n < 0L) ? 0L : n; // ignore transient negative values } /** * Returns the value to which the specified key is mapped, * or {@code null} if this map contains no mapping for the key. * * <p>More formally, if this map contains a mapping from a key * {@code k} to a value {@code v} such that {@code key.equals(k)}, * then this method returns {@code v}; otherwise it returns * {@code null}. (There can be at most one such mapping.) * * @throws NullPointerException if the specified key is null */ @SuppressWarnings("unchecked") public V get(Object key) { if (key == null) throw new NullPointerException(); return (V)internalGet(key); } /** * Returns the value to which the specified key is mapped, * or the given defaultValue if this map contains no mapping for the key. * * @param key the key * @param defaultValue the value to return if this map contains * no mapping for the given key * @return the mapping for the key, if present; else the defaultValue * @throws NullPointerException if the specified key is null */ @SuppressWarnings("unchecked") public V getValueOrDefault(Object key, V defaultValue) { if (key == null) throw new NullPointerException(); V v = (V) internalGet(key); return v == null ? defaultValue : v; } /** * Tests if the specified object is a key in this table. * * @param key possible key * @return {@code true} if and only if the specified object * is a key in this table, as determined by the * {@code equals} method; {@code false} otherwise * @throws NullPointerException if the specified key is null */ public boolean containsKey(Object key) { if (key == null) throw new NullPointerException(); return internalGet(key) != null; } /** * Returns {@code true} if this map maps one or more keys to the * specified value. Note: This method may require a full traversal * of the map, and is much slower than method {@code containsKey}. * * @param value value whose presence in this map is to be tested * @return {@code true} if this map maps one or more keys to the * specified value * @throws NullPointerException if the specified value is null */ public boolean containsValue(Object value) { if (value == null) throw new NullPointerException(); Object v; Traverser<K,V,Object> it = new Traverser<K,V,Object>(this); while ((v = it.advance()) != null) { if (v == value || value.equals(v)) return true; } return false; } public K findKey(Object value) { if (value == null) throw new NullPointerException(); Object v; Traverser<K,V,Object> it = new Traverser<K,V,Object>(this); while ((v = it.advance()) != null) { if (v == value || value.equals(v)) return it.nextKey; } return null; } /** * Legacy method testing if some key maps into the specified value * in this table. This method is identical in functionality to * {@link #containsValue}, and exists solely to ensure * full compatibility with class {@link java.util.Hashtable}, * which supported this method prior to introduction of the * Java Collections framework. * * @param value a value to search for * @return {@code true} if and only if some key maps to the * {@code value} argument in this table as * determined by the {@code equals} method; * {@code false} otherwise * @throws NullPointerException if the specified value is null */ public boolean contains(Object value) { return containsValue(value); } /** * Maps the specified key to the specified value in this table. * Neither the key nor the value can be null. * * <p>The value can be retrieved by calling the {@code get} method * with a key that is equal to the original key. * * @param key key with which the specified value is to be associated * @param value value to be associated with the specified key * @return the previous value associated with {@code key}, or * {@code null} if there was no mapping for {@code key} * @throws NullPointerException if the specified key or value is null */ @SuppressWarnings("unchecked") public V put(K key, V value) { if (key == null || value == null) throw new NullPointerException(); return (V)internalPut(key, value); } /** * {@inheritDoc} * * @return the previous value associated with the specified key, * or {@code null} if there was no mapping for the key * @throws NullPointerException if the specified key or value is null */ @SuppressWarnings("unchecked") public V putIfAbsent(K key, V value) { if (key == null || value == null) throw new NullPointerException(); return (V)internalPutIfAbsent(key, value); } /** * Copies all of the mappings from the specified map to this one. * These mappings replace any mappings that this map had for any of the * keys currently in the specified map. * * @param m mappings to be stored in this map */ public void putAll(Map<? extends K, ? extends V> m) { internalPutAll(m); } /** * If the specified key is not already associated with a value, * computes its value using the given mappingFunction and enters * it into the map unless null. This is equivalent to * <pre> {@code * if (map.containsKey(key)) * return map.get(key); * value = mappingFunction.apply(key); * if (value != null) * map.put(key, value); * return value;}</pre> * * except that the action is performed atomically. If the * function returns {@code null} no mapping is recorded. If the * function itself throws an (unchecked) exception, the exception * is rethrown to its caller, and no mapping is recorded. Some * attempted update operations on this map by other threads may be * blocked while computation is in progress, so the computation * should be short and simple, and must not attempt to update any * other mappings of this Map. The most appropriate usage is to * construct a new object serving as an initial mapped value, or * memoized result, as in: * * <pre> {@code * map.computeIfAbsent(key, new Fun<K, V>() { * public V map(K k) { return new Value(f(k)); }});}</pre> * * @param key key with which the specified value is to be associated * @param mappingFunction the function to compute a value * @return the current (existing or computed) value associated with * the specified key, or null if the computed value is null * @throws NullPointerException if the specified key or mappingFunction * is null * @throws IllegalStateException if the computation detectably * attempts a recursive update to this map that would * otherwise never complete * @throws RuntimeException or Error if the mappingFunction does so, * in which case the mapping is left unestablished */ @SuppressWarnings("unchecked") public V computeIfAbsent (K key, Fun<? super K, ? extends V> mappingFunction) { if (key == null || mappingFunction == null) throw new NullPointerException(); return (V)internalComputeIfAbsent(key, mappingFunction); } /** * If the given key is present, computes a new mapping value given a key and * its current mapped value. This is equivalent to * <pre> {@code * if (map.containsKey(key)) { * value = remappingFunction.apply(key, map.get(key)); * if (value != null) * map.put(key, value); * else * map.remove(key); * } * }</pre> * * except that the action is performed atomically. If the * function returns {@code null}, the mapping is removed. If the * function itself throws an (unchecked) exception, the exception * is rethrown to its caller, and the current mapping is left * unchanged. Some attempted update operations on this map by * other threads may be blocked while computation is in progress, * so the computation should be short and simple, and must not * attempt to update any other mappings of this Map. For example, * to either create or append new messages to a value mapping: * * @param key key with which the specified value is to be associated * @param remappingFunction the function to compute a value * @return the new value associated with the specified key, or null if none * @throws NullPointerException if the specified key or remappingFunction * is null * @throws IllegalStateException if the computation detectably * attempts a recursive update to this map that would * otherwise never complete * @throws RuntimeException or Error if the remappingFunction does so, * in which case the mapping is unchanged */ @SuppressWarnings("unchecked") public V computeIfPresent (K key, BiFun<? super K, ? super V, ? extends V> remappingFunction) { if (key == null || remappingFunction == null) throw new NullPointerException(); return (V)internalCompute(key, true, remappingFunction); } /** * Computes a new mapping value given a key and * its current mapped value (or {@code null} if there is no current * mapping). This is equivalent to * <pre> {@code * value = remappingFunction.apply(key, map.get(key)); * if (value != null) * map.put(key, value); * else * map.remove(key); * }</pre> * * except that the action is performed atomically. If the * function returns {@code null}, the mapping is removed. If the * function itself throws an (unchecked) exception, the exception * is rethrown to its caller, and the current mapping is left * unchanged. Some attempted update operations on this map by * other threads may be blocked while computation is in progress, * so the computation should be short and simple, and must not * attempt to update any other mappings of this Map. For example, * to either create or append new messages to a value mapping: * * <pre> {@code * Map<Key, String> map = ...; * final String msg = ...; * map.compute(key, new BiFun<Key, String, String>() { * public String apply(Key k, String v) { * return (v == null) ? msg : v + msg;});}}</pre> * * @param key key with which the specified value is to be associated * @param remappingFunction the function to compute a value * @return the new value associated with the specified key, or null if none * @throws NullPointerException if the specified key or remappingFunction * is null * @throws IllegalStateException if the computation detectably * attempts a recursive update to this map that would * otherwise never complete * @throws RuntimeException or Error if the remappingFunction does so, * in which case the mapping is unchanged */ @SuppressWarnings("unchecked") public V compute (K key, BiFun<? super K, ? super V, ? extends V> remappingFunction) { if (key == null || remappingFunction == null) throw new NullPointerException(); return (V)internalCompute(key, false, remappingFunction); } /** * If the specified key is not already associated * with a value, associate it with the given value. * Otherwise, replace the value with the results of * the given remapping function. This is equivalent to: * <pre> {@code * if (!map.containsKey(key)) * map.put(value); * else { * newValue = remappingFunction.apply(map.get(key), value); * if (value != null) * map.put(key, value); * else * map.remove(key); * } * }</pre> * except that the action is performed atomically. If the * function returns {@code null}, the mapping is removed. If the * function itself throws an (unchecked) exception, the exception * is rethrown to its caller, and the current mapping is left * unchanged. Some attempted update operations on this map by * other threads may be blocked while computation is in progress, * so the computation should be short and simple, and must not * attempt to update any other mappings of this Map. */ @SuppressWarnings("unchecked") public V merge (K key, V value, BiFun<? super V, ? super V, ? extends V> remappingFunction) { if (key == null || value == null || remappingFunction == null) throw new NullPointerException(); return (V)internalMerge(key, value, remappingFunction); } /** * Removes the key (and its corresponding value) from this map. * This method does nothing if the key is not in the map. * * @param key the key that needs to be removed * @return the previous value associated with {@code key}, or * {@code null} if there was no mapping for {@code key} * @throws NullPointerException if the specified key is null */ @SuppressWarnings("unchecked") public V remove(Object key) { if (key == null) throw new NullPointerException(); return (V)internalReplace(key, null, null); } /** * {@inheritDoc} * * @throws NullPointerException if the specified key is null */ public boolean remove(Object key, Object value) { if (key == null) throw new NullPointerException(); if (value == null) return false; return internalReplace(key, null, value) != null; } /** * {@inheritDoc} * * @throws NullPointerException if any of the arguments are null */ public boolean replace(K key, V oldValue, V newValue) { if (key == null || oldValue == null || newValue == null) throw new NullPointerException(); return internalReplace(key, newValue, oldValue) != null; } /** * {@inheritDoc} * * @return the previous value associated with the specified key, * or {@code null} if there was no mapping for the key * @throws NullPointerException if the specified key or value is null */ @SuppressWarnings("unchecked") public V replace(K key, V value) { if (key == null || value == null) throw new NullPointerException(); return (V)internalReplace(key, value, null); } /** * Removes all of the mappings from this map. */ public void clear() { internalClear(); } /** * Returns a {@link Set} view of the keys contained in this map. * The set is backed by the map, so changes to the map are * reflected in the set, and vice-versa. * * @return the set view */ public KeySetView<K,V> keySet() { KeySetView<K,V> ks = keySet; return (ks != null) ? ks : (keySet = new KeySetView<K,V>(this, null)); } /** * Returns a {@link Set} view of the keys in this map, using the * given common mapped value for any additions (i.e., {@link * Collection#add} and {@link Collection#addAll}). This is of * course only appropriate if it is acceptable to use the same * value for all additions from this view. * * @param mappedValue the mapped value to use for any * additions. * @return the set view * @throws NullPointerException if the mappedValue is null */ public KeySetView<K,V> keySet(V mappedValue) { if (mappedValue == null) throw new NullPointerException(); return new KeySetView<K,V>(this, mappedValue); } /** * Returns a {@link Collection} view of the values contained in this map. * The collection is backed by the map, so changes to the map are * reflected in the collection, and vice-versa. */ public ValuesView<K,V> values() { ValuesView<K,V> vs = values; return (vs != null) ? vs : (values = new ValuesView<K,V>(this)); } /** * Returns a {@link Set} view of the mappings contained in this map. * The set is backed by the map, so changes to the map are * reflected in the set, and vice-versa. The set supports element * removal, which removes the corresponding mapping from the map, * via the {@code Iterator.remove}, {@code Set.remove}, * {@code removeAll}, {@code retainAll}, and {@code clear} * operations. It does not support the {@code add} or * {@code addAll} operations. * * <p>The view's {@code iterator} is a "weakly consistent" iterator * that will never throw {@link ConcurrentModificationException}, * and guarantees to traverse elements as they existed upon * construction of the iterator, and may (but is not guaranteed to) * reflect any modifications subsequent to construction. */ public Set<Map.Entry<K,V>> entrySet() { EntrySetView<K,V> es = entrySet; return (es != null) ? es : (entrySet = new EntrySetView<K,V>(this)); } /** * Returns an enumeration of the keys in this table. * * @return an enumeration of the keys in this table * @see #keySet() */ public Enumeration<K> keys() { return new KeyIterator<K,V>(this); } /** * Returns an enumeration of the values in this table. * * @return an enumeration of the values in this table * @see #values() */ public Enumeration<V> elements() { return new ValueIterator<K,V>(this); } /** * Returns a partitionable iterator of the keys in this map. * * @return a partitionable iterator of the keys in this map */ public Spliterator<K> keySpliterator() { return new KeyIterator<K,V>(this); } /** * Returns a partitionable iterator of the values in this map. * * @return a partitionable iterator of the values in this map */ public Spliterator<V> valueSpliterator() { return new ValueIterator<K,V>(this); } /** * Returns a partitionable iterator of the entries in this map. * * @return a partitionable iterator of the entries in this map */ public Spliterator<Map.Entry<K,V>> entrySpliterator() { return new EntryIterator<K,V>(this); } /** * Returns the hash code value for this {@link Map}, i.e., * the sum of, for each key-value pair in the map, * {@code key.hashCode() ^ value.hashCode()}. * * @return the hash code value for this map */ public int hashCode() { int h = 0; Traverser<K,V,Object> it = new Traverser<K,V,Object>(this); Object v; while ((v = it.advance()) != null) { h += it.nextKey.hashCode() ^ v.hashCode(); } return h; } /** * Returns a string representation of this map. The string * representation consists of a list of key-value mappings (in no * particular order) enclosed in braces ("{@code {}}"). Adjacent * mappings are separated by the characters {@code ", "} (comma * and space). Each key-value mapping is rendered as the key * followed by an equals sign ("{@code =}") followed by the * associated value. * * @return a string representation of this map */ public String toString() { Traverser<K,V,Object> it = new Traverser<K,V,Object>(this); StringBuilder sb = new StringBuilder(); sb.append('{'); Object v; if ((v = it.advance()) != null) { for (;;) { Object k = it.nextKey; sb.append(k == this ? "(this Map)" : k); sb.append('='); sb.append(v == this ? "(this Map)" : v); if ((v = it.advance()) == null) break; sb.append(',').append(' '); } } return sb.append('}').toString(); } /** * Compares the specified object with this map for equality. * Returns {@code true} if the given object is a map with the same * mappings as this map. This operation may return misleading * results if either map is concurrently modified during execution * of this method. * * @param o object to be compared for equality with this map * @return {@code true} if the specified object is equal to this map */ public boolean equals(Object o) { if (o != this) { if (!(o instanceof Map)) return false; Map<?,?> m = (Map<?,?>) o; Traverser<K,V,Object> it = new Traverser<K,V,Object>(this); Object val; while ((val = it.advance()) != null) { Object v = m.get(it.nextKey); if (v == null || (v != val && !v.equals(val))) return false; } for (Map.Entry<?,?> e : m.entrySet()) { Object mk, mv, v; if ((mk = e.getKey()) == null || (mv = e.getValue()) == null || (v = internalGet(mk)) == null || (mv != v && !mv.equals(v))) return false; } } return true; } /* ----------------Iterators -------------- */ @SuppressWarnings("serial") static final class KeyIterator<K,V> extends Traverser<K,V,Object> implements Spliterator<K>, Enumeration<K> { KeyIterator(ConcurrentHashMapV8<K, V> map) { super(map); } KeyIterator(Traverser<K,V,Object> it) { super(it); } public KeyIterator<K,V> split() { if (nextKey != null) throw new IllegalStateException(); return new KeyIterator<K,V>(this); } @SuppressWarnings("unchecked") public final K next() { if (nextVal == null && advance() == null) throw new NoSuchElementException(); Object k = nextKey; nextVal = null; return (K) k; } public final K nextElement() { return next(); } } @SuppressWarnings("serial") static final class ValueIterator<K,V> extends Traverser<K,V,Object> implements Spliterator<V>, Enumeration<V> { ValueIterator(ConcurrentHashMapV8<K, V> map) { super(map); } ValueIterator(Traverser<K,V,Object> it) { super(it); } public ValueIterator<K,V> split() { if (nextKey != null) throw new IllegalStateException(); return new ValueIterator<K,V>(this); } @SuppressWarnings("unchecked") public final V next() { Object v; if ((v = nextVal) == null && (v = advance()) == null) throw new NoSuchElementException(); nextVal = null; return (V) v; } public final V nextElement() { return next(); } } @SuppressWarnings("serial") static final class EntryIterator<K,V> extends Traverser<K,V,Object> implements Spliterator<Map.Entry<K,V>> { EntryIterator(ConcurrentHashMapV8<K, V> map) { super(map); } EntryIterator(Traverser<K,V,Object> it) { super(it); } public EntryIterator<K,V> split() { if (nextKey != null) throw new IllegalStateException(); return new EntryIterator<K,V>(this); } @SuppressWarnings("unchecked") public final Map.Entry<K,V> next() { Object v; if ((v = nextVal) == null && (v = advance()) == null) throw new NoSuchElementException(); Object k = nextKey; nextVal = null; return new MapEntry<K,V>((K)k, (V)v, map); } } /** * Exported Entry for iterators */ static final class MapEntry<K,V> implements Map.Entry<K, V> { final K key; // non-null V val; // non-null final ConcurrentHashMapV8<K, V> map; MapEntry(K key, V val, ConcurrentHashMapV8<K, V> map) { this.key = key; this.val = val; this.map = map; } public final K getKey() { return key; } public final V getValue() { return val; } public final int hashCode() { return key.hashCode() ^ val.hashCode(); } public final String toString(){ return key + "=" + val; } public final boolean equals(Object o) { Object k, v; Map.Entry<?,?> e; return ((o instanceof Map.Entry) && (k = (e = (Map.Entry<?,?>)o).getKey()) != null && (v = e.getValue()) != null && (k == key || k.equals(key)) && (v == val || v.equals(val))); } /** * Sets our entry's value and writes through to the map. The * value to return is somewhat arbitrary here. Since we do not * necessarily track asynchronous changes, the most recent * "previous" value could be different from what we return (or * could even have been removed in which case the put will * re-establish). We do not and cannot guarantee more. */ public final V setValue(V value) { if (value == null) throw new NullPointerException(); V v = val; val = value; map.put(key, value); return v; } } /* ---------------- Serialization Support -------------- */ /** * Stripped-down version of helper class used in previous version, * declared for the sake of serialization compatibility */ static class Segment<K,V> implements Serializable { private static final long serialVersionUID = 2249069246763182397L; final float loadFactor; Segment(float lf) { this.loadFactor = lf; } } /** * Saves the state of the {@code ConcurrentHashMapV8} instance to a * stream (i.e., serializes it). * @param s the stream * @serialData * the key (Object) and value (Object) * for each key-value mapping, followed by a null pair. * The key-value mappings are emitted in no particular order. */ @SuppressWarnings("unchecked") private void writeObject(java.io.ObjectOutputStream s) throws java.io.IOException { if (segments == null) { // for serialization compatibility segments = (Segment<K,V>[]) new Segment<?,?>[DEFAULT_CONCURRENCY_LEVEL]; for (int i = 0; i < segments.length; ++i) segments[i] = new Segment<K,V>(LOAD_FACTOR); } s.defaultWriteObject(); Traverser<K,V,Object> it = new Traverser<K,V,Object>(this); Object v; while ((v = it.advance()) != null) { s.writeObject(it.nextKey); s.writeObject(v); } s.writeObject(null); s.writeObject(null); segments = null; // throw away } /** * Reconstitutes the instance from a stream (that is, deserializes it). * @param s the stream */ @SuppressWarnings("unchecked") private void readObject(java.io.ObjectInputStream s) throws java.io.IOException, ClassNotFoundException { s.defaultReadObject(); this.segments = null; // unneeded // initialize transient final field UNSAFE.putObjectVolatile(this, counterOffset, new LongAdder()); // Create all nodes, then place in table once size is known long size = 0L; Node p = null; for (;;) { K k = (K) s.readObject(); V v = (V) s.readObject(); if (k != null && v != null) { int h = spread(k.hashCode()); p = new Node(h, k, v, p); ++size; } else break; } if (p != null) { boolean init = false; int n; if (size >= (long)(MAXIMUM_CAPACITY >>> 1)) n = MAXIMUM_CAPACITY; else { int sz = (int)size; n = tableSizeFor(sz + (sz >>> 1) + 1); } int sc = sizeCtl; boolean collide = false; if (n > sc && UNSAFE.compareAndSwapInt(this, sizeCtlOffset, sc, -1)) { try { if (table == null) { init = true; Node[] tab = new Node[n]; int mask = n - 1; while (p != null) { int j = p.hash & mask; Node next = p.next; Node q = p.next = tabAt(tab, j); setTabAt(tab, j, p); if (!collide && q != null && q.hash == p.hash) collide = true; p = next; } table = tab; counter.add(size); sc = n - (n >>> 2); } } finally { sizeCtl = sc; } if (collide) { // rescan and convert to TreeBins Node[] tab = table; for (int i = 0; i < tab.length; ++i) { int c = 0; for (Node e = tabAt(tab, i); e != null; e = e.next) { if (++c > TREE_THRESHOLD && (e.key instanceof Comparable)) { replaceWithTreeBin(tab, i, e.key); break; } } } } } if (!init) { // Can only happen if unsafely published. while (p != null) { internalPut(p.key, p.val); p = p.next; } } } } // ------------------------------------------------------- // Sams /** Interface describing a void action of one argument */ public interface Action<A> { void apply(A a); } /** Interface describing a void action of two arguments */ public interface BiAction<A,B> { void apply(A a, B b); } /** Interface describing a function of one argument */ public interface Generator<T> { T apply(); } /** Interface describing a function mapping its argument to a double */ public interface ObjectToDouble<A> { double apply(A a); } /** Interface describing a function mapping its argument to a long */ public interface ObjectToLong<A> { long apply(A a); } /** Interface describing a function mapping its argument to an int */ public interface ObjectToInt<A> {int apply(A a); } /** Interface describing a function mapping two arguments to a double */ public interface ObjectByObjectToDouble<A,B> { double apply(A a, B b); } /** Interface describing a function mapping two arguments to a long */ public interface ObjectByObjectToLong<A,B> { long apply(A a, B b); } /** Interface describing a function mapping two arguments to an int */ public interface ObjectByObjectToInt<A,B> {int apply(A a, B b); } /** Interface describing a function mapping a double to a double */ public interface DoubleToDouble { double apply(double a); } /** Interface describing a function mapping a long to a long */ public interface LongToLong { long apply(long a); } /** Interface describing a function mapping an int to an int */ public interface IntToInt { int apply(int a); } /** Interface describing a function mapping two doubles to a double */ public interface DoubleByDoubleToDouble { double apply(double a, double b); } /** Interface describing a function mapping two longs to a long */ public interface LongByLongToLong { long apply(long a, long b); } /** Interface describing a function mapping two ints to an int */ public interface IntByIntToInt { int apply(int a, int b); } /* ----------------Views -------------- */ /** * Base class for views. */ static abstract class CHMView<K, V> { final ConcurrentHashMapV8<K, V> map; CHMView(ConcurrentHashMapV8<K, V> map) { this.map = map; } /** * Returns the map backing this view. * * @return the map backing this view */ public ConcurrentHashMapV8<K,V> getMap() { return map; } public final int size() { return map.size(); } public final boolean isEmpty() { return map.isEmpty(); } public final void clear() { map.clear(); } // implementations below rely on concrete classes supplying these abstract public Iterator<?> iterator(); abstract public boolean contains(Object o); abstract public boolean remove(Object o); private static final String oomeMsg = "Required array size too large"; public final Object[] toArray() { long sz = map.mappingCount(); if (sz > (long)(MAX_ARRAY_SIZE)) throw new OutOfMemoryError(oomeMsg); int n = (int)sz; Object[] r = new Object[n]; int i = 0; Iterator<?> it = iterator(); while (it.hasNext()) { if (i == n) { if (n >= MAX_ARRAY_SIZE) throw new OutOfMemoryError(oomeMsg); if (n >= MAX_ARRAY_SIZE - (MAX_ARRAY_SIZE >>> 1) - 1) n = MAX_ARRAY_SIZE; else n += (n >>> 1) + 1; r = Arrays.copyOf(r, n); } r[i++] = it.next(); } return (i == n) ? r : Arrays.copyOf(r, i); } @SuppressWarnings("unchecked") public final <T> T[] toArray(T[] a) { long sz = map.mappingCount(); if (sz > (long)(MAX_ARRAY_SIZE)) throw new OutOfMemoryError(oomeMsg); int m = (int)sz; T[] r = (a.length >= m) ? a : (T[])java.lang.reflect.Array .newInstance(a.getClass().getComponentType(), m); int n = r.length; int i = 0; Iterator<?> it = iterator(); while (it.hasNext()) { if (i == n) { if (n >= MAX_ARRAY_SIZE) throw new OutOfMemoryError(oomeMsg); if (n >= MAX_ARRAY_SIZE - (MAX_ARRAY_SIZE >>> 1) - 1) n = MAX_ARRAY_SIZE; else n += (n >>> 1) + 1; r = Arrays.copyOf(r, n); } r[i++] = (T)it.next(); } if (a == r && i < n) { r[i] = null; // null-terminate return r; } return (i == n) ? r : Arrays.copyOf(r, i); } public final int hashCode() { int h = 0; for (Iterator<?> it = iterator(); it.hasNext();) h += it.next().hashCode(); return h; } public final String toString() { StringBuilder sb = new StringBuilder(); sb.append('['); Iterator<?> it = iterator(); if (it.hasNext()) { for (;;) { Object e = it.next(); sb.append(e == this ? "(this Collection)" : e); if (!it.hasNext()) break; sb.append(',').append(' '); } } return sb.append(']').toString(); } public final boolean containsAll(Collection<?> c) { if (c != this) { for (Iterator<?> it = c.iterator(); it.hasNext();) { Object e = it.next(); if (e == null || !contains(e)) return false; } } return true; } public final boolean removeAll(Collection<?> c) { boolean modified = false; for (Iterator<?> it = iterator(); it.hasNext();) { if (c.contains(it.next())) { it.remove(); modified = true; } } return modified; } public final boolean retainAll(Collection<?> c) { boolean modified = false; for (Iterator<?> it = iterator(); it.hasNext();) { if (!c.contains(it.next())) { it.remove(); modified = true; } } return modified; } } /** * A view of a ConcurrentHashMapV8 as a {@link Set} of keys, in * which additions may optionally be enabled by mapping to a * common value. This class cannot be directly instantiated. See * {@link #keySet}, {@link #keySet(Object)}, {@link #newKeySet()}, * {@link #newKeySet(int)}. */ public static class KeySetView<K,V> extends CHMView<K,V> implements Set<K>, java.io.Serializable { private static final long serialVersionUID = 7249069246763182397L; private final V value; KeySetView(ConcurrentHashMapV8<K, V> map, V value) { // non-public super(map); this.value = value; } /** * Returns the default mapped value for additions, * or {@code null} if additions are not supported. * * @return the default mapped value for additions, or {@code null} * if not supported. */ public V getMappedValue() { return value; } // implement Set API public boolean contains(Object o) { return map.containsKey(o); } public boolean remove(Object o) { return map.remove(o) != null; } /** * Returns a "weakly consistent" iterator that will never * throw {@link ConcurrentModificationException}, and * guarantees to traverse elements as they existed upon * construction of the iterator, and may (but is not * guaranteed to) reflect any modifications subsequent to * construction. * * @return an iterator over the keys of this map */ public Iterator<K> iterator() { return new KeyIterator<K,V>(map); } public boolean add(K e) { V v; if ((v = value) == null) throw new UnsupportedOperationException(); if (e == null) throw new NullPointerException(); return map.internalPutIfAbsent(e, v) == null; } public boolean addAll(Collection<? extends K> c) { boolean added = false; V v; if ((v = value) == null) throw new UnsupportedOperationException(); for (K e : c) { if (e == null) throw new NullPointerException(); if (map.internalPutIfAbsent(e, v) == null) added = true; } return added; } public boolean equals(Object o) { Set<?> c; return ((o instanceof Set) && ((c = (Set<?>)o) == this || (containsAll(c) && c.containsAll(this)))); } } /** * A view of a ConcurrentHashMapV8 as a {@link Collection} of * values, in which additions are disabled. This class cannot be * directly instantiated. See {@link #values}, * * <p>The view's {@code iterator} is a "weakly consistent" iterator * that will never throw {@link ConcurrentModificationException}, * and guarantees to traverse elements as they existed upon * construction of the iterator, and may (but is not guaranteed to) * reflect any modifications subsequent to construction. */ public static final class ValuesView<K,V> extends CHMView<K,V> implements Collection<V> { ValuesView(ConcurrentHashMapV8<K, V> map) { super(map); } public final boolean contains(Object o) { return map.containsValue(o); } public final boolean remove(Object o) { if (o != null) { Iterator<V> it = new ValueIterator<K,V>(map); while (it.hasNext()) { if (o.equals(it.next())) { it.remove(); return true; } } } return false; } /** * Returns a "weakly consistent" iterator that will never * throw {@link ConcurrentModificationException}, and * guarantees to traverse elements as they existed upon * construction of the iterator, and may (but is not * guaranteed to) reflect any modifications subsequent to * construction. * * @return an iterator over the values of this map */ public final Iterator<V> iterator() { return new ValueIterator<K,V>(map); } public final boolean add(V e) { throw new UnsupportedOperationException(); } public final boolean addAll(Collection<? extends V> c) { throw new UnsupportedOperationException(); } } /** * A view of a ConcurrentHashMapV8 as a {@link Set} of (key, value) * entries. This class cannot be directly instantiated. See * {@link #entrySet}. */ public static final class EntrySetView<K,V> extends CHMView<K,V> implements Set<Map.Entry<K,V>> { EntrySetView(ConcurrentHashMapV8<K, V> map) { super(map); } public final boolean contains(Object o) { Object k, v, r; Map.Entry<?,?> e; return ((o instanceof Map.Entry) && (k = (e = (Map.Entry<?,?>)o).getKey()) != null && (r = map.get(k)) != null && (v = e.getValue()) != null && (v == r || v.equals(r))); } public final boolean remove(Object o) { Object k, v; Map.Entry<?,?> e; return ((o instanceof Map.Entry) && (k = (e = (Map.Entry<?,?>)o).getKey()) != null && (v = e.getValue()) != null && map.remove(k, v)); } /** * Returns a "weakly consistent" iterator that will never * throw {@link ConcurrentModificationException}, and * guarantees to traverse elements as they existed upon * construction of the iterator, and may (but is not * guaranteed to) reflect any modifications subsequent to * construction. * * @return an iterator over the entries of this map */ public final Iterator<Map.Entry<K,V>> iterator() { return new EntryIterator<K,V>(map); } public final boolean add(Entry<K,V> e) { K key = e.getKey(); V value = e.getValue(); if (key == null || value == null) throw new NullPointerException(); return map.internalPut(key, value) == null; } public final boolean addAll(Collection<? extends Entry<K,V>> c) { boolean added = false; for (Entry<K,V> e : c) { if (add(e)) added = true; } return added; } public boolean equals(Object o) { Set<?> c; return ((o instanceof Set) && ((c = (Set<?>)o) == this || (containsAll(c) && c.containsAll(this)))); } } // Unsafe mechanics private static final sun.misc.Unsafe UNSAFE; private static final long counterOffset; private static final long sizeCtlOffset; private static final long ABASE; private static final int ASHIFT; static { int ss; try { UNSAFE = getUnsafe(); Class<?> k = ConcurrentHashMapV8.class; counterOffset = UNSAFE.objectFieldOffset (k.getDeclaredField("counter")); sizeCtlOffset = UNSAFE.objectFieldOffset (k.getDeclaredField("sizeCtl")); Class<?> sc = Node[].class; ABASE = UNSAFE.arrayBaseOffset(sc); ss = UNSAFE.arrayIndexScale(sc); } catch (Exception e) { throw new Error(e); } if ((ss & (ss-1)) != 0) throw new Error("data type scale not a power of two"); ASHIFT = 31 - Integer.numberOfLeadingZeros(ss); } /** * Returns a sun.misc.Unsafe. Suitable for use in a 3rd party package. * Replace with a simple call to Unsafe.getUnsafe when integrating * into a jdk. * * @return a sun.misc.Unsafe */ private static sun.misc.Unsafe getUnsafe() { try { return sun.misc.Unsafe.getUnsafe(); } catch (SecurityException se) { try { return java.security.AccessController.doPrivileged (new java.security .PrivilegedExceptionAction<sun.misc.Unsafe>() { public sun.misc.Unsafe run() throws Exception { java.lang.reflect.Field f = sun.misc .Unsafe.class.getDeclaredField("theUnsafe"); f.setAccessible(true); return (sun.misc.Unsafe) f.get(null); }}); } catch (java.security.PrivilegedActionException e) { throw new RuntimeException("Could not initialize intrinsics", e.getCause()); } } } }