http://git-wip-us.apache.org/repos/asf/ignite/blob/b4ece5fb/modules/core/src/main/java/org/jsr166/ConcurrentHashMap8.java ---------------------------------------------------------------------- diff --git a/modules/core/src/main/java/org/jsr166/ConcurrentHashMap8.java b/modules/core/src/main/java/org/jsr166/ConcurrentHashMap8.java deleted file mode 100644 index f3c8dec..0000000 --- a/modules/core/src/main/java/org/jsr166/ConcurrentHashMap8.java +++ /dev/null @@ -1,3810 +0,0 @@ -/* - * 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/ - */ - -/* - * The latest version of the file was copied from the following CVS repository: - * http://gee.cs.oswego.edu/cgi-bin/viewcvs.cgi/jsr166/ - * - * Corresponding commit version in CVS repository is unknown (lost on our side). - * On the other hand we can't simply synch the latest version from CVS here, because Ignite uses functionality that - * is no longer supported. - */ - -package org.jsr166; - -import java.io.Serializable; -import java.util.AbstractMap; -import java.util.Arrays; -import java.util.Collection; -import java.util.ConcurrentModificationException; -import java.util.Enumeration; -import java.util.HashMap; -import java.util.Hashtable; -import java.util.Iterator; -import java.util.Map; -import java.util.NoSuchElementException; -import java.util.Set; -import java.util.concurrent.ConcurrentMap; -import java.util.concurrent.ThreadLocalRandom; -import java.util.concurrent.atomic.LongAdder; -import java.util.concurrent.locks.AbstractQueuedSynchronizer; - -/** - * 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,LongAdder8> freqs}, you - * can use {@code freqs.computeIfAbsent(k -> new - * LongAdder8()).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. - * - * <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> - * - * @since 1.5 - * @author Doug Lea - * @param <K> the type of keys maintained by this map - * @param <V> the type of mapped values - */ -@SuppressWarnings("ALL") -public class ConcurrentHashMap8<K, V> - implements ConcurrentMap<K, V>, Serializable { - 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 LongAdder8, 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. - */ - private static final int TREE_THRESHOLD = 8; - - /* - * 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) { - try { - Thread.currentThread().interrupt(); - } catch (SecurityException ignore) { - } - } - } - 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; - } - } - - /** - * Returns the TreeNode (or null if not found) for the given key - * starting at given root. - */ - @SuppressWarnings("unchecked") final TreeNode getTreeNode - (int h, Object k, TreeNode p) { - Class<?> c = k.getClass(); - while (p != null) { - int dir, ph; Object pk; Class<?> pc; - if ((ph = p.hash) == h) { - if ((pk = p.key) == k || k.equals(pk)) - return p; - if (c != (pc = pk.getClass()) || - !(k instanceof Comparable) || - (dir = ((Comparable)k).compareTo((Comparable)pk)) == 0) { - dir = (c == pc) ? 0 : c.getName().compareTo(pc.getName()); - TreeNode r = null, s = null, pl, pr; - if (dir >= 0) { - if ((pl = p.left) != null && h <= pl.hash) - s = pl; - } - else if ((pr = p.right) != null && h >= pr.hash) - s = pr; - if (s != null && (r = getTreeNode(h, k, s)) != null) - return r; - } - } - else - dir = (h < ph) ? -1 : 1; - p = (dir > 0) ? p.right : p.left; - } - return null; - } - - /** - * 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; - } - - /** - * Finds or adds a node. - * @return null if added - */ - @SuppressWarnings("unchecked") final TreeNode putTreeNode - (int h, Object k, Object v) { - Class<?> c = k.getClass(); - TreeNode pp = root, p = null; - int dir = 0; - while (pp != null) { // find existing node or leaf to insert at - int ph; Object pk; Class<?> pc; - p = pp; - if ((ph = p.hash) == h) { - if ((pk = p.key) == k || k.equals(pk)) - return p; - if (c != (pc = pk.getClass()) || - !(k instanceof Comparable) || - (dir = ((Comparable)k).compareTo((Comparable)pk)) == 0) { - dir = (c == pc) ? 0 : c.getName().compareTo(pc.getName()); - TreeNode r = null, s = null, pl, pr; - if (dir >= 0) { - if ((pl = p.left) != null && h <= pl.hash) - s = pl; - } - else if ((pr = p.right) != null && h >= pr.hash) - s = pr; - if (s != null && (r = getTreeNode(h, k, s)) != null) - return r; - } - } - else - dir = (h < ph) ? -1 : 1; - pp = (dir > 0) ? p.right : p.left; - } - - TreeNode f = first; - TreeNode x = first = new TreeNode(h, 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 = (p == null) ? null : 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, (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) { - 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. - */ - private static final int tableSizeFor(int c) { - if (c <= 0) - return 1; - - int n = Integer.highestOneBit(c - 1) << 1; - - return (n >= MAXIMUM_CAPACITY) ? MAXIMUM_CAPACITY : n; - } - - /** - * 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 an
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