| /* |
| * 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 initial version of this file was copied from JSR-166: |
| * http://gee.cs.oswego.edu/dl/concurrency-interest/ |
| */ |
| |
| package org.jsr166; |
| |
| import java.util.AbstractCollection; |
| import java.util.AbstractMap; |
| import java.util.AbstractSet; |
| import java.util.ArrayDeque; |
| 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.Queue; |
| import java.util.Set; |
| import java.util.concurrent.ConcurrentMap; |
| import java.util.concurrent.atomic.LongAdder; |
| import java.util.concurrent.locks.ReentrantReadWriteLock; |
| import org.apache.ignite.internal.util.tostring.GridToStringExclude; |
| import org.apache.ignite.internal.util.typedef.internal.S; |
| import org.jetbrains.annotations.Nullable; |
| |
| import static org.jsr166.ConcurrentLinkedHashMap.QueuePolicy.PER_SEGMENT_Q; |
| import static org.jsr166.ConcurrentLinkedHashMap.QueuePolicy.PER_SEGMENT_Q_OPTIMIZED_RMV; |
| import static org.jsr166.ConcurrentLinkedHashMap.QueuePolicy.SINGLE_Q; |
| |
| /** |
| * A hash table supporting full concurrency of retrievals and |
| * adjustable 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 |
| * <tt>Hashtable</tt>. 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 <tt>Hashtable</tt> in programs that rely on its |
| * thread safety but not on its synchronization details. |
| * |
| * <p> Retrieval operations (including <tt>get</tt>) generally do not |
| * block, so may overlap with update operations (including |
| * <tt>put</tt> and <tt>remove</tt>). Retrievals reflect the results |
| * of the most recently <em>completed</em> update operations holding |
| * upon their onset. For aggregate operations such as <tt>putAll</tt> |
| * and <tt>clear</tt>, 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. |
| * |
| * <p> The allowed concurrency among update operations is guided by |
| * the optional <tt>concurrencyLevel</tt> constructor argument |
| * (default <tt>16</tt>), which is used as a hint for internal sizing. The |
| * table is internally partitioned to try to permit the indicated |
| * number of concurrent updates without contention. Because placement |
| * in hash tables is essentially random, the actual concurrency will |
| * vary. Ideally, you should choose a value to accommodate as many |
| * threads as will ever concurrently modify the table. Using a |
| * significantly higher value than you need can waste space and time, |
| * and a significantly lower value can lead to thread contention. But |
| * overestimates and underestimates within an order of magnitude do |
| * not usually have much noticeable impact. A value of one is |
| * appropriate when it is known that only one thread will modify and |
| * all others will only read. Also, resizing this or any other kind of |
| * hash table is a relatively slow operation, so, when possible, it is |
| * a good idea to provide estimates of expected table sizes in |
| * constructors. |
| * |
| * <p/> This implementation differs from |
| * <tt>HashMap</tt> in that it maintains a doubly-linked list running through |
| * all of its entries. This linked list defines the iteration ordering, |
| * which is the order in which keys were inserted into the map |
| * (<i>insertion-order</i>). |
| * |
| * <p> NOTE: Access order is not supported by this map. |
| * |
| * Note that insertion order is not affected |
| * if a key is <i>re-inserted</i> into the map. (A key <tt>k</tt> is |
| * reinserted into a map <tt>m</tt> if <tt>m.put(k, v)</tt> is invoked when |
| * <tt>m.containsKey(k)</tt> would return <tt>true</tt> immediately prior to |
| * the invocation.) |
| * |
| * <p>An optional {@code maxCap} may be passed to the map constructor to |
| * create bounded map that will remove stale mappings automatically when new mappings |
| * are added to the map. |
| * |
| * <p/>When iterating over the key set in insertion order one should note that iterator |
| * will see all removes done since the iterator was created, but will see <b>no</b> |
| * inserts to map. |
| * |
| * <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 <tt>null</tt> to be used as a key or value. |
| * |
| * @author Doug Lea |
| * @param <K> the type of keys maintained by this map |
| * @param <V> the type of mapped values |
| */ |
| public class ConcurrentLinkedHashMap<K, V> extends AbstractMap<K, V> implements ConcurrentMap<K, V> { |
| /* |
| * The basic strategy is to subdivide the table among Segments, |
| * each of which itself is a concurrently readable hash table. |
| */ |
| |
| /* ---------------- Constants -------------- */ |
| |
| /** |
| * The default initial capacity for this table, |
| * used when not otherwise specified in a constructor. |
| */ |
| public static final int DFLT_INIT_CAP = 16; |
| |
| /** |
| * The default load factor for this table, used when not |
| * otherwise specified in a constructor. |
| */ |
| public static final float DFLT_LOAD_FACTOR = 0.75f; |
| |
| /** |
| * The default concurrency level for this table, used when not |
| * otherwise specified in a constructor. |
| */ |
| public static final int DFLT_CONCUR_LVL = 16; |
| |
| /** |
| * The maximum capacity, used if a higher value is implicitly |
| * specified by either of the constructors with arguments. MUST |
| * be a power of two <= 1<<30 to ensure that entries are indexable |
| * using ints. |
| */ |
| public static final int MAX_CAP_LIMIT = 1 << 30; |
| |
| /** |
| * The maximum number of segments to allow; used to bound |
| * constructor arguments. |
| */ |
| public static final int MAX_SEGS = 1 << 16; // slightly conservative |
| |
| /** |
| * Number of unsynchronized retries in {@link #size} and {@link #containsValue} |
| * methods before resorting to locking. This is used to avoid |
| * unbounded retries if tables undergo continuous modification |
| * which would make it impossible to obtain an accurate result. |
| */ |
| public static final int RETRIES_BEFORE_LOCK = 2; |
| |
| /* ---------------- Fields -------------- */ |
| |
| /** |
| * Mask value for indexing into segments. The upper bits of a |
| * key's hash code are used to choose the segment. |
| */ |
| private final int segmentMask; |
| |
| /** Shift value for indexing within segments. */ |
| private final int segmentShift; |
| |
| /** The segments, each of which is a specialized hash table. */ |
| private final Segment<K, V>[] segments; |
| |
| /** Key set. */ |
| private Set<K> keySet; |
| |
| /** Key set. */ |
| private Set<K> descKeySet; |
| |
| /** Entry set */ |
| private Set<Map.Entry<K, V>> entrySet; |
| |
| /** Entry set in descending order. */ |
| private Set<Map.Entry<K, V>> descEntrySet; |
| |
| /** Values collection. */ |
| private Collection<V> vals; |
| |
| /** Values collection in descending order. */ |
| private Collection<V> descVals; |
| |
| /** Queue containing order of entries. */ |
| private final ConcurrentLinkedDeque8<HashEntry<K, V>> entryQ; |
| |
| /** Atomic variable containing map size. */ |
| private final LongAdder size = new LongAdder(); |
| |
| /** */ |
| private final LongAdder modCnt = new LongAdder(); |
| |
| /** */ |
| private final int maxCap; |
| |
| /** */ |
| private final QueuePolicy qPlc; |
| |
| /* ---------------- Small Utilities -------------- */ |
| |
| /** |
| * Applies a supplemental hash function to a given hashCode, which |
| * defends against poor quality hash functions. This is critical |
| * because ConcurrentHashMap uses power-of-two length hash tables, |
| * that otherwise encounter collisions for hashCodes that do not |
| * differ in lower or upper bits. |
| * |
| * @param h Input hash. |
| * @return Hash. |
| */ |
| private static int hash(int h) { |
| // Apply base step of MurmurHash; see http://code.google.com/p/smhasher/ |
| // Despite two multiplies, this is often faster than others |
| // with comparable bit-spread properties. |
| h ^= h >>> 16; |
| h *= 0x85ebca6b; |
| h ^= h >>> 13; |
| h *= 0xc2b2ae35; |
| |
| return ((h >>> 16) ^ h); |
| } |
| |
| /** |
| * Returns the segment that should be used for key with given hash. |
| * |
| * @param hash the hash code for the key |
| * @return the segment |
| */ |
| private Segment<K, V> segmentFor(int hash) { |
| return segments[(hash >>> segmentShift) & segmentMask]; |
| } |
| |
| /* ---------------- Inner Classes -------------- */ |
| |
| /** |
| * ConcurrentHashMap list entry. Note that this is never exported |
| * out as a user-visible Map.Entry. |
| * |
| * Because the value field is volatile, not final, it is legal wrt |
| * the Java Memory Model for an unsynchronized reader to see null |
| * instead of initial value when read via a data race. Although a |
| * reordering leading to this is not likely to ever actually |
| * occur, the Segment.readValueUnderLock method is used as a |
| * snapshot in case a null (pre-initialized) value is ever seen in |
| * an unsynchronized access method. |
| */ |
| @SuppressWarnings({"PublicInnerClass"}) |
| public static final class HashEntry<K, V> { |
| /** Key. */ |
| private final K key; |
| |
| /** Hash of the key after {@code hash()} method is applied. */ |
| private final int hash; |
| |
| /** Value. */ |
| private volatile V val; |
| |
| /** Reference to a node in queue for fast removal operations. */ |
| @GridToStringExclude |
| private volatile ConcurrentLinkedDeque8.Node node; |
| |
| /** Modification count of the map for duplicates exclusion. */ |
| private volatile int modCnt; |
| |
| /** Link to the next entry in a bucket */ |
| @GridToStringExclude |
| private final HashEntry<K, V> next; |
| |
| /** |
| * @param key Key. |
| * @param hash Key hash. |
| * @param next Link to next. |
| * @param val Value. |
| */ |
| HashEntry(K key, int hash, HashEntry<K, V> next, V val) { |
| this.key = key; |
| this.hash = hash; |
| this.next = next; |
| this.val = val; |
| } |
| |
| /** |
| * @param key Key. |
| * @param hash Key hash. |
| * @param next Link to next. |
| * @param val Value. |
| * @param node Queue node. |
| * @param modCnt Mod count. |
| */ |
| HashEntry(K key, int hash, HashEntry<K, V> next, V val, ConcurrentLinkedDeque8.Node node, int modCnt) { |
| this.key = key; |
| this.hash = hash; |
| this.next = next; |
| this.val = val; |
| this.node = node; |
| this.modCnt = modCnt; |
| } |
| |
| /** |
| * Returns key of this entry. |
| * |
| * @return Key. |
| */ |
| public K getKey() { |
| return key; |
| } |
| |
| /** |
| * Return value of this entry. |
| * |
| * @return Value. |
| */ |
| public V getValue() { |
| return val; |
| } |
| |
| /** |
| * Creates new array of entries. |
| * |
| * @param i Size of array. |
| * @param <K> Key type. |
| * @param <V> Value type. |
| * @return Empty array. |
| */ |
| @SuppressWarnings("unchecked") |
| static <K, V> HashEntry<K, V>[] newArray(int i) { |
| return new HashEntry[i]; |
| } |
| |
| /** {@inheritDoc} */ |
| @Override public String toString() { |
| return S.toString(HashEntry.class, this, "key", key, "val", val); |
| } |
| } |
| |
| /** |
| * Segments are specialized versions of hash tables. This |
| * subclasses from ReentrantLock opportunistically, just to |
| * simplify some locking and avoid separate construction. |
| */ |
| @SuppressWarnings({"TransientFieldNotInitialized"}) |
| private final class Segment<K, V> extends ReentrantReadWriteLock { |
| /* |
| * Segments maintain a table of entry lists that are ALWAYS |
| * kept in a consistent state, so can be read without locking. |
| * Next fields of nodes are immutable (final). All list |
| * additions are performed at the front of each bin. This |
| * makes it easy to check changes, and also fast to traverse. |
| * When nodes would otherwise be changed, new nodes are |
| * created to replace them. This works well for hash tables |
| * since the bin lists tend to be short. (The average length |
| * is less than two for the default load factor threshold.) |
| * |
| * Read operations can thus proceed without locking, but rely |
| * on selected uses of volatiles to ensure that completed |
| * write operations performed by other threads are |
| * noticed. For most purposes, the "count" field, tracking the |
| * number of elements, serves as that volatile variable |
| * ensuring visibility. This is convenient because this field |
| * needs to be read in many read operations anyway: |
| * |
| * - All (unsynchronized) read operations must first read the |
| * "count" field, and should not look at table entries if |
| * it is 0. |
| * |
| * - All (synchronized) write operations should write to |
| * the "count" field after structurally changing any bin. |
| * The operations must not take any action that could even |
| * momentarily cause a concurrent read operation to see |
| * inconsistent data. This is made easier by the nature of |
| * the read operations in Map. For example, no operation |
| * can reveal that the table has grown but the threshold |
| * has not yet been updated, so there are no atomicity |
| * requirements for this with respect to reads. |
| * |
| * As a guide, all critical volatile reads and writes to the |
| * count field are marked in code comments. |
| */ |
| |
| /** The number of elements in this segment's region. */ |
| private transient volatile int cnt; |
| |
| /** |
| * Number of updates that alter the size of the table. This is |
| * used during bulk-read methods to make sure they see a |
| * consistent snapshot: If modCounts change during a traversal |
| * of segments computing size or checking containsValue, then |
| * we might have an inconsistent view of state so (usually) |
| * must retry. |
| */ |
| private transient int modCnt; |
| |
| /** |
| * The table is rehashed when its size exceeds this threshold. |
| * (The value of this field is always <tt>(int)(capacity * |
| * loadFactor)</tt>.) |
| */ |
| private transient int threshold; |
| |
| /** The per-segment table. */ |
| private transient volatile HashEntry<K, V>[] tbl; |
| |
| /** |
| * The load factor for the hash table. Even though this value |
| * is same for all segments, it is replicated to avoid needing |
| * links to outer object. |
| */ |
| private final float loadFactor; |
| |
| /** */ |
| private final Queue<HashEntry<K, V>> segEntryQ; |
| |
| /** |
| * @param initCap Segment initial capacity. |
| * @param loadFactor Segment load factor, |
| */ |
| Segment(int initCap, float loadFactor) { |
| this.loadFactor = loadFactor; |
| |
| segEntryQ = qPlc == PER_SEGMENT_Q ? new ArrayDeque<HashEntry<K, V>>() : |
| qPlc == PER_SEGMENT_Q_OPTIMIZED_RMV ? new ConcurrentLinkedDeque8<HashEntry<K, V>>() : null; |
| |
| setTable(HashEntry.<K, V>newArray(initCap)); |
| } |
| |
| /** |
| * Sets table to new HashEntry array. |
| * Call only while holding lock or in constructor. |
| * |
| * @param newTbl New hash table |
| */ |
| void setTable(HashEntry<K, V>[] newTbl) { |
| threshold = (int)(newTbl.length * loadFactor); |
| tbl = newTbl; |
| } |
| |
| /** |
| * Returns properly casted first entry of bin for given hash. |
| * |
| * @param hash Hash of the key. |
| * @return Head of bin's linked list. |
| */ |
| HashEntry<K, V> getFirst(int hash) { |
| HashEntry<K, V>[] tab = tbl; |
| |
| return tab[hash & (tab.length - 1)]; |
| } |
| |
| /** |
| * Reads value field of an entry under lock. Called if value |
| * field ever appears to be null. This is possible only if a |
| * compiler happens to reorder a HashEntry initialization with |
| * its table assignment, which is legal under memory model |
| * but is not known to ever occur. |
| * |
| * @param e Entry that needs to be read. |
| * @return Value of entry. |
| */ |
| V readValueUnderLock(HashEntry<K, V> e) { |
| readLock().lock(); |
| |
| try { |
| return e.val; |
| } |
| finally { |
| readLock().unlock(); |
| } |
| } |
| |
| /* Specialized implementations of map methods */ |
| |
| /** |
| * Performs lock-free read of value for given key. |
| * |
| * @param key Key to be read. |
| * @param hash Hash of the key |
| * @return Stored value |
| */ |
| V get(Object key, int hash) { |
| if (cnt != 0) { // read-volatile |
| HashEntry<K, V> e = getFirst(hash); |
| |
| while (e != null) { |
| if (e.hash == hash && key.equals(e.key)) { |
| V v = e.val; |
| |
| if (v != null) |
| return v; |
| |
| v = readValueUnderLock(e); |
| |
| return v; // recheck |
| } |
| |
| e = e.next; |
| } |
| } |
| |
| return null; |
| } |
| |
| /** |
| * Performs lock-based read of value for given key. |
| * In contrast with {@link #get(Object, int)} it is guaranteed |
| * to be consistent with order-based iterators. |
| * |
| * @param key Key to be read. |
| * @param hash Hash of the key |
| * @return Stored value |
| */ |
| V getSafe(Object key, int hash) { |
| readLock().lock(); |
| |
| try { |
| HashEntry<K, V> e = getFirst(hash); |
| |
| while (e != null) { |
| if (e.hash == hash && key.equals(e.key)) |
| return e.val; |
| |
| e = e.next; |
| } |
| |
| return null; |
| } |
| finally { |
| readLock().unlock(); |
| } |
| } |
| |
| /** |
| * Performs lock-free check of key presence. |
| * |
| * @param key Key to lookup. |
| * @param hash Hash of the key. |
| * @return {@code true} if segment contains this key. |
| */ |
| boolean containsKey(Object key, int hash) { |
| if (cnt != 0) { // read-volatile |
| HashEntry<K, V> e = getFirst(hash); |
| |
| while (e != null) { |
| if (e.hash == hash && key.equals(e.key)) |
| return true; |
| |
| e = e.next; |
| } |
| } |
| |
| return false; |
| } |
| |
| /** |
| * Performs lock-free check of value presence. |
| * |
| * @param val Value. |
| * @return {@code true} if segment contains this key. |
| */ |
| @SuppressWarnings("ForLoopReplaceableByForEach") |
| boolean containsValue(Object val) { |
| if (cnt != 0) { // read-volatile |
| HashEntry<K, V>[] tab = tbl; |
| |
| int len = tab.length; |
| |
| for (int i = 0 ; i < len; i++) { |
| for (HashEntry<K, V> e = tab[i]; e != null; e = e.next) { |
| V v = e.val; |
| |
| if (v == null) // recheck |
| v = readValueUnderLock(e); |
| |
| if (val.equals(v)) |
| return true; |
| } |
| } |
| } |
| |
| return false; |
| } |
| |
| /** |
| * Performs value replacement for a given key with old value check. |
| * |
| * @param key Key to replace. |
| * @param hash Hash of the key. |
| * @param oldVal Old value. |
| * @param newVal New value |
| * @return {@code true} If value was replaced. |
| */ |
| boolean replace(K key, int hash, V oldVal, V newVal) { |
| writeLock().lock(); |
| |
| boolean replaced = false; |
| |
| try { |
| HashEntry<K, V> e = getFirst(hash); |
| |
| while (e != null && (e.hash != hash || !key.equals(e.key))) |
| e = e.next; |
| |
| if (e != null && oldVal.equals(e.val)) { |
| replaced = true; |
| |
| e.val = newVal; |
| } |
| } |
| finally { |
| writeLock().unlock(); |
| } |
| |
| return replaced; |
| } |
| |
| /** |
| * Performs value replacement for a given key with old value check. |
| * |
| * @param key Key to replace. |
| * @param hash Hash of the key. |
| * @param oldVal Old value. |
| * @param newVal New value |
| * @return {@code oldVal}, if value was replaced, non-null object if map |
| * contained some other value and {@code null} if there were no such key. |
| */ |
| V replacex(K key, int hash, V oldVal, V newVal) { |
| writeLock().lock(); |
| |
| V replaced = null; |
| |
| try { |
| HashEntry<K, V> e = getFirst(hash); |
| |
| while (e != null && (e.hash != hash || !key.equals(e.key))) |
| e = e.next; |
| |
| if (e != null) { |
| if (oldVal.equals(e.val)) { |
| replaced = oldVal; |
| |
| e.val = newVal; |
| } |
| else |
| replaced = e.val; |
| } |
| } |
| finally { |
| writeLock().unlock(); |
| } |
| |
| return replaced; |
| } |
| |
| V replace(K key, int hash, V newVal) { |
| writeLock().lock(); |
| |
| V oldVal = null; |
| |
| try { |
| HashEntry<K, V> e = getFirst(hash); |
| |
| while (e != null && (e.hash != hash || !key.equals(e.key))) |
| e = e.next; |
| |
| if (e != null) { |
| oldVal = e.val; |
| |
| e.val = newVal; |
| } |
| } |
| finally { |
| writeLock().unlock(); |
| } |
| |
| return oldVal; |
| } |
| |
| V put(K key, int hash, V val, boolean onlyIfAbsent) { |
| writeLock().lock(); |
| |
| V oldVal; |
| |
| boolean added = false; |
| |
| try { |
| int c = cnt; |
| |
| if (c++ > threshold) // ensure capacity |
| rehash(); |
| |
| HashEntry<K, V>[] tab = tbl; |
| |
| int idx = hash & (tab.length - 1); |
| |
| HashEntry<K, V> first = tab[idx]; |
| |
| HashEntry<K, V> e = first; |
| |
| while (e != null && (e.hash != hash || !key.equals(e.key))) |
| e = e.next; |
| |
| boolean modified = false; |
| |
| if (e != null) { |
| oldVal = e.val; |
| |
| if (!onlyIfAbsent) { |
| e.val = val; |
| |
| ConcurrentLinkedDeque8.Node node = e.node; |
| |
| if (node != null) { |
| HashEntry<K, V> qEntry = (HashEntry<K, V>)node.item(); |
| |
| if (qEntry != null && qEntry != e) |
| qEntry.val = val; |
| } |
| |
| modified = true; |
| } |
| } |
| else { |
| oldVal = null; |
| |
| ++modCnt; |
| |
| size.increment(); |
| |
| e = tab[idx] = new HashEntry<>(key, hash, first, val); |
| |
| ConcurrentLinkedHashMap.this.modCnt.increment(); |
| |
| e.modCnt = ConcurrentLinkedHashMap.this.modCnt.intValue(); |
| |
| cnt = c; // write-volatile |
| |
| added = true; |
| } |
| |
| assert !(added && modified); |
| |
| if (added) { |
| switch (qPlc) { |
| case PER_SEGMENT_Q_OPTIMIZED_RMV: |
| recordInsert(e, (ConcurrentLinkedDeque8)segEntryQ); |
| |
| if (maxCap > 0) |
| checkRemoveEldestEntrySegment(c); |
| |
| break; |
| |
| case PER_SEGMENT_Q: |
| segEntryQ.add(e); |
| |
| if (maxCap > 0) |
| checkRemoveEldestEntrySegment(c); |
| |
| break; |
| |
| default: |
| assert qPlc == SINGLE_Q; |
| |
| recordInsert(e, entryQ); |
| } |
| } |
| } |
| finally { |
| writeLock().unlock(); |
| } |
| |
| if (qPlc == SINGLE_Q && added && maxCap > 0) |
| checkRemoveEldestEntry(); |
| |
| return oldVal; |
| } |
| |
| /** |
| * @param cnt Segment entries count. |
| */ |
| private void checkRemoveEldestEntrySegment(int cnt) { |
| assert maxCap > 0; |
| |
| if (cnt - ((maxCap / segments.length) + 1) > 0) { |
| HashEntry<K, V> e0 = segEntryQ.poll(); |
| |
| assert e0 != null; |
| |
| removeLocked( |
| e0.key, |
| e0.hash, |
| null /*no need to compare*/, |
| false); |
| } |
| } |
| |
| /** |
| * This method is called under the segment lock. |
| */ |
| @SuppressWarnings({"ForLoopReplaceableByForEach"}) |
| void rehash() { |
| HashEntry<K, V>[] oldTbl = tbl; |
| int oldCap = oldTbl.length; |
| |
| if (oldCap >= MAX_CAP_LIMIT) |
| return; |
| |
| /* |
| * Reclassify nodes in each list to new Map. 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. Statistically, at the default |
| * threshold, 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 traversing table |
| * right now. |
| */ |
| |
| int c = cnt; |
| |
| HashEntry<K, V>[] newTbl = HashEntry.newArray(oldCap << 1); |
| |
| threshold = (int)(newTbl.length * loadFactor); |
| |
| int sizeMask = newTbl.length - 1; |
| |
| for (int i = 0; i < oldCap; i++) { |
| // We need to guarantee that any existing reads of old Map can |
| // proceed. So we cannot yet null out each bin. |
| HashEntry<K, V> e = oldTbl[i]; |
| |
| if (e != null) { |
| HashEntry<K, V> next = e.next; |
| |
| int idx = e.hash & sizeMask; |
| |
| // Single node on list |
| if (next == null) |
| newTbl[idx] = e; |
| |
| else { |
| // Reuse trailing consecutive sequence at same slot |
| HashEntry<K, V> lastRun = e; |
| |
| int lastIdx = idx; |
| |
| for (HashEntry<K, V> last = next; last != null; last = last.next) { |
| int k = last.hash & sizeMask; |
| |
| if (k != lastIdx) { |
| lastIdx = k; |
| lastRun = last; |
| } |
| } |
| |
| newTbl[lastIdx] = lastRun; |
| |
| // Clone all remaining nodes |
| for (HashEntry<K, V> p = e; p != lastRun; p = p.next) { |
| int k = p.hash & sizeMask; |
| |
| HashEntry<K, V> n = newTbl[k]; |
| |
| HashEntry<K, V> e0 = new HashEntry<>(p.key, p.hash, n, p.val, p.node, p.modCnt); |
| |
| newTbl[k] = e0; |
| } |
| } |
| } |
| } |
| |
| cnt = c; |
| |
| tbl = newTbl; |
| } |
| |
| /** |
| * Remove; match on key only if value null, else match both. |
| * |
| * @param key Key to be removed. |
| * @param hash Hash of the key. |
| * @param val Value to match. |
| * @param cleanupQ {@code True} if need to cleanup queue. |
| * @return Old value, if entry existed, {@code null} otherwise. |
| */ |
| V remove(Object key, int hash, Object val, boolean cleanupQ) { |
| writeLock().lock(); |
| |
| try { |
| return removeLocked(key, hash, val, cleanupQ); |
| } |
| finally { |
| writeLock().unlock(); |
| } |
| } |
| |
| /** |
| * Locked version of remove. Match on key only if value null, else match both. |
| * |
| * @param key Key to be removed. |
| * @param hash Hash of the key. |
| * @param val Value to match. |
| * @param cleanupQ {@code True} if need to cleanup queue. |
| * @return Old value, if entry existed, {@code null} otherwise. |
| */ |
| @SuppressWarnings({"unchecked"}) |
| V removeLocked(Object key, int hash, Object val, boolean cleanupQ) { |
| int c = cnt - 1; |
| |
| HashEntry<K, V>[] tab = tbl; |
| |
| int idx = hash & (tab.length - 1); |
| |
| HashEntry<K, V> first = tab[idx]; |
| |
| HashEntry<K, V> e = first; |
| |
| while (e != null && (e.hash != hash || !key.equals(e.key))) |
| e = e.next; |
| |
| V oldVal = null; |
| |
| if (e != null) { |
| V v = e.val; |
| |
| if (val == null || val.equals(v)) { |
| oldVal = v; |
| |
| // All entries following removed node can stay |
| // in list, but all preceding ones need to be |
| // cloned. |
| ++modCnt; |
| |
| ConcurrentLinkedHashMap.this.modCnt.increment(); |
| |
| HashEntry<K, V> newFirst = e.next; |
| |
| for (HashEntry<K, V> p = first; p != e; p = p.next) |
| newFirst = new HashEntry<>(p.key, p.hash, newFirst, p.val, p.node, p.modCnt); |
| |
| tab[idx] = newFirst; |
| |
| cnt = c; // write-volatile |
| |
| size.decrement(); |
| } |
| } |
| |
| if (oldVal != null && cleanupQ) { |
| switch (qPlc) { |
| case PER_SEGMENT_Q_OPTIMIZED_RMV: |
| ((ConcurrentLinkedDeque8)segEntryQ).unlinkx(e.node); |
| |
| e.node = null; |
| |
| break; |
| |
| case PER_SEGMENT_Q: |
| // Linear time method call. |
| segEntryQ.remove(e); |
| |
| break; |
| |
| default: |
| assert qPlc == SINGLE_Q; |
| |
| entryQ.unlinkx(e.node); |
| |
| e.node = null; |
| } |
| } |
| |
| return oldVal; |
| } |
| } |
| |
| /* ---------------- Public operations -------------- */ |
| |
| /** |
| * Creates a new, empty map with the specified initial |
| * capacity, load factor, concurrency level and max capacity. |
| * |
| * @param initCap the initial capacity. The implementation |
| * performs internal sizing to accommodate this many elements. |
| * @param loadFactor the load factor threshold, used to control resizing. |
| * Resizing may be performed when the average number of elements per |
| * bin exceeds this threshold. |
| * @param concurLvl the estimated number of concurrently |
| * updating threads. The implementation performs internal sizing |
| * to try to accommodate this many threads. |
| * @param maxCap Max capacity ({@code 0} for unbounded). |
| * @param qPlc Queue policy. |
| * @throws IllegalArgumentException if the initial capacity is |
| * negative or the load factor or concurLvl are |
| * non-positive. |
| */ |
| @SuppressWarnings({"unchecked"}) |
| public ConcurrentLinkedHashMap(int initCap, float loadFactor, int concurLvl, int maxCap, QueuePolicy qPlc) { |
| if (!(loadFactor > 0) || initCap < 0 || concurLvl <= 0) |
| throw new IllegalArgumentException(); |
| |
| if (concurLvl > MAX_SEGS) |
| concurLvl = MAX_SEGS; |
| |
| this.maxCap = maxCap; |
| this.qPlc = qPlc; |
| |
| entryQ = qPlc == SINGLE_Q ? new ConcurrentLinkedDeque8<HashEntry<K, V>>() : null; |
| |
| // Find power-of-two sizes best matching arguments |
| int sshift = 0; |
| |
| int ssize = 1; |
| |
| while (ssize < concurLvl) { |
| ++sshift; |
| ssize <<= 1; |
| } |
| |
| segmentShift = 32 - sshift; |
| |
| segmentMask = ssize - 1; |
| |
| segments = new Segment[ssize]; |
| |
| if (initCap > MAX_CAP_LIMIT) |
| initCap = MAX_CAP_LIMIT; |
| |
| int c = initCap / ssize; |
| |
| if (c * ssize < initCap) |
| ++c; |
| |
| int cap = 1; |
| |
| while (cap < c) |
| cap <<= 1; |
| |
| for (int i = 0; i < segments.length; ++i) |
| segments[i] = new Segment<>(cap, loadFactor); |
| } |
| |
| /** |
| * Creates a new, empty map with the specified initial |
| * capacity, load factor, concurrency level and max capacity. |
| * |
| * @param initCap the initial capacity. The implementation |
| * performs internal sizing to accommodate this many elements. |
| * @param loadFactor the load factor threshold, used to control resizing. |
| * Resizing may be performed when the average number of elements per |
| * bin exceeds this threshold. |
| * @param concurLvl the estimated number of concurrently |
| * updating threads. The implementation performs internal sizing |
| * to try to accommodate this many threads. |
| * @param maxCap Max capacity ({@code 0} for unbounded). |
| * @throws IllegalArgumentException if the initial capacity is |
| * negative or the load factor or concurLvl are |
| * non-positive. |
| */ |
| public ConcurrentLinkedHashMap(int initCap, float loadFactor, int concurLvl, int maxCap) { |
| this(initCap, loadFactor, concurLvl, maxCap, SINGLE_Q); |
| } |
| |
| /** |
| * Creates a new, empty map with the specified initial |
| * capacity, load factor and concurrency level. |
| * |
| * @param initCap the initial capacity. The implementation |
| * performs internal sizing to accommodate this many elements. |
| * @param loadFactor the load factor threshold, used to control resizing. |
| * Resizing may be performed when the average number of elements per |
| * bin exceeds this threshold. |
| * @param concurLvl the estimated number of concurrently |
| * updating threads. The implementation performs internal sizing |
| * to try to accommodate this many threads. |
| * @throws IllegalArgumentException if the initial capacity is |
| * negative or the load factor or concurLvl are |
| * non-positive. |
| */ |
| public ConcurrentLinkedHashMap(int initCap, float loadFactor, int concurLvl) { |
| this(initCap, loadFactor, concurLvl, 0); |
| } |
| |
| /** |
| * Creates a new, empty map with the specified initial capacity |
| * and load factor and with the default concurrencyLevel (16). |
| * |
| * @param initCap The implementation performs internal |
| * sizing to accommodate this many elements. |
| * @param loadFactor the load factor threshold, used to control resizing. |
| * Resizing may be performed when the average number of elements per |
| * bin exceeds this threshold. |
| * @throws IllegalArgumentException if the initial capacity of |
| * elements is negative or the load factor is non-positive |
| * |
| * @since 1.6 |
| */ |
| public ConcurrentLinkedHashMap(int initCap, float loadFactor) { |
| this(initCap, loadFactor, DFLT_CONCUR_LVL); |
| } |
| |
| /** |
| * Creates a new, empty map with the specified initial capacity, |
| * and with default load factor (0.75) and concurrencyLevel (16). |
| * |
| * @param initCap the initial capacity. The implementation |
| * performs internal sizing to accommodate this many elements. |
| * @throws IllegalArgumentException if the initial capacity of |
| * elements is negative. |
| */ |
| public ConcurrentLinkedHashMap(int initCap) { |
| this(initCap, DFLT_LOAD_FACTOR, DFLT_CONCUR_LVL); |
| } |
| |
| /** |
| * Creates a new, empty map with a default initial capacity (16), |
| * load factor (0.75) and concurrencyLevel (16). |
| */ |
| public ConcurrentLinkedHashMap() { |
| this(DFLT_INIT_CAP, DFLT_LOAD_FACTOR, DFLT_CONCUR_LVL); |
| } |
| |
| /** |
| * Creates a new map with the same mappings as the given map. |
| * The map is created with a capacity of 1.5 times the number |
| * of mappings in the given map or 16 (whichever is greater), |
| * and a default load factor (0.75) and concurrencyLevel (16). |
| * |
| * @param m the map |
| */ |
| public ConcurrentLinkedHashMap(Map<? extends K, ? extends V> m) { |
| this(Math.max((int) (m.size() / DFLT_LOAD_FACTOR) + 1, DFLT_INIT_CAP), |
| DFLT_LOAD_FACTOR, DFLT_CONCUR_LVL); |
| |
| putAll(m); |
| } |
| |
| /** |
| * Returns <tt>true</tt> if this map contains no key-value mappings. |
| * |
| * @return <tt>true</tt> if this map contains no key-value mappings. |
| */ |
| @Override public boolean isEmpty() { |
| Segment<K, V>[] segments = this.segments; |
| /* |
| * We keep track of per-segment modCounts to avoid ABA |
| * problems in which an element in one segment was added and |
| * in another removed during traversal, in which case the |
| * table was never actually empty at any point. Note the |
| * similar use of modCounts in the size() and containsValue() |
| * methods, which are the only other methods also susceptible |
| * to ABA problems. |
| */ |
| int[] mc = new int[segments.length]; |
| int mcsum = 0; |
| |
| for (int i = 0; i < segments.length; ++i) { |
| if (segments[i].cnt != 0) |
| return false; |
| else |
| mcsum += mc[i] = segments[i].modCnt; |
| } |
| |
| // If mcsum happens to be zero, then we know we got a snapshot |
| // before any modifications at all were made. This is |
| // probably common enough to bother tracking. |
| if (mcsum != 0) { |
| for (int i = 0; i < segments.length; ++i) { |
| if (segments[i].cnt != 0 || |
| mc[i] != segments[i].modCnt) |
| return false; |
| } |
| } |
| |
| return true; |
| } |
| |
| /** |
| * Returns the number of key-value mappings in this map. If the |
| * map contains more than <tt>Integer.MAX_VALUE</tt> elements, returns |
| * <tt>Integer.MAX_VALUE</tt>. |
| * |
| * @return the number of key-value mappings in this map |
| */ |
| @SuppressWarnings({"LockAcquiredButNotSafelyReleased"}) |
| @Override public int size() { |
| Segment<K, V>[] segments = this.segments; |
| long sum = 0; |
| long check = 0; |
| int[] mc = new int[segments.length]; |
| |
| // Try a few times to get accurate count. On failure due to |
| // continuous async changes in table, resort to locking. |
| for (int k = 0; k < RETRIES_BEFORE_LOCK; ++k) { |
| check = 0; |
| sum = 0; |
| int mcsum = 0; |
| |
| for (int i = 0; i < segments.length; ++i) { |
| sum += segments[i].cnt; |
| mcsum += mc[i] = segments[i].modCnt; |
| } |
| |
| if (mcsum != 0) { |
| for (int i = 0; i < segments.length; ++i) { |
| check += segments[i].cnt; |
| |
| if (mc[i] != segments[i].modCnt) { |
| check = -1; // force retry |
| |
| break; |
| } |
| } |
| } |
| |
| if (check == sum) |
| break; |
| } |
| |
| if (check != sum) { // Resort to locking all segments |
| sum = 0; |
| |
| for (Segment<K, V> segment : segments) |
| segment.readLock().lock(); |
| |
| for (Segment<K, V> segment : segments) |
| sum += segment.cnt; |
| |
| for (Segment<K, V> segment : segments) |
| segment.readLock().unlock(); |
| } |
| |
| return sum > Integer.MAX_VALUE ? Integer.MAX_VALUE : (int)sum; |
| } |
| |
| /** |
| * @return The number of key-value mappings in this map (constant-time). |
| */ |
| public int sizex() { |
| int i = size.intValue(); |
| |
| return i > 0 ? i : 0; |
| } |
| |
| /** |
| * @return <tt>true</tt> if this map contains no key-value mappings |
| */ |
| public boolean isEmptyx() { |
| return sizex() == 0; |
| } |
| |
| /** |
| * 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 |
| */ |
| @Override public V get(Object key) { |
| int hash = hash(key.hashCode()); |
| |
| return segmentFor(hash).get(key, hash); |
| } |
| |
| /** |
| * 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.) |
| * |
| * In contrast with {@link #get(Object)} this method acquires |
| * read lock on segment where the key is mapped. |
| * |
| * @throws NullPointerException if the specified key is null |
| */ |
| public V getSafe(Object key) { |
| int hash = hash(key.hashCode()); |
| |
| return segmentFor(hash).getSafe(key, hash); |
| } |
| |
| /** |
| * Tests if the specified object is a key in this table. |
| * |
| * @param key possible key |
| * @return <tt>true</tt> if and only if the specified object |
| * is a key in this table, as determined by the |
| * <tt>equals</tt> method; <tt>false</tt> otherwise. |
| * @throws NullPointerException if the specified key is null |
| */ |
| @Override public boolean containsKey(Object key) { |
| int hash = hash(key.hashCode()); |
| |
| return segmentFor(hash).containsKey(key, hash); |
| } |
| |
| /** |
| * Returns <tt>true</tt> if this map maps one or more keys to the |
| * specified value. Note: This method requires a full internal |
| * traversal of the hash table, and so is much slower than |
| * method <tt>containsKey</tt>. |
| * |
| * @param val value whose presence in this map is to be tested |
| * @return <tt>true</tt> if this map maps one or more keys to the |
| * specified value |
| * @throws NullPointerException if the specified value is null |
| */ |
| @SuppressWarnings({"LockAcquiredButNotSafelyReleased"}) |
| @Override public boolean containsValue(Object val) { |
| if (val == null) |
| throw new NullPointerException(); |
| |
| // See explanation of modCount use above |
| |
| Segment<K, V>[] segments = this.segments; |
| int[] mc = new int[segments.length]; |
| |
| // Try a few times without locking |
| for (int k = 0; k < RETRIES_BEFORE_LOCK; ++k) { |
| int mcsum = 0; |
| |
| for (int i = 0; i < segments.length; ++i) { |
| mcsum += mc[i] = segments[i].modCnt; |
| |
| if (segments[i].containsValue(val)) |
| return true; |
| } |
| |
| boolean cleanSweep = true; |
| |
| if (mcsum != 0) { |
| for (int i = 0; i < segments.length; ++i) { |
| if (mc[i] != segments[i].modCnt) { |
| cleanSweep = false; |
| |
| break; |
| } |
| } |
| } |
| |
| if (cleanSweep) |
| return false; |
| } |
| |
| // Resort to locking all segments |
| for (Segment<K, V> segment : segments) |
| segment.readLock().lock(); |
| |
| boolean found = false; |
| |
| try { |
| for (Segment<K, V> segment : segments) { |
| if (segment.containsValue(val)) { |
| found = true; |
| |
| break; |
| } |
| } |
| } finally { |
| for (Segment<K, V> segment : segments) |
| segment.readLock().unlock(); |
| } |
| |
| return found; |
| } |
| |
| /** |
| * 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 val a value to search for |
| * @return <tt>true</tt> if and only if some key maps to the |
| * <tt>value</tt> argument in this table as |
| * determined by the <tt>equals</tt> method; |
| * <tt>false</tt> otherwise |
| * @throws NullPointerException if the specified value is null |
| */ |
| public boolean contains(Object val) { |
| return containsValue(val); |
| } |
| |
| /** |
| * 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 <tt>get</tt> method |
| * with a key that is equal to the original key. |
| * |
| * @param key key with which the specified value is to be associated |
| * @param val value to be associated with the specified key |
| * @return the previous value associated with <tt>key</tt>, or |
| * <tt>null</tt> if there was no mapping for <tt>key</tt> |
| * @throws NullPointerException if the specified key or value is null |
| */ |
| @Override public V put(K key, V val) { |
| if (val == null) |
| throw new NullPointerException(); |
| |
| int hash = hash(key.hashCode()); |
| |
| return segmentFor(hash).put(key, hash, val, false); |
| } |
| |
| /** |
| * {@inheritDoc} |
| * |
| * @return the previous value associated with the specified key, |
| * or <tt>null</tt> if there was no mapping for the key |
| * @throws NullPointerException if the specified key or value is null |
| */ |
| @Override public V putIfAbsent(K key, V val) { |
| if (val == null) |
| throw new NullPointerException(); |
| |
| int hash = hash(key.hashCode()); |
| |
| return segmentFor(hash).put(key, hash, val, true); |
| } |
| |
| /** |
| * 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 |
| */ |
| @Override public void putAll(Map<? extends K, ? extends V> m) { |
| for (Map.Entry<? extends K, ? extends V> e : m.entrySet()) |
| put(e.getKey(), e.getValue()); |
| } |
| |
| /** |
| * 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 <tt>key</tt>, or |
| * <tt>null</tt> if there was no mapping for <tt>key</tt> |
| * @throws NullPointerException if the specified key is null |
| */ |
| @Override public V remove(Object key) { |
| int hash = hash(key.hashCode()); |
| |
| return segmentFor(hash).remove(key, hash, null, true); |
| } |
| |
| /** |
| * {@inheritDoc} |
| * |
| * @throws NullPointerException if the specified key is null |
| */ |
| @Override public boolean remove(Object key, Object val) { |
| int hash = hash(key.hashCode()); |
| |
| return val != null && segmentFor(hash).remove(key, hash, val, true) != null; |
| } |
| |
| /** |
| * {@inheritDoc} |
| * |
| * @throws NullPointerException if any of the arguments are null |
| */ |
| @Override public boolean replace(K key, V oldVal, V newVal) { |
| if (oldVal == null || newVal == null) |
| throw new NullPointerException(); |
| |
| int hash = hash(key.hashCode()); |
| |
| return segmentFor(hash).replace(key, hash, oldVal, newVal); |
| } |
| |
| /** |
| * Replaces the entry for a key only if currently mapped to a given value. |
| * This is equivalent to |
| * <pre> |
| * if (map.containsKey(key)) { |
| * if (map.get(key).equals(oldValue)) { |
| * map.put(key, newValue); |
| * return oldValue; |
| * } else |
| * return map.get(key); |
| * } else return null;</pre> |
| * except that the action is performed atomically. |
| * |
| * @param key key with which the specified value is associated |
| * @param oldVal value expected to be associated with the specified key |
| * @param newVal value to be associated with the specified key |
| * @return {@code oldVal}, if value was replaced, non-null previous value if map |
| * contained some other value and {@code null} if there were no such key. |
| */ |
| public V replacex(K key, V oldVal, V newVal) { |
| if (oldVal == null || newVal == null) |
| throw new NullPointerException(); |
| |
| int hash = hash(key.hashCode()); |
| |
| return segmentFor(hash).replacex(key, hash, oldVal, newVal); |
| } |
| |
| /** |
| * {@inheritDoc} |
| * |
| * @return the previous value associated with the specified key, |
| * or <tt>null</tt> if there was no mapping for the key |
| * @throws NullPointerException if the specified key or value is null |
| */ |
| @Override public V replace(K key, V val) { |
| if (val == null) |
| throw new NullPointerException(); |
| |
| int hash = hash(key.hashCode()); |
| |
| return segmentFor(hash).replace(key, hash, val); |
| } |
| |
| /** |
| * Removes all of the mappings from this map. |
| */ |
| @Override public void clear() { |
| throw new UnsupportedOperationException(); |
| } |
| |
| /** |
| * 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. The set supports element |
| * removal, which removes the corresponding mapping from this map, |
| * via the <tt>Iterator.remove</tt>, <tt>Set.remove</tt>, |
| * <tt>removeAll</tt>, <tt>retainAll</tt>, and <tt>clear</tt> |
| * operations. It does not support the <tt>add</tt> or |
| * <tt>addAll</tt> operations. |
| * |
| * <p>The view's <tt>iterator</tt> 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. |
| */ |
| @Override public Set<K> keySet() { |
| Set<K> ks = keySet; |
| |
| return (ks != null) ? ks : (keySet = new KeySet()); |
| } |
| |
| /** |
| * Returns a {@link Set} view of the keys contained in this map |
| * in descending order. |
| * 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 this map, |
| * via the <tt>Iterator.remove</tt>, <tt>Set.remove</tt>, |
| * <tt>removeAll</tt>, <tt>retainAll</tt>, and <tt>clear</tt> |
| * operations. It does not support the <tt>add</tt> or |
| * <tt>addAll</tt> operations. |
| * |
| * <p>The view's <tt>iterator</tt> 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<K> descendingKeySet() { |
| Set<K> ks = descKeySet; |
| |
| return (ks != null) ? ks : (descKeySet = new KeySetDescending()); |
| } |
| |
| /** |
| * 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. The collection |
| * supports element removal, which removes the corresponding |
| * mapping from this map, via the <tt>Iterator.remove</tt>, |
| * <tt>Collection.remove</tt>, <tt>removeAll</tt>, |
| * <tt>retainAll</tt>, and <tt>clear</tt> operations. It does not |
| * support the <tt>add</tt> or <tt>addAll</tt> operations. |
| * |
| * <p>The view's <tt>iterator</tt> 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. |
| */ |
| @Override public Collection<V> values() { |
| Collection<V> vs = vals; |
| |
| return (vs != null) ? vs : (vals = new Values()); |
| } |
| |
| /** |
| * Returns a {@link Collection} view of the values contained in this map |
| * in descending order. |
| * The collection is backed by the map, so changes to the map are |
| * reflected in the collection, and vice-versa. The collection |
| * supports element removal, which removes the corresponding |
| * mapping from this map, via the <tt>Iterator.remove</tt>, |
| * <tt>Collection.remove</tt>, <tt>removeAll</tt>, |
| * <tt>retainAll</tt>, and <tt>clear</tt> operations. It does not |
| * support the <tt>add</tt> or <tt>addAll</tt> operations. |
| * |
| * <p>The view's <tt>iterator</tt> 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 Collection<V> descendingValues() { |
| Collection<V> vs = descVals; |
| |
| return (vs != null) ? vs : (descVals = new ValuesDescending()); |
| } |
| |
| /** |
| * 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 <tt>Iterator.remove</tt>, <tt>Set.remove</tt>, |
| * <tt>removeAll</tt>, <tt>retainAll</tt>, and <tt>clear</tt> |
| * operations. It does not support the <tt>add</tt> or |
| * <tt>addAll</tt> operations. |
| * |
| * <p>The view's <tt>iterator</tt> 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. |
| */ |
| @Override public Set<Map.Entry<K, V>> entrySet() { |
| Set<Map.Entry<K, V>> es = entrySet; |
| |
| return (es != null) ? es : (entrySet = new EntrySet()); |
| } |
| |
| /** |
| * Returns a {@link Set} view of the mappings contained in this map |
| * in descending order. |
| * 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 <tt>Iterator.remove</tt>, <tt>Set.remove</tt>, |
| * <tt>removeAll</tt>, <tt>retainAll</tt>, and <tt>clear</tt> |
| * operations. It does not support the <tt>add</tt> or |
| * <tt>addAll</tt> operations. |
| * |
| * <p>The view's <tt>iterator</tt> 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>> descendingEntrySet() { |
| Set<Map.Entry<K, V>> es = descEntrySet; |
| |
| return (es != null) ? es : (descEntrySet = new EntrySetDescending()); |
| } |
| |
| /** |
| * 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(true); |
| } |
| |
| /** |
| * Returns an enumeration of the keys in this table in descending order. |
| * |
| * @return an enumeration of the keys in this table in descending order. |
| * @see #keySet() |
| */ |
| public Enumeration<K> descendingKeys() { |
| return new KeyIterator(false); |
| } |
| |
| /** |
| * 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(true); |
| } |
| |
| /** |
| * Returns an enumeration of the values in this table in descending order. |
| * |
| * @return an enumeration of the values in this table in descending order. |
| * @see #values() |
| */ |
| public Enumeration<V> descendingElements() { |
| return new ValueIterator(false); |
| } |
| |
| /** |
| * This method is called by hash map whenever a new entry is inserted into map. |
| * <p> |
| * This method is called outside the segment-protection lock and may be called concurrently. |
| * |
| * @param e The new inserted entry. |
| */ |
| @SuppressWarnings({"unchecked"}) |
| private void recordInsert(HashEntry e, ConcurrentLinkedDeque8 q) { |
| e.node = q.addx(e); |
| } |
| |
| /** |
| * Concurrently removes eldest entry from the map. |
| */ |
| private void checkRemoveEldestEntry() { |
| assert maxCap > 0; |
| assert qPlc == SINGLE_Q; |
| |
| int sizex = sizex(); |
| |
| for (int i = maxCap; i < sizex; i++) { |
| HashEntry<K, V> e = entryQ.poll(); |
| |
| if (e != null) |
| segmentFor(e.hash).remove(e.key, e.hash, e.val, false); |
| else |
| return; |
| |
| if (sizex() <= maxCap) |
| return; |
| } |
| } |
| |
| /** |
| * This method is intended for test purposes only. |
| * |
| * @return Queue. |
| */ |
| public ConcurrentLinkedDeque8<HashEntry<K, V>> queue() { |
| return entryQ; |
| } |
| |
| /** |
| * @return Queue policy. |
| */ |
| public QueuePolicy policy() { |
| return qPlc; |
| } |
| |
| /** |
| * Class implementing iteration over map entries. |
| */ |
| private abstract class HashIterator { |
| /** Underlying collection iterator. */ |
| private Iterator<HashEntry<K, V>> delegate; |
| |
| /** Last returned entry, used in {@link #remove()} method. */ |
| private HashEntry<K, V> lastReturned; |
| |
| /** Next entry to return */ |
| private HashEntry<K, V> nextEntry; |
| |
| /** The map modification count at the creation time. */ |
| private int modCnt; |
| |
| /** |
| * @param asc {@code True} for ascending iterator. |
| */ |
| HashIterator(boolean asc) { |
| modCnt = ConcurrentLinkedHashMap.this.modCnt.intValue(); |
| |
| // Init delegate. |
| switch (qPlc) { |
| case SINGLE_Q: |
| delegate = asc ? entryQ.iterator() : entryQ.descendingIterator(); |
| |
| break; |
| |
| default: |
| assert qPlc == PER_SEGMENT_Q || qPlc == PER_SEGMENT_Q_OPTIMIZED_RMV : qPlc; |
| |
| delegate = new HashIteratorDelegate(); |
| } |
| |
| advance(); |
| } |
| |
| /** |
| * @return {@code true} If iterator has elements to iterate. |
| */ |
| public boolean hasMoreElements() { |
| return hasNext(); |
| } |
| |
| /** |
| * @return {@code true} If iterator has elements to iterate. |
| */ |
| public boolean hasNext() { |
| return nextEntry != null; |
| } |
| |
| /** |
| * @return Next entry. |
| */ |
| HashEntry<K, V> nextEntry() { |
| if (nextEntry == null) |
| throw new NoSuchElementException(); |
| |
| lastReturned = nextEntry; |
| |
| advance(); |
| |
| return lastReturned; |
| } |
| |
| /** |
| * Removes entry returned by {@link #nextEntry()}. |
| */ |
| public void remove() { |
| if (lastReturned == null) |
| throw new IllegalStateException(); |
| |
| ConcurrentLinkedHashMap.this.remove(lastReturned.key); |
| |
| lastReturned = null; |
| } |
| |
| /** |
| * Moves iterator to the next position. |
| */ |
| private void advance() { |
| nextEntry = null; |
| |
| while (delegate.hasNext()) { |
| HashEntry<K, V> n = delegate.next(); |
| |
| if (n.modCnt <= modCnt) { |
| nextEntry = n; |
| |
| break; |
| } |
| } |
| } |
| } |
| |
| /** |
| * |
| */ |
| private class HashIteratorDelegate implements Iterator<HashEntry<K, V>> { |
| /** */ |
| private HashEntry<K, V>[] curTbl; |
| |
| /** */ |
| private int nextSegIdx; |
| |
| /** */ |
| private int nextTblIdx; |
| |
| /** */ |
| private HashEntry<K, V> next; |
| |
| /** */ |
| private HashEntry<K, V> next0; |
| |
| /** */ |
| private HashEntry<K, V> cur; |
| |
| /** |
| * |
| */ |
| public HashIteratorDelegate() { |
| nextSegIdx = segments.length - 1; |
| nextTblIdx = -1; |
| |
| advance(); |
| } |
| |
| /** |
| * |
| */ |
| private void advance() { |
| if (next0 != null && advanceInBucket(next0, true)) |
| return; |
| |
| while (nextTblIdx >= 0) { |
| HashEntry<K, V> bucket = curTbl[nextTblIdx--]; |
| |
| if (bucket != null && advanceInBucket(bucket, false)) |
| return; |
| } |
| |
| while (nextSegIdx >= 0) { |
| int nextSegIdx0 = nextSegIdx--; |
| |
| Segment seg = segments[nextSegIdx0]; |
| |
| curTbl = seg.tbl; |
| |
| for (int j = curTbl.length - 1; j >= 0; --j) { |
| HashEntry<K, V> bucket = curTbl[j]; |
| |
| if (bucket != null && advanceInBucket(bucket, false)) { |
| nextTblIdx = j - 1; |
| |
| return; |
| } |
| } |
| } |
| } |
| |
| /** |
| * @param e Current next. |
| * @return {@code True} if advance succeeded. |
| */ |
| private boolean advanceInBucket(@Nullable HashEntry<K, V> e, boolean skipFirst) { |
| if (e == null) |
| return false; |
| |
| next0 = e; |
| |
| do { |
| if (!skipFirst) { |
| next = next0; |
| |
| return true; |
| } |
| else |
| skipFirst = false; |
| } |
| while ((next0 = next0.next) != null); |
| |
| assert next0 == null; |
| |
| next = null; |
| |
| return false; |
| } |
| |
| /** {@inheritDoc} */ |
| @Override public boolean hasNext() { |
| return next != null; |
| } |
| |
| /** {@inheritDoc} */ |
| @Override public HashEntry<K, V> next() { |
| HashEntry<K, V> e = next; |
| |
| if (e == null) |
| throw new NoSuchElementException(); |
| |
| advance(); |
| |
| return e; |
| } |
| |
| /** {@inheritDoc} */ |
| @Override public void remove() { |
| if (cur == null) |
| throw new IllegalStateException(); |
| |
| HashEntry<K, V> e = cur; |
| |
| cur = null; |
| |
| ConcurrentLinkedHashMap.this.remove(e.key, e.val); |
| } |
| } |
| |
| /** |
| * Key iterator implementation. |
| */ |
| private final class KeyIterator extends HashIterator implements Iterator<K>, Enumeration<K> { |
| /** |
| * @param asc {@code True} for ascending iterator. |
| */ |
| private KeyIterator(boolean asc) { |
| super(asc); |
| } |
| |
| /** {@inheritDoc} */ |
| @Override public K next() { |
| return nextEntry().key; |
| } |
| |
| /** {@inheritDoc} */ |
| @Override public K nextElement() { |
| return nextEntry().key; |
| } |
| } |
| |
| /** |
| * Value iterator implementation. |
| */ |
| private final class ValueIterator extends HashIterator implements Iterator<V>, Enumeration<V> { |
| /** |
| * @param asc {@code True} for ascending iterator. |
| */ |
| private ValueIterator(boolean asc) { |
| super(asc); |
| } |
| |
| /** {@inheritDoc} */ |
| @Override public V next() { |
| return nextEntry().val; |
| } |
| |
| /** {@inheritDoc} */ |
| @Override public V nextElement() { |
| return nextEntry().val; |
| } |
| } |
| |
| /** |
| * Custom Entry class used by EntryIterator.next(), that relays |
| * setValue changes to the underlying map. |
| */ |
| private final class WriteThroughEntry extends AbstractMap.SimpleEntry<K, V> { |
| /** |
| * @param k Key |
| * @param v Value |
| */ |
| WriteThroughEntry(K k, V v) { |
| super(k,v); |
| } |
| |
| /** |
| * Set our entry's value and write through to the map. The |
| * value to return is somewhat arbitrary here. Since a |
| * WriteThroughEntry does 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. |
| */ |
| @Override public V setValue(V val) { |
| if (val == null) |
| throw new NullPointerException(); |
| |
| V v = super.setValue(val); |
| |
| put(getKey(), val); |
| |
| return v; |
| } |
| } |
| |
| /** |
| * Entry iterator implementation. |
| */ |
| private final class EntryIterator extends HashIterator implements Iterator<Entry<K, V>> { |
| /** |
| * @param asc {@code True} for ascending iterator. |
| */ |
| private EntryIterator(boolean asc) { |
| super(asc); |
| } |
| |
| /** {@inheritDoc} */ |
| @Override public Map.Entry<K, V> next() { |
| HashEntry<K, V> e = nextEntry(); |
| |
| return new WriteThroughEntry(e.key, e.val); |
| } |
| } |
| |
| /** |
| * Key set of the map. |
| */ |
| private abstract class AbstractKeySet extends AbstractSet<K> { |
| /** {@inheritDoc} */ |
| @Override public int size() { |
| return ConcurrentLinkedHashMap.this.size(); |
| } |
| |
| /** {@inheritDoc} */ |
| @Override public boolean contains(Object o) { |
| return containsKey(o); |
| } |
| |
| /** {@inheritDoc} */ |
| @Override public boolean remove(Object o) { |
| return ConcurrentLinkedHashMap.this.remove(o) != null; |
| } |
| |
| /** {@inheritDoc} */ |
| @Override public void clear() { |
| ConcurrentLinkedHashMap.this.clear(); |
| } |
| } |
| |
| /** |
| * Key set of the map. |
| */ |
| private final class KeySet extends AbstractKeySet { |
| /** {@inheritDoc} */ |
| @Override public Iterator<K> iterator() { |
| return new KeyIterator(true); |
| } |
| } |
| |
| /** |
| * Key set of the map. |
| */ |
| private final class KeySetDescending extends AbstractKeySet { |
| /** {@inheritDoc} */ |
| @Override public Iterator<K> iterator() { |
| return new KeyIterator(false); |
| } |
| } |
| |
| /** |
| * Values collection of the map. |
| */ |
| private abstract class AbstractValues extends AbstractCollection<V> { |
| /** {@inheritDoc} */ |
| @Override public int size() { |
| return ConcurrentLinkedHashMap.this.size(); |
| } |
| |
| /** {@inheritDoc} */ |
| @Override public boolean contains(Object o) { |
| return containsValue(o); |
| } |
| |
| /** {@inheritDoc} */ |
| @Override public void clear() { |
| ConcurrentLinkedHashMap.this.clear(); |
| } |
| } |
| |
| /** |
| * Values collection of the map. |
| */ |
| private final class Values extends AbstractValues { |
| /** {@inheritDoc} */ |
| @Override public Iterator<V> iterator() { |
| return new ValueIterator(true); |
| } |
| } |
| |
| /** |
| * Values collection of the map. |
| */ |
| private final class ValuesDescending extends AbstractValues { |
| /** {@inheritDoc} */ |
| @Override public Iterator<V> iterator() { |
| return new ValueIterator(false); |
| } |
| } |
| |
| /** |
| * Entry set implementation. |
| */ |
| private abstract class AbstractEntrySet extends AbstractSet<Map.Entry<K, V>> { |
| /** {@inheritDoc} */ |
| @Override public boolean contains(Object o) { |
| if (!(o instanceof Map.Entry)) |
| return false; |
| |
| Map.Entry<?,?> e = (Map.Entry<?,?>)o; |
| |
| V v = get(e.getKey()); |
| |
| return v != null && v.equals(e.getValue()); |
| } |
| |
| /** {@inheritDoc} */ |
| @Override public boolean remove(Object o) { |
| if (!(o instanceof Map.Entry)) |
| return false; |
| |
| Map.Entry<?,?> e = (Map.Entry<?,?>)o; |
| |
| return ConcurrentLinkedHashMap.this.remove(e.getKey(), e.getValue()); |
| } |
| |
| /** {@inheritDoc} */ |
| @Override public int size() { |
| return ConcurrentLinkedHashMap.this.size(); |
| } |
| |
| /** {@inheritDoc} */ |
| @Override public void clear() { |
| ConcurrentLinkedHashMap.this.clear(); |
| } |
| } |
| |
| /** |
| * Entry set implementation. |
| */ |
| private final class EntrySet extends AbstractEntrySet { |
| /** {@inheritDoc} */ |
| @Override public Iterator<Map.Entry<K, V>> iterator() { |
| return new EntryIterator(true); |
| } |
| } |
| |
| /** |
| * Entry set implementation. |
| */ |
| private final class EntrySetDescending extends AbstractEntrySet { |
| /** {@inheritDoc} */ |
| @Override public Iterator<Map.Entry<K, V>> iterator() { |
| return new EntryIterator(false); |
| } |
| } |
| |
| /** |
| * Defines queue policy for this hash map. |
| */ |
| @SuppressWarnings("PublicInnerClass") |
| public enum QueuePolicy { |
| /** |
| * Default policy. Single queue is maintained. Iteration order is preserved. |
| */ |
| SINGLE_Q, |
| |
| /** |
| * Instance of {@code ArrayDeque} is created for each segment. This gives |
| * the fastest "natural" evicts for bounded maps. |
| * <p> |
| * NOTE: Remove operations on map are slower than with other policies. |
| * <p> |
| * NOTE: Iteration order is not preserved, i.e. iteration goes as if it was ordinary hash map. |
| */ |
| PER_SEGMENT_Q, |
| |
| /** |
| * Instance of {@code GridConcurrentLinkedDequeue} is created for each segment. This gives |
| * faster "natural" evicts for bounded queues and better remove operation times. |
| * <p> |
| * NOTE: Iteration order is not preserved, i.e. iteration goes as if it was ordinary hash map. |
| */ |
| PER_SEGMENT_Q_OPTIMIZED_RMV |
| } |
| } |