/**
* Copyright (c) 2014, the Railo Company Ltd.
* Copyright (c) 2015, Lucee Assosication Switzerland
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library. If not, see <http://www.gnu.org/licenses/>.
*
*/
package lucee.commons.collection.concurrent;
import java.io.IOException;
import java.io.Serializable;
import java.util.AbstractCollection;
import java.util.AbstractMap;
import java.util.AbstractSet;
import java.util.Collection;
import java.util.ConcurrentModificationException;
import java.util.Enumeration;
import java.util.Hashtable;
import java.util.Iterator;
import java.util.Map;
import java.util.NoSuchElementException;
import java.util.Set;
import java.util.TreeMap;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.ConcurrentMap;
import java.util.concurrent.atomic.AtomicInteger;
import java.util.concurrent.locks.ReentrantLock;
import lucee.commons.collection.AbstractMapPro;
import lucee.runtime.exp.PageException;
import lucee.runtime.type.KeyImpl;
/**
* <p>Concurrent hash map and linked list implementation of the
* <tt>ConcurrentMap</tt> interface, with predictable iteration order.
* This implementation differs from <tt>ConcurrentHashMap</tt> in that it
* maintains a doubly-linked list running through all of its entries.
* This linked list defines the iteration ordering, which is normally the
* order in which keys were inserted into the map (<i>insertion-order</i>).
* 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>This implementation spares its clients from the unspecified, generally
* chaotic ordering provided by {@link ConcurrentHashMap} (and {@link Hashtable}),
* without incurring the increased cost associated with {@link TreeMap}. It
* can be used to produce a copy of a map that has the same order as the
* original, regardless of the original map's implementation:
* <pre>
* void foo(Map m) {
* Map copy = new ConcurrentLinkedHashMap(m);
* ...
* }
* </pre>
* This technique is particularly useful if a module takes a map on input,
* copies it, and later returns results whose order is determined by that of
* the copy. (Clients generally appreciate having things returned in the same
* order they were presented.)
*
* <p>A special {@link #ConcurrentLinkedHashMap(int,float,int, int,{@link EvictionPolicy}) constructor}
* is provided to create a concurrent linked hash map whose order of iteration
* is the order designated by the relevant eviction policy class. Invoking the
* <tt>put</tt> or <tt>get</tt> method results in an access to the corresponding
* entry (assuming it exists after the invocation completes). The <tt>putAll</tt>
* method generates one entry access for each mapping in the specified map, in the
* order that key-value mappings are provided by the specified map's entry set iterator.
* <i>No other methods generate entry accesses.</i> In particular, operations on
* collection-views do <i>not</i> affect the order of iteration of the backing
* map.
*
* <p>The {@link #removeEldestEntry(Map.Entry)} method may be overridden to
* impose a policy for removing stale mappings automatically when new mappings
* are added to the map.
*
* Performance is likely to be just slightly below that of <tt>ComcurrentHashMap</tt>,
* due to the added expense of maintaining the linked list, with one exception:
* Iteration over the collection-views of a <tt>ConcurrentLinkedHashMap</tt> requires
* time proportional to the <i>size</i> of the map, regardless of its capacity.
* Iteration over a <tt>ConcurrentHashMap</tt> is likely to be more expensive,
* requiring time proportional to its <i>capacity</i>.
*
*
* @author Justin Cater - Original code by Doug Lea
* @param <K> the type of keys maintained by this map
* @param <V> the type of mapped values
*
*/
public class ConcurrentLinkedHashMapPro<K,V> extends AbstractMapPro<K, V>
implements ConcurrentMap<K, V>, Serializable {
private static final long serialVersionUID = -6894959298396386516L;
/*
* 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.
*/
static final int DEFAULT_INITIAL_CAPACITY = 16;
/**
* The default load factor for this table, used when not
* otherwise specified in a constructor.
*/
static final float DEFAULT_LOAD_FACTOR = 0.75f;
/**
* The default concurrency level for this table, used when not
* otherwise specified in a constructor.
*/
static final int DEFAULT_CONCURRENCY_LEVEL = 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.
*/
static final int MAXIMUM_CAPACITY = 1 << 30;
/**
* The maximum number of segments to allow; used to bound
* constructor arguments.
*/
static final int MAX_SEGMENTS = 1 << 16; // slightly conservative
/**
* Number of unsynchronized retries in size and 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.
*/
static final int RETRIES_BEFORE_LOCK = 2;
/**
* The maxSize attribute defines the maximum number of name/value
* pairs the map will hold. The Integer.MAX_VALUE mark disables this upper bound
* limit.
*/
static final int UNLIMITED_SIZE = Integer.MAX_VALUE;
/* ---------------- Fields -------------- */
/**
* Mask value for indexing into segments. The upper bits of a
* key's hash code are used to choose the segment.
*/
final int segmentMask;
/**
* Shift value for indexing within segments.
*/
final int segmentShift;
/**
* The segments, each of which is a specialized hash table
*/
final Segment<K,V>[] segments;
/**
* The eviction policy to be used
*/
final EvictionPolicy evictionPolicy;
/**
* The maxSize attribute defines the maximum number of name/value
* pairs the map will hold. The UNLIMITED_SIZE mark disables
* this upper bound limit.
*/
final int maxSize;
/**
* The head of the doubly linked list.
*/
transient HashEntry<K,V> header;
/**
* The lock for atomic access to the doubly linked list.
*/
transient ReentrantLock modifyListLock;
transient Set<K> keySet;
transient Set<Map.Entry<K,V>> entrySet;
transient Collection<V> values;
/* ---------------- 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.
*/
private static int hash(Object k) {
if(k instanceof KeyImpl) return ((KeyImpl) k).wangJenkinsHash();
// Spread bits to regularize both segment and index locations,
// using variant of single-word Wang/Jenkins hash.
int h=k.hashCode();
h += (h << 15) ^ 0xffffcd7d;
h ^= (h >>> 10);
h += (h << 3);
h ^= (h >>> 6);
h += (h << 2) + (h << 14);
return h ^ (h >>> 16);
}
/**
* Returns the segment that should be used for key with given hash
* @param hash the hash code for the key
* @return the segment
*/
final 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
* backup in case a null (pre-initialized) value is ever seen in
* an unsynchronized access method.
*/
static final class HashEntry<K,V> implements Entry<K,V> {
final K key;
final int hash;
volatile V value;
HashEntry<K,V> next;
HashEntry<K,V> after;
HashEntry<K,V> before;
long accessCount;
final long creationTime;
long lastAccessedTime;
ReentrantLock modifyListLock;
AtomicInteger cloneAllFlag;
HashEntry(K key, int hash, HashEntry<K,V> next, V value, long accessCount, long creationTime, long lastAccessedTime) {
this.key = key;
this.hash = hash;
this.next = next;
this.value = value;
this.accessCount = accessCount;
this.creationTime = creationTime;
this.lastAccessedTime = lastAccessedTime;
}
@SuppressWarnings("unchecked")
static final <K,V> HashEntry<K,V>[] newArray(int i) {
return new HashEntry[i];
}
/**
* Removes this entry from the linked list.
*/
public void remove() {
before.after = after;
after.before = before;
}
/**
* Inserts this entry before the specified existing entry in the list.
*/
public void addBefore(HashEntry<K,V> existingEntry) {
after = existingEntry;
before = existingEntry.before;
before.after = this;
after.before = this;
}
/**
* This method is invoked by the superclass whenever the value
* of a pre-existing entry is read by Map.get or modified by Map.set.
* If the enclosing Map is access-ordered, it moves the entry
* to the end of the list; otherwise, it does nothing.
*/
void recordAccess(HashEntry<K,V> header, EvictionPolicy evictionPolicy) {
waitForModifyPermition(header);
remove();
addBefore((HashEntry<K, V>)evictionPolicy.recordAccess(header, this));
accessCount++;
lastAccessedTime = System.currentTimeMillis();
grandModifyAndCloneAllPermition(header);
}
/**
* This method is invoked by the superclass whenever a new
* entry is inserted by Map.put
*/
void recordInsertion(HashEntry<K,V> header, EvictionPolicy evictionPolicy) {
waitForModifyPermition(header);
addBefore((HashEntry<K, V>)evictionPolicy.recordInsertion(header, this));
grandModifyAndCloneAllPermition(header);
}
void recordRemoval(HashEntry<K,V> header) {
waitForModifyPermition(header);
remove();
grandModifyAndCloneAllPermition(header);
}
public HashEntry<K,V> clone(HashEntry<K,V> next, HashEntry<K,V> header) {
waitForModifyPermition(header);
HashEntry<K,V> nextEntry = after;
remove();
HashEntry<K,V> theClone = new HashEntry<K, V>(key, hash, next, value, accessCount, creationTime, lastAccessedTime);
theClone.addBefore(nextEntry);
grandModifyAndCloneAllPermition(header);
return theClone;
}
public HashEntry<K,V> cloneAll(HashEntry<K,V> header) {
waitForCloneAllPermition(header);
HashEntry<K,V> rootClone = new HashEntry<K, V>(key, hash, next, value, accessCount, creationTime, lastAccessedTime);
rootClone.before = rootClone.after = rootClone;
HashEntry<K,V> pointer = after;
while(pointer != header) {
HashEntry<K,V> nextClone = new HashEntry<K, V>(pointer.key, pointer.hash, pointer.next, pointer.value, pointer.accessCount, pointer.creationTime, pointer.lastAccessedTime);
nextClone.addBefore(rootClone);
pointer = pointer.after;
}
grandModifyPermition(header);
return rootClone;
}
private void waitForModifyPermition(HashEntry<K,V> header) {
while(!checkForModifyPermition(header)) {
try {
Thread.sleep(0,1);
} catch (InterruptedException e) {}
}
}
private boolean checkForModifyPermition(HashEntry<K,V> header) {
if(header.cloneAllFlag.getAndDecrement() <= 0) {
header.modifyListLock.lock();
return true;
}
header.cloneAllFlag.getAndIncrement();
return false;
}
private void grandModifyAndCloneAllPermition(HashEntry<K,V> header) {
header.modifyListLock.unlock();
header.cloneAllFlag.getAndIncrement();
}
private void waitForCloneAllPermition(HashEntry<K,V> header) {
while(!checkForCloneAllPermition(header)) {
try {
Thread.sleep(0,1);
} catch (InterruptedException e) {}
}
}
private boolean checkForCloneAllPermition(HashEntry<K,V> header) {
if(header.cloneAllFlag.getAndIncrement() >= 0)
return true;
grandModifyPermition(header);
return false;
}
private void grandModifyPermition(HashEntry<K,V> header) {
header.cloneAllFlag.getAndDecrement();
}
@Override
public K getKey() {
return key;
}
@Override
public V getValue() {
return value;
}
@Override
public V setValue(V value) {
V oldValue = this.value;
this.value = value;
return oldValue;
}
@Override
public Entry<K, V> getAfter() {
return after;
}
@Override
public Entry<K, V> getBefore() {
return before;
}
@Override
public long getAccessCount() {
return accessCount;
}
@Override
public long getCreationTime() {
return creationTime;
}
@Override
public long getLastAccessTime() {
return lastAccessedTime;
}
}
/**
* Segments are specialized versions of hash tables. This
* subclasses from ReentrantLock opportunistically, just to
* simplify some locking and avoid separate construction.
*/
static final class Segment<K,V> extends ReentrantLock implements Serializable {
/*
* 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.
*/
private static final long serialVersionUID = 2249069246763182397L;
/**
* The number of elements in this segment's region.
*/
transient volatile int count;
/**
* 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.
*/
transient int modCount;
/**
* The table is rehashed when its size exceeds this threshold.
* (The value of this field is always <tt>(int)(capacity *
* loadFactor)</tt>.)
*/
transient int threshold;
/**
* The per-segment table.
*/
transient volatile HashEntry<K,V>[] table;
/**
* 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.
*
* @serial
*/
final float loadFactor;
/**
* The eviction policy for this linked hash map. Even though this value
* is same for all segments, it is replicated to avoid needing
* links to outer object.
*
* @serial
*/
final EvictionPolicy evictionPolicy;
Segment(int initialCapacity, float lf, EvictionPolicy ep) {
loadFactor = lf;
evictionPolicy = ep;
setTable(HashEntry.<K,V>newArray(initialCapacity));
}
@SuppressWarnings("unchecked")
static final <K,V> Segment<K,V>[] newArray(int i) {
return new Segment[i];
}
/**
* Sets table to new HashEntry array.
* Call only while holding lock or in constructor.
*/
void setTable(HashEntry<K,V>[] newTable) {
threshold = (int)(newTable.length * loadFactor);
table = newTable;
}
/**
* Returns properly casted first entry of bin for given hash.
*/
HashEntry<K,V> getFirst(int hash) {
HashEntry<K,V>[] tab = table;
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.
*/
V readValueUnderLock(HashEntry<K,V> e) {
lock();
try {
return e.value;
} finally {
unlock();
}
}
/* Specialized implementations of map methods */
V get(Object key, int hash, HashEntry<K, V> header, V defaultValue) {
if (count != 0) { // read-volatile
HashEntry<K,V> e = getFirst(hash);
while (e != null) {
if (e.hash == hash && key.equals(e.key)) {
V v = e.value;
if (v != null) {
if(evictionPolicy.accessOrder())
e.recordAccess(header, evictionPolicy);
return v;
}
return readValueUnderLock(e); // recheck
}
e = e.next;
}
}
return defaultValue;
}
boolean containsKey(Object key, int hash) {
if (count != 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;
}
boolean containsValue(Object value) {
if (count != 0) { // read-volatile
HashEntry<K,V>[] tab = table;
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.value;
if (v == null) // recheck
v = readValueUnderLock(e);
if (value.equals(v))
return true;
}
}
}
return false;
}
boolean replace(K key, int hash, V oldValue, V newValue) {
lock();
try {
HashEntry<K,V> e = getFirst(hash);
while (e != null && (e.hash != hash || !key.equals(e.key)))
e = e.next;
boolean replaced = false;
if (e != null && oldValue.equals(e.value)) {
replaced = true;
e.value = newValue;
}
return replaced;
} finally {
unlock();
}
}
V replace(K key, int hash, V newValue) {
lock();
try {
HashEntry<K,V> e = getFirst(hash);
while (e != null && (e.hash != hash || !key.equals(e.key)))
e = e.next;
V oldValue = null;
if (e != null) {
oldValue = e.value;
e.value = newValue;
}
return oldValue;
} finally {
unlock();
}
}
V put(K key, int hash, V value, boolean onlyIfAbsent, HashEntry<K, V> header) {
lock();
try {
int c = count;
if (c++ > threshold) // ensure capacity
rehash(header);
HashEntry<K,V>[] tab = table;
int index = hash & (tab.length - 1);
HashEntry<K,V> first = tab[index];
HashEntry<K,V> e = first;
while (e != null && (e.hash != hash || !key.equals(e.key)))
e = e.next;
V oldValue;
if (e != null) {
oldValue = e.value;
if (!onlyIfAbsent)
e.value = value;
}
else {
oldValue = null;
++modCount;
long now = System.currentTimeMillis();
e = new HashEntry<K,V>(key, hash, first, value, 1, now, now);
if(evictionPolicy.insertionOrder())
e.recordInsertion(header, evictionPolicy);
else
e.addBefore(header);
tab[index] = e;
count = c; // write-volatile
}
return oldValue;
} finally {
unlock();
}
}
void rehash(HashEntry<K, V> header) {
HashEntry<K,V>[] oldTable = table;
int oldCapacity = oldTable.length;
if (oldCapacity >= MAXIMUM_CAPACITY)
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.
*/
HashEntry<K,V>[] newTable = HashEntry.newArray(oldCapacity<<1);
threshold = (int)(newTable.length * loadFactor);
int sizeMask = newTable.length - 1;
for (int i = 0; i < oldCapacity ; 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 = oldTable[i];
if (e != null) {
HashEntry<K,V> next = e.next;
int idx = e.hash & sizeMask;
// Single node on list
if (next == null)
newTable[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;
}
}
newTable[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 = newTable[k];
newTable[k] = p.clone(n, header);
}
}
}
}
table = newTable;
}
/**
* Remove; match on key only if value null, else match both.
*/
V remove(Object key, int hash, Object value, HashEntry<K, V> header, V defaultValue) {
lock();
try {
int c = count - 1;
HashEntry<K,V>[] tab = table;
int index = hash & (tab.length - 1);
HashEntry<K,V> first = tab[index];
HashEntry<K,V> e = first;
while (e != null && (e.hash != hash || !key.equals(e.key)))
e = e.next;
V old = defaultValue;
if (e != null) {
if (value == null || value.equals(e.value)) {
old = e.value;
e.recordRemoval(header);
// All entries following removed node can stay
// in list, but all preceding ones need to be
// cloned.
++modCount;
HashEntry<K,V> newFirst = e.next;
for (HashEntry<K,V> p = first; p != e; p = p.next)
newFirst = p.clone(newFirst, header);
tab[index] = newFirst;
count = c; // write-volatile
}
}
return old;
} finally {
unlock();
}
}
/**
* Remove; match on key only if value null, else match both.
* @throws PageException
*/
V removeE(Map<K,V> m,Object key, int hash, Object value, HashEntry<K, V> header) throws PageException {
lock();
try {
int c = count - 1;
HashEntry<K,V>[] tab = table;
int index = hash & (tab.length - 1);
HashEntry<K,V> first = tab[index];
HashEntry<K,V> e = first;
while (e != null && (e.hash != hash || !key.equals(e.key)))
e = e.next;
if (e != null) {
if (value == null || value.equals(e.value)) {
e.recordRemoval(header);
// All entries following removed node can stay
// in list, but all preceding ones need to be
// cloned.
++modCount;
HashEntry<K,V> newFirst = e.next;
for (HashEntry<K,V> p = first; p != e; p = p.next)
newFirst = p.clone(newFirst, header);
tab[index] = newFirst;
count = c; // write-volatile
return e.value;
}
}
throw AbstractMapPro.invalidKey(m, key, true);
} finally {
unlock();
}
}
void clear(HashEntry<K,V> header) {
if (count != 0) {
lock();
try {
HashEntry<K,V>[] tab = table;
for (int i = 0; i < tab.length ; i++) {
if(tab[i] != null){
tab[i].recordRemoval(header);
tab[i] = null;
}
}
++modCount;
count = 0; // write-volatile
} finally {
unlock();
}
}
}
}
/* ---------------- Public operations -------------- */
/**
* Creates a new, empty map with the specified initial
* capacity, load factor, concurrency level, max size and eviction policy.
*
* @param initialCapacity 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 concurrencyLevel the estimated number of concurrently
* updating threads. The implementation performs internal sizing
* to try to accommodate this many threads.
* @param maxSize the maximum number of name/value pairs this map
* will hold.
* @param evictionPolicy the eviction policy to be used
* @throws IllegalArgumentException if the initial capacity is
* negative or the load factor or concurrencyLevel are
* nonpositive.
*/
public ConcurrentLinkedHashMapPro(int initialCapacity,
float loadFactor, int concurrencyLevel, int maxSize, EvictionPolicy evictionPolicy) {
if (!(loadFactor > 0) || initialCapacity < 0 || concurrencyLevel <= 0)
throw new IllegalArgumentException();
this.maxSize = maxSize;
this.evictionPolicy = evictionPolicy;
if (concurrencyLevel > MAX_SEGMENTS)
concurrencyLevel = MAX_SEGMENTS;
// Find power-of-two sizes best matching arguments
int sshift = 0;
int ssize = 1;
while (ssize < concurrencyLevel) {
++sshift;
ssize <<= 1;
}
segmentShift = 32 - sshift;
segmentMask = ssize - 1;
this.segments = Segment.newArray(ssize);
if (initialCapacity > MAXIMUM_CAPACITY)
initialCapacity = MAXIMUM_CAPACITY;
int c = initialCapacity / ssize;
if (c * ssize < initialCapacity)
++c;
int cap = 1;
while (cap < c)
cap <<= 1;
for (int i = 0; i < this.segments.length; ++i)
this.segments[i] = new Segment<K,V>(cap, loadFactor, evictionPolicy);
header = new HashEntry<K,V>(null, -1, null, null, -1, -1, -1);
header.before = header.after = header;
header.modifyListLock = new ReentrantLock();
header.cloneAllFlag = new AtomicInteger();
}
/**
* Creates a new, empty map with the specified initial capacity
* and load factor and with the default concurrencyLevel (16).
*
* @param initialCapacity 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 nonpositive
*
* @since 1.6
*/
public ConcurrentLinkedHashMapPro(int initialCapacity, float loadFactor) {
this(initialCapacity, loadFactor, DEFAULT_CONCURRENCY_LEVEL, UNLIMITED_SIZE, new FIFOPolicy());
}
/**
* Creates a new, empty map with the specified initial capacity,
* and with default load factor (0.75) and concurrencyLevel (16).
*
* @param initialCapacity the initial capacity. The implementation
* performs internal sizing to accommodate this many elements.
* @throws IllegalArgumentException if the initial capacity of
* elements is negative.
*/
public ConcurrentLinkedHashMapPro(int initialCapacity) {
this(initialCapacity, DEFAULT_LOAD_FACTOR, DEFAULT_CONCURRENCY_LEVEL, UNLIMITED_SIZE, new FIFOPolicy());
}
/**
* Creates a new, empty map with a default initial capacity (16),
* load factor (0.75) and concurrencyLevel (16).
*/
public ConcurrentLinkedHashMapPro() {
this(DEFAULT_INITIAL_CAPACITY, DEFAULT_LOAD_FACTOR, DEFAULT_CONCURRENCY_LEVEL, UNLIMITED_SIZE, new FIFOPolicy());
}
/**
* 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 ConcurrentLinkedHashMapPro(Map<? extends K, ? extends V> m) {
this(Math.max((int) (m.size() / DEFAULT_LOAD_FACTOR) + 1,
DEFAULT_INITIAL_CAPACITY),
DEFAULT_LOAD_FACTOR, DEFAULT_CONCURRENCY_LEVEL, UNLIMITED_SIZE, new FIFOPolicy());
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() {
final 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].count != 0)
return false;
mcsum += mc[i] = segments[i].modCount;
}
// 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].count != 0 ||
mc[i] != segments[i].modCount)
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
*/
@Override
public int size() {
final 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].count;
mcsum += mc[i] = segments[i].modCount;
}
if (mcsum != 0) {
for (int i = 0; i < segments.length; ++i) {
check += segments[i].count;
if (mc[i] != segments[i].modCount) {
check = -1; // force retry
break;
}
}
}
if (check == sum)
break;
}
if (check != sum) { // Resort to locking all segments
sum = 0;
for (int i = 0; i < segments.length; ++i)
segments[i].lock();
for (int i = 0; i < segments.length; ++i)
sum += segments[i].count;
for (int i = 0; i < segments.length; ++i)
segments[i].unlock();
}
if (sum > Integer.MAX_VALUE)
return Integer.MAX_VALUE;
return (int)sum;
}
/**
* 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);
return segmentFor(hash).get(key, hash, header,null);
}
@Override
public V g(K key) throws PageException {
int hash = hash(key);
Segment<K, V> seg = segmentFor(hash);
if (seg.count != 0) { // read-volatile
HashEntry<K,V> e = seg.getFirst(hash);
while (e != null) {
if (e.hash == hash && key.equals(e.key)) {
V v = e.value;
if (v != null) {
if(evictionPolicy.accessOrder())
e.recordAccess(header, evictionPolicy);
return v;
}
return seg.readValueUnderLock(e); // recheck
}
e = e.next;
}
}
throw AbstractMapPro.invalidKey(this, key,false);
}
@Override
public V g(K key, V defaultValue) {
int hash = hash(key);
return segmentFor(hash).get(key, hash, header,defaultValue);
}
/**
* 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);
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 value 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
*/
@Override
public boolean containsValue(Object value) {
if (value == null)
throw new NullPointerException();
// See explanation of modCount use above
final 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].modCount;
if (segments[i].containsValue(value))
return true;
}
boolean cleanSweep = true;
if (mcsum != 0) {
for (int i = 0; i < segments.length; ++i) {
if (mc[i] != segments[i].modCount) {
cleanSweep = false;
break;
}
}
}
if (cleanSweep)
return false;
}
// Resort to locking all segments
for (int i = 0; i < segments.length; ++i)
segments[i].lock();
boolean found = false;
try {
for (int i = 0; i < segments.length; ++i) {
if (segments[i].containsValue(value)) {
found = true;
break;
}
}
} finally {
for (int i = 0; i < segments.length; ++i)
segments[i].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 value 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 value) {
return containsValue(value);
}
/**
* Maps the specified key to the specified value in this table.
* Neither the key nor the value can be null.
*
* <p> The value can be retrieved by calling the <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 value 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 value) {
HashEntry<K, V> evictEntry = (HashEntry<K, V>) evictionPolicy.evictElement(header);
if(evictEntry != null && size() >= maxSize)
segmentFor(evictEntry.hash).remove(evictEntry.key, evictEntry.hash, evictEntry.value, header,null);
int hash = hash(key);
return segmentFor(hash).put(key, hash, value, false, header);
}
/**
* {@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 value) {
if (value == null)
throw new NullPointerException();
HashEntry<K, V> evictEntry = (HashEntry<K, V>) evictionPolicy.evictElement(header);
if(evictEntry != null && size() >= maxSize)
segmentFor(evictEntry.hash).remove(evictEntry.key, evictEntry.hash, evictEntry.value, header,null);
int hash = hash(key);
return segmentFor(hash).put(key, hash, value, true, header);
}
/**
* 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);
return segmentFor(hash).remove(key, hash, null, header,null);
}
@Override
public V r(K key) throws PageException {
int hash = hash(key);
return segmentFor(hash).removeE(this,key, hash, null, header);
}
@Override
public V r(K key, V defaultValue) {
int hash = hash(key);
return segmentFor(hash).remove(key, hash, null, header,defaultValue);
}
/**
* {@inheritDoc}
*
* @throws NullPointerException if the specified key is null
*/
@Override
public boolean remove(Object key, Object value) {
int hash = hash(key);
if (value == null)
return false;
return segmentFor(hash).remove(key, hash, value, header,null) != null;
}
/**
* {@inheritDoc}
*
* @throws NullPointerException if any of the arguments are null
*/
@Override
public boolean replace(K key, V oldValue, V newValue) {
if (oldValue == null || newValue == null)
throw new NullPointerException();
int hash = hash(key);
return segmentFor(hash).replace(key, hash, oldValue, newValue);
}
/**
* {@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 value) {
if (value == null)
throw new NullPointerException();
int hash = hash(key);
return segmentFor(hash).replace(key, hash, value);
}
/**
* Removes all of the mappings from this map.
*/
@Override
public void clear() {
for (int i = 0; i < segments.length; ++i)
segments[i].clear(header);
header.before = header.after = header;
}
/**
* Returns <tt>true</tt> if this map should remove its eldest entry.
* This method is invoked by <tt>put</tt> and <tt>putAll</tt> after
* inserting a new entry into the map. It provides the implementor
* with the opportunity to remove the eldest entry each time a new one
* is added. This is useful if the map represents a cache: it allows
* the map to reduce memory consumption by deleting stale entries.
*
* <p>Sample use: this override will allow the map to grow up to 100
* entries and then delete the eldest entry each time a new entry is
* added, maintaining a steady state of 100 entries.
* <pre>
* private static final int MAX_ENTRIES = 100;
*
* protected boolean removeEldestEntry(Map.Entry eldest) {
* return size() > MAX_ENTRIES;
* }
* </pre>
*
* <p>This method typically does not modify the map in any way,
* instead allowing the map to modify itself as directed by its
* return value. It <i>is</i> permitted for this method to modify
* the map directly, but if it does so, it <i>must</i> return
* <tt>false</tt> (indicating that the map should not attempt any
* further modification). The effects of returning <tt>true</tt>
* after modifying the map from within this method are unspecified.
*
* <p>This implementation merely returns <tt>false</tt> (so that this
* map acts like a normal map - the eldest element is never removed).
*
* @param eldest The least recently inserted entry in the map, or if
* this is an access-ordered map, the least recently accessed
* entry. This is the entry that will be removed it this
* method returns <tt>true</tt>. If the map was empty prior
* to the <tt>put</tt> or <tt>putAll</tt> invocation resulting
* in this invocation, this will be the entry that was just
* inserted; in other words, if the map contains a single
* entry, the eldest entry is also the newest.
* @return <tt>true</tt> if the eldest entry should be removed
* from the map; <tt>false</tt> if it should be retained.
*/
protected boolean removeEldestEntry(Map.Entry<K,V> eldest) {
return false;
}
/**
* 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 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 = values;
return (vs != null) ? vs : (values = new Values());
}
/**
* 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 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();
}
/**
* 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();
}
/* ---------------- Iterator Support -------------- */
abstract class HashIterator {
HashEntry<K,V> nextEntry = null;
HashEntry<K,V> lastReturned = null;
HashEntry<K,V> snapshotHeader = null;
HashIterator() {
if(evictionPolicy.recordAccess(header, header) != null)
snapshotHeader = header.cloneAll(header);
else
snapshotHeader = header;
nextEntry = snapshotHeader.after;
}
public boolean hasMoreElements() { return hasNext(); }
public boolean hasNext() { return nextEntry != snapshotHeader; }
HashEntry<K,V> nextEntry() {
if (nextEntry == snapshotHeader)
throw new NoSuchElementException();
HashEntry<K,V> e = lastReturned = nextEntry;
nextEntry = e.after;
return e;
}
public void remove() {
if (lastReturned == null)
throw new IllegalStateException();
ConcurrentLinkedHashMapPro.this.remove(lastReturned.key);
lastReturned = null;
}
}
final class KeyIterator
extends HashIterator
implements Iterator<K>, Enumeration<K>
{
@Override
public K next() { return super.nextEntry().key; }
@Override
public K nextElement() { return super.nextEntry().key; }
}
final class ValueIterator
extends HashIterator
implements Iterator<V>, Enumeration<V>
{
@Override
public V next() { return super.nextEntry().value; }
@Override
public V nextElement() { return super.nextEntry().value; }
}
/**
* Custom Entry class used by EntryIterator.next(), that relays
* setValue changes to the underlying map.
*/
final class WriteThroughEntry
extends AbstractMap.SimpleEntry<K,V> implements Map.Entry<K,V> {
private static final long serialVersionUID = 1573332674915851631L;
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 value) {
if (value == null) throw new NullPointerException();
V v = super.setValue(value);
ConcurrentLinkedHashMapPro.this.put(getKey(), value);
return v;
}
}
final class EntryIterator
extends HashIterator
implements Iterator<Map.Entry<K,V>>
{
@Override
public Map.Entry<K,V> next() {
HashEntry<K,V> e = super.nextEntry();
return new WriteThroughEntry(e.key, e.value);
}
}
final class KeySet extends AbstractSet<K> {
@Override
public Iterator<K> iterator() {
return new KeyIterator();
}
@Override
public int size() {
return ConcurrentLinkedHashMapPro.this.size();
}
@Override
public boolean isEmpty() {
return ConcurrentLinkedHashMapPro.this.isEmpty();
}
@Override
public boolean contains(Object o) {
return ConcurrentLinkedHashMapPro.this.containsKey(o);
}
@Override
public boolean remove(Object o) {
return ConcurrentLinkedHashMapPro.this.remove(o) != null;
}
@Override
public void clear() {
ConcurrentLinkedHashMapPro.this.clear();
}
}
final class Values extends AbstractCollection<V> {
@Override
public Iterator<V> iterator() {
return new ValueIterator();
}
@Override
public int size() {
return ConcurrentLinkedHashMapPro.this.size();
}
@Override
public boolean isEmpty() {
return ConcurrentLinkedHashMapPro.this.isEmpty();
}
@Override
public boolean contains(Object o) {
return ConcurrentLinkedHashMapPro.this.containsValue(o);
}
@Override
public void clear() {
ConcurrentLinkedHashMapPro.this.clear();
}
}
final class EntrySet extends AbstractSet<Map.Entry<K,V>> {
@Override
public Iterator<Map.Entry<K,V>> iterator() {
return new EntryIterator();
}
@Override
public boolean contains(Object o) {
if (!(o instanceof Map.Entry<?,?>))
return false;
Map.Entry<?,?> e = (Map.Entry<?,?>)o;
V v = ConcurrentLinkedHashMapPro.this.get(e.getKey());
return v != null && v.equals(e.getValue());
}
@Override
public boolean remove(Object o) {
if (!(o instanceof Map.Entry<?,?>))
return false;
Map.Entry<?,?> e = (Map.Entry<?,?>)o;
return ConcurrentLinkedHashMapPro.this.remove(e.getKey(), e.getValue());
}
@Override
public int size() {
return ConcurrentLinkedHashMapPro.this.size();
}
@Override
public boolean isEmpty() {
return ConcurrentLinkedHashMapPro.this.isEmpty();
}
@Override
public void clear() {
ConcurrentLinkedHashMapPro.this.clear();
}
}
/* ---------------- Serialization Support -------------- */
/**
* Save the state of the <tt>ConcurrentHashMap</tt> instance to a
* stream (i.e., serialize it).
* @param s the stream
* @serialData
* the key (Object) and value (Object)
* for each key-value mapping, followed by a null pair.
* The key-value mappings are emitted in no particular order.
*/
private void writeObject(java.io.ObjectOutputStream s) throws IOException {
s.defaultWriteObject();
for (int k = 0; k < segments.length; ++k) {
Segment<K,V> seg = segments[k];
seg.lock();
try {
HashEntry<K,V>[] tab = seg.table;
for (int i = 0; i < tab.length; ++i) {
for (HashEntry<K,V> e = tab[i]; e != null; e = e.next) {
s.writeObject(e.key);
s.writeObject(e.value);
}
}
} finally {
seg.unlock();
}
}
s.writeObject(null);
s.writeObject(null);
}
/**
* Reconstitute the <tt>ConcurrentLinkedHashMap</tt> instance from a
* stream (i.e., deserialize it).
* @param s the stream
*/
private void readObject(java.io.ObjectInputStream s)
throws IOException, ClassNotFoundException {
s.defaultReadObject();
// Initialize each segment to be minimally sized, and let grow.
for (int i = 0; i < segments.length; ++i) {
segments[i].setTable(new HashEntry[1]);
}
// Read the keys and values, and put the mappings in the table
for (;;) {
K key = (K) s.readObject();
V value = (V) s.readObject();
if (key == null)
break;
put(key, value);
}
}
public interface Entry<K,V> extends Map.Entry<K, V> {
/**
* Returns the entry before this entry in the entry list.
*/
Entry<K,V> getBefore();
/**
* Returns the entry after this entry in the entry list.
*/
Entry<K,V> getAfter();
/**
* Returns the entry's access count.
*/
long getAccessCount();
/**
* Returns the entry's creation time in milliseconds.
*/
long getCreationTime();
/**
* Returns the entry's last access time in milliseconds.
*/
long getLastAccessTime();
}
}