[jboss-remoting-commits] JBoss Remoting SVN: r4290 - remoting3/trunk/util/src/main/java/org/jboss/cx/remoting/util.
jboss-remoting-commits at lists.jboss.org
jboss-remoting-commits at lists.jboss.org
Wed Jun 11 18:09:16 EDT 2008
Author: david.lloyd at jboss.com
Date: 2008-06-11 18:09:16 -0400 (Wed, 11 Jun 2008)
New Revision: 4290
Modified:
remoting3/trunk/util/src/main/java/org/jboss/cx/remoting/util/ConcurrentReferenceHashMap.java
Log:
Merge -r5968:5969 from https://svn.jboss.org/repos/jbosscache/experimental/jsr166/src/jsr166y/ConcurrentReferenceHashMap.java
Modified: remoting3/trunk/util/src/main/java/org/jboss/cx/remoting/util/ConcurrentReferenceHashMap.java
===================================================================
--- remoting3/trunk/util/src/main/java/org/jboss/cx/remoting/util/ConcurrentReferenceHashMap.java 2008-06-11 04:28:48 UTC (rev 4289)
+++ remoting3/trunk/util/src/main/java/org/jboss/cx/remoting/util/ConcurrentReferenceHashMap.java 2008-06-11 22:09:16 UTC (rev 4290)
@@ -31,11 +31,11 @@
* An advanced hash table supporting configurable garbage collection semantics
* of keys and values, optional referential-equality, full concurrency of
* retrievals, and adjustable expected concurrency for updates.
- *
+ *
* This table is designed around specific advanced use-cases. If there is any
* doubt whether this table is for you, you most likely should be using
* {@link java.util.concurrent.ConcurrentHashMap} instead.
- *
+ *
* This table supports strong, weak, and soft keys and values. By default keys
* are weak, and values are strong. Such a configuration offers similar behavior
* to {@link java.util.WeakHashMap}, entries of this table are periodically
@@ -48,13 +48,13 @@
* <tt>isEmpty</tt> might return a value greater than the observed number of
* entries. In order to support a high level of concurrency, stale entries are
* only reclaimed during blocking (usually mutating) operations.
- *
+ *
* Enabling soft keys allows entries in this table to remain until their space
* is absolutely needed by the garbage collector. This is unlike weak keys which
* can be reclaimed as soon as they are no longer referenced by a normal strong
* reference. The primary use case for soft keys is a cache, which ideally
* occupies memory that is not in use for as long as possible.
- *
+ *
* By default, values are held using a normal strong reference. This provides
* the commonly desired guarantee that a value will always have at least the
* same life-span as it's key. For this reason, care should be taken to ensure
@@ -62,11 +62,11 @@
* preventing reclamation. If this is unavoidable, then it is recommended to use
* the same reference type in use for the key. However, it should be noted that
* non-strong values may disappear before their corresponding key.
- *
+ *
* While this table does allow the use of both strong keys and values, it is
* recommended to use {@link java.util.concurrent.ConcurrentHashMap} for such a
* configuration, since it is optimized for that case.
- *
+ *
* Just like {@link java.util.concurrent.ConcurrentHashMap}, this class obeys
* the same functional specification as {@link java.util.Hashtable}, and
* includes versions of methods corresponding to each method of
@@ -76,7 +76,7 @@
* 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
@@ -89,7 +89,7 @@
* 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>),
@@ -106,19 +106,19 @@
* 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 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.
- *
+ *
* <p>
* This class is a member of the <a href="{@docRoot}/../technotes/guides/collections/index.html">
* Java Collections Framework</a>.
- *
+ *
* @author Doug Lea
* @author Jason T. Greene
* @param <K> the type of keys maintained by this map
@@ -139,27 +139,27 @@
*/
public static enum ReferenceType {
/** Indicates a normal Java strong reference should be used */
- STRONG,
+ STRONG,
/** Indicates a {@link WeakReference} should be used */
WEAK,
/** Indicates a {@link SoftReference} should be used */
SOFT
};
-
-
+
+
public static enum Option {
- /** Indicates that referential-equality (== instead of .equals()) should
+ /** Indicates that referential-equality (== instead of .equals()) should
* be used when locating keys. This offers similar behavior to {@link IdentityHashMap} */
IDENTITY_COMPARISONS
};
-
+
/* ---------------- Constants -------------- */
static final ReferenceType DEFAULT_KEY_TYPE = ReferenceType.WEAK;
-
+
static final ReferenceType DEFAULT_VALUE_TYPE = ReferenceType.STRONG;
-
-
+
+
/**
* The default initial capacity for this table,
* used when not otherwise specified in a constructor.
@@ -217,7 +217,7 @@
* The segments, each of which is a specialized hash table
*/
final Segment<K,V>[] segments;
-
+
boolean identityComparisons;
transient Set<K> keySet;
@@ -252,46 +252,90 @@
final Segment<K,V> segmentFor(int hash) {
return segments[(hash >>> segmentShift) & segmentMask];
}
-
+
private int hashOf(Object key) {
- return hash(identityComparisons ?
+ return hash(identityComparisons ?
System.identityHashCode(key) : key.hashCode());
}
-
+
/* ---------------- Inner Classes -------------- */
-
+
static interface KeyReference {
int keyHash();
+ Object keyRef();
}
-
+
/**
* A weak-key reference which stores the key hash needed for reclamation.
*/
static final class WeakKeyReference<K> extends WeakReference<K> implements KeyReference {
final int hash;
- WeakKeyReference(K key, int hash, ReferenceQueue<K> refQueue) {
+ WeakKeyReference(K key, int hash, ReferenceQueue<Object> refQueue) {
super(key, refQueue);
this.hash = hash;
}
public final int keyHash() {
return hash;
}
+
+ public final Object keyRef() {
+ return this;
+ }
}
-
+
/**
* A soft-key reference which stores the key hash needed for reclamation.
*/
static final class SoftKeyReference<K> extends SoftReference<K> implements KeyReference {
final int hash;
- SoftKeyReference(K key, int hash, ReferenceQueue<K> refQueue) {
+ SoftKeyReference(K key, int hash, ReferenceQueue<Object> refQueue) {
super(key, refQueue);
this.hash = hash;
}
public final int keyHash() {
return hash;
}
+
+ public final Object keyRef() {
+ return this;
+ }
}
-
+
+ static final class WeakValueReference<V> extends WeakReference<V> implements KeyReference {
+ final Object keyRef;
+ final int hash;
+ WeakValueReference(V value, Object keyRef, int hash, ReferenceQueue<Object> refQueue) {
+ super(value, refQueue);
+ this.keyRef = keyRef;
+ this.hash = hash;
+ }
+
+ public final int keyHash() {
+ return hash;
+ }
+
+ public final Object keyRef() {
+ return keyRef;
+ }
+ }
+
+ static final class SoftValueReference<V> extends SoftReference<V> implements KeyReference {
+ final Object keyRef;
+ final int hash;
+ SoftValueReference(V value, Object keyRef, int hash, ReferenceQueue<Object> refQueue) {
+ super(value, refQueue);
+ this.keyRef = keyRef;
+ this.hash = hash;
+ }
+ public final int keyHash() {
+ return hash;
+ }
+
+ public final Object keyRef() {
+ return keyRef;
+ }
+ }
+
/**
* ConcurrentReferenceHashMap list entry. Note that this is never exported
* out as a user-visible Map.Entry.
@@ -310,56 +354,57 @@
volatile Object valueRef;
final HashEntry<K,V> next;
- HashEntry(K key, int hash, HashEntry<K,V> next, V value,
- ReferenceType keyType, ReferenceType valueType,
- ReferenceQueue<K> refQueue) {
- this.keyRef = newKeyReference(key, keyType, hash, refQueue);
+ HashEntry(K key, int hash, HashEntry<K,V> next, V value,
+ ReferenceType keyType, ReferenceType valueType,
+ ReferenceQueue<Object> refQueue) {
this.hash = hash;
this.next = next;
- this.valueRef = newValueReference(value, valueType);
+ this.keyRef = newKeyReference(key, keyType, refQueue);
+ this.valueRef = newValueReference(value, valueType, refQueue);
}
-
- final Object newKeyReference(K key, ReferenceType keyType, int hash,
- ReferenceQueue<K> refQueue) {
+
+ final Object newKeyReference(K key, ReferenceType keyType,
+ ReferenceQueue<Object> refQueue) {
if (keyType == ReferenceType.WEAK)
return new WeakKeyReference<K>(key, hash, refQueue);
if (keyType == ReferenceType.SOFT)
return new SoftKeyReference<K>(key, hash, refQueue);
-
+
return key;
}
-
- final Object newValueReference(V value, ReferenceType valueType) {
+
+ final Object newValueReference(V value, ReferenceType valueType,
+ ReferenceQueue<Object> refQueue) {
if (valueType == ReferenceType.WEAK)
- return new WeakReference<V>(value);
+ return new WeakValueReference<V>(value, keyRef, hash, refQueue);
if (valueType == ReferenceType.SOFT)
- return new SoftReference<V>(value);
-
+ return new SoftValueReference<V>(value, keyRef, hash, refQueue);
+
return value;
}
-
+
@SuppressWarnings("unchecked")
final K key() {
if (keyRef instanceof Reference)
return ((Reference<K>)keyRef).get();
-
+
return (K) keyRef;
}
-
+
final V value() {
return dereferenceValue(valueRef);
}
-
+
@SuppressWarnings("unchecked")
final V dereferenceValue(Object value) {
if (value instanceof Reference)
return ((Reference<V>)value).get();
-
+
return (V) value;
}
-
- final void setValue(V value, ReferenceType valueType) {
- this.valueRef = newValueReference(value, valueType);
+
+ final void setValue(V value, ReferenceType valueType, ReferenceQueue<Object> refQueue) {
+ this.valueRef = newValueReference(value, valueType, refQueue);
}
@SuppressWarnings("unchecked")
@@ -449,18 +494,18 @@
final float loadFactor;
/**
- * The collected weak-key reference queue for this segment.
+ * The collected weak-key reference queue for this segment.
* This should be (re)initialized whenever table is assigned,
*/
- transient volatile ReferenceQueue<K> refQueue;
-
+ transient volatile ReferenceQueue<Object> refQueue;
+
final ReferenceType keyType;
-
+
final ReferenceType valueType;
-
+
final boolean identityComparisons;
-
- Segment(int initialCapacity, float lf, ReferenceType keyType,
+
+ Segment(int initialCapacity, float lf, ReferenceType keyType,
ReferenceType valueType, boolean identityComparisons) {
loadFactor = lf;
this.keyType = keyType;
@@ -473,11 +518,11 @@
static final <K,V> Segment<K,V>[] newArray(int i) {
return new Segment[i];
}
-
+
private boolean keyEq(Object src, Object dest) {
return identityComparisons ? src == dest : src.equals(dest);
}
-
+
/**
* Sets table to new HashEntry array.
* Call only while holding lock or in constructor.
@@ -485,7 +530,7 @@
void setTable(HashEntry<K,V>[] newTable) {
threshold = (int)(newTable.length * loadFactor);
table = newTable;
- refQueue = new ReferenceQueue<K>();
+ refQueue = new ReferenceQueue<Object>();
}
/**
@@ -495,7 +540,7 @@
HashEntry<K,V>[] tab = table;
return tab[hash & (tab.length - 1)];
}
-
+
HashEntry<K,V> newHashEntry(K key, int hash, HashEntry<K, V> next, V value) {
return new HashEntry<K,V>(key, hash, next, value, keyType, valueType, refQueue);
}
@@ -526,8 +571,8 @@
if (e.hash == hash && keyEq(key, e.key())) {
Object opaque = e.valueRef;
if (opaque != null)
- return e.dereferenceValue(opaque);
-
+ return e.dereferenceValue(opaque);
+
return readValueUnderLock(e); // recheck
}
e = e.next;
@@ -556,12 +601,12 @@
for (HashEntry<K,V> e = tab[i]; e != null; e = e.next) {
Object opaque = e.valueRef;
V v;
-
- if (opaque == null)
+
+ if (opaque == null)
v = readValueUnderLock(e); // recheck
- else
+ else
v = e.dereferenceValue(opaque);
-
+
if (value.equals(v))
return true;
}
@@ -581,7 +626,7 @@
boolean replaced = false;
if (e != null && oldValue.equals(e.value())) {
replaced = true;
- e.setValue(newValue, valueType);
+ e.setValue(newValue, valueType, refQueue);
}
return replaced;
} finally {
@@ -600,7 +645,7 @@
V oldValue = null;
if (e != null) {
oldValue = e.value();
- e.setValue(newValue, valueType);
+ e.setValue(newValue, valueType, refQueue);
}
return oldValue;
} finally {
@@ -617,9 +662,9 @@
if (c++ > threshold) {// ensure capacity
int reduced = rehash();
if (reduced > 0) // adjust from possible weak cleanups
- count = (c -= reduced) - 1; // write-volatile
+ count = (c -= reduced) - 1; // write-volatile
}
-
+
HashEntry<K,V>[] tab = table;
int index = hash & (tab.length - 1);
HashEntry<K,V> first = tab[index];
@@ -631,7 +676,7 @@
if (e != null) {
oldValue = e.value();
if (!onlyIfAbsent)
- e.setValue(value, valueType);
+ e.setValue(value, valueType, refQueue);
}
else {
oldValue = null;
@@ -718,19 +763,19 @@
/**
* Remove; match on key only if value null, else match both.
*/
- V remove(Object key, int hash, Object value, boolean weakRemove) {
+ V remove(Object key, int hash, Object value, boolean refRemove) {
lock();
try {
- if (!weakRemove)
+ if (!refRemove)
removeStale();
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;
- // a weak remove operation compares the WeakReference instance
- while (e != null && (!weakRemove || key != e.keyRef)
- && (e.hash != hash || !keyEq(key, e.key())))
+ // a ref remove operation compares the Reference instance
+ while (e != null && key != e.keyRef
+ && (refRemove || hash != e.hash || !keyEq(key, e.key())))
e = e.next;
V oldValue = null;
@@ -749,7 +794,7 @@
c--;
continue;
}
-
+
newFirst = newHashEntry(pKey, p.hash, newFirst, p.value());
}
tab[index] = newFirst;
@@ -761,14 +806,11 @@
unlock();
}
}
-
+
final void removeStale() {
- if (keyType == ReferenceType.STRONG)
- return;
-
KeyReference ref;
while ((ref = (KeyReference) refQueue.poll()) != null) {
- remove(ref, ref.keyHash(), null, true);
+ remove(ref.keyRef(), ref.keyHash(), null, true);
}
}
@@ -781,7 +823,7 @@
tab[i] = null;
++modCount;
// replace the reference queue to avoid unnecessary stale cleanups
- refQueue = new ReferenceQueue<K>();
+ refQueue = new ReferenceQueue<Object>();
count = 0; // write-volatile
} finally {
unlock();
@@ -797,7 +839,7 @@
/**
* Creates a new, empty map with the specified initial
* capacity, reference types, load factor and concurrency level.
- *
+ *
* Behavioral changing options such as {@link Option#IDENTITY_COMPARISONS}
* can also be specified.
*
@@ -817,7 +859,7 @@
* nonpositive.
*/
public ConcurrentReferenceHashMap(int initialCapacity,
- float loadFactor, int concurrencyLevel,
+ float loadFactor, int concurrencyLevel,
ReferenceType keyType, ReferenceType valueType,
EnumSet<Option> options) {
if (!(loadFactor > 0) || initialCapacity < 0 || concurrencyLevel <= 0)
@@ -845,11 +887,11 @@
int cap = 1;
while (cap < c)
cap <<= 1;
-
+
identityComparisons = options != null && options.contains(Option.IDENTITY_COMPARISONS);
for (int i = 0; i < this.segments.length; ++i)
- this.segments[i] = new Segment<K,V>(cap, loadFactor,
+ this.segments[i] = new Segment<K,V>(cap, loadFactor,
keyType, valueType, identityComparisons);
}
@@ -871,10 +913,10 @@
*/
public ConcurrentReferenceHashMap(int initialCapacity,
float loadFactor, int concurrencyLevel) {
- this(initialCapacity, loadFactor, concurrencyLevel,
+ this(initialCapacity, loadFactor, concurrencyLevel,
DEFAULT_KEY_TYPE, DEFAULT_VALUE_TYPE, null);
}
-
+
/**
* Creates a new, empty map with the specified initial capacity
* and load factor and with the default reference types (weak keys,
@@ -896,7 +938,7 @@
/**
- * Creates a new, empty map with the specified initial capacity,
+ * Creates a new, empty map with the specified initial capacity,
* reference types and with default load factor (0.75) and concurrencyLevel (16).
*
* @param initialCapacity the initial capacity. The implementation
@@ -906,12 +948,12 @@
* @throws IllegalArgumentException if the initial capacity of
* elements is negative.
*/
- public ConcurrentReferenceHashMap(int initialCapacity,
+ public ConcurrentReferenceHashMap(int initialCapacity,
ReferenceType keyType, ReferenceType valueType) {
- this(initialCapacity, DEFAULT_LOAD_FACTOR, DEFAULT_CONCURRENCY_LEVEL,
+ this(initialCapacity, DEFAULT_LOAD_FACTOR, DEFAULT_CONCURRENCY_LEVEL,
keyType, valueType, null);
}
-
+
/**
* Creates a new, empty map with the specified initial capacity,
* and with default reference types (weak keys, strong values),
@@ -1251,15 +1293,15 @@
for (int i = 0; i < segments.length; ++i)
segments[i].clear();
}
-
+
/**
* Removes any stale entries whose keys have been finalized. Use of this
* method is normally not necessary since stale entries are automatically
* removed lazily, when blocking operations are required. However, there
* are some cases where this operation should be performed eagerly, such
- * as cleaning up old references to a ClassLoader in a multi-classloader
+ * as cleaning up old references to a ClassLoader in a multi-classloader
* environment.
- *
+ *
* Note: this method will acquire locks, one at a time, across all segments
* of this table, so if it is to be used, it should be used sparingly.
*/
@@ -1267,8 +1309,8 @@
for (int i = 0; i < segments.length; ++i)
segments[i].removeStale();
}
-
+
/**
* 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
@@ -1393,13 +1435,13 @@
}
}
- public boolean hasNext() {
+ public boolean hasNext() {
while (nextEntry != null) {
- if (nextEntry.key() != null)
+ if (nextEntry.key() != null)
return true;
advance();
}
-
+
return false;
}
@@ -1407,12 +1449,12 @@
do {
if (nextEntry == null)
throw new NoSuchElementException();
-
+
lastReturned = nextEntry;
currentKey = lastReturned.key();
advance();
} while (currentKey == null); // Skip GC'd keys
-
+
return lastReturned;
}
@@ -1627,7 +1669,7 @@
K key = e.key();
if (key == null) // Skip GC'd keys
continue;
-
+
s.writeObject(key);
s.writeObject(e.value());
}
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