com.blogspot.mydailyjava.weaklockfree

Class WeakConcurrentMap<K,V>

java.lang.Object

java.lang.ref.ReferenceQueue<K>

com.blogspot.mydailyjava.weaklockfree.AbstractWeakConcurrentMap<K,V,com.blogspot.mydailyjava.weaklockfree.WeakConcurrentMap.LookupKey<K>>

com.blogspot.mydailyjava.weaklockfree.WeakConcurrentMap<K,V>

All Implemented Interfaces:

Iterable<Map.Entry<K,V>>, Runnable

Direct Known Subclasses:

WeakConcurrentMap.WithInlinedExpunction

public class WeakConcurrentMap<K,V>
extends AbstractWeakConcurrentMap<K,V,com.blogspot.mydailyjava.weaklockfree.WeakConcurrentMap.LookupKey<K>>

A thread-safe map with weak keys. Entries are based on a key's system hash code and keys are considered equal only by reference equality.

This class does not implement the Map interface because this implementation is incompatible with the map contract. While iterating over a map's entries, any key that has not passed iteration is referenced non-weakly.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	WeakConcurrentMap.WithInlinedExpunction<K,V> A WeakConcurrentMap where stale entries are removed as a side effect of interacting with this map.

Nested classes/interfaces inherited from class com.blogspot.mydailyjava.weaklockfree.AbstractWeakConcurrentMap

AbstractWeakConcurrentMap.WeakKey<K>

Constructor Summary

Constructors

Constructor and Description
WeakConcurrentMap(boolean cleanerThread)
WeakConcurrentMap(boolean cleanerThread, boolean reuseKeys)
WeakConcurrentMap(boolean cleanerThread, boolean reuseKeys, ConcurrentMap<AbstractWeakConcurrentMap.WeakKey<K>,V> target)

Method Summary

Modifier and Type	Method and Description
Thread	getCleanerThread()
protected com.blogspot.mydailyjava.weaklockfree.WeakConcurrentMap.LookupKey<K>	getLookupKey(K key) Override with care as it can cause lookup failures if done incorrectly.
protected void	resetLookupKey(com.blogspot.mydailyjava.weaklockfree.WeakConcurrentMap.LookupKey<K> lookupKey) Resets any reusable state in the lookup key.

Methods inherited from class com.blogspot.mydailyjava.weaklockfree.AbstractWeakConcurrentMap

approximateSize, clear, containsKey, defaultValue, expungeStaleEntries, get, getIfPresent, iterator, put, putIfAbsent, putIfProbablyAbsent, remove, run, toString

Methods inherited from class java.lang.ref.ReferenceQueue

poll, remove, remove

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Methods inherited from interface java.lang.Iterable

forEach, spliterator

Constructor Detail

WeakConcurrentMap

public WeakConcurrentMap(boolean cleanerThread)

Parameters:

cleanerThread - true if a thread should be started that removes stale entries.

WeakConcurrentMap

public WeakConcurrentMap(boolean cleanerThread,
                         boolean reuseKeys)

Parameters:

cleanerThread - true if a thread should be started that removes stale entries.

reuseKeys - true if the lookup keys should be reused via a ThreadLocal. Note that setting this to true may result in class loader leaks. See isPersistentClassLoader(ClassLoader) for more details.

WeakConcurrentMap

public WeakConcurrentMap(boolean cleanerThread,
                         boolean reuseKeys,
                         ConcurrentMap<AbstractWeakConcurrentMap.WeakKey<K>,V> target)

Parameters:

cleanerThread - true if a thread should be started that removes stale entries.

reuseKeys - true if the lookup keys should be reused via a ThreadLocal. Note that setting this to true may result in class loader leaks. See isPersistentClassLoader(ClassLoader) for more details.

target - ConcurrentMap implementation that this class wraps.

Method Detail

getLookupKey

protected com.blogspot.mydailyjava.weaklockfree.WeakConcurrentMap.LookupKey<K> getLookupKey(K key)

Description copied from class: AbstractWeakConcurrentMap

Override with care as it can cause lookup failures if done incorrectly. The result must have the same Object.hashCode() as the input and be equal to a weak reference of the key. When overriding this, also override AbstractWeakConcurrentMap.resetLookupKey(L).

Specified by:

getLookupKey in class AbstractWeakConcurrentMap<K,V,com.blogspot.mydailyjava.weaklockfree.WeakConcurrentMap.LookupKey<K>>

resetLookupKey

protected void resetLookupKey(com.blogspot.mydailyjava.weaklockfree.WeakConcurrentMap.LookupKey<K> lookupKey)

Description copied from class: AbstractWeakConcurrentMap

Resets any reusable state in the lookup key.

Specified by:

resetLookupKey in class AbstractWeakConcurrentMap<K,V,com.blogspot.mydailyjava.weaklockfree.WeakConcurrentMap.LookupKey<K>>

getCleanerThread

public Thread getCleanerThread()

Returns:

The cleaner thread or null if no such thread was set.