模块 com.tlcsdm.core

程序包 com.tlcsdm.core.concurrent

类 WeakConcurrentMap<K,V>

java.lang.Object

java.lang.ref.ReferenceQueue<K>

com.tlcsdm.core.concurrent.AbstractWeakConcurrentMap<K,V,WeakConcurrentMap.LookupKey<K>>

com.tlcsdm.core.concurrent.WeakConcurrentMap<K,V>

所有已实现的接口:

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

直接已知子类:

WeakConcurrentMap.WithInlinedExpunction

public class WeakConcurrentMap<K,V>
extends AbstractWeakConcurrentMap<K,V,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.

作者:

unknowIfGuestInDream

嵌套类概要

嵌套类

修饰符和类型	类	说明
(专用程序包) static final class	WeakConcurrentMap.LookupKey<K>
static class	WeakConcurrentMap.WithInlinedExpunction<K,V>	A WeakConcurrentMap where stale entries are removed as a side effect of interacting with this map.

从类继承的嵌套类/接口 com.tlcsdm.core.concurrent.AbstractWeakConcurrentMap

AbstractWeakConcurrentMap.WeakKey<K>

字段概要

字段

修饰符和类型	字段	说明
private static final AtomicLong	ID
private static final ThreadLocal<WeakConcurrentMap.LookupKey<?>>	LOOKUP_KEY_CACHE	Lookup keys are cached thread-locally to avoid allocations on lookups.
private final boolean	reuseKeys
private final Thread	thread

从类继承的字段 com.tlcsdm.core.concurrent.AbstractWeakConcurrentMap

target

构造器概要

构造器

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

方法概要

修饰符和类型	方法	说明
Thread	getCleanerThread()
protected WeakConcurrentMap.LookupKey<K>	getLookupKey(K key)	Override with care as it can cause lookup failures if done incorrectly.
private static boolean	isPersistentClassLoader(ClassLoader classLoader)	Checks whether the provided ClassLoader may be unloaded like a web application class loader, for example.
protected void	resetLookupKey(WeakConcurrentMap.LookupKey<K> lookupKey)	Resets any reusable state in the lookup key.

从类继承的方法 com.tlcsdm.core.concurrent.AbstractWeakConcurrentMap

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

从类继承的方法 java.lang.ref.ReferenceQueue

poll, remove, remove

从类继承的方法 java.lang.Object

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

从接口继承的方法 java.lang.Iterable

forEach, spliterator

字段详细资料

LOOKUP_KEY_CACHE

private static final ThreadLocal<WeakConcurrentMap.LookupKey<?>> LOOKUP_KEY_CACHE

Lookup keys are cached thread-locally to avoid allocations on lookups. This is beneficial as the JIT unfortunately can't reliably replace the WeakConcurrentMap.LookupKey allocation with stack allocations, even though the WeakConcurrentMap.LookupKey does not escape.

ID

private static final AtomicLong ID

thread

private final Thread thread

reuseKeys

private final boolean reuseKeys

构造器详细资料

WeakConcurrentMap

public WeakConcurrentMap(boolean cleanerThread)

参数:

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

WeakConcurrentMap

public WeakConcurrentMap(boolean cleanerThread,
 boolean reuseKeys)

参数:

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)

参数:

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.

方法详细资料

isPersistentClassLoader

private static boolean isPersistentClassLoader(ClassLoader classLoader)

Checks whether the provided ClassLoader may be unloaded like a web application class loader, for example.

If the class loader can't be unloaded, it is safe to use ThreadLocals and to reuse the WeakConcurrentMap.LookupKey. Otherwise, the use of ThreadLocals may lead to class loader leaks as it prevents the class loader this class is loaded by to unload.

参数:

classLoader - The class loader to check.

返回:

true if the provided class loader can be unloaded.

getLookupKey

protected WeakConcurrentMap.LookupKey<K> getLookupKey(K key)

从类复制的说明: 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).

指定者:

getLookupKey 在类中 AbstractWeakConcurrentMap<K,V,WeakConcurrentMap.LookupKey<K>>

resetLookupKey

protected void resetLookupKey(WeakConcurrentMap.LookupKey<K> lookupKey)

从类复制的说明: AbstractWeakConcurrentMap

Resets any reusable state in the lookup key.

指定者:

resetLookupKey 在类中 AbstractWeakConcurrentMap<K,V,WeakConcurrentMap.LookupKey<K>>

getCleanerThread

public Thread getCleanerThread()

返回:

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