SynchronizedHardReferenceQueueWithTimeout (bigdata®)

Overview

Package

Class

Use

Tree

Deprecated

Index

Help

PREV CLASS NEXT CLASS

FRAMES NO FRAMES

SUMMARY: NESTED | FIELD | CONSTR | METHOD

DETAIL: FIELD | CONSTR | METHOD

com.bigdata.cache
Class SynchronizedHardReferenceQueueWithTimeout<T>

java.lang.Object
  com.bigdata.cache.SynchronizedHardReferenceQueueWithTimeout<T>

All Implemented Interfaces:: IHardReferenceQueue<T>

public class SynchronizedHardReferenceQueueWithTimeout<T>
extends Object
implements IHardReferenceQueue<T>
extends Object
implements IHardReferenceQueue<T>

Thread-safe version with timeout for clearing stale references from the queue. Clearing of stale entries is accomplished when a value is added to the SynchronizedHardReferenceQueue. If the value implements the IValueAge interface, then the tail of the queue is tested and any entry on the tail whose age as reported by that interface exceeds a timeout is evicted. This continues until we reach the first value on the tail of the queue whose age is greater than the timeout. This behavior is enabled if a non-ZERO timeout is specified. Stales references are also cleared by a background thread.

Version:: $Id: SynchronizedHardReferenceQueueWithTimeout.java 2265 2009-10-26 12:51:06Z thompsonbry $
Author:: Bryan Thompson

Field Summary
`protected static boolean`	`DEBUG`
`protected static org.apache.log4j.Logger`	`log`
`protected com.bigdata.cache.SynchronizedHardReferenceQueueWithTimeout.InnerHardReferenceQueue<com.bigdata.cache.SynchronizedHardReferenceQueueWithTimeout.ValueAge<T>>`	`queue` Note: Synchronization for the inner `queue` is realized using the outer reference!

Fields inherited from interface com.bigdata.cache.IHardReferenceQueue
`DEFAULT_NSCAN`

Constructor Summary
`SynchronizedHardReferenceQueueWithTimeout(int capacity, int nscan, long timeout)` Optional timeout.
`SynchronizedHardReferenceQueueWithTimeout(int capacity, long timeout)` Variant with no listener and timeout.

Method Summary
`boolean`	`add(T ref)` Add a reference to the cache.
`int`	`capacity()` The cache capacity.
`void`	`clear(boolean clearRefs)` Clears the cache (sets the head, tail and count to zero) without generating eviction notices.
`boolean`	`evict()` Evict the LRU reference.
`void`	`evictAll(boolean clearRefs)` Evict all references, starting with the LRU reference and proceeding to the MRU reference.
`boolean`	`isEmpty()` True iff the cache is empty.
`boolean`	`isFull()` True iff the cache is full.
`int`	`nscan()` The #of references that are tested on append requests.
`T`	`peek()` The reference at the tail of the queue.
`int`	`size()` The #of references in the cache.
`long`	`timeout()` The timeout (in nanoseconds) for an entry in the queue.

Methods inherited from class java.lang.Object
`clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait`

Field Detail

log

protected static final org.apache.log4j.Logger log

DEBUG

protected static final boolean DEBUG

queue

protected final com.bigdata.cache.SynchronizedHardReferenceQueueWithTimeout.InnerHardReferenceQueue<com.bigdata.cache.SynchronizedHardReferenceQueueWithTimeout.ValueAge<T>> queue

Note: Synchronization for the inner queue is realized using the outer reference!

Constructor Detail

SynchronizedHardReferenceQueueWithTimeout

public SynchronizedHardReferenceQueueWithTimeout(int capacity,
                                                 long timeout)

Variant with no listener and timeout.

Parameters:: capacity - The maximum #of references that can be stored on the cache. There is no guarantee that all stored references are distinct.; timeout - The timeout (in nanoseconds) for an entry in the queue. When ZERO (0L), the timeout is disabled.

SynchronizedHardReferenceQueueWithTimeout

public SynchronizedHardReferenceQueueWithTimeout(int capacity,
                                                 int nscan,
                                                 long timeout)

Optional timeout.

Parameters:: capacity - The maximum #of references that can be stored on the cache. There is no guarantee that all stored references are distinct.; nscan - The #of references to scan from the MRU position before appended a reference to the cache. Scanning is used to reduce the chance that references that are touched several times in near succession from entering the cache more than once. The #of reference tests trades off against the latency of adding a reference to the cache.; timeout - The timeout (in nanoseconds) for an entry in the queue. When ZERO (0L), the timeout is disabled.

Method Detail

timeout

public final long timeout()

The timeout (in nanoseconds) for an entry in the queue. When ZERO (0L), the timeout is disabled.