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com.tangosol.net.cache
Class ReadWriteBackingMap.ReadQueue

java.lang.Object
CoherenceApplicationEdition
com.tangosol.net.cache.ReadWriteBackingMap.ReadQueue

Enclosing class:

ReadWriteBackingMap

public class ReadWriteBackingMap.ReadQueue

extends CoherenceApplicationEdition

A queue of keys that should be read from the underlying CacheStore.

Author:

jh 2005.02.08

Constructor Summary

protected

ReadWriteBackingMap.ReadQueue() Construct a ReadQueue.

Method Summary

boolean	add(Object oKey) Add a key to the queue.
void	clear() Remove all keys from the queue.
protected List	getKeyList() Return a list of keys in the queue.
protected Map	getKeyMap() Return a map of keys in the queue.
Object	peek() Wait for a key to be added to the queue and return it without removing it from the queue.
Object	peek(long cMillis) Wait for a key (up to the specified wait time) to be added to the queue and return it without removing it from the queue, or null if the specified wait time has passed).
boolean	remove(Object oKey) Remove a key from the queue if the key is in the queue.
protected ReadWriteBackingMap.ReadLatch	select(long cWaitMillis) Select the next key from the refresh-ahead queue that is a candidate for an asynchronous load.
String	toString() For debugging purposes, present the queue in human-readable format.

Constructor Detail

ReadWriteBackingMap.ReadQueue

protected ReadWriteBackingMap.ReadQueue()

Construct a ReadQueue.

Method Detail

add

public boolean add(Object oKey)

Add a key to the queue. This method has no effect if the key is already queued.

Parameters:

oKey - the key object

Returns:

true if the key was added to the queue; false otherwise

peek

public Object peek()

Wait for a key to be added to the queue and return it without removing it from the queue.

Returns:

the next item in the queue (it will only return null when the backing map is no longer active)

peek

public Object peek(long cMillis)

Wait for a key (up to the specified wait time) to be added to the queue and return it without removing it from the queue, or null if the specified wait time has passed).

Parameters:

cMillis - the number of ms to wait for a key in the queue; pass -1 to wait indefinitely or 0 for no wait

Returns:

the next item in the queue, or null if the wait time has passed or if the backing map is no longer active

remove

public boolean remove(Object oKey)

Remove a key from the queue if the key is in the queue.

Parameters:

oKey - the key object

Returns:

true if the key was removed from the queue; false otherwise

select

protected ReadWriteBackingMap.ReadLatch select(long cWaitMillis)

Select the next key from the refresh-ahead queue that is a candidate for an asynchronous load. A key is a candidate if it can be locked "quickly". <p/> This method performs the selection process by iterating through the refresh-ahead queue starting with the first key in the queue. If the queue is empty, this method will block until a key is added to the queue. A key is skipped if it cannot be locked within the specified wait time. <p/> If a candidate key is found, a new ReadLatch for the key is placed in the control map and returned; otherwise, null is returned.

Parameters:

cWaitMillis - the maximum amount of time (in milliseconds) to wait to select a key and acquire a latch on it; pass -1 to wait indefinitely

Returns:

a ReadLatch for the selected key or null if a candidate key was not found and latched within the specified time

clear

public void clear()

Remove all keys from the queue.

toString

public String toString()

For debugging purposes, present the queue in human-readable format.

Returns:

a String representation of this object

getKeyList

protected List getKeyList()

Return a list of keys in the queue.

Returns:

a list of keys in the queue

getKeyMap

protected Map getKeyMap()

Return a map of keys in the queue. <p/> Note: The map returned from this method is not thread-safe; therefore, a lock on this ReadQueue must be obtained before accessing the map

Returns:

a map of keys in the queue

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