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the next item in the queue (it will only return null when the backing map is no longer active)

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".

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.

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 for a lock on the key to be acquired

Returns:

a ReadLatch for the selected key or null if a candidate key was not found

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.

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