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com.tangosol.util
Class SegmentedConcurrentMap.LockableEntry

java.lang.Object
com.tangosol.util.Base
com.tangosol.util.SegmentedHashMap.Entry
com.tangosol.util.SegmentedConcurrentMap.LockableEntry

All Implemented Interfaces:

java.util.Map.Entry

Enclosing class:

SegmentedConcurrentMap

public class SegmentedConcurrentMap.LockableEntry

extends SegmentedHashMap.Entry

LockableEntry is an Entry that supports locking. See ConcurrentMap

Field Summary

protected short	m_cContend The number of threads that are waiting to lock this Entry.
protected short	m_cLock The lock count (number of times the "lock()" was called by the locking thread).
protected java.lang.Object	m_oLockHolder The lock holder object.

Fields inherited from class com.tangosol.util.SegmentedHashMap.Entry

m_eNext, m_nHash, m_oKey, m_oValue

Constructor Summary

protected

SegmentedConcurrentMap.LockableEntry(java.lang.Object oKey, java.lang.Object oValue, int nHash) Construct a LockableEntry for the given entry.

Method Summary

protected boolean	casValueInternal(java.lang.Object oValueAssume, java.lang.Object oValue) Set the value of this entry to the specified value iff the current value matches the assumed value.
java.lang.Object	getLockHolder() Return the holder of this lockable entry, or null if this entry is not locked.
boolean	isContended() Is there contention (a thread waiting) to lock this Entry?
protected boolean	isLocked() Is this entry Locked?
protected boolean	isSynthetic() Is this Entry synthetic?
protected void	lock(java.lang.Object oHolder) Lock this entry for the specified lock holder.
protected java.lang.Object	setValueInternal(java.lang.Object oValue) Replaces the value corresponding to this entry with the specified value (writes through to the map).
java.lang.String	toString() Render the map entry as a String.
protected boolean	unlock() Unlock this entry.
protected long	waitForNotify(long cWait) Wait for this LockableEntry to be notified that it has been freed by the previous lock-holder.

Methods inherited from class com.tangosol.util.SegmentedHashMap.Entry

equals, getKey, getValue, getValueInternal, hashCode, nextEntry, nextEntry, setNext, setValue

Field Detail

m_oLockHolder

protected volatile java.lang.Object m_oLockHolder

The lock holder object.

m_cLock

protected volatile short m_cLock

The lock count (number of times the "lock()" was called by the locking thread).

m_cContend

protected volatile short m_cContend

The number of threads that are waiting to lock this Entry.

Constructor Detail

SegmentedConcurrentMap.LockableEntry

protected SegmentedConcurrentMap.LockableEntry(java.lang.Object oKey,
                                               java.lang.Object oValue,
                                               int nHash)

Construct a LockableEntry for the given entry.

Parameters:

oKey - key with which the specified value is to be associated

oValue - value to be associated with the specified key

nHash - the hashCode for the specified key

Method Detail

getLockHolder

public java.lang.Object getLockHolder()

Return the holder of this lockable entry, or null if this entry is not locked.

Returns:

the lock holder, or null

isContended

public boolean isContended()

Is there contention (a thread waiting) to lock this Entry?

Returns:

true iff another thread is contending for this Entry

setValueInternal

protected java.lang.Object setValueInternal(java.lang.Object oValue)

Replaces the value corresponding to this entry with the specified value (writes through to the map). The behavior of this call is undefined if the mapping has already been removed from the map.

Overrides:

setValueInternal in class SegmentedHashMap.Entry

Parameters:

oValue - new value to be stored in this entry

Returns:

old value corresponding to the entry, or NO_VALUE if the Entry was synthetic

isSynthetic

protected boolean isSynthetic()

Is this Entry synthetic?

Overrides:

isSynthetic in class SegmentedHashMap.Entry

Returns:

true iff this Entry is synthetic

waitForNotify

protected long waitForNotify(long cWait)

Wait for this LockableEntry to be notified that it has been freed by the previous lock-holder. If the lock is being held by a thread and that thread has died, release the lock.

Note: caller of this method is expected to hold a synchronization monitor for this LockableEntry object while making this call.

Parameters:

cWait - the number of milliseconds to wait for notification to obtain a lock; pass zero to return immediately; pass -1 to block the calling thread until the lock could be obtained

Returns:

updated wait time

lock

protected void lock(java.lang.Object oHolder)

Lock this entry for the specified lock holder.

Note: caller of this method is expected to have locked the segment for this Entry object

Parameters:

oHolder - the holder of this lock

unlock

protected boolean unlock()

Unlock this entry.

Note: caller of this method is expected to have locked the segment for this Entry object

Returns:

true iff the Entry is completely unlocked

casValueInternal

protected boolean casValueInternal(java.lang.Object oValueAssume,
                                   java.lang.Object oValue)

Set the value of this entry to the specified value iff the current value matches the assumed value.

Parameters:

oValueAssume - the assumed value

oValue - the new value

Returns:

true iff the value changed

toString

public java.lang.String toString()

Render the map entry as a String.

Overrides:

toString in class SegmentedHashMap.Entry

Returns:

the details about this entry

isLocked

protected boolean isLocked()

Is this entry Locked?

Returns:

true iff this entry is locked

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