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| java.lang.Object
 java.util.concurrent.locks.AbstractOwnableSynchronizer
java.util.concurrent.locks.AbstractQueuedLongSynchronizer
| AbstractQueuedLongSynchronizer | | abstract public class AbstractQueuedLongSynchronizer extends AbstractOwnableSynchronizer implements java.io.Serializable(Code) | | A version of
AbstractQueuedSynchronizer in
which synchronization state is maintained as a long.
This class has exactly the same structure, properties, and methods
as AbstractQueuedSynchronizer with the exception
that all state-related parameters and results are defined
as long rather than int. This class
may be useful when creating synchronizers such as
multilevel locks and barriers that require
64 bits of state.
See
AbstractQueuedSynchronizer for usage
notes and examples.
since:
1.6
author:
Doug Lea |
| Inner Class :final static class Node | |
| Field Summary | |
| final static long | spinForTimeoutThreshold
The number of nanoseconds for which it is faster to spin
rather than to use timed park. |
| Constructor Summary | |
| protected | AbstractQueuedLongSynchronizer()
Creates a new AbstractQueuedLongSynchronizer instance
with initial synchronization state of zero. |
| Method Summary | |
| final public void | acquire(long arg)
Acquires in exclusive mode, ignoring interrupts. | | final public void | acquireInterruptibly(long arg)
Acquires in exclusive mode, aborting if interrupted.
Implemented by first checking interrupt status, then invoking
at least once
AbstractQueuedLongSynchronizer.tryAcquire , returning on
success. | | final boolean | acquireQueued(Node node, long arg)
Acquires in exclusive uninterruptible mode for thread already in
queue. | | final public void | acquireShared(long arg)
Acquires in shared mode, ignoring interrupts. | | final public void | acquireSharedInterruptibly(long arg)
Acquires in shared mode, aborting if interrupted. | | final boolean | apparentlyFirstQueuedIsExclusive()
Returns
true if the apparent first queued thread, if one
exists, is waiting in exclusive mode. | | final protected boolean | compareAndSetState(long expect, long update)
Atomically sets synchronization state to the given updated
value if the current state value equals the expected value.
This operation has memory semantics of a volatile read
and write.
Parameters:
expect - the expected value
Parameters:
update - the new value true if successful. | | final long | fullyRelease(Node node)
Invokes release with current state value; returns saved state. | | final public Collection<Thread> | getExclusiveQueuedThreads()
Returns a collection containing threads that may be waiting to
acquire in exclusive mode. | | final public Thread | getFirstQueuedThread()
Returns the first (longest-waiting) thread in the queue, or
null if no threads are currently queued. | | final public int | getQueueLength()
Returns an estimate of the number of threads waiting to
acquire. | | final public Collection<Thread> | getQueuedThreads()
Returns a collection containing threads that may be waiting to
acquire. | | final public Collection<Thread> | getSharedQueuedThreads()
Returns a collection containing threads that may be waiting to
acquire in shared mode. | | final protected long | getState()
Returns the current value of synchronization state. | | final public int | getWaitQueueLength(ConditionObject condition)
Returns an estimate of the number of threads waiting on the
given condition associated with this synchronizer. | | final public Collection<Thread> | getWaitingThreads(ConditionObject condition)
Returns a collection containing those threads that may be
waiting on the given condition associated with this
synchronizer. | | final public boolean | hasContended()
Queries whether any threads have ever contended to acquire this
synchronizer; that is if an acquire method has ever blocked. | | final public boolean | hasQueuedPredecessors()
| | final public boolean | hasQueuedThreads()
Queries whether any threads are waiting to acquire. | | final public boolean | hasWaiters(ConditionObject condition)
Queries whether any threads are waiting on the given condition
associated with this synchronizer. | | protected boolean | isHeldExclusively()
Returns
true if synchronization is held exclusively with
respect to the current (calling) thread. | | final boolean | isOnSyncQueue(Node node)
Returns true if a node, always one that was initially placed on
a condition queue, is now waiting to reacquire on sync queue. | | final public boolean | isQueued(Thread thread)
Returns true if the given thread is currently queued. | | final public boolean | owns(ConditionObject condition)
Queries whether the given ConditionObject
uses this synchronizer as its lock. | | final public boolean | release(long arg)
Releases in exclusive mode. | | final public boolean | releaseShared(long arg)
Releases in shared mode. | | final protected void | setState(long newState)
Sets the value of synchronization state. | | public String | toString()
Returns a string identifying this synchronizer, as well as its state. | | final boolean | transferAfterCancelledWait(Node node)
Transfers node, if necessary, to sync queue after a cancelled
wait. | | final boolean | transferForSignal(Node node)
Transfers a node from a condition queue onto sync queue. | | protected boolean | tryAcquire(long arg)
Attempts to acquire in exclusive mode. | | final public boolean | tryAcquireNanos(long arg, long nanosTimeout)
Attempts to acquire in exclusive mode, aborting if interrupted,
and failing if the given timeout elapses. | | protected long | tryAcquireShared(long arg)
Attempts to acquire in shared mode. | | final public boolean | tryAcquireSharedNanos(long arg, long nanosTimeout)
Attempts to acquire in shared mode, aborting if interrupted, and
failing if the given timeout elapses. | | protected boolean | tryRelease(long arg)
Attempts to set the state to reflect a release in exclusive
mode.
This method is always invoked by the thread performing release.
The default implementation throws
UnsupportedOperationException .
Parameters:
arg - the release argument. | | protected boolean | tryReleaseShared(long arg)
Attempts to set the state to reflect a release in shared mode.
This method is always invoked by the thread performing release.
The default implementation throws
UnsupportedOperationException .
Parameters:
arg - the release argument. |
| spinForTimeoutThreshold | | final static long spinForTimeoutThreshold(Code) | | The number of nanoseconds for which it is faster to spin
rather than to use timed park. A rough estimate suffices
to improve responsiveness with very short timeouts.
|
| AbstractQueuedLongSynchronizer | | protected AbstractQueuedLongSynchronizer()(Code) | | Creates a new AbstractQueuedLongSynchronizer instance
with initial synchronization state of zero.
|
| acquireQueued | | final boolean acquireQueued(Node node, long arg)(Code) | | Acquires in exclusive uninterruptible mode for thread already in
queue. Used by condition wait methods as well as acquire.
Parameters:
node - the node
Parameters:
arg - the acquire argument true if interrupted while waiting |
| apparentlyFirstQueuedIsExclusive | | final boolean apparentlyFirstQueuedIsExclusive()(Code) | | Returns
true if the apparent first queued thread, if one
exists, is waiting in exclusive mode. If this method returns
true , and the current thread is attempting to acquire in
shared mode (that is, this method is invoked from
AbstractQueuedLongSynchronizer.tryAcquireShared ) then it is guaranteed that the current thread
is not the first queued thread. Used only as a heuristic in
ReentrantReadWriteLock.
|
| compareAndSetState | | final protected boolean compareAndSetState(long expect, long update)(Code) | | Atomically sets synchronization state to the given updated
value if the current state value equals the expected value.
This operation has memory semantics of a volatile read
and write.
Parameters:
expect - the expected value
Parameters:
update - the new value true if successful. False return indicates that the actualvalue was not equal to the expected value. |
| fullyRelease | | final long fullyRelease(Node node)(Code) | | Invokes release with current state value; returns saved state.
Cancels node and throws exception on failure.
Parameters:
node - the condition node for this wait previous sync state |
| getExclusiveQueuedThreads | | final public Collection<Thread> getExclusiveQueuedThreads()(Code) | | Returns a collection containing threads that may be waiting to
acquire in exclusive mode. This has the same properties
as
AbstractQueuedLongSynchronizer.getQueuedThreads except that it only returns
those threads waiting due to an exclusive acquire.
the collection of threads |
| getFirstQueuedThread | | final public Thread getFirstQueuedThread()(Code) | | Returns the first (longest-waiting) thread in the queue, or
null if no threads are currently queued.
In this implementation, this operation normally returns in
constant time, but may iterate upon contention if other threads are
concurrently modifying the queue.
the first (longest-waiting) thread in the queue, or null if no threads are currently queued |
| getQueueLength | | final public int getQueueLength()(Code) | | Returns an estimate of the number of threads waiting to
acquire. The value is only an estimate because the number of
threads may change dynamically while this method traverses
internal data structures. This method is designed for use in
monitoring system state, not for synchronization
control.
the estimated number of threads waiting to acquire |
| getQueuedThreads | | final public Collection<Thread> getQueuedThreads()(Code) | | Returns a collection containing threads that may be waiting to
acquire. Because the actual set of threads may change
dynamically while constructing this result, the returned
collection is only a best-effort estimate. The elements of the
returned collection are in no particular order. This method is
designed to facilitate construction of subclasses that provide
more extensive monitoring facilities.
the collection of threads |
| getSharedQueuedThreads | | final public Collection<Thread> getSharedQueuedThreads()(Code) | | Returns a collection containing threads that may be waiting to
acquire in shared mode. This has the same properties
as
AbstractQueuedLongSynchronizer.getQueuedThreads except that it only returns
those threads waiting due to a shared acquire.
the collection of threads |
| getState | | final protected long getState()(Code) | | Returns the current value of synchronization state.
This operation has memory semantics of a volatile read.
current state value |
| getWaitQueueLength | | final public int getWaitQueueLength(ConditionObject condition)(Code) | | Returns an estimate of the number of threads waiting on the
given condition associated with this synchronizer. Note that
because timeouts and interrupts may occur at any time, the
estimate serves only as an upper bound on the actual number of
waiters. This method is designed for use in monitoring of the
system state, not for synchronization control.
Parameters:
condition - the condition the estimated number of waiting threads
throws:
IllegalMonitorStateException - if exclusive synchronizationis not held
throws:
IllegalArgumentException - if the given condition isnot associated with this synchronizer
throws:
NullPointerException - if the condition is null |
| getWaitingThreads | | final public Collection<Thread> getWaitingThreads(ConditionObject condition)(Code) | | Returns a collection containing those threads that may be
waiting on the given condition associated with this
synchronizer. Because the actual set of threads may change
dynamically while constructing this result, the returned
collection is only a best-effort estimate. The elements of the
returned collection are in no particular order.
Parameters:
condition - the condition the collection of threads
throws:
IllegalMonitorStateException - if exclusive synchronizationis not held
throws:
IllegalArgumentException - if the given condition isnot associated with this synchronizer
throws:
NullPointerException - if the condition is null |
| hasContended | | final public boolean hasContended()(Code) | | Queries whether any threads have ever contended to acquire this
synchronizer; that is if an acquire method has ever blocked.
In this implementation, this operation returns in
constant time.
true if there has ever been contention |
| hasQueuedPredecessors | | final public boolean hasQueuedPredecessors()(Code) | | |
| hasQueuedThreads | | final public boolean hasQueuedThreads()(Code) | | Queries whether any threads are waiting to acquire. Note that
because cancellations due to interrupts and timeouts may occur
at any time, a
true return does not guarantee that any
other thread will ever acquire.
In this implementation, this operation returns in
constant time.
true if there may be other threads waiting to acquire |
| hasWaiters | | final public boolean hasWaiters(ConditionObject condition)(Code) | | Queries whether any threads are waiting on the given condition
associated with this synchronizer. Note that because timeouts
and interrupts may occur at any time, a true return
does not guarantee that a future signal will awaken
any threads. This method is designed primarily for use in
monitoring of the system state.
Parameters:
condition - the condition true if there are any waiting threads
throws:
IllegalMonitorStateException - if exclusive synchronizationis not held
throws:
IllegalArgumentException - if the given condition isnot associated with this synchronizer
throws:
NullPointerException - if the condition is null |
| isHeldExclusively | | protected boolean isHeldExclusively()(Code) | | Returns
true if synchronization is held exclusively with
respect to the current (calling) thread. This method is invoked
upon each call to a non-waiting
ConditionObject method.
(Waiting methods instead invoke
AbstractQueuedLongSynchronizer.release .)
The default implementation throws
UnsupportedOperationException . This method is invoked
internally only within
ConditionObject methods, so need
not be defined if conditions are not used.
true if synchronization is held exclusively; false otherwise
throws:
UnsupportedOperationException - if conditions are not supported |
| isOnSyncQueue | | final boolean isOnSyncQueue(Node node)(Code) | | Returns true if a node, always one that was initially placed on
a condition queue, is now waiting to reacquire on sync queue.
Parameters:
node - the node true if is reacquiring |
| isQueued | | final public boolean isQueued(Thread thread)(Code) | | Returns true if the given thread is currently queued.
This implementation traverses the queue to determine
presence of the given thread.
Parameters:
thread - the thread true if the given thread is on the queue
throws:
NullPointerException - if the thread is null |
| owns | | final public boolean owns(ConditionObject condition)(Code) | | Queries whether the given ConditionObject
uses this synchronizer as its lock.
Parameters:
condition - the condition true if owned
throws:
NullPointerException - if the condition is null |
| setState | | final protected void setState(long newState)(Code) | | Sets the value of synchronization state.
This operation has memory semantics of a volatile write.
Parameters:
newState - the new state value |
| toString | | public String toString()(Code) | | Returns a string identifying this synchronizer, as well as its state.
The state, in brackets, includes the String
"State =" followed by the current value of
AbstractQueuedLongSynchronizer.getState , and either
"nonempty" or
"empty" depending on whether the
queue is empty.
a string identifying this synchronizer, as well as its state |
| transferAfterCancelledWait | | final boolean transferAfterCancelledWait(Node node)(Code) | | Transfers node, if necessary, to sync queue after a cancelled
wait. Returns true if thread was cancelled before being
signalled.
Parameters:
current - the waiting thread
Parameters:
node - its node true if cancelled before the node was signalled |
| transferForSignal | | final boolean transferForSignal(Node node)(Code) | | Transfers a node from a condition queue onto sync queue.
Returns true if successful.
Parameters:
node - the node true if successfully transferred (else the node wascancelled before signal). |
| tryAcquire | | protected boolean tryAcquire(long arg)(Code) | | Attempts to acquire in exclusive mode. This method should query
if the state of the object permits it to be acquired in the
exclusive mode, and if so to acquire it.
This method is always invoked by the thread performing
acquire. If this method reports failure, the acquire method
may queue the thread, if it is not already queued, until it is
signalled by a release from some other thread. This can be used
to implement method
Lock.tryLock .
The default
implementation throws
UnsupportedOperationException .
Parameters:
arg - the acquire argument. This value is always the onepassed to an acquire method, or is the value saved on entryto a condition wait. The value is otherwise uninterpretedand can represent anything you like. true if successful. Upon success, this object hasbeen acquired.
throws:
IllegalMonitorStateException - if acquiring would place thissynchronizer in an illegal state. This exception must bethrown in a consistent fashion for synchronization to workcorrectly.
throws:
UnsupportedOperationException - if exclusive mode is not supported |
| tryAcquireNanos | | final public boolean tryAcquireNanos(long arg, long nanosTimeout) throws InterruptedException(Code) | | Attempts to acquire in exclusive mode, aborting if interrupted,
and failing if the given timeout elapses. Implemented by first
checking interrupt status, then invoking at least once
AbstractQueuedLongSynchronizer.tryAcquire , returning on success. Otherwise, the thread is
queued, possibly repeatedly blocking and unblocking, invoking
AbstractQueuedLongSynchronizer.tryAcquire until success or the thread is interrupted
or the timeout elapses. This method can be used to implement
method
Lock.tryLock(longTimeUnit) .
Parameters:
arg - the acquire argument. This value is conveyed toAbstractQueuedLongSynchronizer.tryAcquire but is otherwise uninterpreted andcan represent anything you like.
Parameters:
nanosTimeout - the maximum number of nanoseconds to wait true if acquired; false if timed out
throws:
InterruptedException - if the current thread is interrupted |
| tryAcquireShared | | protected long tryAcquireShared(long arg)(Code) | | Attempts to acquire in shared mode. This method should query if
the state of the object permits it to be acquired in the shared
mode, and if so to acquire it.
This method is always invoked by the thread performing
acquire. If this method reports failure, the acquire method
may queue the thread, if it is not already queued, until it is
signalled by a release from some other thread.
The default implementation throws
UnsupportedOperationException .
Parameters:
arg - the acquire argument. This value is always the onepassed to an acquire method, or is the value saved on entryto a condition wait. The value is otherwise uninterpretedand can represent anything you like. a negative value on failure; zero if acquisition in sharedmode succeeded but no subsequent shared-mode acquire cansucceed; and a positive value if acquisition in sharedmode succeeded and subsequent shared-mode acquires mightalso succeed, in which case a subsequent waiting threadmust check availability. (Support for three differentreturn values enables this method to be used in contextswhere acquires only sometimes act exclusively.) Uponsuccess, this object has been acquired.
throws:
IllegalMonitorStateException - if acquiring would place thissynchronizer in an illegal state. This exception must bethrown in a consistent fashion for synchronization to workcorrectly.
throws:
UnsupportedOperationException - if shared mode is not supported |
| tryRelease | | protected boolean tryRelease(long arg)(Code) | | Attempts to set the state to reflect a release in exclusive
mode.
This method is always invoked by the thread performing release.
The default implementation throws
UnsupportedOperationException .
Parameters:
arg - the release argument. This value is always the onepassed to a release method, or the current state value uponentry to a condition wait. The value is otherwiseuninterpreted and can represent anything you like. true if this object is now in a fully releasedstate, so that any waiting threads may attempt to acquire;and false otherwise.
throws:
IllegalMonitorStateException - if releasing would place thissynchronizer in an illegal state. This exception must bethrown in a consistent fashion for synchronization to workcorrectly.
throws:
UnsupportedOperationException - if exclusive mode is not supported |
| tryReleaseShared | | protected boolean tryReleaseShared(long arg)(Code) | | Attempts to set the state to reflect a release in shared mode.
This method is always invoked by the thread performing release.
The default implementation throws
UnsupportedOperationException .
Parameters:
arg - the release argument. This value is always the onepassed to a release method, or the current state value uponentry to a condition wait. The value is otherwiseuninterpreted and can represent anything you like. true if this release of shared mode may permit awaiting acquire (shared or exclusive) to succeed; and false otherwise
throws:
IllegalMonitorStateException - if releasing would place thissynchronizer in an illegal state. This exception must bethrown in a consistent fashion for synchronization to workcorrectly.
throws:
UnsupportedOperationException - if shared mode is not supported |
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