AbstractQueuedLongSynchronizer
abstract class AbstractQueuedLongSynchronizer : AbstractOwnableSynchronizer, Serializable
kotlin.Any | ||
↳ | java.util.concurrent.locks.AbstractOwnableSynchronizer | |
↳ | java.util.concurrent.locks.AbstractQueuedLongSynchronizer |
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.
Summary
Nested classes | |
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open |
Condition implementation for a |
Protected constructors | |
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Constructor for subclasses to call. |
Public methods | |
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Unit |
Acquires in exclusive mode, ignoring interrupts. |
Unit |
acquireInterruptibly(arg: Long) Acquires in exclusive mode, aborting if interrupted. |
Unit |
Acquires in shared mode, ignoring interrupts. |
Unit |
Acquires in shared mode, aborting if interrupted. |
MutableCollection<Thread!>! |
Returns a collection containing threads that may be waiting to acquire in exclusive mode. |
Thread! |
Returns the first (longest-waiting) thread in the queue, or |
Int |
Returns an estimate of the number of threads waiting to acquire. |
MutableCollection<Thread!>! |
Returns a collection containing threads that may be waiting to acquire. |
MutableCollection<Thread!>! |
Returns a collection containing threads that may be waiting to acquire in shared mode. |
Int |
Returns an estimate of the number of threads waiting on the given condition associated with this synchronizer. |
MutableCollection<Thread!>! |
Returns a collection containing those threads that may be waiting on the given condition associated with this synchronizer. |
Boolean |
Queries whether any threads have ever contended to acquire this synchronizer; that is, if an acquire method has ever blocked. |
Boolean |
Queries whether any threads have been waiting to acquire longer than the current thread. |
Boolean |
Queries whether any threads are waiting to acquire. |
Boolean |
hasWaiters(condition: AbstractQueuedLongSynchronizer.ConditionObject!) Queries whether any threads are waiting on the given condition associated with this synchronizer. |
Boolean |
Returns true if the given thread is currently queued. |
Boolean |
owns(condition: AbstractQueuedLongSynchronizer.ConditionObject!) Queries whether the given ConditionObject uses this synchronizer as its lock. |
Boolean |
Releases in exclusive mode. |
Boolean |
Releases in shared mode. |
open String |
toString() Returns a string identifying this synchronizer, as well as its state. |
Boolean |
tryAcquireNanos(arg: Long, nanosTimeout: Long) Attempts to acquire in exclusive mode, aborting if interrupted, and failing if the given timeout elapses. |
Boolean |
tryAcquireSharedNanos(: Long, : Long) Attempts to acquire in shared mode, aborting if interrupted, and failing if the given timeout elapses. |
Protected methods | |
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Boolean |
compareAndSetState(expect: Long, update: Long) Atomically sets synchronization state to the given updated value if the current state value equals the expected value. |
Long |
getState() Returns the current value of synchronization state. |
open Boolean |
Returns |
Unit |
Sets the value of synchronization state. |
open Boolean |
tryAcquire(arg: Long) Attempts to acquire in exclusive mode. |
open Long |
Attempts to acquire in shared mode. |
open Boolean |
tryRelease(arg: Long) Attempts to set the state to reflect a release in exclusive mode. |
open Boolean |
Attempts to set the state to reflect a release in shared mode. |
Inherited functions | |
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Protected constructors
AbstractQueuedLongSynchronizer
protected AbstractQueuedLongSynchronizer()
Constructor for subclasses to call.
Public methods
acquire
fun acquire(arg: Long): Unit
Acquires in exclusive mode, ignoring interrupts. Implemented by invoking at least once tryAcquire
, returning on success. Otherwise the thread is queued, possibly repeatedly blocking and unblocking, invoking tryAcquire
until success. This method can be used to implement method Lock#lock
.
Parameters | |
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arg |
Long: the acquire argument. This value is conveyed to tryAcquire but is otherwise uninterpreted and can represent anything you like. |
acquireInterruptibly
fun acquireInterruptibly(arg: Long): Unit
Acquires in exclusive mode, aborting if interrupted. Implemented by first checking interrupt status, then invoking at least once tryAcquire
, returning on success. Otherwise the thread is queued, possibly repeatedly blocking and unblocking, invoking tryAcquire
until success or the thread is interrupted. This method can be used to implement method Lock#lockInterruptibly
.
Parameters | |
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arg |
Long: the acquire argument. This value is conveyed to tryAcquire but is otherwise uninterpreted and can represent anything you like. |
Exceptions | |
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java.lang.InterruptedException |
if the current thread is interrupted |
acquireShared
fun acquireShared(: Long): Unit
Acquires in shared mode, ignoring interrupts. Implemented by first invoking at least once tryAcquireShared
, returning on success. Otherwise the thread is queued, possibly repeatedly blocking and unblocking, invoking tryAcquireShared
until success.
Parameters | |
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arg |
Long: the acquire argument. This value is conveyed to tryAcquireShared but is otherwise uninterpreted and can represent anything you like. |
acquireSharedInterruptibly
fun acquireSharedInterruptibly(: Long): Unit
Acquires in shared mode, aborting if interrupted. Implemented by first checking interrupt status, then invoking at least once tryAcquireShared
, returning on success. Otherwise the thread is queued, possibly repeatedly blocking and unblocking, invoking tryAcquireShared
until success or the thread is interrupted.
Parameters | |
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arg |
Long: the acquire argument. This value is conveyed to tryAcquireShared but is otherwise uninterpreted and can represent anything you like. |
Exceptions | |
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java.lang.InterruptedException |
if the current thread is interrupted |
getExclusiveQueuedThreads
fun getExclusiveQueuedThreads(): MutableCollection<Thread!>!
Returns a collection containing threads that may be waiting to acquire in exclusive mode. This has the same properties as getQueuedThreads
except that it only returns those threads waiting due to an exclusive acquire.
Return | |
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MutableCollection<Thread!>! |
the collection of threads |
getFirstQueuedThread
fun getFirstQueuedThread(): Thread!
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.
Return | |
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Thread! |
the first (longest-waiting) thread in the queue, or null if no threads are currently queued |
getQueueLength
fun getQueueLength(): Int
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.
Return | |
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Int |
the estimated number of threads waiting to acquire |
getQueuedThreads
fun getQueuedThreads(): MutableCollection<Thread!>!
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.
Return | |
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MutableCollection<Thread!>! |
the collection of threads |
getSharedQueuedThreads
fun getSharedQueuedThreads(): MutableCollection<Thread!>!
Returns a collection containing threads that may be waiting to acquire in shared mode. This has the same properties as getQueuedThreads
except that it only returns those threads waiting due to a shared acquire.
Return | |
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MutableCollection<Thread!>! |
the collection of threads |
getWaitQueueLength
fun getWaitQueueLength(condition: AbstractQueuedLongSynchronizer.ConditionObject!): Int
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 system state, not for synchronization control.
Parameters | |
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condition |
AbstractQueuedLongSynchronizer.ConditionObject!: the condition |
Return | |
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Int |
the estimated number of waiting threads |
Exceptions | |
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java.lang.IllegalMonitorStateException |
if exclusive synchronization is not held |
java.lang.IllegalArgumentException |
if the given condition is not associated with this synchronizer |
java.lang.NullPointerException |
if the condition is null |
getWaitingThreads
fun getWaitingThreads(condition: AbstractQueuedLongSynchronizer.ConditionObject!): MutableCollection<Thread!>!
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 | |
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condition |
AbstractQueuedLongSynchronizer.ConditionObject!: the condition |
Return | |
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MutableCollection<Thread!>! |
the collection of threads |
Exceptions | |
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java.lang.IllegalMonitorStateException |
if exclusive synchronization is not held |
java.lang.IllegalArgumentException |
if the given condition is not associated with this synchronizer |
java.lang.NullPointerException |
if the condition is null |
hasContended
fun hasContended(): Boolean
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.
Return | |
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Boolean |
true if there has ever been contention |
hasQueuedPredecessors
fun hasQueuedPredecessors(): Boolean
Queries whether any threads have been waiting to acquire longer than the current thread.
An invocation of this method is equivalent to (but may be more efficient than):
<code>getFirstQueuedThread() != Thread.currentThread() && hasQueuedThreads()</code>
Note that because cancellations due to interrupts and timeouts may occur at any time, a true
return does not guarantee that some other thread will acquire before the current thread. Likewise, it is possible for another thread to win a race to enqueue after this method has returned false
, due to the queue being empty.
This method is designed to be used by a fair synchronizer to avoid barging. Such a synchronizer's tryAcquire
method should return false
, and its tryAcquireShared
method should return a negative value, if this method returns true
(unless this is a reentrant acquire). For example, the tryAcquire
method for a fair, reentrant, exclusive mode synchronizer might look like this:
<code>protected boolean tryAcquire(long arg) { if (isHeldExclusively()) { // A reentrant acquire; increment hold count return true; } else if (hasQueuedPredecessors()) { return false; } else { // try to acquire normally } }</code>
Return | |
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Boolean |
true if there is a queued thread preceding the current thread, and false if the current thread is at the head of the queue or the queue is empty |
hasQueuedThreads
fun hasQueuedThreads(): Boolean
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.
Return | |
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Boolean |
true if there may be other threads waiting to acquire |
hasWaiters
fun hasWaiters(condition: AbstractQueuedLongSynchronizer.ConditionObject!): Boolean
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 | |
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condition |
AbstractQueuedLongSynchronizer.ConditionObject!: the condition |
Return | |
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Boolean |
true if there are any waiting threads |
Exceptions | |
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java.lang.IllegalMonitorStateException |
if exclusive synchronization is not held |
java.lang.IllegalArgumentException |
if the given condition is not associated with this synchronizer |
java.lang.NullPointerException |
if the condition is null |
isQueued
fun isQueued(thread: Thread!): Boolean
Returns true if the given thread is currently queued.
This implementation traverses the queue to determine presence of the given thread.
Parameters | |
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thread |
Thread!: the thread |
Return | |
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Boolean |
true if the given thread is on the queue |
Exceptions | |
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java.lang.NullPointerException |
if the thread is null |
owns
fun owns(condition: AbstractQueuedLongSynchronizer.ConditionObject!): Boolean
Queries whether the given ConditionObject uses this synchronizer as its lock.
Parameters | |
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condition |
AbstractQueuedLongSynchronizer.ConditionObject!: the condition |
Return | |
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Boolean |
true if owned |
Exceptions | |
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java.lang.NullPointerException |
if the condition is null |
release
fun release(arg: Long): Boolean
Releases in exclusive mode. Implemented by unblocking one or more threads if tryRelease
returns true. This method can be used to implement method Lock#unlock
.
Parameters | |
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arg |
Long: the release argument. This value is conveyed to tryRelease but is otherwise uninterpreted and can represent anything you like. |
Return | |
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Boolean |
the value returned from tryRelease |
releaseShared
fun releaseShared(: Long): Boolean
Releases in shared mode. Implemented by unblocking one or more threads if tryReleaseShared
returns true.
Parameters | |
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arg |
Long: the release argument. This value is conveyed to tryReleaseShared but is otherwise uninterpreted and can represent anything you like. |
Return | |
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Boolean |
the value returned from tryReleaseShared |
toString
open fun toString(): String
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 getState
, and either "nonempty"
or "empty"
depending on whether the queue is empty.
Return | |
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String |
a string identifying this synchronizer, as well as its state |
tryAcquireNanos
fun tryAcquireNanos(
arg: Long,
nanosTimeout: Long
): Boolean
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 tryAcquire
, returning on success. Otherwise, the thread is queued, possibly repeatedly blocking and unblocking, invoking tryAcquire
until success or the thread is interrupted or the timeout elapses. This method can be used to implement method Lock#tryLock(long, TimeUnit)
.
Parameters | |
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arg |
Long: the acquire argument. This value is conveyed to tryAcquire but is otherwise uninterpreted and can represent anything you like. |
nanosTimeout |
Long: the maximum number of nanoseconds to wait |
Return | |
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Boolean |
true if acquired; false if timed out |
Exceptions | |
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java.lang.InterruptedException |
if the current thread is interrupted |
tryAcquireSharedNanos
fun tryAcquireSharedNanos(
: Long,
: Long
): Boolean
Attempts to acquire in shared mode, aborting if interrupted, and failing if the given timeout elapses. Implemented by first checking interrupt status, then invoking at least once tryAcquireShared
, returning on success. Otherwise, the thread is queued, possibly repeatedly blocking and unblocking, invoking tryAcquireShared
until success or the thread is interrupted or the timeout elapses.
Parameters | |
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arg |
Long: the acquire argument. This value is conveyed to tryAcquireShared but is otherwise uninterpreted and can represent anything you like. |
nanosTimeout |
Long: the maximum number of nanoseconds to wait |
Return | |
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Boolean |
true if acquired; false if timed out |
Exceptions | |
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java.lang.InterruptedException |
if the current thread is interrupted |
Protected methods
compareAndSetState
protected fun compareAndSetState(
expect: Long,
update: Long
): Boolean
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 | |
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expect |
Long: the expected value |
update |
Long: the new value |
Return | |
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Boolean |
true if successful. False return indicates that the actual value was not equal to the expected value. |
getState
protected fun getState(): Long
Returns the current value of synchronization state. This operation has memory semantics of a volatile
read.
Return | |
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Long |
current state value |
isHeldExclusively
protected open fun isHeldExclusively(): Boolean
Returns true
if synchronization is held exclusively with respect to the current (calling) thread. This method is invoked upon each call to a ConditionObject
method.
The default implementation throws UnsupportedOperationException
. This method is invoked internally only within ConditionObject
methods, so need not be defined if conditions are not used.
Return | |
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Boolean |
true if synchronization is held exclusively; false otherwise |
Exceptions | |
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java.lang.UnsupportedOperationException |
if conditions are not supported |
setState
protected fun setState(newState: Long): Unit
Sets the value of synchronization state. This operation has memory semantics of a volatile
write.
Parameters | |
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newState |
Long: the new state value |
tryAcquire
protected open fun tryAcquire(arg: Long): Boolean
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 | |
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arg |
Long: the acquire argument. This value is always the one passed to an acquire method, or is the value saved on entry to a condition wait. The value is otherwise uninterpreted and can represent anything you like. |
Return | |
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Boolean |
true if successful. Upon success, this object has been acquired. |
Exceptions | |
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java.lang.IllegalMonitorStateException |
if acquiring would place this synchronizer in an illegal state. This exception must be thrown in a consistent fashion for synchronization to work correctly. |
java.lang.UnsupportedOperationException |
if exclusive mode is not supported |
tryAcquireShared
protected open fun tryAcquireShared(: Long): Long
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 | |
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arg |
Long: the acquire argument. This value is always the one passed to an acquire method, or is the value saved on entry to a condition wait. The value is otherwise uninterpreted and can represent anything you like. |
Return | |
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Long |
a negative value on failure; zero if acquisition in shared mode succeeded but no subsequent shared-mode acquire can succeed; and a positive value if acquisition in shared mode succeeded and subsequent shared-mode acquires might also succeed, in which case a subsequent waiting thread must check availability. (Support for three different return values enables this method to be used in contexts where acquires only sometimes act exclusively.) Upon success, this object has been acquired. |
Exceptions | |
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java.lang.IllegalMonitorStateException |
if acquiring would place this synchronizer in an illegal state. This exception must be thrown in a consistent fashion for synchronization to work correctly. |
java.lang.UnsupportedOperationException |
if shared mode is not supported |
tryRelease
protected open fun tryRelease(arg: Long): Boolean
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 | |
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arg |
Long: the release argument. This value is always the one passed to a release method, or the current state value upon entry to a condition wait. The value is otherwise uninterpreted and can represent anything you like. |
Return | |
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Boolean |
true if this object is now in a fully released state, so that any waiting threads may attempt to acquire; and false otherwise. |
Exceptions | |
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java.lang.IllegalMonitorStateException |
if releasing would place this synchronizer in an illegal state. This exception must be thrown in a consistent fashion for synchronization to work correctly. |
java.lang.UnsupportedOperationException |
if exclusive mode is not supported |
tryReleaseShared
protected open fun tryReleaseShared(: Long): Boolean
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 | |
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arg |
Long: the release argument. This value is always the one passed to a release method, or the current state value upon entry to a condition wait. The value is otherwise uninterpreted and can represent anything you like. |
Return | |
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Boolean |
true if this release of shared mode may permit a waiting acquire (shared or exclusive) to succeed; and false otherwise |
Exceptions | |
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java.lang.IllegalMonitorStateException |
if releasing would place this synchronizer in an illegal state. This exception must be thrown in a consistent fashion for synchronization to work correctly. |
java.lang.UnsupportedOperationException |
if shared mode is not supported |