edu.emory.mathcs.backport.java.util.concurrent.locks
public static class ReentrantReadWriteLock.ReadLock extends Object implements Lock, Serializable
Constructor Summary | |
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protected | ReadLock(ReentrantReadWriteLock lock)
Constructor for use by subclasses
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Method Summary | |
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void | lock()
Acquires the read lock.
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void | lockInterruptibly()
Acquires the read lock unless the current thread is
Thread#interrupt interrupted.
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Condition | newCondition()
Throws {@code UnsupportedOperationException} because
{@code ReadLocks} do not support conditions.
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String | toString()
Returns a string identifying this lock, as well as its lock state.
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boolean | tryLock()
Acquires the read lock only if the write lock is not held by
another thread at the time of invocation.
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boolean | tryLock(long timeout, TimeUnit unit)
Acquires the read lock if the write lock is not held by
another thread within the given waiting time and the
current thread has not been Thread#interrupt
interrupted.
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void | unlock()
Attempts to release this lock.
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Parameters: lock the outer lock object
Throws: NullPointerException if the lock is null
Acquires the read lock if the write lock is not held by another thread and returns immediately.
If the write lock is held by another thread then the current thread becomes disabled for thread scheduling purposes and lies dormant until the read lock has been acquired.
Acquires the read lock if the write lock is not held by another thread and returns immediately.
If the write lock is held by another thread then the current thread becomes disabled for thread scheduling purposes and lies dormant until one of two things happens:
If the current thread:
In this implementation, as this method is an explicit interruption point, preference is given to responding to the interrupt over normal or reentrant acquisition of the lock.
Throws: InterruptedException if the current thread is interrupted
Throws: UnsupportedOperationException always
Returns: a string identifying this lock, as well as its lock state
Acquires the read lock if the write lock is not held by
another thread and returns immediately with the value
{@code true}. Even when this lock has been set to use a
fair ordering policy, a call to {@code tryLock()}
will immediately acquire the read lock if it is
available, whether or not other threads are currently
waiting for the read lock. This "barging" behavior
can be useful in certain circumstances, even though it
breaks fairness. If you want to honor the fairness setting
for this lock, then use
tryLock(0, TimeUnit.SECONDS)
which is almost equivalent
(it also detects interruption).
If the write lock is held by another thread then this method will return immediately with the value {@code false}.
Returns: {@code true} if the read lock was acquired
Acquires the read lock if the write lock is not held by another thread and returns immediately with the value {@code true}. If this lock has been set to use a fair ordering policy then an available lock will not be acquired if any other threads are waiting for the lock. This is in contrast to the tryLock method. If you want a timed {@code tryLock} that does permit barging on a fair lock then combine the timed and un-timed forms together:
if (lock.tryLock() || lock.tryLock(timeout, unit) ) { ... }
If the write lock is held by another thread then the current thread becomes disabled for thread scheduling purposes and lies dormant until one of three things happens:
If the read lock is acquired then the value {@code true} is returned.
If the current thread:
If the specified waiting time elapses then the value {@code false} is returned. If the time is less than or equal to zero, the method will not wait at all.
In this implementation, as this method is an explicit interruption point, preference is given to responding to the interrupt over normal or reentrant acquisition of the lock, and over reporting the elapse of the waiting time.
Parameters: timeout the time to wait for the read lock unit the time unit of the timeout argument
Returns: {@code true} if the read lock was acquired
Throws: InterruptedException if the current thread is interrupted NullPointerException if the time unit is null
If the number of readers is now zero then the lock is made available for write lock attempts.