Build 1.0_r1(from source)

java.util.concurrent.locks
Class ReentrantReadWriteLock.WriteLock

java.lang.Object
  extended by java.util.concurrent.locks.ReentrantReadWriteLock.WriteLock
All Implemented Interfaces:
Serializable, Lock
Enclosing class:
ReentrantReadWriteLock

public static class ReentrantReadWriteLock.WriteLock
extends Object
implements Lock, Serializable

The lock returned by method ReentrantReadWriteLock.writeLock().

See Also:
Serialized Form

Constructor Summary
protected ReentrantReadWriteLock.WriteLock(ReentrantReadWriteLock lock)
          Constructor for use by subclasses.
 
Method Summary
 void lock()
          Acquire the lock.
 void lockInterruptibly()
          Acquires the lock unless the current thread is interrupted.
 Condition newCondition()
          Returns a Condition instance for use with this Lock instance.
 String toString()
          Returns a string identifying this lock, as well as its lock state.
 boolean tryLock()
          Acquires the lock only if it is not held by another thread at the time of invocation.
 boolean tryLock(long timeout, TimeUnit unit)
          Acquires the lock if it is not held by another thread within the given waiting time and the current thread has not been interrupted.
 void unlock()
          Attempts to release this lock.
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait
 

Constructor Detail

ReentrantReadWriteLock.WriteLock

protected ReentrantReadWriteLock.WriteLock(ReentrantReadWriteLock lock)
Constructor for use by subclasses.

Parameters:
lock - the outer lock object
Throws:
NullPointerException - if lock null
Method Detail

lock

public void lock()
Acquire the lock.

Acquires the lock if it is not held by another thread and returns immediately, setting the lock hold count to one.

If the current thread already holds the lock then the hold count is incremented by one and the method returns immediately.

If the lock is held by another thread then the current thread becomes disabled for thread scheduling purposes and lies dormant until the lock has been acquired, at which time the lock hold count is set to one.

Specified by:
lock in interface Lock

lockInterruptibly

public void lockInterruptibly()
                       throws InterruptedException
Acquires the lock unless the current thread is interrupted.

Acquires the lock if it is not held by another thread and returns immediately, setting the lock hold count to one.

If the current thread already holds this lock then the hold count is incremented by one and the method returns immediately.

If the 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 lock is acquired by the current thread then the lock hold count is set to one.

If the current thread:

then InterruptedException is thrown and the current thread's interrupted status is cleared.

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.

Specified by:
lockInterruptibly in interface Lock
Throws:
InterruptedException - if the current thread is interrupted
See Also:
Thread.interrupt()

tryLock

public boolean tryLock()
Acquires the lock only if it is not held by another thread at the time of invocation.

Acquires the lock if it is not held by another thread and returns immediately with the value true, setting the lock hold count to one. Even when this lock has been set to use a fair ordering policy, a call to tryLock() will immediately acquire the lock if it is available, whether or not other threads are currently waiting for the 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 current thread already holds this lock then the hold count is incremented by one and the method returns true.

If the lock is held by another thread then this method will return immediately with the value false.

Specified by:
tryLock in interface Lock
Returns:
true if the lock was free and was acquired by the current thread, or the lock was already held by the current thread; and false otherwise.

tryLock

public boolean tryLock(long timeout,
                       TimeUnit unit)
                throws InterruptedException
Acquires the lock if it is not held by another thread within the given waiting time and the current thread has not been interrupted.

Acquires the lock if it is not held by another thread and returns immediately with the value true, setting the lock hold count to one. 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 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 current thread already holds this lock then the hold count is incremented by one and the method returns true.

If the 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 lock is acquired then the value true is returned and the lock hold count is set to one.

If the current thread:

then InterruptedException is thrown and the current thread's interrupted status is cleared.

If the specified waiting time elapses then the value 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.

Specified by:
tryLock in interface Lock
Parameters:
timeout - the time to wait for the lock
unit - the time unit of the timeout argument
Returns:
true if the lock was free and was acquired by the current thread, or the lock was already held by the current thread; and false if the waiting time elapsed before the lock could be acquired.
Throws:
InterruptedException - if the current thread is interrupted
NullPointerException - if unit is null
See Also:
Thread.interrupt()

unlock

public void unlock()
Attempts to release this lock.

If the current thread is the holder of this lock then the hold count is decremented. If the hold count is now zero then the lock is released. If the current thread is not the holder of this lock then IllegalMonitorStateException is thrown.

Specified by:
unlock in interface Lock
Throws:
IllegalMonitorStateException - if the current thread does not hold this lock.

newCondition

public Condition newCondition()
Returns a Condition instance for use with this Lock instance.

The returned Condition instance supports the same usages as do the Object monitor methods (wait, notify, and notifyAll) when used with the built-in monitor lock.

Specified by:
newCondition in interface Lock
Returns:
the Condition object

toString

public String toString()
Returns a string identifying this lock, as well as its lock state. The state, in brackets includes either the String "Unlocked" or the String "Locked by" followed by the Thread.getName() of the owning thread.

Overrides:
toString in class Object
Returns:
a string identifying this lock, as well as its lock state.

Build 1.0_r1(from source)

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