Serializable
, Lock
ReentrantReadWriteLock
public static class ReentrantReadWriteLock.WriteLock extends Object implements Lock, Serializable
ReentrantReadWriteLock.writeLock()
.Modifier | Constructor | Description |
---|---|---|
protected |
Constructor for use by subclasses. |
Modifier and Type | Method | Description |
---|---|---|
int |
getHoldCount() |
Queries the number of holds on this write lock by the current thread. |
boolean |
isHeldByCurrentThread() |
Queries if this write lock is held by the current thread. |
void |
lock() |
Acquires the write lock. |
void |
lockInterruptibly() |
Acquires the write lock unless the current thread is interrupted. |
Condition |
newCondition() |
|
String |
toString() |
Returns a string identifying this lock, as well as its lock state. |
boolean |
tryLock() |
Acquires the write lock only if it is not held by another thread at the time of invocation. |
boolean |
tryLock |
Acquires the write 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. |
protected WriteLock(ReentrantReadWriteLock lock)
lock
- the outer lock objectNullPointerException
- if the lock is nullpublic void lock()
Acquires the write lock if neither the read nor write lock are held by another thread and returns immediately, setting the write lock hold count to one.
If the current thread already holds the write 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 write lock has been acquired, at which time the write lock hold count is set to one.
public void lockInterruptibly() throws InterruptedException
Acquires the write lock if neither the read nor write lock are held by another thread and returns immediately, setting the write 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 write lock is acquired by the current thread then the lock hold count is set to one.
If the current thread:
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.
lockInterruptibly
in interface Lock
InterruptedException
- if the current thread is interruptedpublic boolean tryLock()
Acquires the write lock if neither the read nor write lock are held by another thread and returns immediately with the value true
, setting the write 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 write 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
.
public boolean tryLock(long timeout, TimeUnit unit) throws InterruptedException
Acquires the write lock if neither the read nor write lock are held by another thread and returns immediately with the value true
, setting the write 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 write 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 write lock is acquired then the value true
is returned and the write lock hold count is set to one.
If the current thread:
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.
tryLock
in interface Lock
timeout
- the time to wait for the write lockunit
- the time unit of the timeout argumenttrue
if the lock was free and was acquired by the current thread, or the write lock was already held by the current thread; and false
if the waiting time elapsed before the lock could be acquired.InterruptedException
- if the current thread is interruptedNullPointerException
- if the time unit is nullpublic void unlock()
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.
unlock
in interface Lock
IllegalMonitorStateException
- if the current thread does not hold this lockpublic Condition newCondition()
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.
Condition
method is called then an IllegalMonitorStateException
is thrown. (Read locks are held independently of write locks, so are not checked or affected. However it is essentially always an error to invoke a condition waiting method when the current thread has also acquired read locks, since other threads that could unblock it will not be able to acquire the write lock.) InterruptedException
will be thrown, and the thread's interrupted status will be cleared. newCondition
in interface Lock
public String toString()
"Unlocked"
or the String "Locked by"
followed by the name of the owning thread.public boolean isHeldByCurrentThread()
ReentrantReadWriteLock.isWriteLockedByCurrentThread()
.true
if the current thread holds this lock and false
otherwisepublic int getHoldCount()
ReentrantReadWriteLock.getWriteHoldCount()
.
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