ReentrantReadWriteLock.ReadLock

public static class ReentrantReadWriteLock.ReadLock extends Object
implements Lock Serializable

The lock returned by method readLock().

Protected Constructor Summary

ReentrantReadWriteLock.ReadLock(ReentrantReadWriteLock lock)
Constructor for use by subclasses.

Public Method Summary

void
lock()
Acquires the read lock.
void
lockInterruptibly()
Acquires the read lock unless the current thread is {@linkplain Thread#interrupt interrupted}.
Condition
newCondition()
Throws UnsupportedOperationException because ReadLocks do not support conditions.
String
toString()
Returns a string identifying this lock, as well as its lock state.
boolean
tryLock()
Acquires the read lock only if the write lock is not held by another thread at the time of invocation.
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 {@linkplain Thread#interrupt interrupted}.
void
unlock()
Attempts to release this lock.

Inherited Method Summary

Protected Constructors

protected ReentrantReadWriteLock.ReadLock (ReentrantReadWriteLock lock)

Constructor for use by subclasses.

Parameters
lock the outer lock object
Throws
NullPointerException if the lock is null

Public Methods

public void lock ()

Acquires the read lock.

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.

public void lockInterruptibly ()

Acquires the read lock unless the current thread is {@linkplain Thread#interrupt interrupted}.

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:

  • The read lock is acquired by the current thread; or
  • Some other thread {@linkplain Thread#interrupt interrupts} the current thread.

If the current thread:

  • has its interrupted status set on entry to this method; or
  • is {@linkplain Thread#interrupt interrupted} while acquiring the read lock,
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.

Throws
InterruptedException if the current thread is interrupted

public Condition newCondition ()

Throws UnsupportedOperationException because ReadLocks do not support conditions.

Returns
  • A new Condition instance for this Lock instance

public String toString ()

Returns a string identifying this lock, as well as its lock state. The state, in brackets, includes the String "Read locks =" followed by the number of held read locks.

Returns
  • a string identifying this lock, as well as its lock state

public boolean tryLock ()

Acquires the read lock only if the write lock is not held by another thread at the time of invocation.

Acquires the read lock if the write lock is not held by another thread and returns immediately with the value true. Even when this lock has been set to use a fair ordering policy, a call to 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 false.

Returns
  • true if the read lock was acquired

public boolean