Class ReentrantLock

java.lang.Object
EDU.oswego.cs.dl.util.concurrent.ReentrantLock
All Implemented Interfaces:
Sync
public class ReentrantLock extends Object implements Sync
A lock with the same semantics as builtin Java synchronized locks: Once a thread has a lock, it can re-obtain it any number of times without blocking. The lock is made available to other threads when as many releases as acquires have occurred.

[ Introduction to this package. ]

  • Field Details

    • owner_

      protected Thread owner_

    • holds_

      protected long holds_

  • Constructor Details

    • ReentrantLock

      public ReentrantLock()

  • Method Details

    • acquire

      public void acquire() throws InterruptedException
      Description copied from interface: Sync
      Wait (possibly forever) until successful passage. Fail only upon interuption. Interruptions always result in `clean' failures. On failure, you can be sure that it has not been acquired, and that no corresponding release should be performed. Conversely, a normal return guarantees that the acquire was successful.
      Specified by:
      acquire in interface Sync
      Throws:
      InterruptedException

    • attempt

      public boolean attempt(long msecs) throws InterruptedException
      Description copied from interface: Sync
      Wait at most msecs to pass; report whether passed.

      The method has best-effort semantics: The msecs bound cannot be guaranteed to be a precise upper bound on wait time in Java. Implementations generally can only attempt to return as soon as possible after the specified bound. Also, timers in Java do not stop during garbage collection, so timeouts can occur just because a GC intervened. So, msecs arguments should be used in a coarse-grained manner. Further, implementations cannot always guarantee that this method will return at all without blocking indefinitely when used in unintended ways. For example, deadlocks may be encountered when called in an unintended context.

      Specified by:
      attempt in interface Sync
      Parameters:
      msecs - the number of milleseconds to wait. An argument less than or equal to zero means not to wait at all. However, this may still require access to a synchronization lock, which can impose unbounded delay if there is a lot of contention among threads.
      Returns:
      true if acquired
      Throws:
      InterruptedException

    • release

      public void release()
      Release the lock.
      Specified by:
      release in interface Sync
      Throws:
      Error - thrown if not current owner of lock

    • release

      public void release(long n)
      Release the lock N times. release(n) is equivalent in effect to: 
        for (int i = 0; i invalid input: '<' n; ++i) release();

      Throws:
      Error - thrown if not current owner of lock or has fewer than N holds on the lock

    • holds

      public long holds()
      Return the number of unreleased acquires performed by the current thread. Returns zero if current thread does not hold lock.