Package EDU.oswego.cs.dl.util.concurrent
Class ReentrantLock
- java.lang.Object
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- EDU.oswego.cs.dl.util.concurrent.ReentrantLock
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- All Implemented Interfaces:
Sync
public class ReentrantLock extends java.lang.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.
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Field Summary
Fields Modifier and Type Field Description protected long
holds_
protected java.lang.Thread
owner_
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Fields inherited from interface EDU.oswego.cs.dl.util.concurrent.Sync
ONE_CENTURY, ONE_DAY, ONE_HOUR, ONE_MINUTE, ONE_SECOND, ONE_WEEK, ONE_YEAR
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Constructor Summary
Constructors Constructor Description ReentrantLock()
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Method Summary
All Methods Instance Methods Concrete Methods Modifier and Type Method Description void
acquire()
Wait (possibly forever) until successful passage.boolean
attempt(long msecs)
Wait at most msecs to pass; report whether passed.long
holds()
Return the number of unreleased acquires performed by the current thread.void
release()
Release the lock.void
release(long n)
Release the lock N times.
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Method Detail
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acquire
public void acquire() throws java.lang.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.
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attempt
public boolean attempt(long msecs) throws java.lang.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 interfaceSync
- 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:
java.lang.InterruptedException
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release
public void release()
Release the lock.
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release
public void release(long n)
Release the lock N times.release(n)
is equivalent in effect to:for (int i = 0; i < n; ++i) release();
- Throws:
java.lang.Error
- thrown if not current owner of lock or has fewer than N holds on the lock
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holds
public long holds()
Return the number of unreleased acquires performed by the current thread. Returns zero if current thread does not hold lock.
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