edu.rice.cs.plt.concurrent
Class LockMap<T>

java.lang.Object
  edu.rice.cs.plt.concurrent.LockMap<T>

public class LockMap<T>
extends Object

A map for associating arbitrary objects with locks for the lifetime of the objects. This allows, for example, synchronization based on the arguments to a method (the alternative of directly locking on the arguments themselves is dangerous, because the argument objects may be used for locking in a different context; two threads locking on the same object for unrelated purposes may lead to deadlock). Each unique key (distinguished via ==) is associated with a different ReentrantLock. Weak references are used to allow keys to be freely garbage-collected.

Constructor Summary

LockMap()

LockMap(int initialCapacity)

Method Summary

ReentrantLock	get(T val) Get the lock associated with the given value.
Runnable	lock(T val) Acquire the lock associated with the given value, and return a Runnable for unlocking when the lock can be released.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

LockMap

public LockMap()

LockMap

public LockMap(int initialCapacity)

Method Detail

get

public ReentrantLock get(T val)

Get the lock associated with the given value. If necessary, allocate and cache a new lock.

lock

public Runnable lock(T val)

Acquire the lock associated with the given value, and return a Runnable for unlocking when the lock can be released. Clients should generally follow this invocation with a try/finally block that guarantees execution of the resulting runnable.

Returns:

A Runnable for invoking lock.unlock(). If invoked incorrectly, may throw an IllegalMonitorStateException.

See Also:

ReentrantLock.lock(), ReentrantLock.unlock()