util/concurrent/FairReentrantLock.java

/*
 * Written by Doug Lea with assistance from members of JCP JSR-166
 * Expert Group and released to the public domain. Use, modify, and
 * redistribute this code in any way without acknowledgement.
 */

package java.util.concurrent;

/**
 * A reentrant mutual exclusion lock that, under contention, favors
 * granting access to the longest-waiting thread.  Programs using fair
 * locks may display lower overall throughput (i.e., are slower) than
 * those using default locks, but have but smaller variances in times
 * to obtain locks.
 * @since 1.5
 * @author Doug Lea
 */

public class FairReentrantLock extends ReentrantLock {
    /**
     * Creates an instance of <tt>FairReentrantLock</tt>.
     */
    public FairReentrantLock() { }

    /**
     * Return true if it is OK to take fast path to lock.  For fair
     * locks, we allow barging only when there are no waiters.
     * @return true if queue empty
     */
    boolean canBarge() {
        return queueEmpty();
    }
}


Revision:	1.3
Committed:	Tue Jul 8 00:46:33 2003 UTC (20 years, 10 months ago) by dl
Branch:	MAIN
CVS Tags:	HEAD
Changes since 1.2:	+0 -0 lines
State:	*FILE REMOVED*
Log Message:	Locks in subpackage; fairness params added
#	Content
1	/*
2	* Written by Doug Lea with assistance from members of JCP JSR-166
3	* Expert Group and released to the public domain. Use, modify, and
4	* redistribute this code in any way without acknowledgement.
5	*/
6
7	package java.util.concurrent;
8
9	/**
10	* A reentrant mutual exclusion lock that, under contention, favors
11	* granting access to the longest-waiting thread. Programs using fair
12	* locks may display lower overall throughput (i.e., are slower) than
13	* those using default locks, but have but smaller variances in times
14	* to obtain locks.
15	* @since 1.5
16	* @author Doug Lea
17	*/
18
19	public class FairReentrantLock extends ReentrantLock {
20	/**
21	* Creates an instance of <tt>FairReentrantLock</tt>.
22	*/
23	public FairReentrantLock() { }
24
25	/**
26	* Return true if it is OK to take fast path to lock. For fair
27	* locks, we allow barging only when there are no waiters.
28	* @return true if queue empty
29	*/
30	boolean canBarge() {
31	return queueEmpty();
32	}
33	}
34
35
36