/*
* This file is part of the Jikes RVM project (http://jikesrvm.org).
*
* This file is licensed to You under the Eclipse Public License (EPL);
* You may not use this file except in compliance with the License. You
* may obtain a copy of the License at
*
* http://www.opensource.org/licenses/eclipse-1.0.php
*
* See the COPYRIGHT.txt file distributed with this work for information
* regarding copyright ownership.
*/
package org.jikesrvm.scheduler;
import org.vmmagic.pragma.Uninterruptible;
import org.vmmagic.pragma.Unpreemptible;
import org.vmmagic.pragma.NonMoving;
import org.vmmagic.pragma.NoOptCompile;
import org.vmmagic.pragma.NoInline;
import org.jikesrvm.VM;
/**
* A heavy condition variable and lock that also disables interrupts while
* the lock is held. Extremely useful for any locks that may be acquired,
* released, or waited upon in the process of performing a GC.
* <p>
* Note that calling any of the Nicely methods on an instance of this
* class is extremely dangerous. These methods may cause you to block on
* GC, which seemingly goes against the very intent of this being a "no
* interrupts" condition variable and lock. However, it makes a subtle
* kind of sense to use these methods, <i>if you're calling them on the
* instance of NoInterruptsCondLock that your thread will wait on when
* blocking on GC</i>. This idiom is used quite a bit.
* <p>
* To ensure that the Nicely methods are used correctly - that is, that
* they are only used by the thread that owns the lock - there are assertions
* in place to ensure that the caller is the owner.
*/
@Uninterruptible
@NonMoving
public class NoYieldpointsMonitor extends Monitor {
@NoInline
@NoOptCompile
public void lockNoHandshake() {
VM.disableYieldpoints();
super.lockNoHandshake();
}
// This method is strange
@Unpreemptible
@NoInline
@NoOptCompile
public void lockWithHandshake() {
VM.disableYieldpoints();
super.lockWithHandshake();
}
@NoInline
@NoOptCompile
public void unlock() {
super.unlock();
VM.enableYieldpoints();
}
}