001    /*
002     *  This file is part of the Jikes RVM project (http://jikesrvm.org).
003     *
004     *  This file is licensed to You under the Eclipse Public License (EPL);
005     *  You may not use this file except in compliance with the License. You
006     *  may obtain a copy of the License at
007     *
008     *      http://www.opensource.org/licenses/eclipse-1.0.php
009     *
010     *  See the COPYRIGHT.txt file distributed with this work for information
011     *  regarding copyright ownership.
012     */
013    package org.mmtk.vm;
014    
015    import org.vmmagic.pragma.Uninterruptible;
016    
017    /**
018     * Provides MMTk access to a heavy lock with condition variable.
019     * Functionally similar to Java monitors, but safe in the darker corners of runtime code.
020     */
021    @Uninterruptible
022    public abstract class Monitor {
023    
024      /**
025       * Block until the lock is acquired.
026       */
027      public abstract void lock();
028    
029      /**
030       * Release the lock.
031       */
032      public abstract void unlock();
033    
034      /**
035       * Wait for a broadcast.
036       */
037      public abstract void await();
038    
039      /**
040       * Send a broadcast.
041       */
042      public abstract void broadcast();
043    }