Interfaces and the foundation for a ReentrantLock implementation

classpath/java/util/concurrent/locks/Condition.java

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+/* Copyright (c) 2008-2014, Avian Contributors
+
+   Permission to use, copy, modify, and/or distribute this software
+   for any purpose with or without fee is hereby granted, provided
+   that the above copyright notice and this permission notice appear
+   in all copies.
+
+   There is NO WARRANTY for this software.  See license.txt for
+   details. */
+
+package java.util.concurrent.locks;
+
+import java.util.Date;
+import java.util.concurrent.TimeUnit;
+
+public interface Condition {
+  public void await();
+  public boolean await(long time, TimeUnit unit);
+  public long awaitNanos(long nanosTimeout);
+  public void awaitUninterruptibly();
+  public boolean awaitUntil(Date deadline);
+  public void signal();
+  public void signalAll();
+}

classpath/java/util/concurrent/locks/Lock.java

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+/* Copyright (c) 2008-2014, Avian Contributors
+
+   Permission to use, copy, modify, and/or distribute this software
+   for any purpose with or without fee is hereby granted, provided
+   that the above copyright notice and this permission notice appear
+   in all copies.
+
+   There is NO WARRANTY for this software.  See license.txt for
+   details. */
+
+package java.util.concurrent.locks;
+
+import java.util.concurrent.TimeUnit;
+
+public interface Lock {
+  public void lock();
+  public void lockInterruptibly() throws InterruptedException;
+  public Condition newCondition();
+  public boolean tryLock();
+  public boolean tryLock(long time, TimeUnit unit) throws InterruptedException;
+  public void unlock();
+}

classpath/java/util/concurrent/locks/LockSupport.java

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+/* Copyright (c) 2008-2014, Avian Contributors
+
+   Permission to use, copy, modify, and/or distribute this software
+   for any purpose with or without fee is hereby granted, provided
+   that the above copyright notice and this permission notice appear
+   in all copies.
+
+   There is NO WARRANTY for this software.  See license.txt for
+   details. */
+
+package java.util.concurrent.locks;
+
+import sun.misc.Unsafe;
+
+public class LockSupport {
+  private LockSupport() {
+    // can't construct
+  }
+  
+  private static final Unsafe unsafe;
+  private static final long parkBlockerOffset;
+  
+  static {
+    unsafe = Unsafe.getUnsafe();
+    try {
+      parkBlockerOffset = unsafe.objectFieldOffset(java.lang.Thread.class.getDeclaredField("parkBlocker"));
+    } catch (Exception ex) { 
+      throw new Error(ex);
+    }
+  }
+  
+  private static void setBlocker(Thread t, Object arg) {
+    unsafe.putObject(t, parkBlockerOffset, arg);
+  }
+  
+  public static void unpark(Thread thread) {
+    if (thread != null) {
+      unsafe.unpark(thread);
+    }
+  }
+  
+  public static void park(Object blocker) {
+    doParkNanos(blocker, 0L);
+  }
+  
+  public static void parkNanos(Object blocker, long nanos) {
+    if (nanos <= 0) {
+      return;
+    }
+    
+    doParkNanos(blocker, nanos);
+  }
+  
+  private static void doParkNanos(Object blocker, long nanos) {
+    Thread t = Thread.currentThread();
+    setBlocker(t, blocker);
+    unsafe.park(false, nanos);
+    setBlocker(t, null);
+  }
+  
+  public static void parkUntil(Object blocker, long deadline) {
+    Thread t = Thread.currentThread();
+    setBlocker(t, blocker);
+    unsafe.park(true, deadline);
+    setBlocker(t, null);
+  }
+  
+  public static Object getBlocker(Thread t) {
+    if (t == null) {
+      throw new NullPointerException();
+    }
+    
+    return unsafe.getObjectVolatile(t, parkBlockerOffset);
+  }
+  
+  public static void park() {
+    unsafe.park(false, 0L);
+  }
+  
+  public static void parkNanos(long nanos) {
+    if (nanos > 0) {
+      unsafe.park(false, nanos);
+    }
+  }
+  
+  public static void parkUntil(long deadline) {
+    unsafe.park(true, deadline);
+  }
+}

classpath/java/util/concurrent/locks/ReadWriteLock.java

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+/* Copyright (c) 2008-2014, Avian Contributors
+
+   Permission to use, copy, modify, and/or distribute this software
+   for any purpose with or without fee is hereby granted, provided
+   that the above copyright notice and this permission notice appear
+   in all copies.
+
+   There is NO WARRANTY for this software.  See license.txt for
+   details. */
+
+package java.util.concurrent.locks;
+
+public interface ReadWriteLock {
+  public Lock readLock();
+  public Lock writeLock();
+}