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diff --git a/libjava/classpath/external/jsr166/java/util/concurrent/locks/LockSupport.java b/libjava/classpath/external/jsr166/java/util/concurrent/locks/LockSupport.java
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+/*
+ * Written by Doug Lea with assistance from members of JCP JSR-166
+ * Expert Group and released to the public domain, as explained at
+ * http://creativecommons.org/licenses/publicdomain
+ */
+
+package java.util.concurrent.locks;
+import java.util.concurrent.*;
+import sun.misc.Unsafe;
+
+
+/**
+ * Basic thread blocking primitives for creating locks and other
+ * synchronization classes.
+ *
+ * <p>This class associates, with each thread that uses it, a permit
+ * (in the sense of the {@link java.util.concurrent.Semaphore
+ * Semaphore} class). A call to {@code park} will return immediately
+ * if the permit is available, consuming it in the process; otherwise
+ * it <em>may</em> block.  A call to {@code unpark} makes the permit
+ * available, if it was not already available. (Unlike with Semaphores
+ * though, permits do not accumulate. There is at most one.)
+ *
+ * <p>Methods {@code park} and {@code unpark} provide efficient
+ * means of blocking and unblocking threads that do not encounter the
+ * problems that cause the deprecated methods {@code Thread.suspend}
+ * and {@code Thread.resume} to be unusable for such purposes: Races
+ * between one thread invoking {@code park} and another thread trying
+ * to {@code unpark} it will preserve liveness, due to the
+ * permit. Additionally, {@code park} will return if the caller's
+ * thread was interrupted, and timeout versions are supported. The
+ * {@code park} method may also return at any other time, for "no
+ * reason", so in general must be invoked within a loop that rechecks
+ * conditions upon return. In this sense {@code park} serves as an
+ * optimization of a "busy wait" that does not waste as much time
+ * spinning, but must be paired with an {@code unpark} to be
+ * effective.
+ *
+ * <p>The three forms of {@code park} each also support a
+ * {@code blocker} object parameter. This object is recorded while
+ * the thread is blocked to permit monitoring and diagnostic tools to
+ * identify the reasons that threads are blocked. (Such tools may
+ * access blockers using method {@link #getBlocker}.) The use of these
+ * forms rather than the original forms without this parameter is
+ * strongly encouraged. The normal argument to supply as a
+ * {@code blocker} within a lock implementation is {@code this}.
+ *
+ * <p>These methods are designed to be used as tools for creating
+ * higher-level synchronization utilities, and are not in themselves
+ * useful for most concurrency control applications.  The {@code park}
+ * method is designed for use only in constructions of the form:
+ * <pre>while (!canProceed()) { ... LockSupport.park(this); }</pre>
+ * where neither {@code canProceed} nor any other actions prior to the
+ * call to {@code park} entail locking or blocking.  Because only one
+ * permit is associated with each thread, any intermediary uses of
+ * {@code park} could interfere with its intended effects.
+ *
+ * <p><b>Sample Usage.</b> Here is a sketch of a first-in-first-out
+ * non-reentrant lock class:
+ * <pre>{@code
+ * class FIFOMutex {
+ *   private final AtomicBoolean locked = new AtomicBoolean(false);
+ *   private final Queue<Thread> waiters
+ *     = new ConcurrentLinkedQueue<Thread>();
+ *
+ *   public void lock() {
+ *     boolean wasInterrupted = false;
+ *     Thread current = Thread.currentThread();
+ *     waiters.add(current);
+ *
+ *     // Block while not first in queue or cannot acquire lock
+ *     while (waiters.peek() != current ||
+ *            !locked.compareAndSet(false, true)) {
+ *        LockSupport.park(this);
+ *        if (Thread.interrupted()) // ignore interrupts while waiting
+ *          wasInterrupted = true;
+ *     }
+ *
+ *     waiters.remove();
+ *     if (wasInterrupted)          // reassert interrupt status on exit
+ *        current.interrupt();
+ *   }
+ *
+ *   public void unlock() {
+ *     locked.set(false);
+ *     LockSupport.unpark(waiters.peek());
+ *   }
+ * }}</pre>
+ */
+
+public class LockSupport {
+    private LockSupport() {} // Cannot be instantiated.
+
+    // Hotspot implementation via intrinsics API
+    private static final Unsafe unsafe = Unsafe.getUnsafe();
+    private static final long parkBlockerOffset;
+
+    static {
+        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) {
+        // Even though volatile, hotspot doesn't need a write barrier here.
+        unsafe.putObject(t, parkBlockerOffset, arg);
+    }
+
+    /**
+     * Makes available the permit for the given thread, if it
+     * was not already available.  If the thread was blocked on
+     * {@code park} then it will unblock.  Otherwise, its next call
+     * to {@code park} is guaranteed not to block. This operation
+     * is not guaranteed to have any effect at all if the given
+     * thread has not been started.
+     *
+     * @param thread the thread to unpark, or {@code null}, in which case
+     *        this operation has no effect
+     */
+    public static void unpark(Thread thread) {
+        if (thread != null)
+            unsafe.unpark(thread);
+    }
+
+    /**
+     * Disables the current thread for thread scheduling purposes unless the
+     * permit is available.
+     *
+     * <p>If the permit is available then it is consumed and the call returns
+     * immediately; otherwise
+     * the current thread becomes disabled for thread scheduling
+     * purposes and lies dormant until one of three things happens:
+     *
+     * <ul>
+     * <li>Some other thread invokes {@link #unpark unpark} with the
+     * current thread as the target; or
+     *
+     * <li>Some other thread {@linkplain Thread#interrupt interrupts}
+     * the current thread; or
+     *
+     * <li>The call spuriously (that is, for no reason) returns.
+     * </ul>
+     *
+     * <p>This method does <em>not</em> report which of these caused the
+     * method to return. Callers should re-check the conditions which caused
+     * the thread to park in the first place. Callers may also determine,
+     * for example, the interrupt status of the thread upon return.
+     *
+     * @param blocker the synchronization object responsible for this
+     *        thread parking
+     * @since 1.6
+     */
+    public static void park(Object blocker) {
+        Thread t = Thread.currentThread();
+        setBlocker(t, blocker);
+        unsafe.park(false, 0L);
+        setBlocker(t, null);
+    }
+
+    /**
+     * Disables the current thread for thread scheduling purposes, for up to
+     * the specified waiting time, unless the permit is available.
+     *
+     * <p>If the permit is available then it is consumed and the call
+     * returns immediately; otherwise the current thread becomes disabled
+     * for thread scheduling purposes and lies dormant until one of four
+     * things happens:
+     *
+     * <ul>
+     * <li>Some other thread invokes {@link #unpark unpark} with the
+     * current thread as the target; or
+     *
+     * <li>Some other thread {@linkplain Thread#interrupt interrupts} the current
+     * thread; or
+     *
+     * <li>The specified waiting time elapses; or
+     *
+     * <li>The call spuriously (that is, for no reason) returns.
+     * </ul>
+     *
+     * <p>This method does <em>not</em> report which of these caused the
+     * method to return. Callers should re-check the conditions which caused
+     * the thread to park in the first place. Callers may also determine,
+     * for example, the interrupt status of the thread, or the elapsed time
+     * upon return.
+     *
+     * @param blocker the synchronization object responsible for this
+     *        thread parking
+     * @param nanos the maximum number of nanoseconds to wait
+     * @since 1.6
+     */
+    public static void parkNanos(Object blocker, long nanos) {
+        if (nanos > 0) {
+            Thread t = Thread.currentThread();
+            setBlocker(t, blocker);
+            unsafe.park(false, nanos);
+            setBlocker(t, null);
+        }
+    }
+
+    /**
+     * Disables the current thread for thread scheduling purposes, until
+     * the specified deadline, unless the permit is available.
+     *
+     * <p>If the permit is available then it is consumed and the call
+     * returns immediately; otherwise the current thread becomes disabled
+     * for thread scheduling purposes and lies dormant until one of four
+     * things happens:
+     *
+     * <ul>
+     * <li>Some other thread invokes {@link #unpark unpark} with the
+     * current thread as the target; or
+     *
+     * <li>Some other thread {@linkplain Thread#interrupt interrupts} the
+     * current thread; or
+     *
+     * <li>The specified deadline passes; or
+     *
+     * <li>The call spuriously (that is, for no reason) returns.
+     * </ul>
+     *
+     * <p>This method does <em>not</em> report which of these caused the
+     * method to return. Callers should re-check the conditions which caused
+     * the thread to park in the first place. Callers may also determine,
+     * for example, the interrupt status of the thread, or the current time
+     * upon return.
+     *
+     * @param blocker the synchronization object responsible for this
+     *        thread parking
+     * @param deadline the absolute time, in milliseconds from the Epoch,
+     *        to wait until
+     * @since 1.6
+     */
+    public static void parkUntil(Object blocker, long deadline) {
+        Thread t = Thread.currentThread();
+        setBlocker(t, blocker);
+        unsafe.park(true, deadline);
+        setBlocker(t, null);
+    }
+
+    /**
+     * Returns the blocker object supplied to the most recent
+     * invocation of a park method that has not yet unblocked, or null
+     * if not blocked.  The value returned is just a momentary
+     * snapshot -- the thread may have since unblocked or blocked on a
+     * different blocker object.
+     *
+     * @return the blocker
+     * @since 1.6
+     */
+    public static Object getBlocker(Thread t) {
+        return unsafe.getObjectVolatile(t, parkBlockerOffset);
+    }
+
+    /**
+     * Disables the current thread for thread scheduling purposes unless the
+     * permit is available.
+     *
+     * <p>If the permit is available then it is consumed and the call
+     * returns immediately; otherwise the current thread becomes disabled
+     * for thread scheduling purposes and lies dormant until one of three
+     * things happens:
+     *
+     * <ul>
+     *
+     * <li>Some other thread invokes {@link #unpark unpark} with the
+     * current thread as the target; or
+     *
+     * <li>Some other thread {@linkplain Thread#interrupt interrupts}
+     * the current thread; or
+     *
+     * <li>The call spuriously (that is, for no reason) returns.
+     * </ul>
+     *
+     * <p>This method does <em>not</em> report which of these caused the
+     * method to return. Callers should re-check the conditions which caused
+     * the thread to park in the first place. Callers may also determine,
+     * for example, the interrupt status of the thread upon return.
+     */
+    public static void park() {
+        unsafe.park(false, 0L);
+    }
+
+    /**
+     * Disables the current thread for thread scheduling purposes, for up to
+     * the specified waiting time, unless the permit is available.
+     *
+     * <p>If the permit is available then it is consumed and the call
+     * returns immediately; otherwise the current thread becomes disabled
+     * for thread scheduling purposes and lies dormant until one of four
+     * things happens:
+     *
+     * <ul>
+     * <li>Some other thread invokes {@link #unpark unpark} with the
+     * current thread as the target; or
+     *
+     * <li>Some other thread {@linkplain Thread#interrupt interrupts}
+     * the current thread; or
+     *
+     * <li>The specified waiting time elapses; or
+     *
+     * <li>The call spuriously (that is, for no reason) returns.
+     * </ul>
+     *
+     * <p>This method does <em>not</em> report which of these caused the
+     * method to return. Callers should re-check the conditions which caused
+     * the thread to park in the first place. Callers may also determine,
+     * for example, the interrupt status of the thread, or the elapsed time
+     * upon return.
+     *
+     * @param nanos the maximum number of nanoseconds to wait
+     */
+    public static void parkNanos(long nanos) {
+        if (nanos > 0)
+            unsafe.park(false, nanos);
+    }
+
+    /**
+     * Disables the current thread for thread scheduling purposes, until
+     * the specified deadline, unless the permit is available.
+     *
+     * <p>If the permit is available then it is consumed and the call
+     * returns immediately; otherwise the current thread becomes disabled
+     * for thread scheduling purposes and lies dormant until one of four
+     * things happens:
+     *
+     * <ul>
+     * <li>Some other thread invokes {@link #unpark unpark} with the
+     * current thread as the target; or
+     *
+     * <li>Some other thread {@linkplain Thread#interrupt interrupts}
+     * the current thread; or
+     *
+     * <li>The specified deadline passes; or
+     *
+     * <li>The call spuriously (that is, for no reason) returns.
+     * </ul>
+     *
+     * <p>This method does <em>not</em> report which of these caused the
+     * method to return. Callers should re-check the conditions which caused
+     * the thread to park in the first place. Callers may also determine,
+     * for example, the interrupt status of the thread, or the current time
+     * upon return.
+     *
+     * @param deadline the absolute time, in milliseconds from the Epoch,
+     *        to wait until
+     */
+    public static void parkUntil(long deadline) {
+        unsafe.park(true, deadline);
+    }
+}