1 files changed, 133 insertions, 0 deletions
diff --git a/external/jsr166/java/util/concurrent/atomic/AtomicBoolean.java b/external/jsr166/java/util/concurrent/atomic/AtomicBoolean.java
new file mode 100644
index 000000000..bd823bd2c
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+++ b/external/jsr166/java/util/concurrent/atomic/AtomicBoolean.java
@@ -0,0 +1,133 @@
+/*
+ * 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.atomic;
+import sun.misc.Unsafe;
+
+/**
+ * A <tt>boolean</tt> value that may be updated atomically. See the
+ * {@link java.util.concurrent.atomic} package specification for
+ * description of the properties of atomic variables. An
+ * <tt>AtomicBoolean</tt> is used in applications such as atomically
+ * updated flags, and cannot be used as a replacement for a
+ * {@link java.lang.Boolean}.
+ *
+ * @since 1.5
+ * @author Doug Lea
+ */
+public class AtomicBoolean implements java.io.Serializable {
+    private static final long serialVersionUID = 4654671469794556979L;
+    // setup to use Unsafe.compareAndSwapInt for updates
+    private static final Unsafe unsafe = Unsafe.getUnsafe();
+    private static final long valueOffset;
+
+    static {
+      try {
+        valueOffset = unsafe.objectFieldOffset
+            (AtomicBoolean.class.getDeclaredField("value"));
+      } catch (Exception ex) { throw new Error(ex); }
+    }
+
+    private volatile int value;
+
+    /**
+     * Creates a new <tt>AtomicBoolean</tt> with the given initial value.
+     *
+     * @param initialValue the initial value
+     */
+    public AtomicBoolean(boolean initialValue) {
+        value = initialValue ? 1 : 0;
+    }
+
+    /**
+     * Creates a new <tt>AtomicBoolean</tt> with initial value <tt>false</tt>.
+     */
+    public AtomicBoolean() {
+    }
+
+    /**
+     * Returns the current value.
+     *
+     * @return the current value
+     */
+    public final boolean get() {
+        return value != 0;
+    }
+
+    /**
+     * Atomically sets the value to the given updated value
+     * if the current value <tt>==</tt> the expected value.
+     *
+     * @param expect the expected value
+     * @param update the new value
+     * @return true if successful. False return indicates that
+     * the actual value was not equal to the expected value.
+     */
+    public final boolean compareAndSet(boolean expect, boolean update) {
+        int e = expect ? 1 : 0;
+        int u = update ? 1 : 0;
+        return unsafe.compareAndSwapInt(this, valueOffset, e, u);
+    }
+
+    /**
+     * Atomically sets the value to the given updated value
+     * if the current value <tt>==</tt> the expected value.
+     * May fail spuriously and does not provide ordering guarantees,
+     * so is only rarely an appropriate alternative to <tt>compareAndSet</tt>.
+     *
+     * @param expect the expected value
+     * @param update the new value
+     * @return true if successful.
+     */
+    public boolean weakCompareAndSet(boolean expect, boolean update) {
+        int e = expect ? 1 : 0;
+        int u = update ? 1 : 0;
+        return unsafe.compareAndSwapInt(this, valueOffset, e, u);
+    }
+
+    /**
+     * Unconditionally sets to the given value.
+     *
+     * @param newValue the new value
+     */
+    public final void set(boolean newValue) {
+        value = newValue ? 1 : 0;
+    }
+
+    /**
+     * Eventually sets to the given value.
+     *
+     * @param newValue the new value
+     * @since 1.6
+     */
+    public final void lazySet(boolean newValue) {
+        int v = newValue ? 1 : 0;
+        unsafe.putOrderedInt(this, valueOffset, v);
+    }
+
+    /**
+     * Atomically sets to the given value and returns the previous value.
+     *
+     * @param newValue the new value
+     * @return the previous value
+     */
+    public final boolean getAndSet(boolean newValue) {
+        for (;;) {
+            boolean current = get();
+            if (compareAndSet(current, newValue))
+                return current;
+        }
+    }
+
+    /**
+     * Returns the String representation of the current value.
+     * @return the String representation of the current value.
+     */
+    public String toString() {
+        return Boolean.toString(get());
+    }
+
+}