1 files changed, 163 insertions, 0 deletions
diff --git a/libjava/classpath/external/jsr166/java/util/concurrent/atomic/AtomicReferenceArray.java b/libjava/classpath/external/jsr166/java/util/concurrent/atomic/AtomicReferenceArray.java
new file mode 100644
index 000000000..91b601ed9
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+++ b/libjava/classpath/external/jsr166/java/util/concurrent/atomic/AtomicReferenceArray.java
@@ -0,0 +1,163 @@
+/*
+ * 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;
+import java.util.*;
+
+/**
+ * An array of object references in which elements may be updated
+ * atomically.  See the {@link java.util.concurrent.atomic} package
+ * specification for description of the properties of atomic
+ * variables.
+ * @since 1.5
+ * @author Doug Lea
+ * @param <E> The base class of elements held in this array
+ */
+public class AtomicReferenceArray<E> implements java.io.Serializable {
+    private static final long serialVersionUID = -6209656149925076980L;
+
+    private static final Unsafe unsafe = Unsafe.getUnsafe();
+    private static final int base = unsafe.arrayBaseOffset(Object[].class);
+    private static final int scale = unsafe.arrayIndexScale(Object[].class);
+    private final Object[] array;
+
+    private long rawIndex(int i) {
+        if (i < 0 || i >= array.length)
+            throw new IndexOutOfBoundsException("index " + i);
+        return base + i * scale;
+    }
+
+    /**
+     * Creates a new AtomicReferenceArray of given length.
+     * @param length the length of the array
+     */
+    public AtomicReferenceArray(int length) {
+        array = new Object[length];
+        // must perform at least one volatile write to conform to JMM
+        if (length > 0)
+            unsafe.putObjectVolatile(array, rawIndex(0), null);
+    }
+
+    /**
+     * Creates a new AtomicReferenceArray with the same length as, and
+     * all elements copied from, the given array.
+     *
+     * @param array the array to copy elements from
+     * @throws NullPointerException if array is null
+     */
+    public AtomicReferenceArray(E[] array) {
+        if (array == null)
+            throw new NullPointerException();
+        int length = array.length;
+        this.array = new Object[length];
+        if (length > 0) {
+            int last = length-1;
+            for (int i = 0; i < last; ++i)
+                this.array[i] = array[i];
+            // Do the last write as volatile
+            E e = array[last];
+            unsafe.putObjectVolatile(this.array, rawIndex(last), e);
+        }
+    }
+
+    /**
+     * Returns the length of the array.
+     *
+     * @return the length of the array
+     */
+    public final int length() {
+        return array.length;
+    }
+
+    /**
+     * Gets the current value at position <tt>i</tt>.
+     *
+     * @param i the index
+     * @return the current value
+     */
+    public final E get(int i) {
+        return (E) unsafe.getObjectVolatile(array, rawIndex(i));
+    }
+
+    /**
+     * Sets the element at position <tt>i</tt> to the given value.
+     *
+     * @param i the index
+     * @param newValue the new value
+     */
+    public final void set(int i, E newValue) {
+        unsafe.putObjectVolatile(array, rawIndex(i), newValue);
+    }
+
+    /**
+     * Eventually sets the element at position <tt>i</tt> to the given value.
+     *
+     * @param i the index
+     * @param newValue the new value
+     * @since 1.6
+     */
+    public final void lazySet(int i, E newValue) {
+        unsafe.putOrderedObject(array, rawIndex(i), newValue);
+    }
+
+
+    /**
+     * Atomically sets the element at position <tt>i</tt> to the given
+     * value and returns the old value.
+     *
+     * @param i the index
+     * @param newValue the new value
+     * @return the previous value
+     */
+    public final E getAndSet(int i, E newValue) {
+        while (true) {
+            E current = get(i);
+            if (compareAndSet(i, current, newValue))
+                return current;
+        }
+    }
+
+    /**
+     * Atomically sets the element at position <tt>i</tt> to the given
+     * updated value if the current value <tt>==</tt> the expected value.
+     * @param i the index
+     * @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(int i, E expect, E update) {
+        return unsafe.compareAndSwapObject(array, rawIndex(i),
+                                         expect, update);
+    }
+
+    /**
+     * Atomically sets the element at position <tt>i</tt> 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 i the index
+     * @param expect the expected value
+     * @param update the new value
+     * @return true if successful.
+     */
+    public final boolean weakCompareAndSet(int i, E expect, E update) {
+        return compareAndSet(i, expect, update);
+    }
+
+    /**
+     * Returns the String representation of the current values of array.
+     * @return the String representation of the current values of array.
+     */
+    public String toString() {
+        if (array.length > 0) // force volatile read
+            get(0);
+        return Arrays.toString(array);
+    }
+
+}