jtulach@1334: /*
jtulach@1334:  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
jtulach@1334:  *
jtulach@1334:  * This code is free software; you can redistribute it and/or modify it
jtulach@1334:  * under the terms of the GNU General Public License version 2 only, as
jtulach@1334:  * published by the Free Software Foundation.  Oracle designates this
jtulach@1334:  * particular file as subject to the "Classpath" exception as provided
jtulach@1334:  * by Oracle in the LICENSE file that accompanied this code.
jtulach@1334:  *
jtulach@1334:  * This code is distributed in the hope that it will be useful, but WITHOUT
jtulach@1334:  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
jtulach@1334:  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
jtulach@1334:  * version 2 for more details (a copy is included in the LICENSE file that
jtulach@1334:  * accompanied this code).
jtulach@1334:  *
jtulach@1334:  * You should have received a copy of the GNU General Public License version
jtulach@1334:  * 2 along with this work; if not, write to the Free Software Foundation,
jtulach@1334:  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
jtulach@1334:  *
jtulach@1334:  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
jtulach@1334:  * or visit www.oracle.com if you need additional information or have any
jtulach@1334:  * questions.
jtulach@1334:  */
jtulach@1334: 
jtulach@1334: /*
jtulach@1334:  * This file is available under and governed by the GNU General Public
jtulach@1334:  * License version 2 only, as published by the Free Software Foundation.
jtulach@1334:  * However, the following notice accompanied the original version of this
jtulach@1334:  * file:
jtulach@1334:  *
jtulach@1334:  * Written by Doug Lea with assistance from members of JCP JSR-166
jtulach@1334:  * Expert Group and released to the public domain, as explained at
jtulach@1334:  * http://creativecommons.org/publicdomain/zero/1.0/
jtulach@1334:  */
jtulach@1334: 
jtulach@1334: package java.util.concurrent.atomic;
jtulach@1334: import sun.misc.Unsafe;
jtulach@1334: import java.util.*;
jtulach@1334: 
jtulach@1334: /**
jtulach@1334:  * An {@code int} array in which elements may be updated atomically.
jtulach@1334:  * See the {@link java.util.concurrent.atomic} package
jtulach@1334:  * specification for description of the properties of atomic
jtulach@1334:  * variables.
jtulach@1334:  * @since 1.5
jtulach@1334:  * @author Doug Lea
jtulach@1334:  */
jtulach@1334: public class AtomicIntegerArray implements java.io.Serializable {
jtulach@1334:     private static final long serialVersionUID = 2862133569453604235L;
jtulach@1334: 
jtulach@1334:     private static final Unsafe unsafe = Unsafe.getUnsafe();
jtulach@1334:     private static final int base = unsafe.arrayBaseOffset(int[].class);
jtulach@1334:     private static final int shift;
jtulach@1334:     private final int[] array;
jtulach@1334: 
jtulach@1334:     static {
jtulach@1334:         int scale = unsafe.arrayIndexScale(int[].class);
jtulach@1334:         if ((scale & (scale - 1)) != 0)
jtulach@1334:             throw new Error("data type scale not a power of two");
jtulach@1334:         shift = 31 - Integer.numberOfLeadingZeros(scale);
jtulach@1334:     }
jtulach@1334: 
jtulach@1334:     private long checkedByteOffset(int i) {
jtulach@1334:         if (i < 0 || i >= array.length)
jtulach@1334:             throw new IndexOutOfBoundsException("index " + i);
jtulach@1334: 
jtulach@1334:         return byteOffset(i);
jtulach@1334:     }
jtulach@1334: 
jtulach@1334:     private static long byteOffset(int i) {
jtulach@1334:         return ((long) i << shift) + base;
jtulach@1334:     }
jtulach@1334: 
jtulach@1334:     /**
jtulach@1334:      * Creates a new AtomicIntegerArray of the given length, with all
jtulach@1334:      * elements initially zero.
jtulach@1334:      *
jtulach@1334:      * @param length the length of the array
jtulach@1334:      */
jtulach@1334:     public AtomicIntegerArray(int length) {
jtulach@1334:         array = new int[length];
jtulach@1334:     }
jtulach@1334: 
jtulach@1334:     /**
jtulach@1334:      * Creates a new AtomicIntegerArray with the same length as, and
jtulach@1334:      * all elements copied from, the given array.
jtulach@1334:      *
jtulach@1334:      * @param array the array to copy elements from
jtulach@1334:      * @throws NullPointerException if array is null
jtulach@1334:      */
jtulach@1334:     public AtomicIntegerArray(int[] array) {
jtulach@1334:         // Visibility guaranteed by final field guarantees
jtulach@1334:         this.array = array.clone();
jtulach@1334:     }
jtulach@1334: 
jtulach@1334:     /**
jtulach@1334:      * Returns the length of the array.
jtulach@1334:      *
jtulach@1334:      * @return the length of the array
jtulach@1334:      */
jtulach@1334:     public final int length() {
jtulach@1334:         return array.length;
jtulach@1334:     }
jtulach@1334: 
jtulach@1334:     /**
jtulach@1334:      * Gets the current value at position {@code i}.
jtulach@1334:      *
jtulach@1334:      * @param i the index
jtulach@1334:      * @return the current value
jtulach@1334:      */
jtulach@1334:     public final int get(int i) {
jtulach@1334:         return getRaw(checkedByteOffset(i));
jtulach@1334:     }
jtulach@1334: 
jtulach@1334:     private int getRaw(long offset) {
jtulach@1334:         return unsafe.getIntVolatile(array, offset);
jtulach@1334:     }
jtulach@1334: 
jtulach@1334:     /**
jtulach@1334:      * Sets the element at position {@code i} to the given value.
jtulach@1334:      *
jtulach@1334:      * @param i the index
jtulach@1334:      * @param newValue the new value
jtulach@1334:      */
jtulach@1334:     public final void set(int i, int newValue) {
jtulach@1334:         unsafe.putIntVolatile(array, checkedByteOffset(i), newValue);
jtulach@1334:     }
jtulach@1334: 
jtulach@1334:     /**
jtulach@1334:      * Eventually sets the element at position {@code i} to the given value.
jtulach@1334:      *
jtulach@1334:      * @param i the index
jtulach@1334:      * @param newValue the new value
jtulach@1334:      * @since 1.6
jtulach@1334:      */
jtulach@1334:     public final void lazySet(int i, int newValue) {
jtulach@1334:         unsafe.putOrderedInt(array, checkedByteOffset(i), newValue);
jtulach@1334:     }
jtulach@1334: 
jtulach@1334:     /**
jtulach@1334:      * Atomically sets the element at position {@code i} to the given
jtulach@1334:      * value and returns the old value.
jtulach@1334:      *
jtulach@1334:      * @param i the index
jtulach@1334:      * @param newValue the new value
jtulach@1334:      * @return the previous value
jtulach@1334:      */
jtulach@1334:     public final int getAndSet(int i, int newValue) {
jtulach@1334:         long offset = checkedByteOffset(i);
jtulach@1334:         while (true) {
jtulach@1334:             int current = getRaw(offset);
jtulach@1334:             if (compareAndSetRaw(offset, current, newValue))
jtulach@1334:                 return current;
jtulach@1334:         }
jtulach@1334:     }
jtulach@1334: 
jtulach@1334:     /**
jtulach@1334:      * Atomically sets the element at position {@code i} to the given
jtulach@1334:      * updated value if the current value {@code ==} the expected value.
jtulach@1334:      *
jtulach@1334:      * @param i the index
jtulach@1334:      * @param expect the expected value
jtulach@1334:      * @param update the new value
jtulach@1334:      * @return true if successful. False return indicates that
jtulach@1334:      * the actual value was not equal to the expected value.
jtulach@1334:      */
jtulach@1334:     public final boolean compareAndSet(int i, int expect, int update) {
jtulach@1334:         return compareAndSetRaw(checkedByteOffset(i), expect, update);
jtulach@1334:     }
jtulach@1334: 
jtulach@1334:     private boolean compareAndSetRaw(long offset, int expect, int update) {
jtulach@1334:         return unsafe.compareAndSwapInt(array, offset, expect, update);
jtulach@1334:     }
jtulach@1334: 
jtulach@1334:     /**
jtulach@1334:      * Atomically sets the element at position {@code i} to the given
jtulach@1334:      * updated value if the current value {@code ==} the expected value.
jtulach@1334:      *
jtulach@1334:      * <p>May <a href="package-summary.html#Spurious">fail spuriously</a>
jtulach@1334:      * and does not provide ordering guarantees, so is only rarely an
jtulach@1334:      * appropriate alternative to {@code compareAndSet}.
jtulach@1334:      *
jtulach@1334:      * @param i the index
jtulach@1334:      * @param expect the expected value
jtulach@1334:      * @param update the new value
jtulach@1334:      * @return true if successful.
jtulach@1334:      */
jtulach@1334:     public final boolean weakCompareAndSet(int i, int expect, int update) {
jtulach@1334:         return compareAndSet(i, expect, update);
jtulach@1334:     }
jtulach@1334: 
jtulach@1334:     /**
jtulach@1334:      * Atomically increments by one the element at index {@code i}.
jtulach@1334:      *
jtulach@1334:      * @param i the index
jtulach@1334:      * @return the previous value
jtulach@1334:      */
jtulach@1334:     public final int getAndIncrement(int i) {
jtulach@1334:         return getAndAdd(i, 1);
jtulach@1334:     }
jtulach@1334: 
jtulach@1334:     /**
jtulach@1334:      * Atomically decrements by one the element at index {@code i}.
jtulach@1334:      *
jtulach@1334:      * @param i the index
jtulach@1334:      * @return the previous value
jtulach@1334:      */
jtulach@1334:     public final int getAndDecrement(int i) {
jtulach@1334:         return getAndAdd(i, -1);
jtulach@1334:     }
jtulach@1334: 
jtulach@1334:     /**
jtulach@1334:      * Atomically adds the given value to the element at index {@code i}.
jtulach@1334:      *
jtulach@1334:      * @param i the index
jtulach@1334:      * @param delta the value to add
jtulach@1334:      * @return the previous value
jtulach@1334:      */
jtulach@1334:     public final int getAndAdd(int i, int delta) {
jtulach@1334:         long offset = checkedByteOffset(i);
jtulach@1334:         while (true) {
jtulach@1334:             int current = getRaw(offset);
jtulach@1334:             if (compareAndSetRaw(offset, current, current + delta))
jtulach@1334:                 return current;
jtulach@1334:         }
jtulach@1334:     }
jtulach@1334: 
jtulach@1334:     /**
jtulach@1334:      * Atomically increments by one the element at index {@code i}.
jtulach@1334:      *
jtulach@1334:      * @param i the index
jtulach@1334:      * @return the updated value
jtulach@1334:      */
jtulach@1334:     public final int incrementAndGet(int i) {
jtulach@1334:         return addAndGet(i, 1);
jtulach@1334:     }
jtulach@1334: 
jtulach@1334:     /**
jtulach@1334:      * Atomically decrements by one the element at index {@code i}.
jtulach@1334:      *
jtulach@1334:      * @param i the index
jtulach@1334:      * @return the updated value
jtulach@1334:      */
jtulach@1334:     public final int decrementAndGet(int i) {
jtulach@1334:         return addAndGet(i, -1);
jtulach@1334:     }
jtulach@1334: 
jtulach@1334:     /**
jtulach@1334:      * Atomically adds the given value to the element at index {@code i}.
jtulach@1334:      *
jtulach@1334:      * @param i the index
jtulach@1334:      * @param delta the value to add
jtulach@1334:      * @return the updated value
jtulach@1334:      */
jtulach@1334:     public final int addAndGet(int i, int delta) {
jtulach@1334:         long offset = checkedByteOffset(i);
jtulach@1334:         while (true) {
jtulach@1334:             int current = getRaw(offset);
jtulach@1334:             int next = current + delta;
jtulach@1334:             if (compareAndSetRaw(offset, current, next))
jtulach@1334:                 return next;
jtulach@1334:         }
jtulach@1334:     }
jtulach@1334: 
jtulach@1334:     /**
jtulach@1334:      * Returns the String representation of the current values of array.
jtulach@1334:      * @return the String representation of the current values of array
jtulach@1334:      */
jtulach@1334:     public String toString() {
jtulach@1334:         int iMax = array.length - 1;
jtulach@1334:         if (iMax == -1)
jtulach@1334:             return "[]";
jtulach@1334: 
jtulach@1334:         StringBuilder b = new StringBuilder();
jtulach@1334:         b.append('[');
jtulach@1334:         for (int i = 0; ; i++) {
jtulach@1334:             b.append(getRaw(byteOffset(i)));
jtulach@1334:             if (i == iMax)
jtulach@1334:                 return b.append(']').toString();
jtulach@1334:             b.append(',').append(' ');
jtulach@1334:         }
jtulach@1334:     }
jtulach@1334: 
jtulach@1334: }