src/share/classes/java/util/concurrent/atomic/AtomicIntegerArray.java
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*** 46,77 ****
* @author Doug Lea
*/
public class AtomicIntegerArray implements java.io.Serializable {
private static final long serialVersionUID = 2862133569453604235L;
- // setup to use Unsafe.compareAndSwapInt for updates
private static final Unsafe unsafe = Unsafe.getUnsafe();
private static final int base = unsafe.arrayBaseOffset(int[].class);
! private static final int scale = unsafe.arrayIndexScale(int[].class);
private final int[] array;
! private long rawIndex(int i) {
if (i < 0 || i >= array.length)
throw new IndexOutOfBoundsException("index " + i);
! return base + (long) i * scale;
}
/**
! * Creates a new AtomicIntegerArray of given length.
*
* @param length the length of the array
*/
public AtomicIntegerArray(int length) {
array = new int[length];
- // must perform at least one volatile write to conform to JMM
- if (length > 0)
- unsafe.putIntVolatile(array, rawIndex(0), 0);
}
/**
* Creates a new AtomicIntegerArray with the same length as, and
* all elements copied from, the given array.
--- 46,86 ----
* @author Doug Lea
*/
public class AtomicIntegerArray implements java.io.Serializable {
private static final long serialVersionUID = 2862133569453604235L;
private static final Unsafe unsafe = Unsafe.getUnsafe();
private static final int base = unsafe.arrayBaseOffset(int[].class);
! private static final int shift;
private final int[] array;
! static {
! int scale = unsafe.arrayIndexScale(int[].class);
! if ((scale & (scale - 1)) != 0)
! throw new Error("data type scale not a power of two");
! shift = 31 - Integer.numberOfLeadingZeros(scale);
! }
!
! private long checkedByteOffset(int i) {
if (i < 0 || i >= array.length)
throw new IndexOutOfBoundsException("index " + i);
!
! return byteOffset(i);
}
+ private static long byteOffset(int i) {
+ return ((long) i << shift) + base;
+ }
+
/**
! * Creates a new AtomicIntegerArray of the given length, with all
! * elements initially zero.
*
* @param length the length of the array
*/
public AtomicIntegerArray(int length) {
array = new int[length];
}
/**
* Creates a new AtomicIntegerArray with the same length as, and
* all elements copied from, the given array.
*** 78,99 ****
*
* @param array the array to copy elements from
* @throws NullPointerException if array is null
*/
public AtomicIntegerArray(int[] array) {
! if (array == null)
! throw new NullPointerException();
! int length = array.length;
! this.array = new int[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
! unsafe.putIntVolatile(this.array, rawIndex(last), array[last]);
}
- }
/**
* Returns the length of the array.
*
* @return the length of the array
--- 87,99 ----
*
* @param array the array to copy elements from
* @throws NullPointerException if array is null
*/
public AtomicIntegerArray(int[] array) {
! // Visibility guaranteed by final field guarantees
! this.array = array.clone();
}
/**
* Returns the length of the array.
*
* @return the length of the array
*** 107,127 ****
*
* @param i the index
* @return the current value
*/
public final int get(int i) {
! return unsafe.getIntVolatile(array, rawIndex(i));
}
/**
* Sets the element at position {@code i} to the given value.
*
* @param i the index
* @param newValue the new value
*/
public final void set(int i, int newValue) {
! unsafe.putIntVolatile(array, rawIndex(i), newValue);
}
/**
* Eventually sets the element at position {@code i} to the given value.
*
--- 107,131 ----
*
* @param i the index
* @return the current value
*/
public final int get(int i) {
! return getRaw(checkedByteOffset(i));
}
+ private int getRaw(long offset) {
+ return unsafe.getIntVolatile(array, offset);
+ }
+
/**
* Sets the element at position {@code i} to the given value.
*
* @param i the index
* @param newValue the new value
*/
public final void set(int i, int newValue) {
! unsafe.putIntVolatile(array, checkedByteOffset(i), newValue);
}
/**
* Eventually sets the element at position {@code i} to the given value.
*
*** 128,138 ****
* @param i the index
* @param newValue the new value
* @since 1.6
*/
public final void lazySet(int i, int newValue) {
! unsafe.putOrderedInt(array, rawIndex(i), newValue);
}
/**
* Atomically sets the element at position {@code i} to the given
* value and returns the old value.
--- 132,142 ----
* @param i the index
* @param newValue the new value
* @since 1.6
*/
public final void lazySet(int i, int newValue) {
! unsafe.putOrderedInt(array, checkedByteOffset(i), newValue);
}
/**
* Atomically sets the element at position {@code i} to the given
* value and returns the old value.
*** 140,152 ****
* @param i the index
* @param newValue the new value
* @return the previous value
*/
public final int getAndSet(int i, int newValue) {
while (true) {
! int current = get(i);
! if (compareAndSet(i, current, newValue))
return current;
}
}
/**
--- 144,157 ----
* @param i the index
* @param newValue the new value
* @return the previous value
*/
public final int getAndSet(int i, int newValue) {
+ long offset = checkedByteOffset(i);
while (true) {
! int current = getRaw(offset);
! if (compareAndSetRaw(offset, current, newValue))
return current;
}
}
/**
*** 158,171 ****
* @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, int expect, int update) {
! return unsafe.compareAndSwapInt(array, rawIndex(i),
! expect, update);
}
/**
* Atomically sets the element at position {@code i} to the given
* updated value if the current value {@code ==} the expected value.
*
* <p>May <a href="package-summary.html#Spurious">fail spuriously</a>
--- 163,179 ----
* @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, int expect, int update) {
! return compareAndSetRaw(checkedByteOffset(i), expect, update);
}
+ private boolean compareAndSetRaw(long offset, int expect, int update) {
+ return unsafe.compareAndSwapInt(array, offset, expect, update);
+ }
+
/**
* Atomically sets the element at position {@code i} to the given
* updated value if the current value {@code ==} the expected value.
*
* <p>May <a href="package-summary.html#Spurious">fail spuriously</a>
*** 186,230 ****
*
* @param i the index
* @return the previous value
*/
public final int getAndIncrement(int i) {
! while (true) {
! int current = get(i);
! int next = current + 1;
! if (compareAndSet(i, current, next))
! return current;
}
- }
/**
* Atomically decrements by one the element at index {@code i}.
*
* @param i the index
* @return the previous value
*/
public final int getAndDecrement(int i) {
! while (true) {
! int current = get(i);
! int next = current - 1;
! if (compareAndSet(i, current, next))
! return current;
}
- }
/**
* Atomically adds the given value to the element at index {@code i}.
*
* @param i the index
* @param delta the value to add
* @return the previous value
*/
public final int getAndAdd(int i, int delta) {
while (true) {
! int current = get(i);
! int next = current + delta;
! if (compareAndSet(i, current, next))
return current;
}
}
/**
--- 194,228 ----
*
* @param i the index
* @return the previous value
*/
public final int getAndIncrement(int i) {
! return getAndAdd(i, 1);
}
/**
* Atomically decrements by one the element at index {@code i}.
*
* @param i the index
* @return the previous value
*/
public final int getAndDecrement(int i) {
! return getAndAdd(i, -1);
}
/**
* Atomically adds the given value to the element at index {@code i}.
*
* @param i the index
* @param delta the value to add
* @return the previous value
*/
public final int getAndAdd(int i, int delta) {
+ long offset = checkedByteOffset(i);
while (true) {
! int current = getRaw(offset);
! if (compareAndSetRaw(offset, current, current + delta))
return current;
}
}
/**
*** 232,286 ****
*
* @param i the index
* @return the updated value
*/
public final int incrementAndGet(int i) {
! while (true) {
! int current = get(i);
! int next = current + 1;
! if (compareAndSet(i, current, next))
! return next;
}
- }
/**
* Atomically decrements by one the element at index {@code i}.
*
* @param i the index
* @return the updated value
*/
public final int decrementAndGet(int i) {
! while (true) {
! int current = get(i);
! int next = current - 1;
! if (compareAndSet(i, current, next))
! return next;
}
- }
/**
* Atomically adds the given value to the element at index {@code i}.
*
* @param i the index
* @param delta the value to add
* @return the updated value
*/
public final int addAndGet(int i, int delta) {
while (true) {
! int current = get(i);
int next = current + delta;
! if (compareAndSet(i, current, next))
return next;
}
}
/**
* 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);
}
}
--- 230,284 ----
*
* @param i the index
* @return the updated value
*/
public final int incrementAndGet(int i) {
! return addAndGet(i, 1);
}
/**
* Atomically decrements by one the element at index {@code i}.
*
* @param i the index
* @return the updated value
*/
public final int decrementAndGet(int i) {
! return addAndGet(i, -1);
}
/**
* Atomically adds the given value to the element at index {@code i}.
*
* @param i the index
* @param delta the value to add
* @return the updated value
*/
public final int addAndGet(int i, int delta) {
+ long offset = checkedByteOffset(i);
while (true) {
! int current = getRaw(offset);
int next = current + delta;
! if (compareAndSetRaw(offset, current, next))
return next;
}
}
/**
* Returns the String representation of the current values of array.
! * @return the String representation of the current values of array
*/
public String toString() {
! int iMax = array.length - 1;
! if (iMax == -1)
! return "[]";
!
! StringBuilder b = new StringBuilder();
! b.append('[');
! for (int i = 0; ; i++) {
! b.append(getRaw(byteOffset(i)));
! if (i == iMax)
! return b.append(']').toString();
! b.append(',').append(' ');
}
+ }
}