org.jctools.util.UnsafeLongArrayAccess Maven / Gradle / Ivy
/*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.jctools.util;
import static org.jctools.util.UnsafeAccess.UNSAFE;
@InternalAPI
public final class UnsafeLongArrayAccess
{
public static final long LONG_ARRAY_BASE;
public static final int LONG_ELEMENT_SHIFT;
static
{
final int scale = UnsafeAccess.UNSAFE.arrayIndexScale(long[].class);
if (8 == scale)
{
LONG_ELEMENT_SHIFT = 3;
}
else
{
throw new IllegalStateException("Unknown pointer size: " + scale);
}
LONG_ARRAY_BASE = UnsafeAccess.UNSAFE.arrayBaseOffset(long[].class);
}
/**
* A plain store (no ordering/fences) of an element to a given offset
*
* @param buffer le buffer
* @param offset computed via {@link UnsafeLongArrayAccess#calcLongElementOffset(long)}
* @param e an orderly kitty
*/
public static void spLongElement(long[] buffer, long offset, long e)
{
UNSAFE.putLong(buffer, offset, e);
}
/**
* An ordered store of an element to a given offset
*
* @param buffer le buffer
* @param offset computed via {@link UnsafeLongArrayAccess#calcCircularLongElementOffset}
* @param e an orderly kitty
*/
public static void soLongElement(long[] buffer, long offset, long e)
{
UNSAFE.putOrderedLong(buffer, offset, e);
}
/**
* A plain load (no ordering/fences) of an element from a given offset.
*
* @param buffer le buffer
* @param offset computed via {@link UnsafeLongArrayAccess#calcLongElementOffset(long)}
* @return the element at the offset
*/
public static long lpLongElement(long[] buffer, long offset)
{
return UNSAFE.getLong(buffer, offset);
}
/**
* A volatile load of an element from a given offset.
*
* @param buffer le buffer
* @param offset computed via {@link UnsafeLongArrayAccess#calcCircularLongElementOffset}
* @return the element at the offset
*/
public static long lvLongElement(long[] buffer, long offset)
{
return UNSAFE.getLongVolatile(buffer, offset);
}
/**
* @param index desirable element index
* @return the offset in bytes within the array for a given index
*/
public static long calcLongElementOffset(long index)
{
return LONG_ARRAY_BASE + (index << LONG_ELEMENT_SHIFT);
}
/**
* Note: circular arrays are assumed a power of 2 in length and the `mask` is (length - 1).
*
* @param index desirable element index
* @param mask (length - 1)
* @return the offset in bytes within the circular array for a given index
*/
public static long calcCircularLongElementOffset(long index, long mask)
{
return LONG_ARRAY_BASE + ((index & mask) << LONG_ELEMENT_SHIFT);
}
/**
* This makes for an easier time generating the atomic queues, and removes some warnings.
*/
public static long[] allocateLongArray(int capacity)
{
return new long[capacity];
}
}