com.couchbase.client.core.deps.org.iq80.snappy.UnsafeMemory Maven / Gradle / Ivy
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The official Couchbase JVM Core IO Library
/*
* Copyright (C) 2011 the original author or authors.
* See the notice.md file distributed with this work for additional
* information regarding copyright ownership.
*
* 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 com.couchbase.client.core.deps.org.iq80.snappy;
import sun.misc.Unsafe;
import java.lang.reflect.Field;
class UnsafeMemory
implements Memory
{
private static final Unsafe unsafe;
static {
try {
Field theUnsafe = Unsafe.class.getDeclaredField("theUnsafe");
theUnsafe.setAccessible(true);
unsafe = (Unsafe) theUnsafe.get(null);
// It seems not all Unsafe implementations implement the following method.
new UnsafeMemory().copyMemory(new byte[1], 0, new byte[1], 0, 1);
}
catch (Exception e) {
throw new RuntimeException(e);
}
}
private static final long BYTE_ARRAY_OFFSET = unsafe.arrayBaseOffset(byte[].class);
private static final long SHORT_ARRAY_OFFSET = unsafe.arrayBaseOffset(short[].class);
private static final long SHORT_ARRAY_STRIDE = unsafe.arrayIndexScale(short[].class);
@Override
public boolean fastAccessSupported()
{
return true;
}
@Override
public int lookupShort(short[] data, int index)
{
assert index >= 0;
assert index <= data.length;
return unsafe.getShort(data, SHORT_ARRAY_OFFSET + (index * SHORT_ARRAY_STRIDE)) & 0xFFFF;
}
@Override
public int loadByte(byte[] data, int index)
{
assert index >= 0;
assert index <= data.length;
return unsafe.getByte(data, BYTE_ARRAY_OFFSET + index) & 0xFF;
}
@Override
public int loadInt(byte[] data, int index)
{
assert index >= 0;
assert index + 4 <= data.length;
return unsafe.getInt(data, BYTE_ARRAY_OFFSET + index);
}
@Override
public void copyLong(byte[] src, int srcIndex, byte[] dest, int destIndex)
{
assert srcIndex >= 0;
assert srcIndex + 8 <= src.length;
assert destIndex >= 0;
assert destIndex + 8 <= dest.length;
long value = unsafe.getLong(src, BYTE_ARRAY_OFFSET + srcIndex);
unsafe.putLong(dest, (BYTE_ARRAY_OFFSET + destIndex), value);
}
@Override
public long loadLong(byte[] data, int index)
{
assert index > 0;
assert index + 4 < data.length;
return unsafe.getLong(data, BYTE_ARRAY_OFFSET + index);
}
@Override
public void copyMemory(byte[] input, int inputIndex, byte[] output, int outputIndex, int length)
{
assert inputIndex >= 0;
assert inputIndex + length <= input.length;
assert outputIndex >= 0;
assert outputIndex + length <= output.length;
unsafe.copyMemory(input, BYTE_ARRAY_OFFSET + inputIndex, output, BYTE_ARRAY_OFFSET + outputIndex, length);
}
}