io.atomix.catalyst.buffer.util.MappedMemory Maven / Gradle / Ivy
/*
* Copyright 2015 the original author or authors.
*
* 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 io.atomix.catalyst.buffer.util;
import sun.misc.Cleaner;
import sun.nio.ch.DirectBuffer;
import java.io.File;
import java.nio.MappedByteBuffer;
import java.nio.channels.FileChannel;
/**
* Mapped memory.
*
* This is a special memory descriptor that handles management of {@link java.nio.MappedByteBuffer} based memory. The
* mapped memory descriptor simply points to the memory address of the underlying byte buffer. When memory is reallocated,
* the parent {@link MappedMemoryAllocator} is used to create a new {@link java.nio.MappedByteBuffer}
* and free the existing buffer.
*
* @author Jordan Halterman
*/
public class MappedMemory extends NativeMemory {
public static final long MAX_SIZE = Integer.MAX_VALUE;
/**
* Allocates memory mapped to a file on disk.
*
* @param file The file to which to map memory.
* @param size The count of the memory to map.
* @return The mapped memory.
* @throws IllegalArgumentException If {@code count} is greater than {@link Integer#MAX_VALUE}
*/
public static MappedMemory allocate(File file, long size) {
return new MappedMemoryAllocator(file).allocate(size);
}
/**
* Allocates memory mapped to a file on disk.
*
* @param file The file to which to map memory.
* @param mode The mode with which to map memory.
* @param size The count of the memory to map.
* @return The mapped memory.
* @throws IllegalArgumentException If {@code count} is greater than {@link Integer#MAX_VALUE}
*/
public static MappedMemory allocate(File file, FileChannel.MapMode mode, long size) {
if (size > MAX_SIZE)
throw new IllegalArgumentException("size cannot be greater than " + MAX_SIZE);
return new MappedMemoryAllocator(file, mode).allocate(size);
}
private final MappedByteBuffer buffer;
public MappedMemory(MappedByteBuffer buffer, MappedMemoryAllocator allocator) {
super(((DirectBuffer) buffer).address(), buffer.capacity(), allocator);
this.buffer = buffer;
}
/**
* Flushes the mapped buffer to disk.
*/
public void flush() {
buffer.force();
}
@Override
public void free() {
Cleaner cleaner = ((DirectBuffer) buffer).cleaner();
if (cleaner != null)
cleaner.clean();
((MappedMemoryAllocator) allocator).release();
}
}