io.atomix.catalyst.buffer.FileBuffer 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;
import io.atomix.catalyst.buffer.util.Memory;
import io.atomix.catalyst.util.reference.ReferenceManager;
import java.io.File;
import java.nio.channels.FileChannel;
/**
* File buffer.
*
* File buffers wrap a simple {@link java.io.RandomAccessFile} instance to provide random access to a file on local disk. All
* operations are delegated directly to the {@link java.io.RandomAccessFile} interface, and limitations are dependent on the
* semantics of the underlying file.
*
* @author Jordan Halterman
*/
public class FileBuffer extends AbstractBuffer {
/**
* Allocates a file buffer of unlimited capacity.
*
* The buffer will initially be allocated with {@code 4096} bytes. As bytes are written to the resulting buffer and
* the original capacity is reached, the buffer's capacity will double.
*
* @param file The file to allocate.
* @return The allocated buffer.
*
* @see FileBuffer#allocate(java.io.File, long)
* @see FileBuffer#allocate(java.io.File, long, long)
* @see FileBuffer#allocate(java.io.File, String, long, long)
*/
public static FileBuffer allocate(File file) {
return allocate(file, FileBytes.DEFAULT_MODE, DEFAULT_INITIAL_CAPACITY, Long.MAX_VALUE);
}
/**
* Allocates a file buffer with the given initial capacity.
*
* If the underlying file is empty, the file count will expand dynamically as bytes are written to the file.
* The underlying {@link FileBytes} will be initialized to the nearest power of {@code 2}.
*
* @param file The file to allocate.
* @param initialCapacity The initial capacity of the bytes to allocate.
* @return The allocated buffer.
*
* @see FileBuffer#allocate(java.io.File)
* @see FileBuffer#allocate(java.io.File, long, long)
* @see FileBuffer#allocate(java.io.File, String, long, long)
*/
public static FileBuffer allocate(File file, long initialCapacity) {
return allocate(file, FileBytes.DEFAULT_MODE, initialCapacity, Long.MAX_VALUE);
}
/**
* Allocates a file buffer.
*
* The underlying {@link java.io.RandomAccessFile} will be created in {@code rw} mode by default.
* The resulting buffer will be initialized with a capacity of {@code initialCapacity}. The underlying {@link FileBytes}
* will be initialized to the nearest power of {@code 2}. As bytes are written to the file the buffer's capacity will
* double up to {@code maxCapacity}.
*
* @param file The file to allocate.
* @param initialCapacity The initial capacity of the buffer.
* @param maxCapacity The maximum allowed capacity of the buffer.
* @return The allocated buffer.
*
* @see FileBuffer#allocate(java.io.File)
* @see FileBuffer#allocate(java.io.File, long)
* @see FileBuffer#allocate(java.io.File, String, long, long)
*/
public static FileBuffer allocate(File file, long initialCapacity, long maxCapacity) {
return allocate(file, FileBytes.DEFAULT_MODE, initialCapacity, maxCapacity);
}
/**
* Allocates a file buffer.
*
* The resulting buffer will be initialized with a capacity of {@code initialCapacity}. The underlying {@link FileBytes}
* will be initialized to the nearest power of {@code 2}. As bytes are written to the file the buffer's capacity will
* double up to {@code maxCapacity}.
*
* @param file The file to allocate.
* @param mode The mode in which to open the underlying {@link java.io.RandomAccessFile}.
* @param initialCapacity The initial capacity of the buffer.
* @param maxCapacity The maximum allowed capacity of the buffer.
* @return The allocated buffer.
*
* @see FileBuffer#allocate(java.io.File)
* @see FileBuffer#allocate(java.io.File, long)
* @see FileBuffer#allocate(java.io.File, long, long)
*/
public static FileBuffer allocate(File file, String mode, long initialCapacity, long maxCapacity) {
return new FileBuffer(new FileBytes(file, mode, Memory.Util.toPow2(initialCapacity)), 0, initialCapacity, maxCapacity);
}
private FileBuffer(Bytes bytes, ReferenceManager referenceManager) {
super(bytes, referenceManager);
}
private FileBuffer(Bytes bytes, long offset, long initialCapacity, long maxCapacity) {
super(bytes, offset, initialCapacity, maxCapacity, null);
}
/**
* Returns the underlying file object.
*
* @return The underlying file.
*/
public File file() {
return ((FileBytes) bytes).file();
}
/**
* Maps a portion of the underlying file into memory in {@link java.nio.channels.FileChannel.MapMode#READ_WRITE} mode
* starting at the current position up to the given {@code count}.
*
* @param size The count of the bytes to map into memory.
* @return The mapped buffer.
* @throws IllegalArgumentException If {@code count} is greater than the maximum allowed
* {@link java.nio.MappedByteBuffer} count: {@link Integer#MAX_VALUE}
*/
public MappedBuffer map(long size) {
return map(position(), size, FileChannel.MapMode.READ_WRITE);
}
/**
* Maps a portion of the underlying file into memory starting at the current position up to the given {@code count}.
*
* @param size The count of the bytes to map into memory.
* @param mode The mode in which to map the bytes into memory.
* @return The mapped buffer.
* @throws IllegalArgumentException If {@code count} is greater than the maximum allowed
* {@link java.nio.MappedByteBuffer} count: {@link Integer#MAX_VALUE}
*/
public MappedBuffer map(long size, FileChannel.MapMode mode) {
return map(position(), size, mode);
}
/**
* Maps a portion of the underlying file into memory in {@link java.nio.channels.FileChannel.MapMode#READ_WRITE} mode
* starting at the given {@code offset} up to the given {@code count}.
*
* @param offset The offset from which to map bytes into memory.
* @param size The count of the bytes to map into memory.
* @return The mapped buffer.
* @throws IllegalArgumentException If {@code count} is greater than the maximum allowed
* {@link java.nio.MappedByteBuffer} count: {@link Integer#MAX_VALUE}
*/
public MappedBuffer map(long offset, long size) {
return map(offset, size, FileChannel.MapMode.READ_WRITE);
}
/**
* Maps a portion of the underlying file into memory starting at the given {@code offset} up to the given {@code count}.
*
* @param offset The offset from which to map bytes into memory.
* @param size The count of the bytes to map into memory.
* @param mode The mode in which to map the bytes into memory.
* @return The mapped buffer.
* @throws IllegalArgumentException If {@code count} is greater than the maximum allowed
* {@link java.nio.MappedByteBuffer} count: {@link Integer#MAX_VALUE}
*/
public MappedBuffer map(long offset, long size, FileChannel.MapMode mode) {
return new MappedBuffer(((FileBytes) bytes).map(offset, size, mode), 0, size, size);
}
@Override
protected void compact(long from, long to, long length) {
byte[] bytes = new byte[1024];
long position = from;
while (position < from + length) {
long size = Math.min((from + length) - position, 1024);
this.bytes.read(position, bytes, 0, size);
this.bytes.write(0, bytes, 0, size);
position += size;
}
}
/**
* Deletes the underlying file.
*/
public void delete() {
((FileBytes) bytes).delete();
}
}