/*
* Copyright 2011 sunli [sunli1223@gmail.com][weibo.com@sunli1223]
*
* 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.google.code.fqueue.log;
import java.io.File;
import java.io.IOException;
import java.io.RandomAccessFile;
import java.lang.reflect.Method;
import java.nio.ByteBuffer;
import java.nio.MappedByteBuffer;
import java.nio.channels.FileChannel;
import java.nio.channels.FileChannel.MapMode;
import java.security.AccessController;
import java.security.PrivilegedAction;
import java.util.concurrent.atomic.AtomicInteger;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import com.google.code.fqueue.exception.FileFormatException;
/**
* 数据索引文件
*
* @author sunli
* @date 2011-5-18
* @version $Id: LogIndex.java 2 2011-07-31 12:25:36Z sunli1223@gmail.com $
*/
public class LogIndex {
final Logger log = LoggerFactory.getLogger(LogIndex.class);
private final int dbFileLimitLength = 32;
private RandomAccessFile dbRandFile = null;
private FileChannel fc;
private MappedByteBuffer mappedByteBuffer;
/**
* 文件操作位置信息
*/
private String magicString = null;
private int version = -1;
private int readerPosition = -1;
private int writerPosition = -1;
private int readerIndex = -1;
private int writerIndex = -1;
private AtomicInteger size = new AtomicInteger();
public LogIndex(String path) throws IOException, FileFormatException {
File dbFile = new File(path);
// 文件不存在，创建文件
if (dbFile.exists() == false) {
dbFile.createNewFile();
dbRandFile = new RandomAccessFile(dbFile, "rwd");
dbRandFile.write(LogEntity.MAGIC.getBytes());// magic
dbRandFile.writeInt(1);// 8version
dbRandFile.writeInt(LogEntity.messageStartPosition);// 12 reader
// pos
dbRandFile.writeInt(LogEntity.messageStartPosition); // 16write
// pos
dbRandFile.writeInt(1);// 20readerindex
dbRandFile.writeInt(1);// 24writerindex
dbRandFile.writeInt(0);// 28 size
magicString = LogEntity.MAGIC;
version = 1;
readerPosition = LogEntity.messageStartPosition;
writerPosition = LogEntity.messageStartPosition;
readerIndex = 1;
writerIndex = 1;
} else {
dbRandFile = new RandomAccessFile(dbFile, "rwd");
if (dbRandFile.length() < 32) {
throw new FileFormatException("file format error");
}
byte[] b = new byte[this.dbFileLimitLength];
dbRandFile.read(b);
ByteBuffer buffer = ByteBuffer.wrap(b);
b = new byte[LogEntity.MAGIC.getBytes().length];
buffer.get(b);
magicString = new String(b);
version = buffer.getInt();
readerPosition = buffer.getInt();
writerPosition = buffer.getInt();
readerIndex = buffer.getInt();
writerIndex = buffer.getInt();
size.set(buffer.getInt());
}
fc = dbRandFile.getChannel();
mappedByteBuffer = fc.map(MapMode.READ_WRITE, 0, this.dbFileLimitLength);
}
/**
* 记录写位置
*
* @param pos
*/
public void putWriterPosition(int pos) {
mappedByteBuffer.position(16);
mappedByteBuffer.putInt(pos);
this.writerPosition = pos;
}
/**
* 记录读取的位置
*
* @param pos
*/
public void putReaderPosition(int pos) {
mappedByteBuffer.position(12);
mappedByteBuffer.putInt(pos);
this.readerPosition = pos;
}
/**
* 记录写文件索引
*
* @param index
*/
public void putWriterIndex(int index) {
mappedByteBuffer.position(24);
mappedByteBuffer.putInt(index);
this.writerIndex = index;
}
/**
* 记录读取文件索引
*
* @param index
*/
public void putReaderIndex(int index) {
mappedByteBuffer.position(20);
mappedByteBuffer.putInt(index);
this.readerIndex = index;
}
public void incrementSize() {
int num = size.incrementAndGet();
mappedByteBuffer.position(28);
mappedByteBuffer.putInt(num);
}
public void decrementSize() {
int num = size.decrementAndGet();
mappedByteBuffer.position(28);
mappedByteBuffer.putInt(num);
}
public String getMagicString() {
return magicString;
}
public int getVersion() {
return version;
}
public int getReaderPosition() {
return readerPosition;
}
public int getWriterPosition() {
return writerPosition;
}
public int getReaderIndex() {
return readerIndex;
}
public int getWriterIndex() {
return writerIndex;
}
public int getSize() {
return size.get();
}
/**
* 关闭索引文件
*/
public void close() {
try {
mappedByteBuffer.force();
AccessController.doPrivileged(new PrivilegedAction<Object>() {
public Object run() {
try {
Method getCleanerMethod = mappedByteBuffer.getClass().getMethod("cleaner", new Class[0]);
getCleanerMethod.setAccessible(true);
sun.misc.Cleaner cleaner = (sun.misc.Cleaner) getCleanerMethod.invoke(mappedByteBuffer,
new Object[0]);
cleaner.clean();
} catch (Exception e) {
log.error("close logindexy file error:", e);
}
return null;
}
});
fc.close();
dbRandFile.close();
mappedByteBuffer = null;
fc = null;
dbRandFile = null;
} catch (IOException e) {
log.error("close logindex file error:", e);
}
}
public String headerInfo() {
StringBuilder sb = new StringBuilder();
sb.append(" magicString:");
sb.append(magicString);
sb.append(" version:");
sb.append(version);
sb.append(" readerPosition:");
sb.append(readerPosition);
sb.append(" writerPosition:");
sb.append(writerPosition);
sb.append(" size:");
sb.append(size);
sb.append(" readerIndex:");
sb.append(readerIndex);
sb.append(" writerIndex:");
sb.append(writerIndex);
return sb.toString();
}
}