/*
* Copyright 2013 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 org.gradle.cache.internal.filelock;
import org.gradle.api.Nullable;
import org.gradle.internal.io.RandomAccessFileInputStream;
import org.gradle.internal.io.RandomAccessFileOutputStream;
import java.io.*;
import java.nio.channels.FileLock;
public class LockInfoAccess {
public static final int INFORMATION_REGION_SIZE = 2052;
private final LockInfoSerializer lockInfoSerializer = new LockInfoSerializer();
private final long infoRegionPos;
public LockInfoAccess(long infoRegionPos) {
this.infoRegionPos = infoRegionPos;
}
public LockInfo readLockInfo(RandomAccessFile lockFileAccess) throws IOException {
if (lockFileAccess.length() <= infoRegionPos) {
return new LockInfo();
} else {
lockFileAccess.seek(infoRegionPos);
DataInputStream inputStream = new DataInputStream(new BufferedInputStream(new RandomAccessFileInputStream(lockFileAccess)));
byte protocolVersion = inputStream.readByte();
if (protocolVersion != lockInfoSerializer.getVersion()) {
throw new IllegalStateException(String.format("Unexpected lock protocol found in lock file. Expected %s, found %s.", lockInfoSerializer.getVersion(), protocolVersion));
}
return lockInfoSerializer.read(inputStream);
}
}
public void writeLockInfo(RandomAccessFile lockFileAccess, LockInfo lockInfo) throws IOException {
lockFileAccess.seek(infoRegionPos);
DataOutputStream outstr = new DataOutputStream(new BufferedOutputStream(new RandomAccessFileOutputStream(lockFileAccess)));
outstr.writeByte(lockInfoSerializer.getVersion());
lockInfoSerializer.write(outstr, lockInfo);
outstr.flush();
lockFileAccess.setLength(lockFileAccess.getFilePointer());
}
public void clearLockInfo(RandomAccessFile lockFileAccess) throws IOException {
lockFileAccess.setLength(Math.min(lockFileAccess.length(), infoRegionPos));
}
@Nullable
public FileLock tryLock(RandomAccessFile lockFileAccess, boolean shared) throws IOException {
return lockFileAccess.getChannel().tryLock(infoRegionPos, INFORMATION_REGION_SIZE - infoRegionPos, shared);
}
}