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FileLockManager.java
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FileLockManager.java
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/*
* Copyright (c) 2020, WSO2 Inc. (http://www.wso2.org) All Rights Reserved.
*
* WSO2 Inc. licenses this file to you 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.wso2.carbon.connector.filelock;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.commons.vfs2.FileSystemException;
import org.wso2.carbon.connector.connection.FileSystemHandler;
/**
* Manages file locks.
*/
public final class FileLockManager {
private FileSystemHandler conHandler;
private boolean isClustered;
private FileLockStore lockStore;
private static final Log log = LogFactory.getLog(FileLockManager.class);
/**
* Creates a FileLockManager.
* It will be attached to the connection.
*
* @param conHandler Connection handler
* @param isClustered True if you need to enable cluster-wide locks
* for the files.
*/
public FileLockManager(FileSystemHandler conHandler, boolean isClustered) {
this.conHandler = conHandler;
this.isClustered = isClustered;
this.lockStore = new FileLockStore();
}
/**
* Try and acquire a lock for the file. This marks
* that the file is processed by the operation. Make
* sure to release it after done with the operation.
*
* @param filePath Path of the file to acquire lock for
* @param expiryTime After how many milliseconds lock should expire.
* After expiry some other process can acquire it.
* @return True if lock is acquired.
*/
public boolean tryAndAcquireLock(String filePath, long expiryTime) {
return acquireLock(filePath, expiryTime);
}
/**
* Try several times and acquire a lock for the file. This marks
* that the file is processed by the operation. Make
* sure to release it after done with the operation.
*
* @param filePath Path of the file to acquire lock for
* @param expiryTime After how many milliseconds lock should expire
* @param maxRetryTimes Maximum times to try to get the lock
* @param retryInterval Time between two failure tries to get the lock
* @return True if lock is acquired.
*/
public boolean tryAndAcquireLock(String filePath, long expiryTime, int maxRetryTimes, int retryInterval) {
int tryCount = 0;
boolean lockAcquired = false;
while (tryCount < maxRetryTimes) {
lockAcquired = acquireLock(filePath, expiryTime);
if (lockAcquired) {
break;
} else {
try {
Thread.sleep(retryInterval);
} catch (InterruptedException e) {
Thread.currentThread().interrupt();
}
}
tryCount = tryCount + 1;
}
return lockAcquired;
}
/**
* Release the lock for the file.
*
* @param filePath Path of the file to release lock for
*/
public void releaseLock(String filePath) {
if (isClustered) {
releaseGlobal(filePath);
} else {
releaseLocal(filePath);
}
}
public void releaseAllLocks() {
lockStore.releaseAllLocks();
}
private boolean acquireLock(String filePath, long expiresIn) {
boolean lockAcquired;
if (log.isDebugEnabled()) {
log.debug("[FileConnector] Trying to acquire file lock for " + filePath);
}
if (isClustered) {
lockAcquired = tryAndAcquireGlobal(filePath, expiresIn);
} else {
lockAcquired = tryAndAcquireLocal(filePath, expiresIn);
}
if (log.isDebugEnabled()) {
log.debug("[FileConnector] lock acquire state for " + filePath + " is = " + lockAcquired);
}
return lockAcquired;
}
private boolean tryAndAcquireLocal(String filePath, long expiresIn) {
FileLock localLock = new LocalFileLock(filePath, expiresIn);
return lockStore.add(localLock);
}
private void releaseLocal(String filePath) {
lockStore.remove(filePath);
if(log.isDebugEnabled()) {
log.debug("Released local lock for filePath " + filePath);
}
}
private boolean tryAndAcquireGlobal(String filePath, long expiresIn) {
GlobalFileLock globalLock;
boolean globalLockAcquired = false;
try {
globalLock = new GlobalFileLock(filePath, expiresIn, conHandler);
} catch (FileSystemException e) {
log.error("[FileConnector] Failed to create GlobalFileLock ", e);
return false;
}
boolean locallyAcquired = lockStore.add(globalLock);
if (locallyAcquired) {
globalLockAcquired = globalLock.tryAndAcquire();
if (!globalLockAcquired) {
lockStore.remove(filePath);
if(log.isDebugEnabled()) {
log.debug("[FileConnector] Released local lock as failed to acquire global lock");
}
}
}
return globalLockAcquired;
}
private void releaseGlobal(String filePath) {
//get object and call release
FileLock globalLock = lockStore.remove(filePath);
if (globalLock != null) {
globalLock.release();
}
}
}