001 /**
002 * Licensed to the Apache Software Foundation (ASF) under one or more
003 * contributor license agreements. See the NOTICE file distributed with
004 * this work for additional information regarding copyright ownership.
005 * The ASF licenses this file to You under the Apache License, Version 2.0
006 * (the "License"); you may not use this file except in compliance with
007 * the License. You may obtain a copy of the License at
008 *
009 * http://www.apache.org/licenses/LICENSE-2.0
010 *
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the License for the specific language governing permissions and
015 * limitations under the License.
016 */
017 package org.apache.camel.component.file.strategy;
018
019 import java.io.File;
020 import java.io.IOException;
021 import java.io.RandomAccessFile;
022 import java.nio.channels.Channel;
023 import java.nio.channels.FileChannel;
024 import java.nio.channels.FileLock;
025
026 import org.apache.camel.Exchange;
027 import org.apache.camel.LoggingLevel;
028 import org.apache.camel.component.file.GenericFile;
029 import org.apache.camel.component.file.GenericFileEndpoint;
030 import org.apache.camel.component.file.GenericFileOperations;
031 import org.apache.camel.util.CamelLogger;
032 import org.apache.camel.util.IOHelper;
033 import org.apache.camel.util.StopWatch;
034 import org.slf4j.Logger;
035 import org.slf4j.LoggerFactory;
036
037 /**
038 * Acquires exclusive read lock to the given file. Will wait until the lock is granted.
039 * After granting the read lock it is released, we just want to make sure that when we start
040 * consuming the file its not currently in progress of being written by third party.
041 */
042 public class FileLockExclusiveReadLockStrategy extends MarkerFileExclusiveReadLockStrategy {
043 private static final Logger LOG = LoggerFactory.getLogger(FileLockExclusiveReadLockStrategy.class);
044 private long timeout;
045 private long checkInterval = 1000;
046 private FileLock lock;
047 private String lockFileName;
048 private LoggingLevel readLockLoggingLevel = LoggingLevel.WARN;
049
050 @Override
051 public void prepareOnStartup(GenericFileOperations<File> operations, GenericFileEndpoint<File> endpoint) {
052 // noop
053 }
054
055 @Override
056 public boolean acquireExclusiveReadLock(GenericFileOperations<File> operations, GenericFile<File> file, Exchange exchange) throws Exception {
057 // must call super
058 if (!super.acquireExclusiveReadLock(operations, file, exchange)) {
059 return false;
060 }
061
062 File target = new File(file.getAbsoluteFilePath());
063
064 LOG.trace("Waiting for exclusive read lock to file: {}", target);
065
066 FileChannel channel = null;
067 RandomAccessFile randomAccessFile = null;
068 try {
069 randomAccessFile = new RandomAccessFile(target, "rw");
070 // try to acquire rw lock on the file before we can consume it
071 channel = randomAccessFile.getChannel();
072
073 boolean exclusive = false;
074 StopWatch watch = new StopWatch();
075
076 while (!exclusive) {
077 // timeout check
078 if (timeout > 0) {
079 long delta = watch.taken();
080 if (delta > timeout) {
081 CamelLogger.log(LOG, readLockLoggingLevel,
082 "Cannot acquire read lock within " + timeout + " millis. Will skip the file: " + target);
083 // we could not get the lock within the timeout period, so return false
084 return false;
085 }
086 }
087
088 // get the lock using either try lock or not depending on if we are using timeout or not
089 try {
090 lock = timeout > 0 ? channel.tryLock() : channel.lock();
091 } catch (IllegalStateException ex) {
092 // Also catch the OverlappingFileLockException here. Do nothing here
093 }
094 if (lock != null) {
095 LOG.trace("Acquired exclusive read lock: {} to file: {}", lock, target);
096 lockFileName = target.getName();
097 exclusive = true;
098 } else {
099 boolean interrupted = sleep();
100 if (interrupted) {
101 // we were interrupted while sleeping, we are likely being shutdown so return false
102 return false;
103 }
104 }
105 }
106 } catch (IOException e) {
107 // must handle IOException as some apps on Windows etc. will still somehow hold a lock to a file
108 // such as AntiVirus or MS Office that has special locks for it's supported files
109 if (timeout == 0) {
110 // if not using timeout, then we cant retry, so rethrow
111 throw e;
112 }
113 LOG.debug("Cannot acquire read lock. Will try again.", e);
114 boolean interrupted = sleep();
115 if (interrupted) {
116 // we were interrupted while sleeping, we are likely being shutdown so return false
117 return false;
118 }
119 } finally {
120 IOHelper.close(channel, "while acquiring exclusive read lock for file: " + lockFileName, LOG);
121 IOHelper.close(randomAccessFile, "while acquiring exclusive read lock for file: " + lockFileName, LOG);
122 }
123
124 return true;
125 }
126
127 @Override
128 public void releaseExclusiveReadLock(GenericFileOperations<File> operations,
129 GenericFile<File> file, Exchange exchange) throws Exception {
130
131 // must call super
132 super.releaseExclusiveReadLock(operations, file, exchange);
133
134 if (lock != null) {
135 Channel channel = lock.channel();
136 try {
137 lock.release();
138 } finally {
139 // must close channel first
140 IOHelper.close(channel, "while releasing exclusive read lock for file: " + lockFileName, LOG);
141 }
142 }
143 }
144
145 private boolean sleep() {
146 LOG.trace("Exclusive read lock not granted. Sleeping for {} millis.", checkInterval);
147 try {
148 Thread.sleep(checkInterval);
149 return false;
150 } catch (InterruptedException e) {
151 LOG.debug("Sleep interrupted while waiting for exclusive read lock, so breaking out");
152 return true;
153 }
154 }
155
156 public long getTimeout() {
157 return timeout;
158 }
159
160 @Override
161 public void setTimeout(long timeout) {
162 this.timeout = timeout;
163 }
164
165 @Override
166 public void setCheckInterval(long checkInterval) {
167 this.checkInterval = checkInterval;
168 }
169
170 @Override
171 public void setReadLockLoggingLevel(LoggingLevel readLockLoggingLevel) {
172 this.readLockLoggingLevel = readLockLoggingLevel;
173 }
174
175 }