/**
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF 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.apache.camel.component.file.strategy;
import java.io.File;
import org.apache.camel.Exchange;
import org.apache.camel.LoggingLevel;
import org.apache.camel.component.file.GenericFile;
import org.apache.camel.component.file.GenericFileOperations;
import org.apache.camel.util.CamelLogger;
import org.apache.camel.util.StopWatch;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
/**
* Acquires exclusive read lock to the given file by checking whether the file is being
* changed by scanning the file at different intervals (to detect changes).
*/
public class FileChangedExclusiveReadLockStrategy extends MarkerFileExclusiveReadLockStrategy {
private static final Logger LOG = LoggerFactory.getLogger(FileChangedExclusiveReadLockStrategy.class);
private long timeout;
private long checkInterval = 1000;
private long minLength = 1;
private LoggingLevel readLockLoggingLevel = LoggingLevel.WARN;
@Override
public boolean acquireExclusiveReadLock(GenericFileOperations<File> operations, GenericFile<File> file, Exchange exchange) throws Exception {
// must call super
if (!super.acquireExclusiveReadLock(operations, file, exchange)) {
return false;
}
File target = new File(file.getAbsoluteFilePath());
boolean exclusive = false;
LOG.trace("Waiting for exclusive read lock to file: {}", file);
long lastModified = Long.MIN_VALUE;
long length = Long.MIN_VALUE;
StopWatch watch = new StopWatch();
while (!exclusive) {
// timeout check
if (timeout > 0) {
long delta = watch.taken();
if (delta > timeout) {
CamelLogger.log(LOG, readLockLoggingLevel,
"Cannot acquire read lock within " + timeout + " millis. Will skip the file: " + file);
// we could not get the lock within the timeout period, so return false
return false;
}
}
long newLastModified = target.lastModified();
long newLength = target.length();
LOG.trace("Previous last modified: {}, new last modified: {}", lastModified, newLastModified);
LOG.trace("Previous length: {}, new length: {}", length, newLength);
if (length >= minLength && (newLastModified == lastModified && newLength == length)) {
LOG.trace("Read lock acquired.");
exclusive = true;
} else {
// set new base file change information
lastModified = newLastModified;
length = newLength;
boolean interrupted = sleep();
if (interrupted) {
// we were interrupted while sleeping, we are likely being shutdown so return false
return false;
}
}
}
return exclusive;
}
private boolean sleep() {
LOG.trace("Exclusive read lock not granted. Sleeping for {} millis.", checkInterval);
try {
Thread.sleep(checkInterval);
return false;
} catch (InterruptedException e) {
LOG.debug("Sleep interrupted while waiting for exclusive read lock, so breaking out");
return true;
}
}
public long getTimeout() {
return timeout;
}
@Override
public void setTimeout(long timeout) {
this.timeout = timeout;
}
public long getCheckInterval() {
return checkInterval;
}
@Override
public void setCheckInterval(long checkInterval) {
this.checkInterval = checkInterval;
}
@Override
public void setReadLockLoggingLevel(LoggingLevel readLockLoggingLevel) {
this.readLockLoggingLevel = readLockLoggingLevel;
}
public long getMinLength() {
return minLength;
}
public void setMinLength(long minLength) {
this.minLength = minLength;
}
}