/*
* Copyright 2014 Cisco Systems, Inc.
*
* 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.cisco.oss.foundation.logging.appender;
import org.apache.log4j.helpers.FileHelper;
import org.apache.log4j.helpers.LogLog;
import java.io.File;
import java.io.IOException;
/**
* Responsible for providing compression strategy instances (via factory
* methods), implementing template methods used by specific strategies, and the
* creation of compressed backup files.
*
* @author <a href="mailto:simon_park_mail AT yahoo DOT co DOT uk">Simon
* Park</a>
* @version 1.4
*/
abstract class LogFileCompressionStrategy {
static final LogFileCompressionStrategy ZIP = new ZipFileCompressionStrategy();
static final LogFileCompressionStrategy GZIP = new GzipFileCompressionStrategy();
static final LogFileCompressionStrategy DEFAULT = new LogFileCompressionStrategy() {
boolean compress(File backupFile, File deflatedFile,
AppenderRollingProperties properties) {
return false;
}
String getAlgorithmName() {
return "error";
}
boolean isCompressed(File backupFile) {
return true;
}
};
static final boolean existsFor(final AppenderRollingProperties properties) {
return (!LogFileCompressionStrategy.DEFAULT
.equals(findCompressionStrategy(properties)));
}
static final LogFileCompressionStrategy findCompressionStrategy(
final AppenderRollingProperties properties) {
if (ZIP.isRequiredStrategy(properties)) {
LogLog.debug("Using ZIP compression");
return ZIP;
}
if (GZIP.isRequiredStrategy(properties)) {
LogLog.debug("Using GZIP compression");
return GZIP;
}
LogLog.debug("Not using compression");
return DEFAULT;
}
static final LogFileCompressionStrategy[] strategies() {
// default strategy must not be included
return new LogFileCompressionStrategy[] { ZIP, GZIP };
}
/**
* Compress the backup file as per the implemented algorithm.
*
* @param backupFile
* The file to be compressed.
* @param deflatedFile
* The target file to which the compressed stream will be written.
* @param properties
* The appender's configuration.
* @return <tt>true</tt> if compression was successful
*/
abstract boolean compress(File backupFile, File deflatedFile,
AppenderRollingProperties properties);
/**
* @return The name to be used in the suffix of the compressed file.
*/
abstract String getAlgorithmName();
abstract boolean isCompressed(File backupFile);
/**
* @param properties
* The appender's configuration.
* @return <tt>true</tt> if the algorithm name of this strategy matches the
* configured name.
*/
final boolean isRequiredStrategy(final AppenderRollingProperties properties) {
return this.getAlgorithmName().equalsIgnoreCase(
properties.getCompressionAlgorithm());
}
/**
* Template method responsible for file compression checks, file creation, and
* delegation to specific strategy implementations.
*
* @param backupFile
* The file to be compressed.
* @param properties
* The appender's configuration.
*/
final void compress(final File backupFile,
final AppenderRollingProperties properties) {
if (this.isCompressed(backupFile)) {
LogLog.debug("Backup log file " + backupFile.getName()
+ " is already compressed");
return; // try not to do unnecessary work
}
final long lastModified = backupFile.lastModified();
if (0L == lastModified) {
LogLog.debug("Backup log file " + backupFile.getName()
+ " may have been scavenged");
return; // backup file may have been scavenged
}
final File deflatedFile = this.createDeflatedFile(backupFile);
if (deflatedFile == null) {
LogLog.debug("Backup log file " + backupFile.getName()
+ " may have been scavenged");
return; // an error occurred creating the file
}
if (this.compress(backupFile, deflatedFile, properties)) {
deflatedFile.setLastModified(lastModified);
FileHelper.getInstance().deleteExisting(backupFile);
LogLog.debug("Compressed backup log file to " + deflatedFile.getName());
} else {
FileHelper.getInstance().deleteExisting(deflatedFile); // clean up
LogLog
.debug("Unable to compress backup log file " + backupFile.getName());
}
}
private File createDeflatedFile(final File backupFile) {
try {
final FileHelper fileHelper = FileHelper.getInstance();
final File deflatedFile = new File(fileHelper.parentDirOf(backupFile),
backupFile.getName() + '.' + this.getAlgorithmName());
fileHelper.deleteExisting(deflatedFile);
if (deflatedFile.createNewFile()) {
return deflatedFile;
} else {
LogLog.warn("Unable to create compressed backup log file");
return null;
}
} catch (IOException e) {
LogLog.error("Unable to create compressed backup log file", e);
return null;
}
}
}