ch.ivyteam.ivy.maven.engine.deploy.FileLogForwarder.java Source code

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Here is the source code for ch.ivyteam.ivy.maven.engine.deploy.FileLogForwarder.java

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/*
 * Copyright (C) 2016 AXON IVY AG
 *
 * 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 ch.ivyteam.ivy.maven.engine.deploy;

import java.io.File;
import java.io.IOException;
import java.io.RandomAccessFile;

import org.apache.commons.io.filefilter.FileFilterUtils;
import org.apache.commons.io.filefilter.IOFileFilter;
import org.apache.commons.io.monitor.FileAlterationListenerAdaptor;
import org.apache.commons.io.monitor.FileAlterationMonitor;
import org.apache.commons.io.monitor.FileAlterationObserver;
import org.apache.maven.plugin.MojoExecutionException;
import org.apache.maven.plugin.logging.Log;

/**
 * Detects new log lines in file and forwards them to an {@link LogLineHandler}.
 * @since 6.1.0
 */
class FileLogForwarder {
    private final File engineLog;
    private final Log mavenLog;

    private FileAlterationMonitor monitor;
    private LogLineHandler logLineHandler;

    /**
     * @param engineLog the log file to watch for new lines
     * @param mavenLog the target logger
     */
    FileLogForwarder(File engineLog, Log mavenLog, LogLineHandler handler) {
        this.engineLog = engineLog;
        this.mavenLog = mavenLog;
        this.logLineHandler = handler;
    }

    public synchronized void activate() throws MojoExecutionException {
        IOFileFilter logFilter = FileFilterUtils.and(FileFilterUtils.fileFileFilter(),
                FileFilterUtils.nameFileFilter(engineLog.getName()));
        FileAlterationObserver fileObserver = new FileAlterationObserver(engineLog.getParent(), logFilter);
        fileObserver.addListener(new LogModificationListener());
        monitor = new FileAlterationMonitor(100);
        monitor.addObserver(fileObserver);
        try {
            monitor.start();
        } catch (Exception ex) {
            throw new MojoExecutionException("Failed to activate deploy log forwarder", ex);
        }
    }

    public synchronized void deactivate() throws MojoExecutionException {
        try {
            if (monitor != null) {
                monitor.stop(0);
            }
        } catch (Exception ex) {
            throw new MojoExecutionException("Failed to deactivate deploy log forwarder", ex);
        } finally {
            monitor = null;
        }
    }

    private class LogModificationListener extends FileAlterationListenerAdaptor {
        private long lastReadPosition = 0;

        @Override
        public void onFileChange(File log) {
            try (RandomAccessFile readableLog = new RandomAccessFile(log, "r");) {
                readableLog.seek(lastReadPosition);
                readNewLines(readableLog);
                lastReadPosition = readableLog.getFilePointer();
            } catch (Exception ex) {
                mavenLog.warn("Failed to get engine deploy log content", ex);
            }
        }

        private void readNewLines(RandomAccessFile readableLog) throws IOException {
            String line = null;
            while ((line = readableLog.readLine()) != null) {
                logLineHandler.handleLine(line);
            }
        }
    }

    static interface LogLineHandler {
        void handleLine(String newLogLine);
    }

}