org.apache.hadoop.hbase.monitoring.LogMonitoring.java Source code

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Here is the source code for org.apache.hadoop.hbase.monitoring.LogMonitoring.java

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/**
 *
 * 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.hadoop.hbase.monitoring;

import java.io.BufferedReader;
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.nio.channels.FileChannel;
import java.util.Enumeration;
import java.util.Set;

import org.apache.hadoop.classification.InterfaceAudience;
import org.apache.hadoop.io.IOUtils;
import org.apache.log4j.Appender;
import org.apache.log4j.FileAppender;
import org.apache.log4j.Logger;

import com.google.common.collect.Sets;

/**
 * Utility functions for reading the log4j logs that are
 * being written by HBase.
 */
@InterfaceAudience.Private
public abstract class LogMonitoring {
    public static Set<File> getActiveLogFiles() throws IOException {
        Set<File> ret = Sets.newHashSet();
        Appender a;
        @SuppressWarnings("unchecked")
        Enumeration<Appender> e = Logger.getRootLogger().getAllAppenders();
        while (e.hasMoreElements()) {
            a = e.nextElement();
            if (a instanceof FileAppender) {
                FileAppender fa = (FileAppender) a;
                String filename = fa.getFile();
                ret.add(new File(filename));
            }
        }
        return ret;
    }

    public static void dumpTailOfLogs(PrintWriter out, long tailKb) throws IOException {
        Set<File> logs = LogMonitoring.getActiveLogFiles();
        for (File f : logs) {
            out.println("+++++++++++++++++++++++++++++++");
            out.println(f.getAbsolutePath());
            out.println("+++++++++++++++++++++++++++++++");
            try {
                dumpTailOfLog(f, out, tailKb);
            } catch (IOException ioe) {
                out.println("Unable to dump log at " + f);
                ioe.printStackTrace(out);
            }
            out.println("\n\n");
        }
    }

    private static void dumpTailOfLog(File f, PrintWriter out, long tailKb) throws IOException {
        FileInputStream fis = new FileInputStream(f);
        BufferedReader r = null;
        try {
            FileChannel channel = fis.getChannel();
            channel.position(Math.max(0, channel.size() - tailKb * 1024));
            r = new BufferedReader(new InputStreamReader(fis));
            r.readLine(); // skip the first partial line
            String line;
            while ((line = r.readLine()) != null) {
                out.println(line);
            }
        } finally {
            if (r != null)
                IOUtils.closeStream(r);
            IOUtils.closeStream(fis);
        }
    }
}