com.lenovo.tensorhusky.common.utils.ProcessIdFileReader.java Source code

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Here is the source code for com.lenovo.tensorhusky.common.utils.ProcessIdFileReader.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
 * <p>
 * http://www.apache.org/licenses/LICENSE-2.0
 * <p>
 * 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.lenovo.tensorhusky.common.utils;

import java.io.BufferedReader;
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStreamReader;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.util.Shell;

/**
 * Helper functionality to read the pid from a file.
 */
public class ProcessIdFileReader {

    private static final Log LOG = LogFactory.getLog(ProcessIdFileReader.class);

    /**
     * Get the process id from specified file path. Parses each line to find a
     * valid number and returns the first one found.
     *
     * @return Process Id if obtained from path specified else null
     * @throws IOException
     */
    public static String getProcessId(Path path, boolean check) throws IOException {
        if (path == null) {
            throw new IOException("Trying to access process id from a null path");
        }

        LOG.debug("Accessing pid from pid file " + path);
        String processId = null;
        BufferedReader bufReader = null;

        try {
            File file = new File(path.toString());
            if (file.exists()) {
                FileInputStream fis = new FileInputStream(file);
                bufReader = new BufferedReader(new InputStreamReader(fis, "UTF-8"));

                while (true) {
                    String line = bufReader.readLine();
                    if (line == null) {
                        break;
                    }
                    String temp = line.trim();
                    if (!temp.isEmpty()) {
                        if (Shell.WINDOWS) {
                            // On Windows, pid is expected to be a container ID, so
                            // find first
                            // line that parses successfully as a container ID.
                            try {
                                processId = temp;
                                break;
                            } catch (Exception e) {
                                // do nothing
                            }
                        } else {
                            // Otherwise, find first line containing a numeric pid.
                            if (check) {
                                try {
                                    Long pid = Long.valueOf(temp);
                                    if (pid > 0) {
                                        processId = temp;
                                        break;
                                    }
                                } catch (Exception e) {
                                    // do nothing
                                }
                            } else {
                                processId = temp;
                            }
                        }
                    }
                }
            }
        } finally {
            if (bufReader != null) {
                bufReader.close();
            }
        }
        LOG.debug("Got pid " + (processId != null ? processId : "null") + " from path " + path);
        return processId;
    }

}