| /** |
| * 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.yarn.server.nodemanager.util; |
| |
| import java.io.BufferedReader; |
| import java.io.File; |
| import java.io.FileInputStream; |
| import java.io.IOException; |
| import java.io.InputStreamReader; |
| import org.slf4j.Logger; |
| import org.slf4j.LoggerFactory; |
| |
| import org.apache.hadoop.fs.Path; |
| import org.apache.hadoop.util.Shell; |
| import org.apache.hadoop.yarn.api.records.ContainerId; |
| import org.apache.hadoop.yarn.util.ConverterUtils; |
| |
| /** |
| * Helper functionality to read the pid from a file. |
| */ |
| public class ProcessIdFileReader { |
| |
| private static final Logger LOG = |
| LoggerFactory.getLogger(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) throws IOException { |
| if (path == null) { |
| throw new IOException("Trying to access process id from a null path"); |
| } |
| if (LOG.isDebugEnabled()) { |
| 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 { |
| ContainerId.fromString(temp); |
| processId = temp; |
| break; |
| } catch (Exception e) { |
| // do nothing |
| } |
| } |
| else { |
| // Otherwise, find first line containing a numeric pid. |
| try { |
| long pid = Long.parseLong(temp); |
| if (pid > 0) { |
| processId = temp; |
| break; |
| } |
| } catch (Exception e) { |
| // do nothing |
| } |
| } |
| } |
| } |
| } |
| } finally { |
| if (bufReader != null) { |
| bufReader.close(); |
| } |
| } |
| if (LOG.isDebugEnabled()) { |
| LOG.debug("Got pid " + (processId != null ? processId : "null") |
| + " from path " + path); |
| } |
| return processId; |
| } |
| |
| } |