| /* |
| * 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.reef.runtime.common.evaluator; |
| |
| import org.apache.reef.util.OSUtils; |
| import org.apache.reef.wake.EventHandler; |
| import org.apache.reef.wake.time.runtime.event.RuntimeStart; |
| |
| import javax.annotation.concurrent.GuardedBy; |
| import javax.annotation.concurrent.ThreadSafe; |
| import javax.inject.Inject; |
| import java.io.File; |
| import java.io.FileNotFoundException; |
| import java.io.PrintWriter; |
| import java.io.UnsupportedEncodingException; |
| import java.util.logging.Level; |
| import java.util.logging.Logger; |
| |
| /** |
| * This Handler writes the Process ID (PID) to a file with a name given in PID_FILE_NAME to the local working directory. |
| */ |
| @ThreadSafe |
| public final class PIDStoreStartHandler implements EventHandler<RuntimeStart> { |
| /** |
| * The file name of the PID file created in the current working directory of the process. |
| */ |
| public static final String PID_FILE_NAME = "PID.txt"; |
| |
| private static final Logger LOG = Logger.getLogger(PIDStoreStartHandler.class.getName()); |
| |
| @GuardedBy("this") |
| private boolean pidIsWritten = false; |
| |
| @Inject |
| private PIDStoreStartHandler() { |
| } |
| |
| /** |
| * This call is idempotent: It will only write the PID exactly once per instance. |
| * |
| * @param startTime |
| */ |
| @Override |
| public synchronized void onNext(final RuntimeStart startTime) { |
| if (this.isPidNotWritten()) { |
| final long pid = OSUtils.getPID(); |
| final File outfile = new File(PID_FILE_NAME); |
| LOG.log(Level.FINEST, "Storing pid `" + pid + "` in file " + outfile.getAbsolutePath()); |
| try (PrintWriter p = new PrintWriter(PID_FILE_NAME, "UTF-8")) { |
| p.write(String.valueOf(pid)); |
| p.write("\n"); |
| } catch (final FileNotFoundException | UnsupportedEncodingException e) { |
| LOG.log(Level.WARNING, "Unable to create PID file.", e); |
| } |
| this.pidIsWritten = true; |
| } else { |
| LOG.log(Level.FINEST, "PID already written."); |
| } |
| } |
| |
| |
| /** |
| * @return true, if the PID hasn't been written yet. |
| */ |
| private synchronized boolean isPidNotWritten() { |
| return !this.pidIsWritten; |
| } |
| } |