content: /*
   * Copyright (c) 2014, 2016, Oracle and/or its affiliates. All rights reserved.
   * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   *
   * This code is free software; you can redistribute it and/or modify it
   * under the terms of the GNU General Public License version 2 only, as
   * published by the Free Software Foundation.  Oracle designates this
   * particular file as subject to the "Classpath" exception as provided
   * by Oracle in the LICENSE file that accompanied this code.
   *
   * This code is distributed in the hope that it will be useful, but WITHOUT
   * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
   * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
   * version 2 for more details (a copy is included in the LICENSE file that
   * accompanied this code).
   *
   * You should have received a copy of the GNU General Public License version
   * 2 along with this work; if not, write to the Free Software Foundation,
   * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
   *
   * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
   * or visit www.oracle.com if you need additional information or have any
   * questions.
   */
  
  package openjdk.tools.sjavac.server;
  
  import openjdk.tools.javac.main.Main.Result;
  import openjdk.tools.sjavac.Log;
  
  import java.util.Timer;
  import java.util.TimerTask;
  
  /**
   * An sjavac implementation that keeps track of idleness and shuts down the
   * given Terminable upon idleness timeout.
   *
   * An idleness timeout kicks in {@code idleTimeout} milliseconds after the last
   * request is completed.
   *
   *  <p><b>This is NOT part of any supported API.
   *  If you write code that depends on this, you do so at your own risk.
   *  This code and its internal interfaces are subject to change or
   *  deletion without notice.</b>
   */
  public class IdleResetSjavac implements Sjavac {
  
      private final Sjavac delegate;
      private final Terminable toShutdown;
      private final Timer idlenessTimer = new Timer();
      private final long idleTimeout;
      private int outstandingCalls = 0;
  
      // Class invariant: idlenessTimerTask != null <-> idlenessTimerTask is scheduled
      private TimerTask idlenessTimerTask;
  
      public IdleResetSjavac(Sjavac delegate,
                             Terminable toShutdown,
                             long idleTimeout) {
          this.delegate = delegate;
          this.toShutdown = toShutdown;
          this.idleTimeout = idleTimeout;
          scheduleTimeout();
      }
  
      @Override
      public Result compile(String[] args) {
          startCall();
          try {
              return delegate.compile(args);
          } finally {
              endCall();
          }
      }
  
      private synchronized void startCall() {
          // Was there no outstanding calls before this call?
          if (++outstandingCalls == 1) {
              // Then the timer task must have been scheduled
              if (idlenessTimerTask == null)
                  throw new IllegalStateException("Idle timeout already cancelled");
              // Cancel timeout task
              idlenessTimerTask.cancel();
              idlenessTimerTask = null;
          }
      }
  
      private synchronized void endCall() {
          if (--outstandingCalls == 0) {
              // No more outstanding calls. Schedule timeout.
              scheduleTimeout();
          }
      }
  
      private void scheduleTimeout() {
          if (idlenessTimerTask != null)
              throw new IllegalStateException("Idle timeout already scheduled");
          idlenessTimerTask = new TimerTask() {
              public void run() {
                  Log.setLogForCurrentThread(ServerMain.getErrorLog());
                  toShutdown.shutdown("Server has been idle for " + (idleTimeout / 1000) + " seconds.");
              }
          };
          idlenessTimer.schedule(idlenessTimerTask, idleTimeout);
      }
  
      @Override
      public void shutdown() {
          idlenessTimer.cancel();
          delegate.shutdown();
      }
  
  }
  