/**
    * 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.errorhandling;
  
  import java.util.Timer;
  import java.util.TimerTask;
  
  import org.apache.commons.logging.Log;
  import org.apache.commons.logging.LogFactory;
  import org.apache.hadoop.hbase.classification.InterfaceAudience;
  import org.apache.hadoop.hbase.util.EnvironmentEdgeManager;
  
  /**
   * Time a given process/operation and report a failure if the elapsed time exceeds the max allowed
   * time.
   * <p>
   * The timer won't start tracking time until calling {@link #start()}. If {@link #complete()} or
   * {@link #trigger()} is called before {@link #start()}, calls to {@link #start()} will fail.
   */
  @InterfaceAudience.Private
  public class TimeoutExceptionInjector {
  
    private static final Log LOG = LogFactory.getLog(TimeoutExceptionInjector.class);
  
    private final long maxTime;
    private volatile boolean complete;
    private final Timer timer;
    private final TimerTask timerTask;
    private long start = -1;
  
    /**
     * Create a generic timer for a task/process.
     * @param listener listener to notify if the process times out
     * @param maxTime max allowed running time for the process. Timer starts on calls to
     *          {@link #start()}
     */
    public TimeoutExceptionInjector(final ForeignExceptionListener listener, final long maxTime) {
      this.maxTime = maxTime;
      timer = new Timer();
      timerTask = new TimerTask() {
        @Override
        public void run() {
          // ensure we don't run this task multiple times
          synchronized (this) {
            // quick exit if we already marked the task complete
            if (TimeoutExceptionInjector.this.complete) return;
            // mark the task is run, to avoid repeats
            TimeoutExceptionInjector.this.complete = true;
          }
          long end = EnvironmentEdgeManager.currentTime();
          TimeoutException tee =  new TimeoutException(
              "Timeout caused Foreign Exception", start, end, maxTime);
          String source = "timer-" + timer;
          listener.receive(new ForeignException(source, tee));
        }
      };
    }
  
    public long getMaxTime() {
      return maxTime;
    }
  
    /**
     * For all time forward, do not throw an error because the process has completed.
     */
    public void complete() {
      synchronized (this.timerTask) {
        if (this.complete) {
          LOG.warn("Timer already marked completed, ignoring!");
          return;
        }
        if (LOG.isDebugEnabled()) {
          LOG.debug("Marking timer as complete - no error notifications will be received for " +
            "this timer.");
        }
        this.complete = true;
      }
      this.timer.cancel();
    }
  
    /**
     * Start a timer to fail a process if it takes longer than the expected time to complete.
     * <p>
     * Non-blocking.
    * @throws IllegalStateException if the timer has already been marked done via {@link #complete()}
    *           or {@link #trigger()}
    */
   public synchronized void start() throws IllegalStateException {
     if (this.start >= 0) {
       LOG.warn("Timer already started, can't be started again. Ignoring second request.");
       return;
     }
     LOG.debug("Scheduling process timer to run in: " + maxTime + " ms");
     timer.schedule(timerTask, maxTime);
     this.start = EnvironmentEdgeManager.currentTime();
   }
 
   /**
    * Trigger the timer immediately.
    * <p>
    * Exposed for testing.
    */
   public void trigger() {
     synchronized (timerTask) {
       if (this.complete) {
         LOG.warn("Timer already completed, not triggering.");
         return;
       }
       LOG.debug("Triggering timer immediately!");
       this.timer.cancel();
       this.timerTask.run();
     }
   }
 }