hbase-common/src/main/java/org/apache/hadoop/hbase/util/Sleeper.java

   1 /**
   2  *
   3  * Licensed to the Apache Software Foundation (ASF) under one
   4  * or more contributor license agreements.  See the NOTICE file
   5  * distributed with this work for additional information
   6  * regarding copyright ownership.  The ASF licenses this file
   7  * to you under the Apache License, Version 2.0 (the
   8  * "License"); you may not use this file except in compliance
   9  * with the License.  You may obtain a copy of the License at
  10  *
  11  *     http://www.apache.org/licenses/LICENSE-2.0
  12  *
  13  * Unless required by applicable law or agreed to in writing, software
  14  * distributed under the License is distributed on an "AS IS" BASIS,
  15  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  16  * See the License for the specific language governing permissions and
  17  * limitations under the License.
  18  */
  19 package org.apache.hadoop.hbase.util;
  20
  21 import org.apache.hadoop.hbase.Stoppable;
  22 import org.apache.yetus.audience.InterfaceAudience;
  23 import org.slf4j.Logger;
  24 import org.slf4j.LoggerFactory;
  25
  26 /**
  27  * Sleeper for current thread.
  28  * Sleeps for passed period.  Also checks passed boolean and if interrupted,
  29  * will return if the flag is set (rather than go back to sleep until its
  30  * sleep time is up).
  31  */
  32 @InterfaceAudience.Private
  33 public class Sleeper {
  34   private static final Logger LOG = LoggerFactory.getLogger(Sleeper.class);
  35   private final int period;
  36   private final Stoppable stopper;
  37   private static final long MINIMAL_DELTA_FOR_LOGGING = 10000;
  38
  39   private final Object sleepLock = new Object();
  40   private boolean triggerWake = false;
  41
  42   /**
  43    * @param sleep sleep time in milliseconds
  44    * @param stopper When {@link Stoppable#isStopped()} is true, this thread will
  45    *    cleanup and exit cleanly.
  46    */
  47   public Sleeper(final int sleep, final Stoppable stopper) {
  48     this.period = sleep;
  49     this.stopper = stopper;
  50   }
  51
  52   /**
  53    * If currently asleep, stops sleeping; if not asleep, will skip the next
  54    * sleep cycle.
  55    */
  56   public void skipSleepCycle() {
  57     synchronized (sleepLock) {
  58       triggerWake = true;
  59       sleepLock.notifyAll();
  60     }
  61   }
  62
  63   /**
  64    * Sleep for period.
  65    */
  66   public void sleep() {
  67     sleep(this.period);
  68   }
  69
  70   public void sleep(long sleepTime) {
  71     if (this.stopper.isStopped()) {
  72       return;
  73     }
  74     long now = System.currentTimeMillis();
  75     long currentSleepTime = sleepTime;
  76     while (currentSleepTime > 0) {
  77       long woke = -1;
  78       try {
  79         synchronized (sleepLock) {
  80           if (triggerWake) {
  81             break;
  82           }
  83
  84           sleepLock.wait(currentSleepTime);
  85         }
  86         woke = System.currentTimeMillis();
  87         long slept = woke - now;
  88         if (slept - this.period > MINIMAL_DELTA_FOR_LOGGING) {
  89           LOG.warn("We slept {}ms instead of {}ms, this is likely due to a long " +
  90               "garbage collecting pause and it's usually bad, see " +
  91               "http://hbase.apache.org/book.html#trouble.rs.runtime.zkexpired", slept, this.period);
  92         }
  93       } catch(InterruptedException iex) {
  94         // We we interrupted because we're meant to stop?  If not, just
  95         // continue ignoring the interruption
  96         if (this.stopper.isStopped()) {
  97           return;
  98         }
  99       }
 100       // Recalculate waitTime.
 101       woke = (woke == -1)? System.currentTimeMillis(): woke;
 102       currentSleepTime = this.period - (woke - now);
 103     }
 104     synchronized(sleepLock) {
 105       triggerWake = false;
 106     }
 107   }
 108
 109   /**
 110    * @return the sleep period in milliseconds
 111    */
 112   public final int getPeriod() {
 113     return period;
 114   }
 115 }