/**
    *
    * 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.regionserver;
  
  import java.io.IOException;
  import java.util.Map.Entry;
  import java.util.concurrent.ConcurrentHashMap;
  import java.util.concurrent.atomic.AtomicBoolean;
  import java.util.concurrent.locks.ReentrantLock;
  
  import org.apache.commons.logging.Log;
  import org.apache.commons.logging.LogFactory;
  import org.apache.hadoop.hbase.classification.InterfaceAudience;
  import org.apache.hadoop.hbase.HConstants;
  import org.apache.hadoop.hbase.RemoteExceptionHandler;
  import org.apache.hadoop.hbase.Server;
  import org.apache.hadoop.hbase.regionserver.wal.FSHLog;
  import org.apache.hadoop.hbase.regionserver.wal.FailedLogCloseException;
  import org.apache.hadoop.hbase.util.EnvironmentEdgeManager;
  import org.apache.hadoop.hbase.wal.WAL;
  import org.apache.hadoop.hbase.regionserver.wal.WALActionsListener;
  import org.apache.hadoop.hbase.util.Bytes;
  import org.apache.hadoop.hbase.util.HasThread;
  
  /**
   * Runs periodically to determine if the WAL should be rolled.
   *
   * NOTE: This class extends Thread rather than Chore because the sleep time
   * can be interrupted when there is something to do, rather than the Chore
   * sleep time which is invariant.
   *
   * TODO: change to a pool of threads
   */
  @InterfaceAudience.Private
  @edu.umd.cs.findbugs.annotations.SuppressWarnings(value="JLM_JSR166_UTILCONCURRENT_MONITORENTER",
    justification="Use of an atomic type both as monitor and condition variable is intended")
  public class LogRoller extends HasThread {
    private static final Log LOG = LogFactory.getLog(LogRoller.class);
    private final ReentrantLock rollLock = new ReentrantLock();
    private final AtomicBoolean rollLog = new AtomicBoolean(false);
    private final ConcurrentHashMap<WAL, RollController> wals =
        new ConcurrentHashMap<WAL, RollController>();
    private final Server server;
    protected final RegionServerServices services;
    // Period to roll log.
    private final long rollPeriod;
    private final int threadWakeFrequency;
    // The interval to check low replication on hlog's pipeline
    private final long checkLowReplicationInterval;
  
    public void addWAL(final WAL wal) {
      if (null == wals.putIfAbsent(wal, new RollController(wal))) {
        wal.registerWALActionsListener(new WALActionsListener.Base() {
          @Override
          public void logRollRequested(WALActionsListener.RollRequestReason reason) {
            RollController controller = wals.get(wal);
            if (controller == null) {
              wals.putIfAbsent(wal, new RollController(wal));
              controller = wals.get(wal);
            }
            controller.requestRoll();
            // TODO logs will contend with each other here, replace with e.g. DelayedQueue
            synchronized(rollLog) {
              rollLog.set(true);
              rollLog.notifyAll();
            }
          }
        });
      }
    }
  
    public void requestRollAll() {
      for (RollController controller : wals.values()) {
        controller.requestRoll();
      }
      synchronized(rollLog) {
        rollLog.set(true);
        rollLog.notifyAll();
      }
    }
  
    /** @param server */
    public LogRoller(final Server server, final RegionServerServices services) {
     super("LogRoller");
     this.server = server;
     this.services = services;
     this.rollPeriod = this.server.getConfiguration().
       getLong("hbase.regionserver.logroll.period", 3600000);
     this.threadWakeFrequency = this.server.getConfiguration().
       getInt(HConstants.THREAD_WAKE_FREQUENCY, 10 * 1000);
     this.checkLowReplicationInterval = this.server.getConfiguration().getLong(
         "hbase.regionserver.hlog.check.lowreplication.interval", 30 * 1000);
   }
 
   @Override
   public void interrupt() {
     // Wake up if we are waiting on rollLog. For tests.
     synchronized (rollLog) {
       this.rollLog.notify();
     }
     super.interrupt();
   }
 
   /**
    * we need to check low replication in period, see HBASE-18132
    */
   void checkLowReplication(long now) {
     try {
       for (Entry<WAL, RollController> entry : wals.entrySet()) {
         WAL wal = entry.getKey();
         boolean neeRollAlready = entry.getValue().needsRoll(now);
         if(wal instanceof FSHLog && !neeRollAlready) {
           FSHLog hlog = (FSHLog)wal;
           if ((now - hlog.getLastTimeCheckLowReplication())
               > this.checkLowReplicationInterval) {
             hlog.checkLogRoll();
           }
         }
       }
     } catch (Throwable e) {
       LOG.warn("Failed checking low replication", e);
     }
   }
 
   @Override
   public void run() {
     while (!server.isStopped()) {
       long now = EnvironmentEdgeManager.currentTime();
       checkLowReplication(now);
       if (!rollLog.get()) {
         boolean periodic = false;
         for (RollController controller : wals.values()) {
           if (controller.needsPeriodicRoll(now)) {
             periodic = true;
             break;
           }
         }
         if (!periodic) {
           synchronized (rollLog) {
             try {
               if (!rollLog.get()) {
                 rollLog.wait(this.threadWakeFrequency);
               }
             } catch (InterruptedException e) {
               // Fall through
             }
           }
           continue;
         }
       }
       rollLock.lock(); // FindBugs UL_UNRELEASED_LOCK_EXCEPTION_PATH
       try {
         for (Entry<WAL, RollController> entry : wals.entrySet()) {
           final WAL wal = entry.getKey();
           RollController controller = entry.getValue();
           if (controller.isRollRequested()) {
             // WAL roll requested, fall through
             LOG.debug("WAL " + wal + " roll requested");
           } else if (controller.needsPeriodicRoll(now)) {
             // Time for periodic roll, fall through
             LOG.debug("WAL " + wal + " roll period " + this.rollPeriod + "ms elapsed");
           } else {
             continue;
           }
           // Force the roll if the logroll.period is elapsed or if a roll was requested.
           // The returned value is an array of actual region names.
           final byte [][] regionsToFlush = controller.rollWal(now);
           if (regionsToFlush != null) {
             for (byte [] r: regionsToFlush) scheduleFlush(r);
           }
         }
       } catch (FailedLogCloseException e) {
         server.abort("Failed log close in log roller", e);
       } catch (java.net.ConnectException e) {
         server.abort("Failed log close in log roller", e);
       } catch (IOException ex) {
         LOG.fatal("Aborting", ex);
         // Abort if we get here.  We probably won't recover an IOE. HBASE-1132
         server.abort("IOE in log roller",
           RemoteExceptionHandler.checkIOException(ex));
       } catch (Exception ex) {
         final String msg = "Failed rolling WAL; aborting to recover edits!";
         LOG.error(msg, ex);
         server.abort(msg, ex);
       } finally {
         try {
           rollLog.set(false);
         } finally {
           rollLock.unlock();
         }
       }
     }
     LOG.info("LogRoller exiting.");
   }
 
   /**
    * @param encodedRegionName Encoded name of region to flush.
    */
   private void scheduleFlush(final byte [] encodedRegionName) {
     boolean scheduled = false;
     Region r = this.services.getFromOnlineRegions(Bytes.toString(encodedRegionName));
     FlushRequester requester = null;
     if (r != null) {
       requester = this.services.getFlushRequester();
       if (requester != null) {
         // force flushing all stores to clean old logs
         requester.requestFlush(r, true);
         scheduled = true;
       }
     }
     if (!scheduled) {
       LOG.warn("Failed to schedule flush of " +
         Bytes.toString(encodedRegionName) + ", region=" + r + ", requester=" +
         requester);
     }
   }
 
   /**
    * For testing only
    * @return true if all WAL roll finished
    */
   public boolean walRollFinished() {
     long now = EnvironmentEdgeManager.currentTime();
     for (RollController controller : wals.values()) {
       if (controller.needsRoll(now)) {
         return false;
       }
     }
     return true;
   }
 
   /**
    * Independently control the roll of each wal. When use multiwal,
    * can avoid all wal roll together. see HBASE-24665 for detail
    */
   protected class RollController {
     private final WAL wal;
     private final AtomicBoolean rollRequest;
     private long lastRollTime;
 
     RollController(WAL wal) {
       this.wal = wal;
       this.rollRequest = new AtomicBoolean(false);
       this.lastRollTime = EnvironmentEdgeManager.currentTime();
     }
 
     public void requestRoll() {
       this.rollRequest.set(true);
     }
 
     public byte[][] rollWal(long now) throws IOException {
       this.lastRollTime = now;
       byte[][] regionsToFlush = wal.rollWriter(true);
       this.rollRequest.set(false);
       return regionsToFlush;
     }
 
     public boolean isRollRequested() {
       return rollRequest.get();
     }
 
     public boolean needsPeriodicRoll(long now) {
       return (now - this.lastRollTime) > rollPeriod;
     }
 
     public boolean needsRoll(long now) {
       return isRollRequested() || needsPeriodicRoll(now);
     }
   }
 }