/**
 *
 * 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.Closeable;
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.hadoop.hbase.HConstants;
import org.apache.hadoop.hbase.Server;
import org.apache.hadoop.hbase.regionserver.wal.AbstractFSWAL;
import org.apache.hadoop.hbase.regionserver.wal.FailedLogCloseException;
import org.apache.hadoop.hbase.regionserver.wal.WALActionsListener;
import org.apache.hadoop.hbase.util.Bytes;
import org.apache.hadoop.hbase.util.HasThread;
import org.apache.hadoop.hbase.wal.WAL;
import org.apache.hadoop.ipc.RemoteException;
import org.apache.yetus.audience.InterfaceAudience;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.apache.hbase.thirdparty.com.google.common.annotations.VisibleForTesting;

/**
 * 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
@VisibleForTesting
public class LogRoller extends HasThread implements Closeable {
  private static final Logger LOG = LoggerFactory.getLogger(LogRoller.class);
  private final ReentrantLock rollLock = new ReentrantLock();
  private final AtomicBoolean rollLog = new AtomicBoolean(false);
  private final ConcurrentHashMap<WAL, Boolean> walNeedsRoll = new ConcurrentHashMap<>();
  private final Server server;
  protected final RegionServerServices services;
  private volatile long lastrolltime = System.currentTimeMillis();
  // Period to roll log.
  private final long rollperiod;
  private final int threadWakeFrequency;
  // The interval to check low replication on hlog's pipeline
  private long checkLowReplicationInterval;

  private volatile boolean running = true;

  public void addWAL(final WAL wal) {
    if (null == walNeedsRoll.putIfAbsent(wal, Boolean.FALSE)) {
      wal.registerWALActionsListener(new WALActionsListener() {
        @Override
        public void logRollRequested(boolean lowReplicas) {
          walNeedsRoll.put(wal, Boolean.TRUE);
          // TODO logs will contend with each other here, replace with e.g. DelayedQueue
          synchronized(rollLog) {
            rollLog.set(true);
            rollLog.notifyAll();
          }
        }
      });
    }
  }

  public void requestRollAll() {
    for (WAL wal : walNeedsRoll.keySet()) {
      walNeedsRoll.put(wal, Boolean.TRUE);
    }
    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, Boolean> entry : walNeedsRoll.entrySet()) {
        WAL wal = entry.getKey();
        boolean needRollAlready = entry.getValue();
        if (needRollAlready || !(wal instanceof AbstractFSWAL)) {
          continue;
        }
        ((AbstractFSWAL<?>) wal).checkLogLowReplication(checkLowReplicationInterval);
      }
    } catch (Throwable e) {
      LOG.warn("Failed checking low replication", e);
    }
  }

  private void abort(String reason, Throwable cause) {
    // close all WALs before calling abort on RS.
    // This is because AsyncFSWAL replies on us for rolling a new writer to make progress, and if we
    // failed, AsyncFSWAL may be stuck, so we need to close it to let the upper layer know that it
    // is already broken.
    for (WAL wal : walNeedsRoll.keySet()) {
      // shutdown rather than close here since we are going to abort the RS and the wals need to be
      // split when recovery
      try {
        wal.shutdown();
      } catch (IOException e) {
        LOG.warn("Failed to shutdown wal", e);
      }
    }
    server.abort(reason, cause);
  }

  @Override
  public void run() {
    while (running) {
      long now = System.currentTimeMillis();
      checkLowReplication(now);
      boolean periodic = false;
      if (!rollLog.get()) {
        periodic = (now - this.lastrolltime) > this.rollperiod;
        if (!periodic) {
          synchronized (rollLog) {
            try {
              if (!rollLog.get()) {
                rollLog.wait(this.threadWakeFrequency);
              }
            } catch (InterruptedException e) {
              // Fall through
            }
          }
          continue;
        }
        // Time for periodic roll
        LOG.debug("Wal roll period {} ms elapsed", this.rollperiod);
      } else {
        LOG.debug("WAL roll requested");
      }
      rollLock.lock(); // FindBugs UL_UNRELEASED_LOCK_EXCEPTION_PATH
      try {
        this.lastrolltime = now;
        for (Entry<WAL, Boolean> entry : walNeedsRoll.entrySet()) {
          final WAL wal = entry.getKey();
          // 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 = wal.rollWriter(periodic ||
              entry.getValue().booleanValue());
          walNeedsRoll.put(wal, Boolean.FALSE);
          if (regionsToFlush != null) {
            for (byte[] r : regionsToFlush) {
              scheduleFlush(r);
            }
          }
        }
      } catch (FailedLogCloseException e) {
        abort("Failed log close in log roller", e);
      } catch (java.net.ConnectException e) {
        abort("Failed log close in log roller", e);
      } catch (IOException ex) {
        // Abort if we get here.  We probably won't recover an IOE. HBASE-1132
        abort("IOE in log roller",
          ex instanceof RemoteException ? ((RemoteException) ex).unwrapRemoteException() : ex);
      } catch (Exception ex) {
        LOG.error("Log rolling failed", ex);
        abort("Log rolling failed", 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;
    HRegion r = (HRegion) this.services.getRegion(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, FlushLifeCycleTracker.DUMMY);
        scheduled = true;
      }
    }
    if (!scheduled) {
      LOG.warn("Failed to schedule flush of {}, region={}, requester={}",
        Bytes.toString(encodedRegionName), r, requester);
    }
  }

  /**
   * For testing only
   * @return true if all WAL roll finished
   */
  @VisibleForTesting
  public boolean walRollFinished() {
    for (boolean needRoll : walNeedsRoll.values()) {
      if (needRoll) {
        return false;
      }
    }
    return true;
  }

  @Override
  public void close() {
    running = false;
    interrupt();
  }
}