/**
    * 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.util.concurrent.atomic.AtomicBoolean;
  import org.apache.hadoop.hbase.classification.InterfaceAudience;
  import org.apache.hadoop.metrics2.MetricHistogram;
  import org.apache.hadoop.metrics2.MetricsRecordBuilder;
  import org.apache.hadoop.metrics2.lib.DynamicMetricsRegistry;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  @InterfaceAudience.Private
  public class MetricsUserSourceImpl implements MetricsUserSource {
    private static final Logger LOG = LoggerFactory.getLogger(MetricsUserSourceImpl.class);
  
    private final String userNamePrefix;
  
    private final String user;
  
    private final String userGetKey;
    private final String userScanTimeKey;
    private final String userPutKey;
    private final String userDeleteKey;
    private final String userIncrementKey;
    private final String userAppendKey;
    private final String userReplayKey;
  
    private MetricHistogram getHisto;
    private MetricHistogram scanTimeHisto;
    private MetricHistogram putHisto;
    private MetricHistogram deleteHisto;
    private MetricHistogram incrementHisto;
    private MetricHistogram appendHisto;
    private MetricHistogram replayHisto;
  
    private final int hashCode;
  
    private AtomicBoolean closed = new AtomicBoolean(false);
    private final MetricsUserAggregateSourceImpl agg;
    private final DynamicMetricsRegistry registry;
  
    public MetricsUserSourceImpl(String user, MetricsUserAggregateSourceImpl agg) {
      if (LOG.isDebugEnabled()) {
        LOG.debug("Creating new MetricsUserSourceImpl for user " + user);
      }
  
      this.user = user;
      this.agg = agg;
      this.registry = agg.getMetricsRegistry();
  
      this.userNamePrefix = "user_" + user + "_metric_";
  
      hashCode = userNamePrefix.hashCode();
  
      userGetKey = userNamePrefix + MetricsRegionServerSource.GET_KEY;
      userScanTimeKey = userNamePrefix + MetricsRegionServerSource.SCAN_TIME_KEY;
      userPutKey = userNamePrefix + MetricsRegionServerSource.PUT_KEY;
      userDeleteKey = userNamePrefix + MetricsRegionServerSource.DELETE_KEY;
      userIncrementKey = userNamePrefix + MetricsRegionServerSource.INCREMENT_KEY;
      userAppendKey = userNamePrefix + MetricsRegionServerSource.APPEND_KEY;
      userReplayKey = userNamePrefix + MetricsRegionServerSource.REPLAY_KEY;
  
      agg.register(this);
    }
  
    @Override
    public void register() {
      synchronized (this) {
        getHisto = registry.newTimeHistogram(userGetKey);
        scanTimeHisto = registry.newTimeHistogram(userScanTimeKey);
        putHisto = registry.newTimeHistogram(userPutKey);
        deleteHisto = registry.newTimeHistogram(userDeleteKey);
        incrementHisto = registry.newTimeHistogram(userIncrementKey);
        appendHisto = registry.newTimeHistogram(userAppendKey);
        replayHisto = registry.newTimeHistogram(userReplayKey);
      }
    }
  
    @Override
    public void deregister() {
      boolean wasClosed = closed.getAndSet(true);
  
     // Has someone else already closed this for us?
     if (wasClosed) {
       return;
     }
 
     if (LOG.isDebugEnabled()) {
       LOG.debug("Removing user Metrics for user: " + user);
     }
 
     synchronized (this) {
       registry.removeMetric(userGetKey);
       registry.removeMetric(userScanTimeKey);
       registry.removeMetric(userPutKey);
       registry.removeMetric(userDeleteKey);
       registry.removeMetric(userIncrementKey);
       registry.removeMetric(userAppendKey);
       registry.removeMetric(userReplayKey);
     }
   }
 
   @Override
   public String getUser() {
     return user;
   }
 
   @Override
   public int compareTo(MetricsUserSource source) {
     if (source == null) {
       return -1;
     }
     if (!(source instanceof MetricsUserSourceImpl)) {
       return -1;
     }
 
     MetricsUserSourceImpl impl = (MetricsUserSourceImpl) source;
 
     return Long.compare(hashCode, impl.hashCode);
   }
 
   @Override
   public int hashCode() {
     return hashCode;
   }
 
   @Override
   public boolean equals(Object obj) {
     return obj == this ||
         (obj instanceof MetricsUserSourceImpl && compareTo((MetricsUserSourceImpl) obj) == 0);
   }
 
   void snapshot(MetricsRecordBuilder mrb, boolean ignored) {
     // If there is a close that started be double extra sure
     // that we're not getting any locks and not putting data
     // into the metrics that should be removed. So early out
     // before even getting the lock.
     if (closed.get()) {
       return;
     }
 
     // Grab the read
     // This ensures that removes of the metrics
     // can't happen while we are putting them back in.
     synchronized (this) {
 
       // It's possible that a close happened between checking
       // the closed variable and getting the lock.
       if (closed.get()) {
         return;
       }
     }
   }
 
   @Override
   public void updatePut(long t) {
     putHisto.add(t);
   }
 
   @Override
   public void updateDelete(long t) {
     deleteHisto.add(t);
   }
 
   @Override
   public void updateGet(long t) {
     getHisto.add(t);
   }
 
   @Override
   public void updateIncrement(long t) {
     incrementHisto.add(t);
   }
 
   @Override
   public void updateAppend(long t) {
     appendHisto.add(t);
   }
 
   @Override
   public void updateReplay(long t) {
     replayHisto.add(t);
   }
 
   @Override
   public void updateScanTime(long t) {
     scanTimeHisto.add(t);
   }
 }