package org.apache.directmemory.measures;
   
   /*
    * 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.
   */
  
  import static java.lang.String.format;
  
  import java.text.DecimalFormat;
  import java.util.HashMap;
  import java.util.Map;
  import java.util.concurrent.atomic.AtomicLong;
  
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  public class MonitorServiceImpl
      implements MonitorService
  {
  
      private final AtomicLong hits = new AtomicLong( 0 );
  
      private long totalTime = 0;
  
      private long min = -1;
  
      private long max = -1;
  
      public final String name;
  
      private static final Logger LOG = LoggerFactory.getLogger( MonitorServiceImpl.class );
  
      //TODO: MONITORS looks like a good candidate to become a private field
      public static final Map<String, MonitorServiceImpl> MONITORS = new HashMap<String, MonitorServiceImpl>();
  
      public MonitorServiceImpl( String name )
      {
          this.name = name;
      }
  
      public long start()
      {
          return System.nanoTime();
      }
  
      public long stop( long begunAt )
      {
          hits.incrementAndGet();
          final long lastAccessed = System.nanoTime();
          final long elapsed = lastAccessed - begunAt;
          totalTime += elapsed;
          if ( elapsed > max && hits.get() > 0 )
          {
              max = elapsed;
          }
          if ( elapsed < min && hits.get() > 0 )
          {
              min = elapsed;
          }
          return elapsed;
      }
  
      public long hits()
      {
          return hits.get();
      }
  
      public long totalTime()
      {
          return totalTime;
      }
  
      public long average()
      {
          return hits.get() > 0 ? totalTime / hits.get() : 0;
      }
  
      public String toString()
      {
          return format( "%1$s hits: %2$d, avg: %3$s ms, tot: %4$s seconds", name, hits.get(),
                         new DecimalFormat( "####.###" ).format( (double) average() / 1000000 ),
                         new DecimalFormat( "####.###" ).format( (double) totalTime / 1000000000 ) );
      }
  
     public void dump( String prefix )
     {
         for ( MonitorServiceImpl monitor : MonitorServiceImpl.MONITORS.values() )
         {
             if ( monitor.name.startsWith( prefix ) )
             {
                 LOG.info( monitor.toString() );
             }
         }
     }
 
     public void dump()
     {
         dump( "" );
     }
 
     public String getName()
     {
         return name;
     }
 
     public AtomicLong getHits()
     {
         return hits;
     }
 
     public long getTotalTime()
     {
         return totalTime;
     }
 
     @Override
     public void addToTotalTime( long time )
     {
         totalTime += time;
     }
 
     public long getMin()
     {
         return min;
     }
 
     public void setMin( long min )
     {
         this.min = min;
     }
 
     public long getMax()
     {
         return max;
     }
 
     public void setMax( long max )
     {
         this.max = max;
     }
 
 
 }