/*
    *  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.mina.core.service;
  
  import java.util.concurrent.atomic.AtomicInteger;
  import java.util.concurrent.locks.Lock;
  import java.util.concurrent.locks.ReentrantLock;
  
  /**
   * Provides usage statistics for an {@link AbstractIoService} instance.
   * 
   * @author <a href="http://mina.apache.org">Apache MINA Project</a>
   * @since 2.0.0-M3
   */
  public class IoServiceStatistics {
  
      private IoService service;
  
      /** The number of bytes read per second */
      private double readBytesThroughput;
  
      /** The number of bytes written per second */
      private double writtenBytesThroughput;
  
      /** The number of messages read per second */
      private double readMessagesThroughput;
  
      /** The number of messages written per second */
      private double writtenMessagesThroughput;
  
      /** The biggest number of bytes read per second */
      private double largestReadBytesThroughput;
  
      /** The biggest number of bytes written per second */
      private double largestWrittenBytesThroughput;
  
      /** The biggest number of messages read per second */
      private double largestReadMessagesThroughput;
  
      /** The biggest number of messages written per second */
      private double largestWrittenMessagesThroughput;
  
      /** The number of read bytes since the service has been started */
      private long readBytes;
  
      /** The number of written bytes since the service has been started */
      private long writtenBytes;
  
      /** The number of read messages since the service has been started */
      private long readMessages;
  
      /** The number of written messages since the service has been started */
      private long writtenMessages;
  
      /** The time the last read operation occurred */
      private long lastReadTime;
  
      /** The time the last write operation occurred */
      private long lastWriteTime;
  
      private long lastReadBytes;
  
      private long lastWrittenBytes;
  
      private long lastReadMessages;
  
      private long lastWrittenMessages;
  
      private long lastThroughputCalculationTime;
  
      private int scheduledWriteBytes;
  
      private int scheduledWriteMessages;
  
      /** The time (in second) between the computation of the service's statistics */
      private final AtomicInteger throughputCalculationInterval = new AtomicInteger(3);
  
      private final Lock throughputCalculationLock = new ReentrantLock();
  
      /**
       * Creates a new IoServiceStatistics instance
       * 
      * @param service The {@link IoService} for which we want statistics
      */
     public IoServiceStatistics(IoService service) {
         this.service = service;
     }
 
     /**
      * @return The maximum number of sessions which were being managed at the
      *         same time.
      */
     public final int getLargestManagedSessionCount() {
         return ((AbstractIoService)service).getListeners().getLargestManagedSessionCount();
     }
 
     /**
      * @return The cumulative number of sessions which were managed (or are
      *         being managed) by this service, which means 'currently managed
      *         session count + closed session count'.
      */
     public final long getCumulativeManagedSessionCount() {
         return ((AbstractIoService)service).getListeners().getCumulativeManagedSessionCount();
     }
 
     /**
      * @return the time in millis when the last I/O operation (read or write)
      *         occurred.
      */
     public final long getLastIoTime() {
         throughputCalculationLock.lock();
 
         try {
             return Math.max(lastReadTime, lastWriteTime);
         } finally {
             throughputCalculationLock.unlock();
         }
     }
 
     /**
      * @return The time in millis when the last read operation occurred.
      */
     public final long getLastReadTime() {
         throughputCalculationLock.lock();
 
         try {
             return lastReadTime;
         } finally {
             throughputCalculationLock.unlock();
         }
     }
 
     /**
      * @return The time in millis when the last write operation occurred.
      */
     public final long getLastWriteTime() {
         throughputCalculationLock.lock();
 
         try {
             return lastWriteTime;
         } finally {
             throughputCalculationLock.unlock();
         }
     }
 
     /**
      * @return The number of bytes this service has read so far
      */
     public final long getReadBytes() {
         throughputCalculationLock.lock();
 
         try {
             return readBytes;
         } finally {
             throughputCalculationLock.unlock();
         }
     }
 
     /**
      * @return The number of bytes this service has written so far
      */
     public final long getWrittenBytes() {
         throughputCalculationLock.lock();
 
         try {
             return writtenBytes;
         } finally {
             throughputCalculationLock.unlock();
         }
     }
 
     /**
      * @return The number of messages this services has read so far
      */
     public final long getReadMessages() {
         throughputCalculationLock.lock();
 
         try {
             return readMessages;
         } finally {
             throughputCalculationLock.unlock();
         }
     }
 
     /**
      * @return The number of messages this service has written so far
      */
     public final long getWrittenMessages() {
         throughputCalculationLock.lock();
 
         try {
             return writtenMessages;
         } finally {
             throughputCalculationLock.unlock();
         }
     }
 
     /**
      * @return The number of read bytes per second.
      */
     public final double getReadBytesThroughput() {
         throughputCalculationLock.lock();
 
         try {
             resetThroughput();
             return readBytesThroughput;
         } finally {
             throughputCalculationLock.unlock();
         }
     }
 
     /**
      * @return The number of written bytes per second.
      */
     public final double getWrittenBytesThroughput() {
         throughputCalculationLock.lock();
 
         try {
             resetThroughput();
             return writtenBytesThroughput;
         } finally {
             throughputCalculationLock.unlock();
         }
     }
 
     /**
      * @return The number of read messages per second.
      */
     public final double getReadMessagesThroughput() {
         throughputCalculationLock.lock();
 
         try {
             resetThroughput();
             return readMessagesThroughput;
         } finally {
             throughputCalculationLock.unlock();
         }
     }
 
     /**
      * @return The number of written messages per second.
      */
     public final double getWrittenMessagesThroughput() {
         throughputCalculationLock.lock();
 
         try {
             resetThroughput();
             return writtenMessagesThroughput;
         } finally {
             throughputCalculationLock.unlock();
         }
     }
 
     /**
      * @return The maximum number of bytes read per second since the service has
      *         been started.
      */
     public final double getLargestReadBytesThroughput() {
         throughputCalculationLock.lock();
 
         try {
             return largestReadBytesThroughput;
         } finally {
             throughputCalculationLock.unlock();
         }
     }
 
     /**
      * @return The maximum number of bytes written per second since the service
      *         has been started.
      */
     public final double getLargestWrittenBytesThroughput() {
         throughputCalculationLock.lock();
 
         try {
             return largestWrittenBytesThroughput;
         } finally {
             throughputCalculationLock.unlock();
         }
     }
 
     /**
      * @return The maximum number of messages read per second since the service
      *         has been started.
      */
     public final double getLargestReadMessagesThroughput() {
         throughputCalculationLock.lock();
 
         try {
             return largestReadMessagesThroughput;
         } finally {
             throughputCalculationLock.unlock();
         }
     }
 
     /**
      * @return The maximum number of messages written per second since the
      *         service has been started.
      */
     public final double getLargestWrittenMessagesThroughput() {
         throughputCalculationLock.lock();
 
         try {
             return largestWrittenMessagesThroughput;
         } finally {
             throughputCalculationLock.unlock();
         }
     }
 
     /**
      * @return the interval (seconds) between each throughput calculation. The
      *         default value is <tt>3</tt> seconds.
      */
     public final int getThroughputCalculationInterval() {
         return throughputCalculationInterval.get();
     }
 
     /**
      * @return the interval (milliseconds) between each throughput calculation.
      * The default value is <tt>3</tt> seconds.
      */
     public final long getThroughputCalculationIntervalInMillis() {
         return throughputCalculationInterval.get() * 1000L;
     }
 
     /**
      * Sets the interval (seconds) between each throughput calculation.  The
      * default value is <tt>3</tt> seconds.
      * 
      * @param throughputCalculationInterval The interval between two calculation
      */
     public final void setThroughputCalculationInterval(int throughputCalculationInterval) {
         if (throughputCalculationInterval < 0) {
             throw new IllegalArgumentException("throughputCalculationInterval: " + throughputCalculationInterval);
         }
 
         this.throughputCalculationInterval.set(throughputCalculationInterval);
     }
 
     /**
      * Sets last time at which a read occurred on the service.
      * 
      * @param lastReadTime
      *            The last time a read has occurred
      */
     protected final void setLastReadTime(long lastReadTime) {
         throughputCalculationLock.lock();
 
         try {
             this.lastReadTime = lastReadTime;
         } finally {
             throughputCalculationLock.unlock();
         }
     }
 
     /**
      * Sets last time at which a write occurred on the service.
      * 
      * @param lastWriteTime
      *            The last time a write has occurred
      */
     protected final void setLastWriteTime(long lastWriteTime) {
         throughputCalculationLock.lock();
 
         try {
             this.lastWriteTime = lastWriteTime;
         } finally {
             throughputCalculationLock.unlock();
         }
     }
 
     /**
      * Resets the throughput counters of the service if no session is currently
      * managed.
      */
     private void resetThroughput() {
         if (service.getManagedSessionCount() == 0) {
             readBytesThroughput = 0;
             writtenBytesThroughput = 0;
             readMessagesThroughput = 0;
             writtenMessagesThroughput = 0;
         }
     }
 
     /**
      * Updates the throughput counters.
      * 
      * @param currentTime The current time
      */
     public void updateThroughput(long currentTime) {
         throughputCalculationLock.lock();
 
         try {
             int interval = (int) (currentTime - lastThroughputCalculationTime);
             long minInterval = getThroughputCalculationIntervalInMillis();
 
             if ((minInterval == 0) || (interval < minInterval)) {
                 return;
             }
 
             readBytesThroughput = (readBytes - lastReadBytes) * 1000.0 / interval;
             writtenBytesThroughput = (writtenBytes - lastWrittenBytes) * 1000.0 / interval;
             readMessagesThroughput = (readMessages - lastReadMessages) * 1000.0 / interval;
             writtenMessagesThroughput = (writtenMessages - lastWrittenMessages) * 1000.0 / interval;
 
             if (readBytesThroughput > largestReadBytesThroughput) {
                 largestReadBytesThroughput = readBytesThroughput;
             }
 
             if (writtenBytesThroughput > largestWrittenBytesThroughput) {
                 largestWrittenBytesThroughput = writtenBytesThroughput;
             }
 
             if (readMessagesThroughput > largestReadMessagesThroughput) {
                 largestReadMessagesThroughput = readMessagesThroughput;
             }
 
             if (writtenMessagesThroughput > largestWrittenMessagesThroughput) {
                 largestWrittenMessagesThroughput = writtenMessagesThroughput;
             }
 
             lastReadBytes = readBytes;
             lastWrittenBytes = writtenBytes;
             lastReadMessages = readMessages;
             lastWrittenMessages = writtenMessages;
 
             lastThroughputCalculationTime = currentTime;
         } finally {
             throughputCalculationLock.unlock();
         }
     }
 
     /**
      * Increases the count of read bytes by <code>nbBytesRead</code> and sets
      * the last read time to <code>currentTime</code>.
      * 
      * @param nbBytesRead
      *            The number of bytes read
      * @param currentTime
      *            The date those bytes were read
      */
     public final void increaseReadBytes(long nbBytesRead, long currentTime) {
         throughputCalculationLock.lock();
 
         try {
             readBytes += nbBytesRead;
             lastReadTime = currentTime;
         } finally {
             throughputCalculationLock.unlock();
         }
     }
 
     /**
      * Increases the count of read messages by 1 and sets the last read time to
      * <code>currentTime</code>.
      * 
      * @param currentTime
      *            The time the message has been read
      */
     public final void increaseReadMessages(long currentTime) {
         throughputCalculationLock.lock();
 
         try {
             readMessages++;
             lastReadTime = currentTime;
         } finally {
             throughputCalculationLock.unlock();
         }
     }
 
     /**
      * Increases the count of written bytes by <code>nbBytesWritten</code> and
      * sets the last write time to <code>currentTime</code>.
      * 
      * @param nbBytesWritten
      *            The number of bytes written
      * @param currentTime
      *            The date those bytes were written
      */
     public final void increaseWrittenBytes(int nbBytesWritten, long currentTime) {
         throughputCalculationLock.lock();
 
         try {
             writtenBytes += nbBytesWritten;
             lastWriteTime = currentTime;
         } finally {
             throughputCalculationLock.unlock();
         }
     }
 
     /**
      * Increases the count of written messages by 1 and sets the last write time
      * to <code>currentTime</code>.
      * 
      * @param currentTime
      *            The date the message were written
      */
     public final void increaseWrittenMessages(long currentTime) {
         throughputCalculationLock.lock();
 
         try {
             writtenMessages++;
             lastWriteTime = currentTime;
         } finally {
             throughputCalculationLock.unlock();
         }
     }
 
     /**
      * @return The count of bytes scheduled for write.
      */
     public final int getScheduledWriteBytes() {
         throughputCalculationLock.lock();
 
         try {
             return scheduledWriteBytes;
         } finally {
             throughputCalculationLock.unlock();
         }
     }
 
     /**
      * Increments by <code>increment</code> the count of bytes scheduled for write.
      * 
      * @param increment The number of added bytes fro write
      */
     public final void increaseScheduledWriteBytes(int increment) {
         throughputCalculationLock.lock();
 
         try {
             scheduledWriteBytes += increment;
         } finally {
             throughputCalculationLock.unlock();
         }
     }
 
     /**
      * @return the count of messages scheduled for write.
      */
     public final int getScheduledWriteMessages() {
         throughputCalculationLock.lock();
 
         try {
             return scheduledWriteMessages;
         } finally {
             throughputCalculationLock.unlock();
         }
     }
 
     /**
      * Increments the count of messages scheduled for write.
      */
     public final void increaseScheduledWriteMessages() {
         throughputCalculationLock.lock();
 
         try {
             scheduledWriteMessages++;
         } finally {
             throughputCalculationLock.unlock();
         }
     }
 
     /**
      * Decrements the count of messages scheduled for write.
      */
     public final void decreaseScheduledWriteMessages() {
         throughputCalculationLock.lock();
 
         try {
             scheduledWriteMessages--;
         } finally {
             throughputCalculationLock.unlock();
         }
     }
 
     /**
      * Sets the time at which throughput counters where updated.
      * 
      * @param lastThroughputCalculationTime The time at which throughput counters where updated.
      */
     protected void setLastThroughputCalculationTime(long lastThroughputCalculationTime) {
         throughputCalculationLock.lock();
 
         try {
             this.lastThroughputCalculationTime = lastThroughputCalculationTime;
         } finally {
             throughputCalculationLock.unlock();
         }
     }
 }