content: /* jcifs smb client library in Java
   * Copyright (C) 2000  "Michael B. Allen" <jcifs at samba dot org>
   * 
   * This library is free software; you can redistribute it and/or
   * modify it under the terms of the GNU Lesser General Public
   * License as published by the Free Software Foundation; either
   * version 2.1 of the License, or (at your option) any later version.
   * 
   * This library is distributed in the hope that it will be useful,
   * but WITHOUT ANY WARRANTY; without even the implied warranty of
   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   * Lesser General Public License for more details.
   * 
   * You should have received a copy of the GNU Lesser General Public
   * License along with this library; if not, write to the Free Software
   * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
   */
  
  package jcifs.smb;
  
  
  import java.util.Arrays;
  
  import jcifs.BufferCache;
  import jcifs.Configuration;
  
  
  /**
   * Cache for reusable byte buffers
   * 
   * @internal
   */
  public class BufferCacheImpl implements BufferCache {
  
      private final Object[] cache;
      private final int bufferSize;
      private int freeBuffers = 0;
  
  
      /**
       * 
       * @param cfg
       */
      public BufferCacheImpl ( Configuration cfg ) {
          this(cfg.getBufferCacheSize(), cfg.getMaximumBufferSize());
      }
  
  
      /**
       * @param maxBuffers
       * @param maxSize
       * 
       */
      public BufferCacheImpl ( int maxBuffers, int maxSize ) {
          this.cache = new Object[maxBuffers];
          this.bufferSize = maxSize;
      }
  
  
      /**
       * {@inheritDoc}
       *
       * @see jcifs.BufferCache#getBuffer()
       */
      @Override
      public byte[] getBuffer () {
          synchronized ( this.cache ) {
              byte[] buf;
  
              if ( this.freeBuffers > 0 ) {
                  for ( int i = 0; i < this.cache.length; i++ ) {
                      if ( this.cache[ i ] != null ) {
                          buf = (byte[]) this.cache[ i ];
                          this.cache[ i ] = null;
                          this.freeBuffers--;
                          return buf;
                      }
                  }
              }
              return new byte[this.bufferSize];
          }
      }
  
  
      /**
       * {@inheritDoc}
       *
       * @see jcifs.BufferCache#releaseBuffer(byte[])
       */
      @Override
      public void releaseBuffer ( byte[] buf ) {
          if ( buf == null ) {
              return;
          }
          // better safe than sorry: prevent leaks if there is some out of bound access
          Arrays.fill(buf, (byte) 0);
          synchronized ( this.cache ) {
              if ( this.freeBuffers < this.cache.length ) {
                  for ( int i = 0; i < this.cache.length; i++ ) {
                      if ( this.cache[ i ] == null ) {
                          this.cache[ i ] = buf;
                          this.freeBuffers++;
                          return;
                      }
                  }
              }
          }
      }
  }
  