directbytebufferpool.java

这是一个基于java编写的torrent的P2P源码

          bytesToFree += buffSizes[i];
        }
      }
      //reduce max size for next round
      maxPoolSize--;
    }
    
    //free buffers from the pools
    pos = 0;
    it = buffersMap.values().iterator();
    while (it.hasNext()) {
      //for each pool
      ArrayList bufferPool = (ArrayList)it.next();
      synchronized( bufferPool ) {
        int size = bufferPool.size();
        //remove the buffers from the end
        for (int i=(size - 1); i >= (size - numToFree[pos]); i--) {
          bufferPool.remove(i);
        }
      }
      
      pos++;
    }
    
    runGarbageCollection();
  }
  
  
  
  
  private long bytesFree() {
    long bytesUsed = 0;
    synchronized( poolsLock ) {
      //count up total bytes used by free buffers
      Iterator it = buffersMap.keySet().iterator();
      while (it.hasNext()) {
        Integer keyVal = (Integer)it.next();
        ArrayList bufferPool = (ArrayList)buffersMap.get(keyVal);
      
        bytesUsed += keyVal.intValue() * bufferPool.size();
      }
    }
    return bytesUsed;
  }
  
  
  /*
  private final HashMap in_use_counts = new HashMap();
  
  private void addInUse( int size ) {
    Integer key = new Integer( size );
    synchronized( in_use_counts ) {
      Integer count = (Integer)in_use_counts.get( key );
      if( count == null )  count = new Integer( 1 );
      else  count = new Integer( count.intValue() + 1 );
      in_use_counts.put( key, count );
    }
  }
  
  private void remInUse( int size ) {
    Integer key = new Integer( size );
    synchronized( in_use_counts ) {
      Integer count = (Integer)in_use_counts.get( key );
      if( count == null ) System.out.println("count = null");
      if( count.intValue() == 0 ) System.out.println("count = 0");
      in_use_counts.put( key, new Integer( count.intValue() - 1 ) );
    }
  }
  
  private void printInUse() {
    synchronized( in_use_counts ) {
      for( Iterator i = in_use_counts.keySet().iterator(); i.hasNext(); ) {
        Integer key = (Integer)i.next();
        int count = ((Integer)in_use_counts.get( key )).intValue();
        int size = key.intValue();
        if( count > 0 ) {
          if( size < 1024 )  System.out.print("[" +size+ " x " +count+ "] ");
          else  System.out.print("[" +size/1024+ "K x " +count+ "] ");
        }
      }
      System.out.println();
    }
  }
  */
  
  	private void
	printInUse(
		boolean		verbose )
  	{
  		if ( DEBUG_PRINT_MEM ){
	  		CacheFileManager cm	= null;
	  		
			try{
	 			cm = CacheFileManagerFactory.getSingleton();
	 			
			}catch( Throwable e ){
					
				Debug.printStackTrace( e );
			}
	 
	  		synchronized( handed_out ){
	    	
	  			Iterator	it = handed_out.values().iterator();
	  			
	  			Map	cap_map		= new TreeMap();
	  			Map	alloc_map	= new TreeMap();
	  			
	  			while( it.hasNext()){
	  				
	  				DirectByteBuffer	db = (DirectByteBuffer)it.next();
	  				
	  				if ( verbose ){
		  				String	trace = db.getTraceString();
		  				
		  				if ( trace != null ){
		  					
		  					System.out.println( trace );
		  				}
	  				}
	  				
	  				Integer cap 	= new Integer( db.getBufferInternal().capacity());
	  				Byte	alloc 	= new Byte( db.getAllocator());
	  				
	  				myInteger	c = (myInteger)cap_map.get(cap);
	  				
	  				if ( c == null ){
	  					
	  					c	= new myInteger();
	  					
	  					cap_map.put( cap, c );
	  				}
	  				
	  				c.value++;
	  				
					myInteger	a = (myInteger)alloc_map.get(alloc);
	  				
	  				if ( a == null ){
	  					
	  					a	= new myInteger();
	  					
	  					alloc_map.put( alloc, a );
	  				}
	  				
	  				a.value++;				
	  			}
	  			
	  			it = cap_map.keySet().iterator();
	  			
	  			while( it.hasNext()){
	  				
	  				Integer		key 	= (Integer)it.next();
	  				myInteger	count 	= (myInteger)cap_map.get( key );
	  				
	  		        if( key.intValue() < 1024 ){
	  		        	
	  		        	System.out.print("[" +key.intValue()+ " x " +count.value+ "] ");
	  		        	
	  		        }else{  
	  		        	
	  		        	System.out.print("[" +key.intValue()/1024+ "K x " +count.value+ "] ");
	  		        }
	  			}
	  			
	  			System.out.println();
	  			
				it = alloc_map.keySet().iterator();
	  			
	  			while( it.hasNext()){
	  				
	  				Byte		key 	= (Byte)it.next();
	  				myInteger	count 	= (myInteger)alloc_map.get( key );
	  				
	  	        	System.out.print("[" + DirectByteBuffer.AL_DESCS[key.intValue()]+ " x " +count.value+ "] ");
	  			}
	  			
	  			if ( cm != null ){
	  				
	  				CacheFileManagerStats stats = cm.getStats();
	  				
	  				System.out.print( " - Cache: " );
	  	  			
	  				
					System.out.print( "sz=" + stats.getSize());
					System.out.print( ",us=" + stats.getUsedSize());
					System.out.print( ",cw=" + stats.getBytesWrittenToCache());
					System.out.print( ",cr=" + stats.getBytesReadFromCache());
					System.out.print( ",fw=" + stats.getBytesWrittenToFile());
					System.out.print( ",fr=" + stats.getBytesReadFromFile());
					
	  			}
	  			
	  			System.out.println();
				
				if ( DEBUG_HANDOUT_SIZES ){
					it = size_counts.entrySet().iterator();
					
					String	str = "";
						
					while( it.hasNext()){
						
						Map.Entry	entry = (Map.Entry)it.next();
						
						str += (str.length()==0?"":",") + entry.getKey() + "=" + entry.getValue();
					}
					
					System.out.println( str );
				}
				
				String str = "";
				
				for (int i=0;i<slice_entries.length;i++){
				
					boolean[]	allocs = slice_allocs[i];
					int	alloc_count = 0;
					for (int j=0;j<allocs.length;j++){
						if( allocs[j]){
							alloc_count++;
						}
					}
					str += (i==0?"":",") + "["+SLICE_ENTRY_SIZES[i]+"]f=" +slice_entries[i].size()+",a=" + (alloc_count*SLICE_ENTRY_ALLOC_SIZES[i]) + ",u=" +slice_use_count[i];
				}
				
				System.out.println( "slices: " + str );

	  		}
  		}
  	}
  	
	
		// Slice buffer management
	
	protected DirectByteBuffer
	getSliceBuffer(
		byte		_allocator,
		int			_length )
	{
		int	slice_index = getSliceIndex( _length );
		
		List		my_slice_entries 	= slice_entries[slice_index];

		synchronized( my_slice_entries ){
	
			boolean[]	my_allocs			= slice_allocs[slice_index];
			
			sliceBuffer	sb = null;
			
			if ( my_slice_entries.size() > 0 ){
				
				sb = (sliceBuffer)my_slice_entries.remove(0);
				
				slice_use_count[slice_index]++;
				
			}else{
				
					// find a free slot
				
				short	slot = -1;
				
				for (short i=0;i<my_allocs.length;i++){
					
					if( !my_allocs[i]){
						
						slot	= i;
			
						break;
					}
				}
				
				if ( slot != -1 ){
					
					short	slice_entry_size 	= SLICE_ENTRY_SIZES[slice_index];
					short	slice_entry_count	= SLICE_ENTRY_ALLOC_SIZES[slice_index];
					
					ByteBuffer	chunk = ByteBuffer.allocateDirect(  slice_entry_size*slice_entry_count  );
					
					my_allocs[slot] = true;
					
					for (short i=0;i<slice_entry_count;i++){
						
						chunk.limit((i+1)*slice_entry_size);
						chunk.position(i*slice_entry_size);
						
						ByteBuffer	slice = chunk.slice();
						
						sliceBuffer new_buffer = new sliceBuffer( slice, slot, i );
						
						if ( i == 0 ){
							
							sb = new_buffer;
							
							slice_use_count[slice_index]++;
							
						}else{
							
							my_slice_entries.add( new_buffer );
						}
					}
				}else{
					
					if ( !slice_alloc_fails[slice_index] ){
						
						slice_alloc_fails[slice_index]	= true;
						
						Debug.out( "Run out of slice space for '" + SLICE_ENTRY_SIZES[slice_index] + ", reverting to normal allocation" );
					}
					
					ByteBuffer buff = ByteBuffer.allocate( _length );
					
				    return( new DirectByteBuffer( _allocator, buff, this ));

				}
			}
			
			sliceDBB dbb = new sliceDBB( _allocator, sb );

			return( dbb );
		}
	}
	
	protected void
	freeSliceBuffer(
		DirectByteBuffer	ddb )
	{		
		if ( ddb instanceof sliceDBB ){
			
			int	slice_index = getSliceIndex( ddb.getBufferInternal().capacity());

			List		my_slice_entries 	= slice_entries[slice_index];

			synchronized( my_slice_entries ){
			
				my_slice_entries.add( 0, ((sliceDBB)ddb).getSliceBuffer());
			}
		}
	}
	
	protected void
	compactSlices()
	{
			// we don't maintain the buffers in sorted order as this is too costly. however, we
			// always allocate and free from the start of the free list, so unused buffer space
			// will be at the end of the list. we periodically sort this list into allocate block
			// order so that if an entire block isn't used for one compaction cycle all of
			// its elements will end up together, if you see what I mean :P
		
			// when we find an entire block is unused then we just drop them from the list to
			// permit them (and the underlying block) to be garbage collected
		
		for (int i=0;i<slice_entries.length;i++){
			
			int			entries_per_alloc 	= SLICE_ENTRY_ALLOC_SIZES[i];
	
			List	l = slice_entries[i];
	
				// no point in trying gc if not enough entries
			
			if ( l.size() >= entries_per_alloc ){
			
				synchronized( l ){
					
					Collections.sort( l,
						new Comparator()
						{
							public int
							compare(
								Object	o1,
								Object	o2 )
							{
								sliceBuffer	sb1 = (sliceBuffer)o1;
								sliceBuffer	sb2 = (sliceBuffer)o2;
								
								int	res = sb1.getAllocID() - sb2.getAllocID();
								
								if ( res == 0 ){
									
									res = sb1.getSliceID() - sb2.getSliceID();
								}
								
								return( res );
							}
						});
			
					boolean[]	allocs				= slice_allocs[i];
			
					Iterator	it = l.iterator();
					
					int	current_alloc 	= -1;
					int entry_count		= 0;
			
					boolean	freed_one	= false;
					
					while( it.hasNext()){
						
						sliceBuffer	sb = (sliceBuffer)it.next();
						
						int	aid = sb.getAllocID();
						
						if ( aid != current_alloc ){
							
							if ( entry_count == entries_per_alloc ){
								
								// System.out.println( "CompactSlices[" + SLICE_ENTRY_SIZES[i]+"] freeing " + aid );
								
								freed_one	= true;
								
								allocs[aid]	= false;					
							}
							
							current_alloc	= aid;
							
							entry_count		= 1;
							
						}else{
							
							entry_count++;
						}
					}
					
					if ( entry_count == entries_per_alloc ){
						
						// System.out.println( "CompactSlices[" + SLICE_ENTRY_SIZES[i]+"] freeing " + current_alloc );
						
						freed_one	= true;
						
						allocs[current_alloc]	= false;					
					}
					
					if ( freed_one ){
						
						it = l.iterator();
						
						while( it.hasNext()){
							
							sliceBuffer	sb = (sliceBuffer)it.next();
							
							if ( !allocs[ sb.getAllocID()]){
								
								it.remove();
							}
						}
					}
				}
			}
		}
	}
	
	protected int
	getSliceIndex( 
		int	_length )
	{
		for (int i=0;i<SLICE_ENTRY_SIZES.length;i++){
			
			if ( _length <= SLICE_ENTRY_SIZES[i] ){
				
				return( i );
			}
		}
		
		Debug.out( "eh?");
		
		return( 0 );
	}
	
 	protected static class
	sliceBuffer
	{
		private ByteBuffer	buffer;
		private short		alloc_id;
		private short		slice_id;
		
		protected
		sliceBuffer(
			ByteBuffer	_buffer,
			short		_alloc_id,
			short		_slice_id )
		{
			buffer		= _buffer;
			alloc_id	= _alloc_id;
			slice_id	= _slice_id;
		}
		
		protected ByteBuffer
		getBuffer()
		{
			return( buffer );
		}
		
		protected short
		getAllocID()
		{
			return( alloc_id );
		}
		
		protected short
		getSliceID()
		{
			return( slice_id );
		}
	}
	
	protected static class
	sliceDBB
		extends DirectByteBuffer
	{
		private sliceBuffer	slice_buffer;

		protected
		sliceDBB(
			byte		_allocator,
			sliceBuffer	_sb )
		{	
			super( _allocator, _sb.getBuffer(), pool );
	
			slice_buffer	= _sb;
		}
		
		protected sliceBuffer
		getSliceBuffer()
		{
			return( slice_buffer );
		}
	}
	
 	protected static class
	myInteger
  	{
  		int	value;
  	}
}