externalseedreaderimpl.java

这是一个基于java编写的torrent的P2P源码

		 */
	
	public int
	readBytes(
		int		max )
	{
			// permission to read a bunch of bytes
		
			// we're out of step here due to multiple threads so we have to report what
			// has already happened and prepare for what will
		
		int	res = 0;
		
		synchronized( rate_sem ){
			
			if ( rate_bytes_read > 0 ){
				
				res = rate_bytes_read;
				
				if ( res > max ){
					
					res = max;
				}
				
				rate_bytes_read -= res;
			}
			
			int	rem = max - res;
			
			if ( rem > rate_bytes_permitted ){
				
				if ( rate_bytes_permitted == 0 ){
					
					rate_sem.release();
				}
				
				rate_bytes_permitted = rem;
			}
		}
		
		return( res );
	}
	
	public int
	getPermittedBytes()
	
		throws ExternalSeedException
	{
		synchronized( rate_sem ){
			
			if ( rate_bytes_permitted > 0 ){
				
				return( rate_bytes_permitted );
			}
		}
		
		if ( !rate_sem.reserve( 1000 )){
			
			return( 1 );	// one byte a sec to check for connection liveness
		}
		
		return( rate_bytes_permitted );
	}
	
	public void
	reportBytesRead(
		int		num )
	{
		synchronized( rate_sem ){
			
			rate_bytes_read += num;
			
			rate_bytes_permitted -= num;
			
			if ( rate_bytes_permitted < 0 ){
				
				rate_bytes_permitted = 0;
			}
		}
	}
	
	public int
	getPercentDoneOfCurrentIncomingRequest()
	{
		ExternalSeedReaderRequest	cr = current_request;
		
		if ( cr == null ){
			
			return( 0 );
		}
		
		return( cr.getPercentDoneOfCurrentIncomingRequest());
	}
	
	public int
	getMaximumNumberOfRequests()
	{
		if ( getRequestCount() == 0 ){
			
			return((int)(( getPieceGroupSize() * torrent.getPieceSize() ) / PeerReadRequest.NORMAL_REQUEST_SIZE ));
			
		}else{
			
			return( 0 );
		}
	}

	public void
	calculatePriorityOffsets(
		PeerManager		peer_manager,
		int[]			base_priorities )
	{
		try{
			Piece[]	pieces = peer_manager.getPieces();
			
			int	piece_group_size = getPieceGroupSize();
			
			int[]	contiguous_best_pieces = new int[piece_group_size];
			int[]	contiguous_highest_pri = new int[piece_group_size];
					
			Arrays.fill( contiguous_highest_pri, -1 );
			
			int	contiguous			= 0;
			int	contiguous_best_pri	= -1;
			
			int	max_contiguous	= 0;
			
			int	max_free_reqs		= 0;
			int max_free_reqs_piece	= -1;
			
			for (int i=0;i<pieces.length;i++){
				
				Piece	piece = pieces[i];
				
				if ( piece.isFullyAllocatable()){
			
					contiguous++;
					
					int	base_pri = base_priorities[i];
					
					if ( base_pri > contiguous_best_pri ){
						
						contiguous_best_pri	= base_pri;
					}
					
					for (int j=0;j<contiguous && j<contiguous_highest_pri.length;j++){
						
						if ( contiguous_best_pri > contiguous_highest_pri[j] ){
							
							contiguous_highest_pri[j]	= contiguous_best_pri;
							contiguous_best_pieces[j]	= i - j;
						}
						
						if ( j+1 > max_contiguous ){
								
							max_contiguous	= j+1;
						}
					}
		
				}else{
					
					contiguous			= 0;
					contiguous_best_pri	= -1;
					
					if ( max_contiguous == 0 ){
						
						int	free_reqs = piece.getAllocatableRequestCount();
						
						if ( free_reqs > max_free_reqs ){
							
							max_free_reqs 		= free_reqs;
							max_free_reqs_piece	= i;
						}
					}
				}
			}
					
			if ( max_contiguous == 0 ){
			
				if ( max_free_reqs_piece >= 0 ){
					
					priority_offsets	 = new int[ (int)getTorrent().getPieceCount()];

					priority_offsets[max_free_reqs_piece] = 10000;
					
				}else{
					
					priority_offsets	= null;
				}
			}else{
				
				priority_offsets	 = new int[ (int)getTorrent().getPieceCount()];
				
				int	start_piece = contiguous_best_pieces[max_contiguous-1];
				
				for (int i=start_piece;i<start_piece+max_contiguous;i++){
								
					priority_offsets[i] = 10000 - (i-start_piece);
				}
			}
		}catch( Throwable e ){
			
			Debug.printStackTrace(e);
			
			priority_offsets	= null;
		}
	}
	
	protected abstract int
	getPieceGroupSize();
	
	protected abstract boolean
	getRequestCanSpanPieces();
	
	public int[]
	getPriorityOffsets()
	{
		return( priority_offsets );
	}
	
	protected int
	selectRequests(
		List	requests )
	{
		long	next_start = -1;
		
		int	last_piece_number = -1;
		
		for (int i=0;i<requests.size();i++){
			
			PeerReadRequest	request = (PeerReadRequest)requests.get(i);
			
			int	this_piece_number	= request.getPieceNumber();
			
			if ( last_piece_number != -1 && last_piece_number != this_piece_number ){
				
				if ( !getRequestCanSpanPieces()){
					
					return( i );
				}
			}
			
			long	this_start = this_piece_number * torrent.getPieceSize() + request.getOffset();
			
			if ( next_start != -1 && this_start != next_start ){
				
				return(i);
			}
			
			next_start	= this_start + request.getLength();
			
			last_piece_number	= this_piece_number;
		}
		
		return( requests.size());
	}

	protected abstract void
	readData(
		ExternalSeedReaderRequest	request )
	
		throws ExternalSeedException;
	
	protected void
	processRequests(
		List		requests )
	{	
		boolean	ok = false;
				
		ExternalSeedReaderRequest	request = new ExternalSeedReaderRequest( this, requests );
		
		active_read_request = request;
		
		try{
			current_request = request;
			
			readData( request );
													
			ok	= true;

		}catch( ExternalSeedException 	e ){
			
			if ( e.isPermanentFailure()){
				
				permanent_fail	= true;
			}
			
			status = "Failed: " + Debug.getNestedExceptionMessage(e);
			
			request.failed();
			
		}catch( Throwable e ){
			
			status = "Failed: " + Debug.getNestedExceptionMessage(e);
				
			request.failed();
			
		}finally{
			
			active_read_request = null;
			
			if ( ok ){
				
				last_failed_read	= 0;
				
				consec_failures		= 0;

			}else{
				last_failed_read	= getSystemTime();
				
				consec_failures++;
			}
		}
	}
	
	public void
	addRequests(
		List	new_requests )
	{
		try{
			requests_mon.enter();
			
			if ( !active ){
				
				Debug.out( "request added when not active!!!!" );
			}
				
			for (int i=0;i<new_requests.size();i++){
			
				requests.add( new_requests.get(i));

				request_sem.release();
			}
						
			if ( request_thread == null ){
				
				plugin.getPluginInterface().getUtilities().createThread(
						"RequestProcessor",
						new Runnable()
						{
							public void
							run()
							{
								processRequests();
							}
						});
			}

		}finally{
			
			requests_mon.exit();
		}
	}
	
	public void
	cancelRequest(
		PeerReadRequest	request )
	{
		try{
			requests_mon.enter();
			
			if ( requests.contains( request ) && !request.isCancelled()){
				
				request.cancel();
			}
			
		}finally{
			
			requests_mon.exit();
		}
	}
	
	public void
	cancelAllRequests()
	{
		try{
			requests_mon.enter();
			
			for (int i=0;i<requests.size();i++){
				
				PeerReadRequest	request = (PeerReadRequest)requests.get(i);
			
				if ( !request.isCancelled()){
	
					request.cancel();
				}
			}	
			
			if ( active_read_request != null ){
				
				active_read_request.cancel();
			}
		}finally{
			
			requests_mon.exit();
		}	
	}
	
	public int
	getRequestCount()
	{
		try{
			requests_mon.enter();

			return( requests.size());
			
		}finally{
			
			requests_mon.exit();
		}	
	}
	
	public List
	getExpiredRequests()
	{
		List	res = null;
		
		try{
			requests_mon.enter();
			
			for (int i=0;i<requests.size();i++){
				
				PeerReadRequest	request = (PeerReadRequest)requests.get(i);
				
				if ( request.isExpired()){
					
					if ( res == null ){
						
						res = new ArrayList();
					}
					
					res.add( request );
				}
			}			
		}finally{
			
			requests_mon.exit();
		}	
		
		return( res );
	}
	
	public List
	getRequests()
	{
		List	res = null;
		
		try{
			requests_mon.enter();
			
			res = new ArrayList( requests );
			
		}finally{
			
			requests_mon.exit();
		}	
		
		return( res );
	}
	
	protected void
	informComplete(
		PeerReadRequest		request,
		byte[]				buffer )
	{
		PooledByteBuffer pool_buffer = plugin.getPluginInterface().getUtilities().allocatePooledByteBuffer( buffer );
		
		for (int i=0;i<listeners.size();i++){
			
			try{
				((ExternalSeedReaderListener)listeners.get(i)).requestComplete( request, pool_buffer );
				
			}catch( Throwable e ){
				
				e.printStackTrace();
			}
		}		
	}
	
	protected void
	informCancelled(
		PeerReadRequest		request )
	{
		for (int i=0;i<listeners.size();i++){
			
			try{
				((ExternalSeedReaderListener)listeners.get(i)).requestCancelled( request );
				
			}catch( Throwable e ){
				
				e.printStackTrace();
			}
		}		
	}
	
	protected void
	informFailed(
		PeerReadRequest	request )
	{
		for (int i=0;i<listeners.size();i++){
			
			try{
				((ExternalSeedReaderListener)listeners.get(i)).requestFailed( request );
				
			}catch( Throwable e ){
				
				e.printStackTrace();
			}
		}
	}
	
	public void
	addListener(
		ExternalSeedReaderListener	l )
	{
		listeners.add( l );
	}
	
	public void
	removeListener(
		ExternalSeedReaderListener	l )
	{
		listeners.remove( l );
	}
	
	protected int
	getIntParam(
		Map			map,
		String		name,
		int			def )
	{
		Object	obj = map.get(name);
		
		if ( obj instanceof Long ){
			
			return(((Long)obj).intValue());
		}
		
		return( def );
	}
	
	protected boolean
	getBooleanParam(
		Map			map,
		String		name,
		boolean		def )
	{
		return( getIntParam( map, name, def?1:0) != 0 );
	}
}