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1   //
2   //  ========================================================================
3   //  Copyright (c) 1995-2016 Mort Bay Consulting Pty. Ltd.
4   //  ------------------------------------------------------------------------
5   //  All rights reserved. This program and the accompanying materials
6   //  are made available under the terms of the Eclipse Public License v1.0
7   //  and Apache License v2.0 which accompanies this distribution.
8   //
9   //      The Eclipse Public License is available at
10  //      http://www.eclipse.org/legal/epl-v10.html
11  //
12  //      The Apache License v2.0 is available at
13  //      http://www.opensource.org/licenses/apache2.0.php
14  //
15  //  You may elect to redistribute this code under either of these licenses.
16  //  ========================================================================
17  //
18  
19  package org.eclipse.jetty.http2.generator;
20  
21  import java.nio.ByteBuffer;
22  
23  import org.eclipse.jetty.http2.Flags;
24  import org.eclipse.jetty.http2.frames.Frame;
25  import org.eclipse.jetty.http2.frames.FrameType;
26  import org.eclipse.jetty.http2.frames.PriorityFrame;
27  import org.eclipse.jetty.io.ByteBufferPool;
28  import org.eclipse.jetty.util.BufferUtil;
29  
30  public class PriorityGenerator extends FrameGenerator
31  {
32      public PriorityGenerator(HeaderGenerator headerGenerator)
33      {
34          super(headerGenerator);
35      }
36  
37      @Override
38      public int generate(ByteBufferPool.Lease lease, Frame frame)
39      {
40          PriorityFrame priorityFrame = (PriorityFrame)frame;
41          return generatePriority(lease, priorityFrame.getStreamId(), priorityFrame.getParentStreamId(), priorityFrame.getWeight(), priorityFrame.isExclusive());
42      }
43  
44      public int generatePriority(ByteBufferPool.Lease lease, int streamId, int parentStreamId, int weight, boolean exclusive)
45      {
46          ByteBuffer header = generateHeader(lease, FrameType.PRIORITY, PriorityFrame.PRIORITY_LENGTH, Flags.NONE, streamId);
47          generatePriorityBody(header, streamId, parentStreamId, weight, exclusive);
48          BufferUtil.flipToFlush(header, 0);
49          lease.append(header, true);
50          return Frame.HEADER_LENGTH + PriorityFrame.PRIORITY_LENGTH;
51      }
52  
53      public void generatePriorityBody(ByteBuffer header, int streamId, int parentStreamId, int weight, boolean exclusive)
54      {
55          if (streamId < 0)
56              throw new IllegalArgumentException("Invalid stream id: " + streamId);
57          if (parentStreamId < 0)
58              throw new IllegalArgumentException("Invalid parent stream id: " + parentStreamId);
59          if (parentStreamId == streamId)
60              throw new IllegalArgumentException("Stream " + streamId + " cannot depend on stream " + parentStreamId);
61          if (weight < 1 || weight > 256)
62              throw new IllegalArgumentException("Invalid weight: " + weight);
63  
64          if (exclusive)
65              parentStreamId |= 0x80_00_00_00;
66          header.putInt(parentStreamId);
67          header.put((byte)(weight - 1));
68      }
69  }