1 //
2 // ========================================================================
3 // Copyright (c) 1995-2013 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.spdy;
20
21 import java.util.concurrent.TimeUnit;
22
23 import org.eclipse.jetty.spdy.api.DataInfo;
24 import org.eclipse.jetty.spdy.api.Stream;
25 import org.eclipse.jetty.spdy.frames.WindowUpdateFrame;
26
27 public class SPDYv3FlowControlStrategy implements FlowControlStrategy
28 {
29 private volatile int windowSize;
30
31 @Override
32 public int getWindowSize(ISession session)
33 {
34 return windowSize;
35 }
36
37 @Override
38 public void setWindowSize(ISession session, int windowSize)
39 {
40 int prevWindowSize = this.windowSize;
41 this.windowSize = windowSize;
42 for (Stream stream : session.getStreams())
43 ((IStream)stream).updateWindowSize(windowSize - prevWindowSize);
44 }
45
46 @Override
47 public void onNewStream(ISession session, IStream stream)
48 {
49 stream.updateWindowSize(windowSize);
50 }
51
52 @Override
53 public void onWindowUpdate(ISession session, IStream stream, int delta)
54 {
55 if (stream != null)
56 stream.updateWindowSize(delta);
57 }
58
59 @Override
60 public void updateWindow(ISession session, IStream stream, int delta)
61 {
62 stream.updateWindowSize(delta);
63 }
64
65 @Override
66 public void onDataReceived(ISession session, IStream stream, DataInfo dataInfo)
67 {
68 // Do nothing
69 }
70
71 @Override
72 public void onDataConsumed(ISession session, IStream stream, DataInfo dataInfo, int delta)
73 {
74 // This is the algorithm for flow control.
75 // This method may be called multiple times with delta=1, but we only send a window
76 // update when the whole dataInfo has been consumed.
77 // Other policies may be to send window updates when consumed() is greater than
78 // a certain threshold, etc. but for now the policy is not pluggable for simplicity.
79 // Note that the frequency of window updates depends on the read buffer, that
80 // should not be too smaller than the window size to avoid frequent window updates.
81 // Therefore, a pluggable policy should be able to modify the read buffer capacity.
82 int length = dataInfo.length();
83 if (dataInfo.consumed() == length && !stream.isClosed() && length > 0)
84 {
85 WindowUpdateFrame windowUpdateFrame = new WindowUpdateFrame(session.getVersion(), stream.getId(), length);
86 session.control(stream, windowUpdateFrame, 0, TimeUnit.MILLISECONDS, null, null);
87 }
88 }
89 }