1 /*
2 * Copyright 2014 The Netty Project
3 *
4 * The Netty Project licenses this file to you under the Apache License, version 2.0 (the
5 * "License"); you may not use this file except in compliance with the License. You may obtain a
6 * copy of the License at:
7 *
8 * https://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software distributed under the License
11 * is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express
12 * or implied. See the License for the specific language governing permissions and limitations under
13 * the License.
14 */
15 package io.netty.handler.codec.http2;
16
17 import io.netty.channel.ChannelHandlerContext;
18
19 /**
20 * Base interface for all HTTP/2 flow controllers.
21 */
22 public interface Http2FlowController {
23 /**
24 * Set the {@link ChannelHandlerContext} for which to apply flow control on.
25 * <p>
26 * This <strong>must</strong> be called to properly initialize the {@link Http2FlowController}.
27 * Not calling this is considered a programming error.
28 * @param ctx The {@link ChannelHandlerContext} for which to apply flow control on.
29 * @throws Http2Exception if any protocol-related error occurred.
30 */
31 void channelHandlerContext(ChannelHandlerContext ctx) throws Http2Exception;
32
33 /**
34 * Sets the connection-wide initial flow control window and updates all stream windows (but not the connection
35 * stream window) by the delta.
36 * <p>
37 * Represents the value for
38 * <a href="https://tools.ietf.org/html/rfc7540#section-6.5.2">SETTINGS_INITIAL_WINDOW_SIZE</a>. This method should
39 * only be called by Netty (not users) as a result of a receiving a {@code SETTINGS} frame.
40 *
41 * @param newWindowSize the new initial window size.
42 * @throws Http2Exception thrown if any protocol-related error occurred.
43 */
44 void initialWindowSize(int newWindowSize) throws Http2Exception;
45
46 /**
47 * Gets the connection-wide initial flow control window size that is used as the basis for new stream flow
48 * control windows.
49 * <p>
50 * Represents the value for
51 * <a href="https://tools.ietf.org/html/rfc7540#section-6.5.2">SETTINGS_INITIAL_WINDOW_SIZE</a>. The initial value
52 * returned by this method must be {@link Http2CodecUtil#DEFAULT_WINDOW_SIZE}.
53 */
54 int initialWindowSize();
55
56 /**
57 * Get the portion of the flow control window for the given stream that is currently available for sending/receiving
58 * frames which are subject to flow control. This quantity is measured in number of bytes.
59 */
60 int windowSize(Http2Stream stream);
61
62 /**
63 * Increments the size of the stream's flow control window by the given delta.
64 * <p>
65 * In the case of a {@link Http2RemoteFlowController} this is called upon receipt of a
66 * {@code WINDOW_UPDATE} frame from the remote endpoint to mirror the changes to the window
67 * size.
68 * <p>
69 * For a {@link Http2LocalFlowController} this can be called to request the expansion of the
70 * window size published by this endpoint. It is up to the implementation, however, as to when a
71 * {@code WINDOW_UPDATE} is actually sent.
72 *
73 * @param stream The subject stream. Use {@link Http2Connection#connectionStream()} for
74 * requesting the size of the connection window.
75 * @param delta the change in size of the flow control window.
76 * @throws Http2Exception thrown if a protocol-related error occurred.
77 */
78 void incrementWindowSize(Http2Stream stream, int delta) throws Http2Exception;
79 }