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.netty5.handler.codec.http2;
16
17 import io.netty5.channel.ChannelHandlerContext;
18 import io.netty5.util.internal.UnstableApi;
19
20 /**
21 * Base interface for all HTTP/2 flow controllers.
22 */
23 @UnstableApi
24 public interface Http2FlowController {
25 /**
26 * Set the {@link ChannelHandlerContext} for which to apply flow control on.
27 * <p>
28 * This <strong>must</strong> be called to properly initialize the {@link Http2FlowController}.
29 * Not calling this is considered a programming error.
30 * @param ctx The {@link ChannelHandlerContext} for which to apply flow control on.
31 * @throws Http2Exception if any protocol-related error occurred.
32 */
33 void channelHandlerContext(ChannelHandlerContext ctx) throws Http2Exception;
34
35 /**
36 * Sets the connection-wide initial flow control window and updates all stream windows (but not the connection
37 * stream window) by the delta.
38 * <p>
39 * Represents the value for
40 * <a href="https://tools.ietf.org/html/rfc7540#section-6.5.2">SETTINGS_INITIAL_WINDOW_SIZE</a>. This method should
41 * only be called by Netty (not users) as a result of a receiving a {@code SETTINGS} frame.
42 *
43 * @param newWindowSize the new initial window size.
44 * @throws Http2Exception thrown if any protocol-related error occurred.
45 */
46 void initialWindowSize(int newWindowSize) throws Http2Exception;
47
48 /**
49 * Gets the connection-wide initial flow control window size that is used as the basis for new stream flow
50 * control windows.
51 * <p>
52 * Represents the value for
53 * <a href="https://tools.ietf.org/html/rfc7540#section-6.5.2">SETTINGS_INITIAL_WINDOW_SIZE</a>. The initial value
54 * returned by this method must be {@link Http2CodecUtil#DEFAULT_WINDOW_SIZE}.
55 */
56 int initialWindowSize();
57
58 /**
59 * Get the portion of the flow control window for the given stream that is currently available for sending/receiving
60 * frames which are subject to flow control. This quantity is measured in number of bytes.
61 */
62 int windowSize(Http2Stream stream);
63
64 /**
65 * Increments the size of the stream's flow control window by the given delta.
66 * <p>
67 * In the case of a {@link Http2RemoteFlowController} this is called upon receipt of a
68 * {@code WINDOW_UPDATE} frame from the remote endpoint to mirror the changes to the window
69 * size.
70 * <p>
71 * For a {@link Http2LocalFlowController} this can be called to request the expansion of the
72 * window size published by this endpoint. It is up to the implementation, however, as to when a
73 * {@code WINDOW_UPDATE} is actually sent.
74 *
75 * @param stream The subject stream. Use {@link Http2Connection#connectionStream()} for
76 * requesting the size of the connection window.
77 * @param delta the change in size of the flow control window.
78 * @throws Http2Exception thrown if a protocol-related error occurred.
79 */
80 void incrementWindowSize(Http2Stream stream, int delta) throws Http2Exception;
81 }