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.buffer.ByteBuf;
18
19 /**
20 * A {@link Http2FlowController} for controlling the inbound flow of {@code DATA} frames from the remote endpoint.
21 */
22 public interface Http2LocalFlowController extends Http2FlowController {
23 /**
24 * Sets the writer to be use for sending {@code WINDOW_UPDATE} frames. This must be called before any flow
25 * controlled data is received.
26 *
27 * @param frameWriter the HTTP/2 frame writer.
28 */
29 Http2LocalFlowController frameWriter(Http2FrameWriter frameWriter);
30
31 /**
32 * Receives an inbound {@code DATA} frame from the remote endpoint and applies flow control policies to it for both
33 * the {@code stream} as well as the connection. If any flow control policies have been violated, an exception is
34 * raised immediately, otherwise the frame is considered to have "passed" flow control.
35 * <p/>
36 * If {@code stream} is {@code null} or closed, flow control should only be applied to the connection window and the
37 * bytes are immediately consumed.
38 *
39 * @param stream the subject stream for the received frame. The connection stream object must not be used. If {@code
40 * stream} is {@code null} or closed, flow control should only be applied to the connection window and the bytes are
41 * immediately consumed.
42 * @param data payload buffer for the frame.
43 * @param padding additional bytes that should be added to obscure the true content size. Must be between 0 and
44 * 256 (inclusive).
45 * @param endOfStream Indicates whether this is the last frame to be sent from the remote endpoint for this stream.
46 * @throws Http2Exception if any flow control errors are encountered.
47 */
48 void receiveFlowControlledFrame(Http2Stream stream, ByteBuf data, int padding,
49 boolean endOfStream) throws Http2Exception;
50
51 /**
52 * Indicates that the application has consumed a number of bytes for the given stream and is therefore ready to
53 * receive more data from the remote endpoint. The application must consume any bytes that it receives or the flow
54 * control window will collapse. Consuming bytes enables the flow controller to send {@code WINDOW_UPDATE} to
55 * restore a portion of the flow control window for the stream.
56 * <p/>
57 * If {@code stream} is {@code null} or closed (i.e. {@link Http2Stream#state()} method returns {@link
58 * Http2Stream.State#CLOSED}), calling this method has no effect.
59 *
60 * @param stream the stream for which window space should be freed. The connection stream object must not be used.
61 * If {@code stream} is {@code null} or closed (i.e. {@link Http2Stream#state()} method returns {@link
62 * Http2Stream.State#CLOSED}), calling this method has no effect.
63 * @param numBytes the number of bytes to be returned to the flow control window.
64 * @return true if a {@code WINDOW_UPDATE} was sent, false otherwise.
65 * @throws Http2Exception if the number of bytes returned exceeds the {@link #unconsumedBytes(Http2Stream)} for the
66 * stream.
67 */
68 boolean consumeBytes(Http2Stream stream, int numBytes) throws Http2Exception;
69
70 /**
71 * The number of bytes for the given stream that have been received but not yet consumed by the
72 * application.
73 *
74 * @param stream the stream for which window space should be freed.
75 * @return the number of unconsumed bytes for the stream.
76 */
77 int unconsumedBytes(Http2Stream stream);
78
79 /**
80 * Get the initial flow control window size for the given stream. This quantity is measured in number of bytes. Note
81 * the unavailable window portion can be calculated by {@link #initialWindowSize()} - {@link
82 * #windowSize(Http2Stream)}.
83 */
84 int initialWindowSize(Http2Stream stream);
85 }