1/*
2 * Copyright (c) 2015, 2016, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.  Oracle designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * by Oracle in the LICENSE file that accompanied this code.
10 *
11 * This code is distributed in the hope that it will be useful, but WITHOUT
12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
14 * version 2 for more details (a copy is included in the LICENSE file that
15 * accompanied this code).
16 *
17 * You should have received a copy of the GNU General Public License version
18 * 2 along with this work; if not, write to the Free Software Foundation,
19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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24 */
25package jdk.incubator.http;
26
27import jdk.incubator.http.internal.frame.SettingsFrame;
28import jdk.incubator.http.internal.frame.WindowUpdateFrame;
29
30import java.util.concurrent.atomic.AtomicInteger;
31
32abstract class WindowUpdateSender {
33
34
35    final int limit;
36    final Http2Connection connection;
37    final AtomicInteger received = new AtomicInteger(0);
38
39    WindowUpdateSender(Http2Connection connection) {
40        this(connection, connection.clientSettings.getParameter(SettingsFrame.INITIAL_WINDOW_SIZE));
41    }
42
43    WindowUpdateSender(Http2Connection connection, int initWindowSize) {
44        this(connection, connection.getMaxReceiveFrameSize(), initWindowSize);
45    }
46
47    WindowUpdateSender(Http2Connection connection, int maxFrameSize, int initWindowSize) {
48        this.connection = connection;
49        int v0 = Math.max(0, initWindowSize - maxFrameSize);
50        int v1 = (initWindowSize + (maxFrameSize - 1)) / maxFrameSize;
51        v1 = v1 * maxFrameSize / 2;
52        // send WindowUpdate heuristic:
53        // - we got data near half of window size
54        //   or
55        // - remaining window size reached max frame size.
56        limit = Math.min(v0, v1);
57    }
58
59    abstract int getStreamId();
60
61    void update(int delta) {
62        if (received.addAndGet(delta) > limit) {
63            synchronized (this) {
64                int tosend = received.get();
65                if( tosend > limit) {
66                    received.getAndAdd(-tosend);
67                    sendWindowUpdate(tosend);
68                }
69            }
70        }
71    }
72
73    void sendWindowUpdate(int delta) {
74        connection.sendUnorderedFrame(new WindowUpdateFrame(getStreamId(), delta));
75    }
76
77
78}
79