1 /*

     2  * Copyright (c) 2015, 2017, 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.

    20  *

    21  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

    22  * or visit www.oracle.com if you need additional information or have any

    23  * questions.

    24  */

    25 package jdk.incubator.http;

    26 

    27 import java.lang.System.Logger.Level;

    28 import jdk.incubator.http.internal.frame.SettingsFrame;

    29 import jdk.incubator.http.internal.frame.WindowUpdateFrame;

    30 import jdk.incubator.http.internal.common.Utils;

    31 

    32 import java.util.concurrent.atomic.AtomicInteger;

    33 

    34 abstract class WindowUpdateSender {

    35 

    36     final static boolean DEBUG = Utils.DEBUG;

    37     final System.Logger debug =

    38             Utils.getDebugLogger(this::dbgString, DEBUG);

    39 

    40     final int limit;

    41     final Http2Connection connection;

    42     final AtomicInteger received = new AtomicInteger(0);

    43 

    44     WindowUpdateSender(Http2Connection connection) {

    45         this(connection, connection.clientSettings.getParameter(SettingsFrame.INITIAL_WINDOW_SIZE));

    46     }

    47 

    48     WindowUpdateSender(Http2Connection connection, int initWindowSize) {

    49         this(connection, connection.getMaxReceiveFrameSize(), initWindowSize);

    50     }

    51 

    52     WindowUpdateSender(Http2Connection connection, int maxFrameSize, int initWindowSize) {

    53         this.connection = connection;

    54         int v0 = Math.max(0, initWindowSize - maxFrameSize);

    55         int v1 = (initWindowSize + (maxFrameSize - 1)) / maxFrameSize;

    56         v1 = v1 * maxFrameSize / 2;

    57         // send WindowUpdate heuristic:

    58         // - we got data near half of window size

    59         //   or

    60         // - remaining window size reached max frame size.

    61         limit = Math.min(v0, v1);

    62         debug.log(Level.DEBUG, "maxFrameSize=%d, initWindowSize=%d, limit=%d",

    63                 maxFrameSize, initWindowSize, limit);

    64     }

    65 

    66     abstract int getStreamId();

    67 

    68     void update(int delta) {

    69         debug.log(Level.DEBUG, "update: %d", delta);

    70         if (received.addAndGet(delta) > limit) {

    71             synchronized (this) {

    72                 int tosend = received.get();

    73                 if( tosend > limit) {

    74                     received.getAndAdd(-tosend);

    75                     sendWindowUpdate(tosend);

    76                 }

    77             }

    78         }

    79     }

    80 

    81     void sendWindowUpdate(int delta) {

    82         debug.log(Level.DEBUG, "sending window update: %d", delta);

    83         connection.sendUnorderedFrame(new WindowUpdateFrame(getStreamId(), delta));

    84     }

    85 

    86     String dbgString() {

    87         return "WindowUpdateSender(stream: " + getStreamId() + ")";

    88     }

    89 

    90 }