1 /*

     2  * Copyright (c) 2015, 2018, 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 

    26 package jdk.internal.net.http;

    27 

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

    29 import jdk.internal.net.http.frame.SettingsFrame;

    30 import jdk.internal.net.http.frame.WindowUpdateFrame;

    31 import jdk.internal.net.http.common.Utils;

    32 

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

    34 

    35 abstract class WindowUpdateSender {

    36 

    37     final static boolean DEBUG = Utils.DEBUG;

    38     final System.Logger debug =

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

    40 

    41     final int limit;

    42     final Http2Connection connection;

    43     final AtomicInteger received = new AtomicInteger(0);

    44 

    45     WindowUpdateSender(Http2Connection connection) {

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

    47     }

    48 

    49     WindowUpdateSender(Http2Connection connection, int initWindowSize) {

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

    51     }

    52 

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

    54         this.connection = connection;

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

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

    57         v1 = v1 * maxFrameSize / 2;

    58         // send WindowUpdate heuristic:

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

    60         //   or

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

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

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

    64                 maxFrameSize, initWindowSize, limit);

    65     }

    66 

    67     abstract int getStreamId();

    68 

    69     void update(int delta) {

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

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

    72             synchronized (this) {

    73                 int tosend = received.get();

    74                 if( tosend > limit) {

    75                     received.getAndAdd(-tosend);

    76                     sendWindowUpdate(tosend);

    77                 }

    78             }

    79         }

    80     }

    81 

    82     void sendWindowUpdate(int delta) {

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

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

    85     }

    86 

    87     String dbgString() {

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

    89     }

    90 

    91 }