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.
  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 jdk.incubator.http.internal.frame.SettingsFrame;
  28 import jdk.incubator.http.internal.frame.WindowUpdateFrame;
  29 
  30 import java.util.concurrent.atomic.AtomicInteger;
  31 
  32 abstract 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 }