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     }
  63 
  64     abstract int getStreamId();
  65 
  66     void update(int delta) {
  67         debug.log(Level.DEBUG, "update: %d", delta);
  68         if (received.addAndGet(delta) > limit) {
  69             synchronized (this) {
  70                 int tosend = received.get();
  71                 if( tosend > limit) {
  72                     received.getAndAdd(-tosend);
  73                     sendWindowUpdate(tosend);
  74                 }
  75             }
  76         }
  77     }
  78 
  79     void sendWindowUpdate(int delta) {
  80         debug.log(Level.DEBUG, "sending window update: %d", delta);
  81         connection.sendUnorderedFrame(new WindowUpdateFrame(getStreamId(), delta));
  82     }
  83 
  84     String dbgString() {
  85         return "WindowUpdateSender(stream: " + getStreamId() + ")";
  86     }
  87 
  88 }