1 /* |
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2 * Copyright (c) 2017, 2018, Oracle and/or its affiliates. All rights reserved. |
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3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
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4 * |
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5 * This code is free software; you can redistribute it and/or modify it |
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6 * under the terms of the GNU General Public License version 2 only, as |
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7 * published by the Free Software Foundation. Oracle designates this |
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8 * particular file as subject to the "Classpath" exception as provided |
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9 * by Oracle in the LICENSE file that accompanied this code. |
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10 * |
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11 * This code is distributed in the hope that it will be useful, but WITHOUT |
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12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
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13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
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14 * version 2 for more details (a copy is included in the LICENSE file that |
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15 * accompanied this code). |
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16 * |
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17 * You should have received a copy of the GNU General Public License version |
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18 * 2 along with this work; if not, write to the Free Software Foundation, |
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19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
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20 * |
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21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
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22 * or visit www.oracle.com if you need additional information or have any |
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23 * questions. |
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24 */ |
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25 |
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26 package java.net.http.internal; |
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27 |
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28 import java.io.EOFException; |
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29 import java.io.IOException; |
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30 import java.lang.System.Logger.Level; |
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31 import java.nio.ByteBuffer; |
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32 import java.util.List; |
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33 import java.util.Objects; |
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34 import java.util.concurrent.Flow; |
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35 import java.util.concurrent.atomic.AtomicLong; |
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36 import java.util.concurrent.atomic.AtomicReference; |
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37 import java.nio.channels.SelectableChannel; |
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38 import java.nio.channels.SelectionKey; |
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39 import java.nio.channels.SocketChannel; |
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40 import java.util.ArrayList; |
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41 import java.util.function.Consumer; |
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42 import java.util.function.Supplier; |
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43 |
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44 import java.net.http.internal.common.Demand; |
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45 import java.net.http.internal.common.FlowTube; |
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46 import java.net.http.internal.common.SequentialScheduler; |
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47 import java.net.http.internal.common.SequentialScheduler.DeferredCompleter; |
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48 import java.net.http.internal.common.SequentialScheduler.RestartableTask; |
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49 import java.net.http.internal.common.Utils; |
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50 |
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51 /** |
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52 * A SocketTube is a terminal tube plugged directly into the socket. |
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53 * The read subscriber should call {@code subscribe} on the SocketTube before |
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54 * the SocketTube can be subscribed to the write publisher. |
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55 */ |
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56 final class SocketTube implements FlowTube { |
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57 |
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58 static final boolean DEBUG = Utils.DEBUG; // revisit: temporary developer's flag |
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59 final System.Logger debug = Utils.getDebugLogger(this::dbgString, DEBUG); |
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60 static final AtomicLong IDS = new AtomicLong(); |
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61 |
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62 private final HttpClientImpl client; |
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63 private final SocketChannel channel; |
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64 private final Supplier<ByteBuffer> buffersSource; |
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65 private final Object lock = new Object(); |
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66 private final AtomicReference<Throwable> errorRef = new AtomicReference<>(); |
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67 private final InternalReadPublisher readPublisher; |
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68 private final InternalWriteSubscriber writeSubscriber; |
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69 private final long id = IDS.incrementAndGet(); |
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70 |
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71 public SocketTube(HttpClientImpl client, SocketChannel channel, |
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72 Supplier<ByteBuffer> buffersSource) { |
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73 this.client = client; |
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74 this.channel = channel; |
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75 this.buffersSource = buffersSource; |
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76 this.readPublisher = new InternalReadPublisher(); |
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77 this.writeSubscriber = new InternalWriteSubscriber(); |
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78 } |
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79 |
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80 // private static Flow.Subscription nopSubscription() { |
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81 // return new Flow.Subscription() { |
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82 // @Override public void request(long n) { } |
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83 // @Override public void cancel() { } |
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84 // }; |
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85 // } |
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86 |
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87 /** |
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88 * Returns {@code true} if this flow is finished. |
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89 * This happens when this flow internal read subscription is completed, |
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90 * either normally (EOF reading) or exceptionally (EOF writing, or |
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91 * underlying socket closed, or some exception occurred while reading or |
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92 * writing to the socket). |
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93 * |
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94 * @return {@code true} if this flow is finished. |
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95 */ |
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96 public boolean isFinished() { |
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97 InternalReadPublisher.InternalReadSubscription subscription = |
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98 readPublisher.subscriptionImpl; |
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99 return subscription != null && subscription.completed |
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100 || subscription == null && errorRef.get() != null; |
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101 } |
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102 |
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103 // ===================================================================== // |
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104 // Flow.Publisher // |
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105 // ======================================================================// |
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106 |
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107 /** |
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108 * {@inheritDoc } |
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109 * @apiNote This method should be called first. In particular, the caller |
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110 * must ensure that this method must be called by the read |
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111 * subscriber before the write publisher can call {@code onSubscribe}. |
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112 * Failure to adhere to this contract may result in assertion errors. |
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113 */ |
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114 @Override |
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115 public void subscribe(Flow.Subscriber<? super List<ByteBuffer>> s) { |
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116 Objects.requireNonNull(s); |
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117 assert s instanceof TubeSubscriber : "Expected TubeSubscriber, got:" + s; |
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118 readPublisher.subscribe(s); |
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119 } |
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120 |
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121 |
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122 // ===================================================================== // |
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123 // Flow.Subscriber // |
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124 // ======================================================================// |
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125 |
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126 /** |
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127 * {@inheritDoc } |
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128 * @apiNote The caller must ensure that {@code subscribe} is called by |
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129 * the read subscriber before {@code onSubscribe} is called by |
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130 * the write publisher. |
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131 * Failure to adhere to this contract may result in assertion errors. |
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132 */ |
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133 @Override |
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134 public void onSubscribe(Flow.Subscription subscription) { |
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135 writeSubscriber.onSubscribe(subscription); |
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136 } |
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137 |
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138 @Override |
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139 public void onNext(List<ByteBuffer> item) { |
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140 writeSubscriber.onNext(item); |
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141 } |
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142 |
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143 @Override |
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144 public void onError(Throwable throwable) { |
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145 writeSubscriber.onError(throwable); |
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146 } |
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147 |
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148 @Override |
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149 public void onComplete() { |
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150 writeSubscriber.onComplete(); |
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151 } |
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152 |
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153 // ===================================================================== // |
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154 // Events // |
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155 // ======================================================================// |
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156 |
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157 /** |
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158 * A restartable task used to process tasks in sequence. |
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159 */ |
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160 private static class SocketFlowTask implements RestartableTask { |
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161 final Runnable task; |
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162 private final Object monitor = new Object(); |
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163 SocketFlowTask(Runnable task) { |
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164 this.task = task; |
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165 } |
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166 @Override |
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167 public final void run(DeferredCompleter taskCompleter) { |
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168 try { |
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169 // non contentious synchronized for visibility. |
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170 synchronized(monitor) { |
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171 task.run(); |
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172 } |
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173 } finally { |
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174 taskCompleter.complete(); |
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175 } |
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176 } |
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177 } |
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178 |
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179 // This is best effort - there's no guarantee that the printed set |
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180 // of values is consistent. It should only be considered as |
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181 // weakly accurate - in particular in what concerns the events states, |
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182 // especially when displaying a read event state from a write event |
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183 // callback and conversely. |
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184 void debugState(String when) { |
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185 if (debug.isLoggable(Level.DEBUG)) { |
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186 StringBuilder state = new StringBuilder(); |
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187 |
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188 InternalReadPublisher.InternalReadSubscription sub = |
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189 readPublisher.subscriptionImpl; |
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190 InternalReadPublisher.ReadEvent readEvent = |
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191 sub == null ? null : sub.readEvent; |
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192 Demand rdemand = sub == null ? null : sub.demand; |
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193 InternalWriteSubscriber.WriteEvent writeEvent = |
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194 writeSubscriber.writeEvent; |
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195 AtomicLong wdemand = writeSubscriber.writeDemand; |
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196 int rops = readEvent == null ? 0 : readEvent.interestOps(); |
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197 long rd = rdemand == null ? 0 : rdemand.get(); |
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198 int wops = writeEvent == null ? 0 : writeEvent.interestOps(); |
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199 long wd = wdemand == null ? 0 : wdemand.get(); |
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200 |
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201 state.append(when).append(" Reading: [ops=") |
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202 .append(rops).append(", demand=").append(rd) |
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203 .append(", stopped=") |
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204 .append((sub == null ? false : sub.readScheduler.isStopped())) |
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205 .append("], Writing: [ops=").append(wops) |
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206 .append(", demand=").append(wd) |
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207 .append("]"); |
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208 debug.log(Level.DEBUG, state.toString()); |
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209 } |
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210 } |
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211 |
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212 /** |
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213 * A repeatable event that can be paused or resumed by changing |
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214 * its interestOps. |
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215 * When the event is fired, it is first paused before being signaled. |
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216 * It is the responsibility of the code triggered by {@code signalEvent} |
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217 * to resume the event if required. |
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218 */ |
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219 private static abstract class SocketFlowEvent extends AsyncEvent { |
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220 final SocketChannel channel; |
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221 final int defaultInterest; |
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222 volatile int interestOps; |
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223 volatile boolean registered; |
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224 SocketFlowEvent(int defaultInterest, SocketChannel channel) { |
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225 super(AsyncEvent.REPEATING); |
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226 this.defaultInterest = defaultInterest; |
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227 this.channel = channel; |
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228 } |
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229 final boolean registered() {return registered;} |
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230 final void resume() { |
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231 interestOps = defaultInterest; |
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232 registered = true; |
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233 } |
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234 final void pause() {interestOps = 0;} |
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235 @Override |
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236 public final SelectableChannel channel() {return channel;} |
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237 @Override |
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238 public final int interestOps() {return interestOps;} |
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239 |
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240 @Override |
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241 public final void handle() { |
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242 pause(); // pause, then signal |
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243 signalEvent(); // won't be fired again until resumed. |
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244 } |
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245 @Override |
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246 public final void abort(IOException error) { |
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247 debug().log(Level.DEBUG, () -> "abort: " + error); |
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248 pause(); // pause, then signal |
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249 signalError(error); // should not be resumed after abort (not checked) |
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250 } |
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251 |
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252 protected abstract void signalEvent(); |
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253 protected abstract void signalError(Throwable error); |
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254 abstract System.Logger debug(); |
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255 } |
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256 |
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257 // ===================================================================== // |
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258 // Writing // |
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259 // ======================================================================// |
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260 |
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261 // This class makes the assumption that the publisher will call |
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262 // onNext sequentially, and that onNext won't be called if the demand |
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263 // has not been incremented by request(1). |
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264 // It has a 'queue of 1' meaning that it will call request(1) in |
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265 // onSubscribe, and then only after its 'current' buffer list has been |
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266 // fully written and current set to null; |
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267 private final class InternalWriteSubscriber |
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268 implements Flow.Subscriber<List<ByteBuffer>> { |
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269 |
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270 volatile Flow.Subscription subscription; |
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271 volatile List<ByteBuffer> current; |
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272 volatile boolean completed; |
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273 final WriteEvent writeEvent = new WriteEvent(channel, this); |
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274 final AtomicLong writeDemand = new AtomicLong(); |
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275 |
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276 @Override |
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277 public void onSubscribe(Flow.Subscription subscription) { |
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278 Flow.Subscription previous = this.subscription; |
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279 this.subscription = subscription; |
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280 debug.log(Level.DEBUG, "subscribed for writing"); |
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281 if (current == null) { |
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282 if (previous == subscription || previous == null) { |
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283 if (writeDemand.compareAndSet(0, 1)) { |
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284 subscription.request(1); |
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285 } |
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286 } else { |
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287 writeDemand.set(1); |
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288 subscription.request(1); |
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289 } |
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290 } |
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291 } |
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292 |
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293 @Override |
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294 public void onNext(List<ByteBuffer> bufs) { |
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295 assert current == null; // this is a queue of 1. |
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296 assert subscription != null; |
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297 current = bufs; |
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298 tryFlushCurrent(client.isSelectorThread()); // may be in selector thread |
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299 // For instance in HTTP/2, a received SETTINGS frame might trigger |
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300 // the sending of a SETTINGS frame in turn which might cause |
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301 // onNext to be called from within the same selector thread that the |
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302 // original SETTINGS frames arrived on. If rs is the read-subscriber |
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303 // and ws is the write-subscriber then the following can occur: |
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304 // ReadEvent -> rs.onNext(bytes) -> process server SETTINGS -> write |
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305 // client SETTINGS -> ws.onNext(bytes) -> tryFlushCurrent |
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306 debugState("leaving w.onNext"); |
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307 } |
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308 |
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309 // we don't use a SequentialScheduler here: we rely on |
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310 // onNext() being called sequentially, and not being called |
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311 // if we haven't call request(1) |
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312 // onNext is usually called from within a user/executor thread. |
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313 // we will perform the initial writing in that thread. |
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314 // if for some reason, not all data can be written, the writeEvent |
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315 // will be resumed, and the rest of the data will be written from |
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316 // the selector manager thread when the writeEvent is fired. |
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317 // If we are in the selector manager thread, then we will use the executor |
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318 // to call request(1), ensuring that onNext() won't be called from |
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319 // within the selector thread. |
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320 // If we are not in the selector manager thread, then we don't care. |
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321 void tryFlushCurrent(boolean inSelectorThread) { |
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322 List<ByteBuffer> bufs = current; |
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323 if (bufs == null) return; |
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324 try { |
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325 assert inSelectorThread == client.isSelectorThread() : |
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326 "should " + (inSelectorThread ? "" : "not ") |
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327 + " be in the selector thread"; |
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328 long remaining = Utils.remaining(bufs); |
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329 debug.log(Level.DEBUG, "trying to write: %d", remaining); |
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330 long written = writeAvailable(bufs); |
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331 debug.log(Level.DEBUG, "wrote: %d", remaining); |
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332 if (written == -1) { |
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333 signalError(new EOFException("EOF reached while writing")); |
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334 return; |
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335 } |
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336 assert written <= remaining; |
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337 if (remaining - written == 0) { |
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338 current = null; |
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339 writeDemand.decrementAndGet(); |
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340 Runnable requestMore = this::requestMore; |
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341 if (inSelectorThread) { |
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342 assert client.isSelectorThread(); |
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343 client.theExecutor().execute(requestMore); |
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344 } else { |
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345 assert !client.isSelectorThread(); |
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346 requestMore.run(); |
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347 } |
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348 } else { |
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349 resumeWriteEvent(inSelectorThread); |
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350 } |
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351 } catch (Throwable t) { |
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352 signalError(t); |
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353 subscription.cancel(); |
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354 } |
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355 } |
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356 |
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357 void requestMore() { |
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358 try { |
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359 if (completed) return; |
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360 long d = writeDemand.get(); |
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361 if (writeDemand.compareAndSet(0,1)) { |
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362 debug.log(Level.DEBUG, "write: requesting more..."); |
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363 subscription.request(1); |
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364 } else { |
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365 debug.log(Level.DEBUG, "write: no need to request more: %d", d); |
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366 } |
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367 } catch (Throwable t) { |
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368 debug.log(Level.DEBUG, () -> |
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369 "write: error while requesting more: " + t); |
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370 signalError(t); |
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371 subscription.cancel(); |
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372 } finally { |
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373 debugState("leaving requestMore: "); |
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374 } |
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375 } |
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376 |
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377 @Override |
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378 public void onError(Throwable throwable) { |
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379 signalError(throwable); |
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380 } |
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381 |
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382 @Override |
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383 public void onComplete() { |
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384 completed = true; |
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385 // no need to pause the write event here: the write event will |
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386 // be paused if there is nothing more to write. |
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387 List<ByteBuffer> bufs = current; |
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388 long remaining = bufs == null ? 0 : Utils.remaining(bufs); |
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389 debug.log(Level.DEBUG, "write completed, %d yet to send", remaining); |
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390 debugState("InternalWriteSubscriber::onComplete"); |
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391 } |
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392 |
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393 void resumeWriteEvent(boolean inSelectorThread) { |
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394 debug.log(Level.DEBUG, "scheduling write event"); |
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395 resumeEvent(writeEvent, this::signalError); |
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396 } |
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397 |
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398 // void pauseWriteEvent() { |
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399 // debug.log(Level.DEBUG, "pausing write event"); |
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400 // pauseEvent(writeEvent, this::signalError); |
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401 // } |
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402 |
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403 void signalWritable() { |
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404 debug.log(Level.DEBUG, "channel is writable"); |
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405 tryFlushCurrent(true); |
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406 } |
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407 |
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408 void signalError(Throwable error) { |
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409 debug.log(Level.DEBUG, () -> "write error: " + error); |
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410 completed = true; |
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411 readPublisher.signalError(error); |
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412 } |
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413 |
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414 // A repeatable WriteEvent which is paused after firing and can |
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415 // be resumed if required - see SocketFlowEvent; |
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416 final class WriteEvent extends SocketFlowEvent { |
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417 final InternalWriteSubscriber sub; |
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418 WriteEvent(SocketChannel channel, InternalWriteSubscriber sub) { |
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419 super(SelectionKey.OP_WRITE, channel); |
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420 this.sub = sub; |
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421 } |
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422 @Override |
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423 protected final void signalEvent() { |
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424 try { |
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425 client.eventUpdated(this); |
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426 sub.signalWritable(); |
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427 } catch(Throwable t) { |
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428 sub.signalError(t); |
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429 } |
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430 } |
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431 |
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432 @Override |
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433 protected void signalError(Throwable error) { |
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434 sub.signalError(error); |
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435 } |
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436 |
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437 @Override |
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438 System.Logger debug() { |
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439 return debug; |
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440 } |
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441 |
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442 } |
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443 |
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444 } |
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445 |
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446 // ===================================================================== // |
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447 // Reading // |
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448 // ===================================================================== // |
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449 |
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450 // The InternalReadPublisher uses a SequentialScheduler to ensure that |
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451 // onNext/onError/onComplete are called sequentially on the caller's |
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452 // subscriber. |
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453 // However, it relies on the fact that the only time where |
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454 // runOrSchedule() is called from a user/executor thread is in signalError, |
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455 // right after the errorRef has been set. |
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456 // Because the sequential scheduler's task always checks for errors first, |
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457 // and always terminate the scheduler on error, then it is safe to assume |
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458 // that if it reaches the point where it reads from the channel, then |
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459 // it is running in the SelectorManager thread. This is because all |
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460 // other invocation of runOrSchedule() are triggered from within a |
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461 // ReadEvent. |
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462 // |
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463 // When pausing/resuming the event, some shortcuts can then be taken |
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464 // when we know we're running in the selector manager thread |
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465 // (in that case there's no need to call client.eventUpdated(readEvent); |
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466 // |
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467 private final class InternalReadPublisher |
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468 implements Flow.Publisher<List<ByteBuffer>> { |
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469 private final InternalReadSubscription subscriptionImpl |
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470 = new InternalReadSubscription(); |
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471 AtomicReference<ReadSubscription> pendingSubscription = new AtomicReference<>(); |
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472 private volatile ReadSubscription subscription; |
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473 |
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474 @Override |
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475 public void subscribe(Flow.Subscriber<? super List<ByteBuffer>> s) { |
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476 Objects.requireNonNull(s); |
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477 |
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478 TubeSubscriber sub = FlowTube.asTubeSubscriber(s); |
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479 ReadSubscription target = new ReadSubscription(subscriptionImpl, sub); |
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480 ReadSubscription previous = pendingSubscription.getAndSet(target); |
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481 |
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482 if (previous != null && previous != target) { |
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483 debug.log(Level.DEBUG, |
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484 () -> "read publisher: dropping pending subscriber: " |
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485 + previous.subscriber); |
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486 previous.errorRef.compareAndSet(null, errorRef.get()); |
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487 previous.signalOnSubscribe(); |
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488 if (subscriptionImpl.completed) { |
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489 previous.signalCompletion(); |
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490 } else { |
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491 previous.subscriber.dropSubscription(); |
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492 } |
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493 } |
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494 |
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495 debug.log(Level.DEBUG, "read publisher got subscriber"); |
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496 subscriptionImpl.signalSubscribe(); |
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497 debugState("leaving read.subscribe: "); |
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498 } |
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499 |
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500 void signalError(Throwable error) { |
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501 if (!errorRef.compareAndSet(null, error)) { |
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502 return; |
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503 } |
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504 subscriptionImpl.handleError(); |
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505 } |
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506 |
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507 final class ReadSubscription implements Flow.Subscription { |
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508 final InternalReadSubscription impl; |
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509 final TubeSubscriber subscriber; |
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510 final AtomicReference<Throwable> errorRef = new AtomicReference<>(); |
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511 volatile boolean subscribed; |
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512 volatile boolean cancelled; |
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513 volatile boolean completed; |
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514 |
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515 public ReadSubscription(InternalReadSubscription impl, |
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516 TubeSubscriber subscriber) { |
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517 this.impl = impl; |
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518 this.subscriber = subscriber; |
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519 } |
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520 |
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521 @Override |
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522 public void cancel() { |
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523 cancelled = true; |
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524 } |
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525 |
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526 @Override |
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527 public void request(long n) { |
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528 if (!cancelled) { |
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529 impl.request(n); |
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530 } else { |
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531 debug.log(Level.DEBUG, |
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532 "subscription cancelled, ignoring request %d", n); |
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533 } |
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534 } |
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535 |
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536 void signalCompletion() { |
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537 assert subscribed || cancelled; |
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538 if (completed || cancelled) return; |
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539 synchronized (this) { |
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540 if (completed) return; |
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541 completed = true; |
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542 } |
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543 Throwable error = errorRef.get(); |
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544 if (error != null) { |
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545 debug.log(Level.DEBUG, () -> |
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546 "forwarding error to subscriber: " |
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547 + error); |
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548 subscriber.onError(error); |
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549 } else { |
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550 debug.log(Level.DEBUG, "completing subscriber"); |
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551 subscriber.onComplete(); |
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552 } |
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553 } |
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554 |
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555 void signalOnSubscribe() { |
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556 if (subscribed || cancelled) return; |
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557 synchronized (this) { |
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558 if (subscribed || cancelled) return; |
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559 subscribed = true; |
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560 } |
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561 subscriber.onSubscribe(this); |
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562 debug.log(Level.DEBUG, "onSubscribe called"); |
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563 if (errorRef.get() != null) { |
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564 signalCompletion(); |
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565 } |
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566 } |
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567 } |
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568 |
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569 final class InternalReadSubscription implements Flow.Subscription { |
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570 |
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571 private final Demand demand = new Demand(); |
|
572 final SequentialScheduler readScheduler; |
|
573 private volatile boolean completed; |
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574 private final ReadEvent readEvent; |
|
575 private final AsyncEvent subscribeEvent; |
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576 |
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577 InternalReadSubscription() { |
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578 readScheduler = new SequentialScheduler(new SocketFlowTask(this::read)); |
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579 subscribeEvent = new AsyncTriggerEvent(this::signalError, |
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580 this::handleSubscribeEvent); |
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581 readEvent = new ReadEvent(channel, this); |
|
582 } |
|
583 |
|
584 /* |
|
585 * This method must be invoked before any other method of this class. |
|
586 */ |
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587 final void signalSubscribe() { |
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588 if (readScheduler.isStopped() || completed) { |
|
589 // if already completed or stopped we can handle any |
|
590 // pending connection directly from here. |
|
591 debug.log(Level.DEBUG, |
|
592 "handling pending subscription while completed"); |
|
593 handlePending(); |
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594 } else { |
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595 try { |
|
596 debug.log(Level.DEBUG, |
|
597 "registering subscribe event"); |
|
598 client.registerEvent(subscribeEvent); |
|
599 } catch (Throwable t) { |
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600 signalError(t); |
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601 handlePending(); |
|
602 } |
|
603 } |
|
604 } |
|
605 |
|
606 final void handleSubscribeEvent() { |
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607 assert client.isSelectorThread(); |
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608 debug.log(Level.DEBUG, "subscribe event raised"); |
|
609 readScheduler.runOrSchedule(); |
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610 if (readScheduler.isStopped() || completed) { |
|
611 // if already completed or stopped we can handle any |
|
612 // pending connection directly from here. |
|
613 debug.log(Level.DEBUG, |
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614 "handling pending subscription when completed"); |
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615 handlePending(); |
|
616 } |
|
617 } |
|
618 |
|
619 |
|
620 /* |
|
621 * Although this method is thread-safe, the Reactive-Streams spec seems |
|
622 * to not require it to be as such. It's a responsibility of the |
|
623 * subscriber to signal demand in a thread-safe manner. |
|
624 * |
|
625 * https://github.com/reactive-streams/reactive-streams-jvm/blob/dd24d2ab164d7de6c316f6d15546f957bec29eaa/README.md |
|
626 * (rules 2.7 and 3.4) |
|
627 */ |
|
628 @Override |
|
629 public final void request(long n) { |
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630 if (n > 0L) { |
|
631 boolean wasFulfilled = demand.increase(n); |
|
632 if (wasFulfilled) { |
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633 debug.log(Level.DEBUG, "got some demand for reading"); |
|
634 resumeReadEvent(); |
|
635 // if demand has been changed from fulfilled |
|
636 // to unfulfilled register read event; |
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637 } |
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638 } else { |
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639 signalError(new IllegalArgumentException("non-positive request")); |
|
640 } |
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641 debugState("leaving request("+n+"): "); |
|
642 } |
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643 |
|
644 @Override |
|
645 public final void cancel() { |
|
646 pauseReadEvent(); |
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647 readScheduler.stop(); |
|
648 } |
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649 |
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650 private void resumeReadEvent() { |
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651 debug.log(Level.DEBUG, "resuming read event"); |
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652 resumeEvent(readEvent, this::signalError); |
|
653 } |
|
654 |
|
655 private void pauseReadEvent() { |
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656 debug.log(Level.DEBUG, "pausing read event"); |
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657 pauseEvent(readEvent, this::signalError); |
|
658 } |
|
659 |
|
660 |
|
661 final void handleError() { |
|
662 assert errorRef.get() != null; |
|
663 readScheduler.runOrSchedule(); |
|
664 } |
|
665 |
|
666 final void signalError(Throwable error) { |
|
667 if (!errorRef.compareAndSet(null, error)) { |
|
668 return; |
|
669 } |
|
670 debug.log(Level.DEBUG, () -> "got read error: " + error); |
|
671 readScheduler.runOrSchedule(); |
|
672 } |
|
673 |
|
674 final void signalReadable() { |
|
675 readScheduler.runOrSchedule(); |
|
676 } |
|
677 |
|
678 /** The body of the task that runs in SequentialScheduler. */ |
|
679 final void read() { |
|
680 // It is important to only call pauseReadEvent() when stopping |
|
681 // the scheduler. The event is automatically paused before |
|
682 // firing, and trying to pause it again could cause a race |
|
683 // condition between this loop, which calls tryDecrementDemand(), |
|
684 // and the thread that calls request(n), which will try to resume |
|
685 // reading. |
|
686 try { |
|
687 while(!readScheduler.isStopped()) { |
|
688 if (completed) return; |
|
689 |
|
690 // make sure we have a subscriber |
|
691 if (handlePending()) { |
|
692 debug.log(Level.DEBUG, "pending subscriber subscribed"); |
|
693 return; |
|
694 } |
|
695 |
|
696 // If an error was signaled, we might not be in the |
|
697 // the selector thread, and that is OK, because we |
|
698 // will just call onError and return. |
|
699 ReadSubscription current = subscription; |
|
700 TubeSubscriber subscriber = current.subscriber; |
|
701 Throwable error = errorRef.get(); |
|
702 if (error != null) { |
|
703 completed = true; |
|
704 // safe to pause here because we're finished anyway. |
|
705 pauseReadEvent(); |
|
706 debug.log(Level.DEBUG, () -> "Sending error " + error |
|
707 + " to subscriber " + subscriber); |
|
708 current.errorRef.compareAndSet(null, error); |
|
709 current.signalCompletion(); |
|
710 readScheduler.stop(); |
|
711 debugState("leaving read() loop with error: "); |
|
712 return; |
|
713 } |
|
714 |
|
715 // If we reach here then we must be in the selector thread. |
|
716 assert client.isSelectorThread(); |
|
717 if (demand.tryDecrement()) { |
|
718 // we have demand. |
|
719 try { |
|
720 List<ByteBuffer> bytes = readAvailable(); |
|
721 if (bytes == EOF) { |
|
722 if (!completed) { |
|
723 debug.log(Level.DEBUG, "got read EOF"); |
|
724 completed = true; |
|
725 // safe to pause here because we're finished |
|
726 // anyway. |
|
727 pauseReadEvent(); |
|
728 current.signalCompletion(); |
|
729 readScheduler.stop(); |
|
730 } |
|
731 debugState("leaving read() loop after EOF: "); |
|
732 return; |
|
733 } else if (Utils.remaining(bytes) > 0) { |
|
734 // the subscriber is responsible for offloading |
|
735 // to another thread if needed. |
|
736 debug.log(Level.DEBUG, () -> "read bytes: " |
|
737 + Utils.remaining(bytes)); |
|
738 assert !current.completed; |
|
739 subscriber.onNext(bytes); |
|
740 // we could continue looping until the demand |
|
741 // reaches 0. However, that would risk starving |
|
742 // other connections (bound to other socket |
|
743 // channels) - as other selected keys activated |
|
744 // by the selector manager thread might be |
|
745 // waiting for this event to terminate. |
|
746 // So resume the read event and return now... |
|
747 resumeReadEvent(); |
|
748 debugState("leaving read() loop after onNext: "); |
|
749 return; |
|
750 } else { |
|
751 // nothing available! |
|
752 debug.log(Level.DEBUG, "no more bytes available"); |
|
753 // re-increment the demand and resume the read |
|
754 // event. This ensures that this loop is |
|
755 // executed again when the socket becomes |
|
756 // readable again. |
|
757 demand.increase(1); |
|
758 resumeReadEvent(); |
|
759 debugState("leaving read() loop with no bytes"); |
|
760 return; |
|
761 } |
|
762 } catch (Throwable x) { |
|
763 signalError(x); |
|
764 continue; |
|
765 } |
|
766 } else { |
|
767 debug.log(Level.DEBUG, "no more demand for reading"); |
|
768 // the event is paused just after firing, so it should |
|
769 // still be paused here, unless the demand was just |
|
770 // incremented from 0 to n, in which case, the |
|
771 // event will be resumed, causing this loop to be |
|
772 // invoked again when the socket becomes readable: |
|
773 // This is what we want. |
|
774 // Trying to pause the event here would actually |
|
775 // introduce a race condition between this loop and |
|
776 // request(n). |
|
777 debugState("leaving read() loop with no demand"); |
|
778 break; |
|
779 } |
|
780 } |
|
781 } catch (Throwable t) { |
|
782 debug.log(Level.DEBUG, "Unexpected exception in read loop", t); |
|
783 signalError(t); |
|
784 } finally { |
|
785 handlePending(); |
|
786 } |
|
787 } |
|
788 |
|
789 boolean handlePending() { |
|
790 ReadSubscription pending = pendingSubscription.getAndSet(null); |
|
791 if (pending == null) return false; |
|
792 debug.log(Level.DEBUG, "handling pending subscription for %s", |
|
793 pending.subscriber); |
|
794 ReadSubscription current = subscription; |
|
795 if (current != null && current != pending && !completed) { |
|
796 current.subscriber.dropSubscription(); |
|
797 } |
|
798 debug.log(Level.DEBUG, "read demand reset to 0"); |
|
799 subscriptionImpl.demand.reset(); // subscriber will increase demand if it needs to. |
|
800 pending.errorRef.compareAndSet(null, errorRef.get()); |
|
801 if (!readScheduler.isStopped()) { |
|
802 subscription = pending; |
|
803 } else { |
|
804 debug.log(Level.DEBUG, "socket tube is already stopped"); |
|
805 } |
|
806 debug.log(Level.DEBUG, "calling onSubscribe"); |
|
807 pending.signalOnSubscribe(); |
|
808 if (completed) { |
|
809 pending.errorRef.compareAndSet(null, errorRef.get()); |
|
810 pending.signalCompletion(); |
|
811 } |
|
812 return true; |
|
813 } |
|
814 } |
|
815 |
|
816 |
|
817 // A repeatable ReadEvent which is paused after firing and can |
|
818 // be resumed if required - see SocketFlowEvent; |
|
819 final class ReadEvent extends SocketFlowEvent { |
|
820 final InternalReadSubscription sub; |
|
821 ReadEvent(SocketChannel channel, InternalReadSubscription sub) { |
|
822 super(SelectionKey.OP_READ, channel); |
|
823 this.sub = sub; |
|
824 } |
|
825 @Override |
|
826 protected final void signalEvent() { |
|
827 try { |
|
828 client.eventUpdated(this); |
|
829 sub.signalReadable(); |
|
830 } catch(Throwable t) { |
|
831 sub.signalError(t); |
|
832 } |
|
833 } |
|
834 |
|
835 @Override |
|
836 protected final void signalError(Throwable error) { |
|
837 sub.signalError(error); |
|
838 } |
|
839 |
|
840 @Override |
|
841 System.Logger debug() { |
|
842 return debug; |
|
843 } |
|
844 } |
|
845 |
|
846 } |
|
847 |
|
848 // ===================================================================== // |
|
849 // Socket Channel Read/Write // |
|
850 // ===================================================================== // |
|
851 static final int MAX_BUFFERS = 3; |
|
852 static final List<ByteBuffer> EOF = List.of(); |
|
853 |
|
854 private List<ByteBuffer> readAvailable() throws IOException { |
|
855 ByteBuffer buf = buffersSource.get(); |
|
856 assert buf.hasRemaining(); |
|
857 |
|
858 int read; |
|
859 int pos = buf.position(); |
|
860 List<ByteBuffer> list = null; |
|
861 while (buf.hasRemaining()) { |
|
862 while ((read = channel.read(buf)) > 0) { |
|
863 if (!buf.hasRemaining()) break; |
|
864 } |
|
865 |
|
866 // nothing read; |
|
867 if (buf.position() == pos) { |
|
868 // An empty list signal the end of data, and should only be |
|
869 // returned if read == -1. |
|
870 // If we already read some data, then we must return what we have |
|
871 // read, and -1 will be returned next time the caller attempts to |
|
872 // read something. |
|
873 if (list == null && read == -1) { // eof |
|
874 list = EOF; |
|
875 break; |
|
876 } |
|
877 } |
|
878 buf.limit(buf.position()); |
|
879 buf.position(pos); |
|
880 if (list == null) { |
|
881 list = List.of(buf); |
|
882 } else { |
|
883 if (!(list instanceof ArrayList)) { |
|
884 list = new ArrayList<>(list); |
|
885 } |
|
886 list.add(buf); |
|
887 } |
|
888 if (read <= 0 || list.size() == MAX_BUFFERS) break; |
|
889 buf = buffersSource.get(); |
|
890 pos = buf.position(); |
|
891 assert buf.hasRemaining(); |
|
892 } |
|
893 return list; |
|
894 } |
|
895 |
|
896 private long writeAvailable(List<ByteBuffer> bytes) throws IOException { |
|
897 ByteBuffer[] srcs = bytes.toArray(Utils.EMPTY_BB_ARRAY); |
|
898 final long remaining = Utils.remaining(srcs); |
|
899 long written = 0; |
|
900 while (remaining > written) { |
|
901 long w = channel.write(srcs); |
|
902 if (w == -1 && written == 0) return -1; |
|
903 if (w == 0) break; |
|
904 written += w; |
|
905 } |
|
906 return written; |
|
907 } |
|
908 |
|
909 private void resumeEvent(SocketFlowEvent event, |
|
910 Consumer<Throwable> errorSignaler) { |
|
911 boolean registrationRequired; |
|
912 synchronized(lock) { |
|
913 registrationRequired = !event.registered(); |
|
914 event.resume(); |
|
915 } |
|
916 try { |
|
917 if (registrationRequired) { |
|
918 client.registerEvent(event); |
|
919 } else { |
|
920 client.eventUpdated(event); |
|
921 } |
|
922 } catch(Throwable t) { |
|
923 errorSignaler.accept(t); |
|
924 } |
|
925 } |
|
926 |
|
927 private void pauseEvent(SocketFlowEvent event, |
|
928 Consumer<Throwable> errorSignaler) { |
|
929 synchronized(lock) { |
|
930 event.pause(); |
|
931 } |
|
932 try { |
|
933 client.eventUpdated(event); |
|
934 } catch(Throwable t) { |
|
935 errorSignaler.accept(t); |
|
936 } |
|
937 } |
|
938 |
|
939 @Override |
|
940 public void connectFlows(TubePublisher writePublisher, |
|
941 TubeSubscriber readSubscriber) { |
|
942 debug.log(Level.DEBUG, "connecting flows"); |
|
943 this.subscribe(readSubscriber); |
|
944 writePublisher.subscribe(this); |
|
945 } |
|
946 |
|
947 |
|
948 @Override |
|
949 public String toString() { |
|
950 return dbgString(); |
|
951 } |
|
952 |
|
953 final String dbgString() { |
|
954 return "SocketTube("+id+")"; |
|
955 } |
|
956 } |
|