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| 1 | +/* |
| 2 | + * The original file is licensed under the following license: |
| 3 | + * |
| 4 | + * Copyright 2016 The Netty Project |
| 5 | + * |
| 6 | + * The Netty Project licenses this file to you under the Apache License, |
| 7 | + * version 2.0 (the "License"); you may not use this file except in compliance |
| 8 | + * with the License. You may obtain a copy of the License at: |
| 9 | + * |
| 10 | + * https://www.apache.org/licenses/LICENSE-2.0 |
| 11 | + * |
| 12 | + * Unless required by applicable law or agreed to in writing, software |
| 13 | + * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT |
| 14 | + * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the |
| 15 | + * License for the specific language governing permissions and limitations |
| 16 | + * under the License. |
| 17 | + * |
| 18 | + * --- |
| 19 | + * |
| 20 | + * This file is based on the io/netty/handler/flush/FlushConsolidationHandler.java file from Netty (v4.1). |
| 21 | + * It was modified to fit to bungee's use of forwarded connections. |
| 22 | + * All modifications are licensed under the "Modified BSD 3-Clause License" to be found at |
| 23 | + * https://github.com/SpigotMC/BungeeCord/blob/master/LICENSE |
| 24 | + */ |
| 25 | +package net.md_5.bungee.netty.flush; |
| 26 | + |
| 27 | +import io.netty.channel.Channel; |
| 28 | +import io.netty.channel.ChannelDuplexHandler; |
| 29 | +import io.netty.channel.ChannelHandler; |
| 30 | +import io.netty.channel.ChannelHandlerContext; |
| 31 | +import io.netty.channel.ChannelOutboundHandler; |
| 32 | +import io.netty.channel.ChannelOutboundInvoker; |
| 33 | +import io.netty.channel.ChannelPipeline; |
| 34 | +import io.netty.channel.ChannelPromise; |
| 35 | +import io.netty.util.internal.ObjectUtil; |
| 36 | +import java.util.concurrent.Future; |
| 37 | + |
| 38 | +/** |
| 39 | + * {@link ChannelDuplexHandler} which consolidates {@link Channel#flush()} / {@link ChannelHandlerContext#flush()} |
| 40 | + * operations (which also includes |
| 41 | + * {@link Channel#writeAndFlush(Object)} / {@link Channel#writeAndFlush(Object, ChannelPromise)} and |
| 42 | + * {@link ChannelOutboundInvoker#writeAndFlush(Object)} / |
| 43 | + * {@link ChannelOutboundInvoker#writeAndFlush(Object, ChannelPromise)}). |
| 44 | + * <p> |
| 45 | + * Flush operations are generally speaking expensive as these may trigger a syscall on the transport level. Thus it is |
| 46 | + * in most cases (where write latency can be traded with throughput) a good idea to try to minimize flush operations |
| 47 | + * as much as possible. |
| 48 | + * <p> |
| 49 | + * If a {@link FlushSignalingHandler} signalises a read loop is currently ongoing, |
| 50 | + * {@link #flush(ChannelHandlerContext)} will not be passed on to the next {@link ChannelOutboundHandler} in the |
| 51 | + * {@link ChannelPipeline}, as it will pick up any pending flushes when |
| 52 | + * {@link #channelReadComplete(ChannelHandlerContext)} is triggered. |
| 53 | + * If no read loop is ongoing, the behavior depends on the {@code consolidateWhenNoReadInProgress} constructor argument: |
| 54 | + * <ul> |
| 55 | + * <li>if {@code false}, flushes are passed on to the next handler directly;</li> |
| 56 | + * <li>if {@code true}, the invocation of the next handler is submitted as a separate task on the event loop. Under |
| 57 | + * high throughput, this gives the opportunity to process other flushes before the task gets executed, thus |
| 58 | + * batching multiple flushes into one.</li> |
| 59 | + * </ul> |
| 60 | + * If {@code explicitFlushAfterFlushes} is reached the flush will be forwarded as well (whether while in a read loop, or |
| 61 | + * while batching outside of a read loop). |
| 62 | + * <p> |
| 63 | + * If the {@link Channel} becomes non-writable it will also try to execute any pending flush operations. |
| 64 | + * <p> |
| 65 | + * The {@link BungeeFlushConsolidationHandler} should be put as first {@link ChannelHandler} in the |
| 66 | + * {@link ChannelPipeline} to have the best effect. |
| 67 | + */ |
| 68 | +public final class BungeeFlushConsolidationHandler extends ChannelDuplexHandler |
| 69 | +{ |
| 70 | + private final int explicitFlushAfterFlushes; |
| 71 | + private final boolean consolidateWhenNoReadInProgress; |
| 72 | + private final Runnable flushTask; |
| 73 | + private int flushPendingCount; |
| 74 | + boolean readInProgress; |
| 75 | + ChannelHandlerContext ctx; |
| 76 | + private Future<?> nextScheduledFlush; |
| 77 | + |
| 78 | + /** |
| 79 | + * The default number of flushes after which a flush will be forwarded to downstream handlers (whether while in a |
| 80 | + * read loop, or while batching outside of a read loop). |
| 81 | + */ |
| 82 | + public static final int DEFAULT_EXPLICIT_FLUSH_AFTER_FLUSHES = 256; |
| 83 | + |
| 84 | + /** |
| 85 | + * Creates a new instance with bungee's default values |
| 86 | + * |
| 87 | + * @param toClient whether this handler is for a bungee-client connection |
| 88 | + * @return a new instance of BungeeFlushConsolidationHandler |
| 89 | + */ |
| 90 | + public static BungeeFlushConsolidationHandler newInstance(boolean toClient) |
| 91 | + { |
| 92 | + // Currently the toClient boolean is ignored. It is present in case we find different parameters neccessary |
| 93 | + // for client and server connections. |
| 94 | + return new BungeeFlushConsolidationHandler( 20, false ); |
| 95 | + } |
| 96 | + |
| 97 | + /** |
| 98 | + * Create new instance which explicit flush after {@value DEFAULT_EXPLICIT_FLUSH_AFTER_FLUSHES} pending flush |
| 99 | + * operations at the latest. |
| 100 | + */ |
| 101 | + private BungeeFlushConsolidationHandler() |
| 102 | + { |
| 103 | + this( DEFAULT_EXPLICIT_FLUSH_AFTER_FLUSHES, false ); |
| 104 | + } |
| 105 | + |
| 106 | + /** |
| 107 | + * Create new instance which doesn't consolidate flushes when no read is in progress. |
| 108 | + * |
| 109 | + * @param explicitFlushAfterFlushes the number of flushes after which an explicit flush will be done. |
| 110 | + */ |
| 111 | + private BungeeFlushConsolidationHandler(int explicitFlushAfterFlushes) |
| 112 | + { |
| 113 | + this( explicitFlushAfterFlushes, false ); |
| 114 | + } |
| 115 | + |
| 116 | + /** |
| 117 | + * Create new instance. |
| 118 | + * |
| 119 | + * @param explicitFlushAfterFlushes the number of flushes after which an explicit flush will be done. |
| 120 | + * @param consolidateWhenNoReadInProgress whether to consolidate flushes even when no read loop is currently |
| 121 | + * ongoing. |
| 122 | + */ |
| 123 | + private BungeeFlushConsolidationHandler(int explicitFlushAfterFlushes, boolean consolidateWhenNoReadInProgress) |
| 124 | + { |
| 125 | + this.explicitFlushAfterFlushes = ObjectUtil.checkPositive( explicitFlushAfterFlushes, "explicitFlushAfterFlushes" ); |
| 126 | + this.consolidateWhenNoReadInProgress = consolidateWhenNoReadInProgress; |
| 127 | + this.flushTask = consolidateWhenNoReadInProgress ? new Runnable() |
| 128 | + { |
| 129 | + @Override |
| 130 | + public void run() |
| 131 | + { |
| 132 | + if ( flushPendingCount > 0 && !readInProgress ) |
| 133 | + { |
| 134 | + flushPendingCount = 0; |
| 135 | + nextScheduledFlush = null; |
| 136 | + ctx.flush(); |
| 137 | + } // else we'll flush when the read completes |
| 138 | + } |
| 139 | + } : null; |
| 140 | + } |
| 141 | + |
| 142 | + @Override |
| 143 | + public void handlerAdded(ChannelHandlerContext ctx) throws Exception |
| 144 | + { |
| 145 | + this.ctx = ctx; |
| 146 | + } |
| 147 | + |
| 148 | + @Override |
| 149 | + public void flush(ChannelHandlerContext ctx) throws Exception |
| 150 | + { |
| 151 | + if ( readInProgress ) |
| 152 | + { |
| 153 | + // If there is still a read in progress we are sure we will see a channelReadComplete(...) call. Thus |
| 154 | + // we only need to flush if we reach the explicitFlushAfterFlushes limit. |
| 155 | + if ( ++flushPendingCount == explicitFlushAfterFlushes ) |
| 156 | + { |
| 157 | + flushNow( ctx ); |
| 158 | + } |
| 159 | + } else if ( consolidateWhenNoReadInProgress ) |
| 160 | + { |
| 161 | + // Flush immediately if we reach the threshold, otherwise schedule |
| 162 | + if ( ++flushPendingCount == explicitFlushAfterFlushes ) |
| 163 | + { |
| 164 | + flushNow( ctx ); |
| 165 | + } else |
| 166 | + { |
| 167 | + scheduleFlush( ctx ); |
| 168 | + } |
| 169 | + } else |
| 170 | + { |
| 171 | + // Always flush directly |
| 172 | + flushNow( ctx ); |
| 173 | + } |
| 174 | + } |
| 175 | + |
| 176 | + @Override |
| 177 | + public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception |
| 178 | + { |
| 179 | + // To ensure we not miss to flush anything, do it now. |
| 180 | + resetReadAndFlushIfNeeded( ctx ); |
| 181 | + ctx.fireExceptionCaught( cause ); |
| 182 | + } |
| 183 | + |
| 184 | + @Override |
| 185 | + public void disconnect(ChannelHandlerContext ctx, ChannelPromise promise) throws Exception |
| 186 | + { |
| 187 | + // Try to flush one last time if flushes are pending before disconnect the channel. |
| 188 | + resetReadAndFlushIfNeeded( ctx ); |
| 189 | + ctx.disconnect( promise ); |
| 190 | + } |
| 191 | + |
| 192 | + @Override |
| 193 | + public void close(ChannelHandlerContext ctx, ChannelPromise promise) throws Exception |
| 194 | + { |
| 195 | + // Try to flush one last time if flushes are pending before close the channel. |
| 196 | + resetReadAndFlushIfNeeded( ctx ); |
| 197 | + ctx.close( promise ); |
| 198 | + } |
| 199 | + |
| 200 | + @Override |
| 201 | + public void channelWritabilityChanged(ChannelHandlerContext ctx) throws Exception |
| 202 | + { |
| 203 | + if ( !ctx.channel().isWritable() ) |
| 204 | + { |
| 205 | + // The writability of the channel changed to false, so flush all consolidated flushes now to free up memory. |
| 206 | + flushIfNeeded( ctx ); |
| 207 | + } |
| 208 | + ctx.fireChannelWritabilityChanged(); |
| 209 | + } |
| 210 | + |
| 211 | + @Override |
| 212 | + public void handlerRemoved(ChannelHandlerContext ctx) throws Exception |
| 213 | + { |
| 214 | + flushIfNeeded( ctx ); |
| 215 | + } |
| 216 | + |
| 217 | + void resetReadAndFlushIfNeeded(ChannelHandlerContext ctx) |
| 218 | + { |
| 219 | + readInProgress = false; |
| 220 | + flushIfNeeded( ctx ); |
| 221 | + } |
| 222 | + |
| 223 | + void flushIfNeeded(ChannelHandlerContext ctx) |
| 224 | + { |
| 225 | + if ( flushPendingCount > 0 ) |
| 226 | + { |
| 227 | + flushNow( ctx ); |
| 228 | + } |
| 229 | + } |
| 230 | + |
| 231 | + private void flushNow(ChannelHandlerContext ctx) |
| 232 | + { |
| 233 | + cancelScheduledFlush(); |
| 234 | + flushPendingCount = 0; |
| 235 | + ctx.flush(); |
| 236 | + } |
| 237 | + |
| 238 | + private void scheduleFlush(final ChannelHandlerContext ctx) |
| 239 | + { |
| 240 | + if ( nextScheduledFlush == null ) |
| 241 | + { |
| 242 | + // Run as soon as possible, but still yield to give a chance for additional writes to enqueue. |
| 243 | + nextScheduledFlush = ctx.channel().eventLoop().submit( flushTask ); |
| 244 | + } |
| 245 | + } |
| 246 | + |
| 247 | + private void cancelScheduledFlush() |
| 248 | + { |
| 249 | + if ( nextScheduledFlush != null ) |
| 250 | + { |
| 251 | + nextScheduledFlush.cancel( false ); |
| 252 | + nextScheduledFlush = null; |
| 253 | + } |
| 254 | + } |
| 255 | +} |
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