PendingWriteQueue.java — netty Source File

Source Code

/*
 * Copyright 2014 The Netty Project
 *
 * The Netty Project licenses this file to you under the Apache License,
 * version 2.0 (the "License"); you may not use this file except in compliance
 * with the License. You may obtain a copy of the License at:
 *
 *   https://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
 * License for the specific language governing permissions and limitations
 * under the License.
 */
package io.netty.channel;

import io.netty.buffer.AbstractReferenceCountedByteBuf;
import io.netty.util.Recycler;
import io.netty.util.ReferenceCountUtil;
import io.netty.util.concurrent.EventExecutor;
import io.netty.util.concurrent.PromiseCombiner;
import io.netty.util.internal.ObjectPool;
import io.netty.util.internal.ObjectUtil;
import io.netty.util.internal.SystemPropertyUtil;
import io.netty.util.internal.logging.InternalLogger;
import io.netty.util.internal.logging.InternalLoggerFactory;

/**
 * A queue of write operations which are pending for later execution. It also updates the
 * {@linkplain Channel#isWritable() writability} of the associated {@link Channel}, so that
 * the pending write operations are also considered to determine the writability.
 */
public final class PendingWriteQueue {
    private static final InternalLogger logger = InternalLoggerFactory.getInstance(PendingWriteQueue.class);
    // Assuming a 64-bit JVM:
    //  - 16 bytes object header
    //  - 4 reference fields
    //  - 1 long fields
    private static final int PENDING_WRITE_OVERHEAD =
            SystemPropertyUtil.getInt("io.netty.transport.pendingWriteSizeOverhead", 64);

    private final ChannelOutboundInvoker invoker;
    private final EventExecutor executor;
    private final PendingBytesTracker tracker;

    // head and tail pointers for the linked-list structure. If empty head and tail are null.
    private PendingWrite head;
    private PendingWrite tail;
    private int size;
    private long bytes;

    public PendingWriteQueue(ChannelHandlerContext ctx) {
        tracker = PendingBytesTracker.newTracker(ctx.channel());
        this.invoker = ctx;
        this.executor = ctx.executor();
    }

    public PendingWriteQueue(Channel channel) {
        tracker = PendingBytesTracker.newTracker(channel);
// ... (282 more lines)