AdaptiveRecvByteBufAllocator.java — netty Source File

Source Code

/*
 * Copyright 2012 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.util.internal.AdaptiveCalculator;

import static io.netty.util.internal.ObjectUtil.checkPositive;

/**
 * The {@link RecvByteBufAllocator} that automatically increases and
 * decreases the predicted buffer size on feed back.
 * <p>
 * It gradually increases the expected number of readable bytes if the previous
 * read fully filled the allocated buffer.  It gradually decreases the expected
 * number of readable bytes if the read operation was not able to fill a certain
 * amount of the allocated buffer two times consecutively.  Otherwise, it keeps
 * returning the same prediction.
 */
public class AdaptiveRecvByteBufAllocator extends DefaultMaxMessagesRecvByteBufAllocator {

    public static final int DEFAULT_MINIMUM = 64;
    // Use an initial value that is bigger than the common MTU of 1500
    public static final int DEFAULT_INITIAL = 2048;
    public static final int DEFAULT_MAXIMUM = 65536;

    /**
     * @deprecated There is state for {@link #maxMessagesPerRead()} which is typically based upon channel type.
     */
    @Deprecated
    public static final AdaptiveRecvByteBufAllocator DEFAULT = new AdaptiveRecvByteBufAllocator();

    private final class HandleImpl extends MaxMessageHandle {
        private final AdaptiveCalculator calculator;

        HandleImpl(int minimum, int initial, int maximum) {
            calculator = new AdaptiveCalculator(minimum, initial, maximum);
        }

        @Override
        public void lastBytesRead(int bytes) {
            // If we read as much as we asked for we should check if we need to ramp up the size of our next guess.
            // This helps adjust more quickly when large amounts of data is pending and can avoid going back to
            // the selector to check for more data. Going back to the selector can add significant latency for large
            // data transfers.
            if (bytes == attemptedBytesRead()) {
                calculator.record(bytes);
            }
// ... (61 more lines)