CompletionQueue.java — netty Source File

Source Code

/*
 * Copyright 2024 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.uring;

import java.lang.invoke.MethodHandles;
import java.lang.invoke.VarHandle;
import java.nio.ByteBuffer;
import java.nio.ByteOrder;
import java.util.StringJoiner;

/**
 * Completion queue implementation for io_uring.
 */
final class CompletionQueue {
    private static final VarHandle INT_HANDLE =
            MethodHandles.byteBufferViewVarHandle(int[].class, ByteOrder.nativeOrder());

    //these offsets are used to access specific properties
    //CQE (https://github.com/axboe/liburing/blob/master/src/include/liburing/io_uring.h#L162)
    private static final int CQE_USER_DATA_FIELD = 0;
    private static final int CQE_RES_FIELD = 8;
    private static final int CQE_FLAGS_FIELD = 12;

    //these unsigned integer pointers(shared with the kernel) will be changed by the kernel and us
    // using a VarHandle.
    private final ByteBuffer khead;
    private final ByteBuffer ktail;
    private final ByteBuffer kflags;
    private final ByteBuffer completionQueueArray;
    private final ByteBuffer[] extraCqeData;

    final int ringSize;
    final long ringAddress;
    final int ringFd;
    final int ringEntries;
    final int ringCapacity;
    private final int cqeLength;

    private final int ringMask;
    private int ringHead;
    private boolean closed;

    CompletionQueue(ByteBuffer kHead, ByteBuffer kTail, int ringMask, int ringEntries, ByteBuffer kflags,
                    ByteBuffer completionQueueArray, int ringSize, long ringAddress,
                    int ringFd, int ringCapacity, int cqeLength, boolean extraCqeDataNeeded) {
        this.khead = kHead;
        this.ktail = kTail;
// ... (142 more lines)