io.grpc.netty.MaxConnectionIdleManager.java Source code

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Here is the source code for io.grpc.netty.MaxConnectionIdleManager.java

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/*
 * Copyright 2017 The gRPC Authors
 *
 * Licensed 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
 *
 *     http://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.grpc.netty;

import com.google.common.annotations.VisibleForTesting;
import io.grpc.internal.LogExceptionRunnable;
import io.netty.channel.ChannelHandlerContext;
import java.util.concurrent.ScheduledExecutorService;
import java.util.concurrent.ScheduledFuture;
import java.util.concurrent.TimeUnit;
import javax.annotation.CheckForNull;

/**
 * Monitors connection idle time; shutdowns the connection if the max connection idle is reached.
 */
abstract class MaxConnectionIdleManager {
    private static final Ticker systemTicker = new Ticker() {
        @Override
        public long nanoTime() {
            return System.nanoTime();
        }
    };

    private final long maxConnectionIdleInNanos;
    private final Ticker ticker;

    @CheckForNull
    private ScheduledFuture<?> shutdownFuture;
    private Runnable shutdownTask;
    private ScheduledExecutorService scheduler;
    private long nextIdleMonitorTime;
    private boolean shutdownDelayed;
    private boolean isActive;

    MaxConnectionIdleManager(long maxConnectionIdleInNanos) {
        this(maxConnectionIdleInNanos, systemTicker);
    }

    @VisibleForTesting
    MaxConnectionIdleManager(long maxConnectionIdleInNanos, Ticker ticker) {
        this.maxConnectionIdleInNanos = maxConnectionIdleInNanos;
        this.ticker = ticker;
    }

    /** A {@link NettyServerHandler} was added to the transport. */
    void start(ChannelHandlerContext ctx) {
        start(ctx, ctx.executor());
    }

    @VisibleForTesting
    void start(final ChannelHandlerContext ctx, final ScheduledExecutorService scheduler) {
        this.scheduler = scheduler;
        nextIdleMonitorTime = ticker.nanoTime() + maxConnectionIdleInNanos;

        shutdownTask = new LogExceptionRunnable(new Runnable() {
            @Override
            public void run() {
                if (shutdownDelayed) {
                    if (!isActive) {
                        // delay shutdown
                        shutdownFuture = scheduler.schedule(shutdownTask, nextIdleMonitorTime - ticker.nanoTime(),
                                TimeUnit.NANOSECONDS);
                        shutdownDelayed = false;
                    }
                    // if isActive, exit. Will schedule a new shutdownFuture once onTransportIdle
                } else {
                    close(ctx);
                    shutdownFuture = null;
                }
            }
        });

        shutdownFuture = scheduler.schedule(shutdownTask, maxConnectionIdleInNanos, TimeUnit.NANOSECONDS);
    }

    /**
     * Closes the connection by sending GO_AWAY with status code NO_ERROR and ASCII debug data
     * max_idle and then doing the graceful connection termination.
     */
    abstract void close(ChannelHandlerContext ctx);

    /** There are outstanding RPCs on the transport. */
    void onTransportActive() {
        isActive = true;
        shutdownDelayed = true;
    }

    /** There are no outstanding RPCs on the transport. */
    void onTransportIdle() {
        isActive = false;
        if (shutdownFuture == null) {
            return;
        }
        if (shutdownFuture.isDone()) {
            shutdownDelayed = false;
            shutdownFuture = scheduler.schedule(shutdownTask, maxConnectionIdleInNanos, TimeUnit.NANOSECONDS);
        } else {
            nextIdleMonitorTime = ticker.nanoTime() + maxConnectionIdleInNanos;
        }
    }

    /** Transport is being terminated. */
    void onTransportTermination() {
        if (shutdownFuture != null) {
            shutdownFuture.cancel(false);
            shutdownFuture = null;
        }
    }

    @VisibleForTesting
    interface Ticker {
        long nanoTime();
    }
}