SimpleChannelPool Class — netty Architecture

Source Code

transport/src/main/java/io/netty/channel/pool/SimpleChannelPool.java lines 43–425

public class SimpleChannelPool implements ChannelPool {
    private static final AttributeKey<SimpleChannelPool> POOL_KEY =
        AttributeKey.newInstance("io.netty.channel.pool.SimpleChannelPool");
    private final Deque<Channel> deque = PlatformDependent.newConcurrentDeque();
    private final ChannelPoolHandler handler;
    private final ChannelHealthChecker healthCheck;
    private final Bootstrap bootstrap;
    private final boolean releaseHealthCheck;
    private final boolean lastRecentUsed;

    /**
     * Creates a new instance using the {@link ChannelHealthChecker#ACTIVE}.
     *
     * @param bootstrap         the {@link Bootstrap} that is used for connections
     * @param handler           the {@link ChannelPoolHandler} that will be notified for the different pool actions
     */
    public SimpleChannelPool(Bootstrap bootstrap, final ChannelPoolHandler handler) {
        this(bootstrap, handler, ChannelHealthChecker.ACTIVE);
    }

    /**
     * Creates a new instance.
     *
     * @param bootstrap         the {@link Bootstrap} that is used for connections
     * @param handler           the {@link ChannelPoolHandler} that will be notified for the different pool actions
     * @param healthCheck       the {@link ChannelHealthChecker} that will be used to check if a {@link Channel} is
     *                          still healthy when obtain from the {@link ChannelPool}
     */
    public SimpleChannelPool(Bootstrap bootstrap, final ChannelPoolHandler handler, ChannelHealthChecker healthCheck) {
        this(bootstrap, handler, healthCheck, true);
    }

    /**
     * Creates a new instance.
     *
     * @param bootstrap          the {@link Bootstrap} that is used for connections
     * @param handler            the {@link ChannelPoolHandler} that will be notified for the different pool actions
     * @param healthCheck        the {@link ChannelHealthChecker} that will be used to check if a {@link Channel} is
     *                           still healthy when obtain from the {@link ChannelPool}
     * @param releaseHealthCheck will check channel health before offering back if this parameter set to {@code true};
     *                           otherwise, channel health is only checked at acquisition time
     */
    public SimpleChannelPool(Bootstrap bootstrap, final ChannelPoolHandler handler, ChannelHealthChecker healthCheck,
                             boolean releaseHealthCheck) {
        this(bootstrap, handler, healthCheck, releaseHealthCheck, true);
    }

    /**
     * Creates a new instance.
     *
     * @param bootstrap          the {@link Bootstrap} that is used for connections
     * @param handler            the {@link ChannelPoolHandler} that will be notified for the different pool actions
     * @param healthCheck        the {@link ChannelHealthChecker} that will be used to check if a {@link Channel} is
     *                           still healthy when obtain from the {@link ChannelPool}
     * @param releaseHealthCheck will check channel health before offering back if this parameter set to {@code true};
     *                           otherwise, channel health is only checked at acquisition time
     * @param lastRecentUsed    {@code true} {@link Channel} selection will be LIFO, if {@code false} FIFO.
     */
    public SimpleChannelPool(Bootstrap bootstrap, final ChannelPoolHandler handler, ChannelHealthChecker healthCheck,
                             boolean releaseHealthCheck, boolean lastRecentUsed) {
        this.handler = checkNotNull(handler, "handler");
        this.healthCheck = checkNotNull(healthCheck, "healthCheck");
        this.releaseHealthCheck = releaseHealthCheck;
        // Clone the original Bootstrap as we want to set our own handler
        this.bootstrap = checkNotNull(bootstrap, "bootstrap").clone();
        this.bootstrap.handler(new ChannelInitializer<Channel>() {
            @Override
            protected void initChannel(Channel ch) throws Exception {
                assert ch.eventLoop().inEventLoop();
                handler.channelCreated(ch);
            }
        });
        this.lastRecentUsed = lastRecentUsed;
    }

    /**
     * Returns the {@link Bootstrap} this pool will use to open new connections.
     *
     * @return the {@link Bootstrap} this pool will use to open new connections
     */
    protected Bootstrap bootstrap() {