import org.apache.cassandra.metrics.ClientMetrics; //导入依赖的package包/类
private void registerMetrics()
{
    ClientMetrics.instance.addCounter("connectedNativeClients", new Callable<Integer>()
    {
        @Override
        public Integer call() throws Exception
        {
            return connectionTracker.getConnectedClients();
        }
    });
}
 

import org.apache.cassandra.metrics.ClientMetrics; //导入依赖的package包/类
private void registerMetrics()
{
    ClientMetrics.instance.addCounter("connectedThriftClients", new Callable<Integer>()
    {
        @Override
        public Integer call() throws Exception
        {
            return ThriftSessionManager.instance.getConnectedClients();
        }
    });
}
 

import org.apache.cassandra.metrics.ClientMetrics; //导入依赖的package包/类
/**
 * Creates netty thread pools and event loops.
 */
@VisibleForTesting
synchronized void initialize()
{
    if (initialized)
        return;

    // prepare netty resources
    eventExecutorGroup = new RequestThreadPoolExecutor();

    if (useEpoll())
    {
        workerGroup = new EpollEventLoopGroup();
        logger.info("Netty using native Epoll event loop");
    }
    else
    {
        workerGroup = new NioEventLoopGroup();
        logger.info("Netty using Java NIO event loop");
    }

    int nativePort = DatabaseDescriptor.getNativeTransportPort();
    int nativePortSSL = DatabaseDescriptor.getNativeTransportPortSSL();
    InetAddress nativeAddr = DatabaseDescriptor.getRpcAddress();

    org.apache.cassandra.transport.Server.Builder builder = new org.apache.cassandra.transport.Server.Builder()
                                                            .withEventExecutor(eventExecutorGroup)
                                                            .withEventLoopGroup(workerGroup)
                                                            .withHost(nativeAddr);

    if (!DatabaseDescriptor.getClientEncryptionOptions().enabled)
    {
        servers = Collections.singleton(builder.withSSL(false).withPort(nativePort).build());
    }
    else
    {
        if (nativePort != nativePortSSL)
        {
            // user asked for dedicated ssl port for supporting both non-ssl and ssl connections
            servers = Collections.unmodifiableList(
                                                  Arrays.asList(
                                                               builder.withSSL(false).withPort(nativePort).build(),
                                                               builder.withSSL(true).withPort(nativePortSSL).build()
                                                  )
            );
        }
        else
        {
            // ssl only mode using configured native port
            servers = Collections.singleton(builder.withSSL(true).withPort(nativePort).build());
        }
    }

    // register metrics
    ClientMetrics.instance.addCounter("connectedNativeClients", () ->
    {
        int ret = 0;
        for (Server server : servers)
            ret += server.getConnectedClients();
        return ret;
    });

    initialized = true;
}