参考自rocketmq

    1. if (this.lockChannelTables.tryLock(LOCK_TIMEOUT_MILLIS, TimeUnit.MILLISECONDS)) {
    2.     try {
    3.         boolean createNewConnection;
    4.         cw = this.channelTables.get(addr);
    5.         if (cw != null) {
    7.             if (cw.isOK()) {
    8.                 return cw.getChannel();
    9.             } else if (!cw.getChannelFuture().isDone()) {
    10.                 createNewConnection = false;
    11.             } else {
    12.                 this.channelTables.remove(addr);
    13.                 createNewConnection = true;
    14.             }
    15.         } else {
    16.             createNewConnection = true;
    17.         }
    19.         if (createNewConnection) {
    20.             ChannelFuture channelFuture = this.bootstrap.connect(RemotingHelper.string2SocketAddress(addr));
    21.             log.info("createChannel: begin to connect remote host[{}] asynchronously", addr);
    22.             cw = new ChannelWrapper(channelFuture);
    23.             this.channelTables.put(addr, cw);
    24.         }
    25.     } catch (Exception e) {
    26.         log.error("createChannel: create channel exception", e);
    27.     } finally {
    28.         this.lockChannelTables.unlock();
    29.     }
    30. } else {
    31.     log.warn("createChannel: try to lock channel table, but timeout, {}ms", LOCK_TIMEOUT_MILLIS);
    32. }