Re-using ClientBootstrap… but why?

dnadoba · September 1, 2023, 11:01pm

As long as you share the same EventLoopGroup with different ClientBootstraps you will use the EventLoops from the same pool and you are fine. Nothing wrong with creating multiple ClientBoostraps as connection just calls next() on the EventLoopGroup anyway:

github.com

apple/swift-nio/blob/34a7663c0534efcb470daea402e3b28a0e4291f9/Sources/NIOPosix/Bootstrap.swift#L953


      
              return try SocketChannel(eventLoop: eventLoop as! SelectableEventLoop, protocolFamily: protocolFamily, enableMPTCP: self.enableMPTCP)
          }
          
          /// Specify the `host` and `port` to connect to for the TCP `Channel` that will be established.
          ///
          /// - parameters:
          ///     - host: The host to connect to.
          ///     - port: The port to connect to.
          /// - returns: An `EventLoopFuture<Channel>` to deliver the `Channel` when connected.
          public func connect(host: String, port: Int) -> EventLoopFuture<Channel> {
              let loop = self.group.next()
              let resolver = self.resolver ?? GetaddrinfoResolver(loop: loop,
                                                                  aiSocktype: .stream,
                                                                  aiProtocol: .tcp)
              let connector = HappyEyeballsConnector(resolver: resolver,
                                                     loop: loop,
                                                     host: host,
                                                     port: port,
                                                     connectTimeout: self.connectTimeout) { eventLoop, protocolFamily in
                  return self.initializeAndRegisterNewChannel(eventLoop: eventLoop, protocolFamily: protocolFamily) {
                      $0.eventLoop.makeSucceededFuture(())

Note that channelInitializer may be called multiple times because we may try to race IPv4 and IPv6 connections simultaneously and setup a full channel for each.