Support returning OkHttpClient subclasses from OkHttpClient.Builder#build()

Hello,

Here is a simplified view of my problem:

class MyOkHttpClient : OkHttpClient() {
  // override something here
}

val client = MyOkHttpClient()
val newClient = client.newBuilder().build()

Given the above code, I would like newClient to be an instance of MyOkHttpClient.

My use case is: I’m trying to inspect websocket network traffic on Android. This isn’t supported by Android Profiler as far as I can tell, but it seems it should be possible with Stetho with a bit of work: http://zenandroid.io/monitoring-websockets-with-stetho/

However, I’m using OkHttp via Ktor. I can provide a preconfigued instance of OkHttpClient to Ktor, but the Ktor OkHttpEngine calls newBuilder().build() and thus ends up using OkHttpClient, not MyOkHttpClient:

https://github.com/ktorio/ktor/blob/21bb0a7a05f135a5ffb312ef83149fbc25899b86/ktor-client/ktor-client-okhttp/jvm/src/io/ktor/client/engine/okhttp/OkHttpEngine.kt#L133-L144

It would seem the purpose of declaring OkHttpClient to be open is obviated somewhat by the fact that Builder#build() always returns OkHttpClient. Allowing users to override Builder#build() or pass a factory for creating instances of OkHttpClient would address this.

How do you feel about this?

Thanks

[chrisfillmore]

Just to follow up, in case anyone has a similar use case, my pull request with Ktor was merged and it is now possible to pass a WebSocket.Factory to its configuration: https://github.com/ktorio/ktor/pull/2035

[chrisfillmore]

Calling the Stetho method NetworkEventReporter#webSocketFrameSent depends on overriding OkHttp method WebSocket#send(). For example:

class StethoWebSocket(
  private val wrappedSocket: WebSocket,
  private val requestId: String
 ) : WebSocket by wrappedSocket {
  private val reporter = NetworkEventReporterImpl.get()

  override fun send(text: String): Boolean {
    reporter.webSocketFrameSent(SimpleTextInspectorWebSocketFrame(requestId, text))
    return wrappedSocket.send(text)
  }

  override fun send(bytes: ByteString): Boolean {
    reporter.webSocketFrameSent(SimpleBinaryInspectorWebSocketFrame(requestId, bytes.toByteArray()))
    return wrappedSocket.send(bytes)
  }
}

Other reporting methods (webSocketFrameReceived, etc) depend on OkHttp WebSocketListener.

I have filed an issue with Ktor: https://youtrack.jetbrains.com/issue/KTOR-951