"Wait for Ready" RPCs retry even if data was written to the wire

[dfawley]

Once data is written to the wire, unless we are certain the remote server did not receive it, gRPC cannot resend an RPC. However, we are doing this in many cases. E.g., in the event an error occurs while waiting for a response from the remote server:

grpc-go/call.go

Lines 292 to 294 in 1253dac

	if _, ok := err.(transport.ConnectionError); (ok || err == transport.ErrStreamDrain) && !c.failFast {
	continue
	}

[xiang90]

for read request, we do want to retry. i think we need to provide options to users.

[dfawley]

This would be covered by retry support (gRFC A6), but it isn't otherwise a part of gRPC.

[xiang90]

@dfawley awesome. good to learn.