improve RPC client logging (#171)

We currently only debug log successfully sent messages to RPC.
For debugging, it would be better to see the attempt and any failures.
Adjust logging to provide more information when debugging.
Also include the message name at debug level instead of just trace.

json_rpc/clients/httpclient.nim

@@ -76,6 +76,10 @@ method call*(client: RpcHttpClient, name: string,
       except CatchableError as exc: # shouldn't happen
         debug "Error closing JSON-RPC HTTP resuest/response", err = exc.msg
 
+  debug "Sending message to RPC server",
+         address = client.httpAddress, msg_len = len(reqBody), name
+  trace "Message", msg = reqBody
+
   req = HttpClientRequestRef.post(client.httpSession,
                                   client.httpAddress.get,
                                   body = reqBody.toOpenArrayByte(0, reqBody.len - 1),
@@ -84,27 +88,29 @@ method call*(client: RpcHttpClient, name: string,
     try:
       await req.send()
     except CancelledError as e:
+      debug "Cancelled POST Request with JSON-RPC", e = e.msg
       closeRefs()
       raise e
     except CatchableError as e:
+      debug "Failed to send POST Request with JSON-RPC", e = e.msg
       closeRefs()
       raise (ref RpcPostError)(msg: "Failed to send POST Request with JSON-RPC: " & e.msg, parent: e)
 
   if res.status < 200 or res.status >= 300: # res.status is not 2xx (success)
+    debug "Unsuccessful POST Request with JSON-RPC",
+      status = res.status, reason = res.reason
     closeRefs()
     raise (ref ErrorResponse)(status: res.status, msg: res.reason)
 
-  debug "Message sent to RPC server",
-         address = client.httpAddress, msg_len = len(reqBody)
-  trace "Message", msg = reqBody
-
   let resBytes =
     try:
       await res.getBodyBytes(client.maxBodySize)
     except CancelledError as e:
+      debug "Cancelled POST Response for JSON-RPC", e = e.msg
       closeRefs()
       raise e
     except CatchableError as e:
+      debug "Failed to read POST Response for JSON-RPC", e = e.msg
       closeRefs()
       raise (ref FailedHttpResponse)(msg: "Failed to read POST Response for JSON-RPC: " & e.msg, parent: e)
 
@@ -122,6 +128,7 @@ method call*(client: RpcHttpClient, name: string,
     client.processMessage(resText)
   except CatchableError as e:
     # Need to clean up in case the answer was invalid
+    debug "Failed to process POST Response for JSON-RPC", e = e.msg
     client.awaiting.del(id)
     closeRefs()
     raise e
@@ -136,6 +143,7 @@ method call*(client: RpcHttpClient, name: string,
     return newFut.read()
   else:
     # TODO: Provide more clarity regarding the failure here
+    debug "Invalid POST Response for JSON-RPC"
     raise newException(InvalidResponse, "Invalid response")
 
 proc connect*(client: RpcHttpClient, url: string) {.async.} =