[Metrics] Instrument http request (time it takes for request (back and forth) and time it takes to process that request (separately))

[D4G4]

I was planning to provide my custom HttpClient to my Graphql object.
The custom HttpClient has the metrics tracking attached to it.
I can either use Datadog or Firebase Performance, or even my custom client to achieve it.

class MyClient extends BaseClient {
  MyClient(this.delegate);
  final Client delegate;
  @override
  Future<StreamedResponse> send(BaseRequest request) {
    _logRequest(request);
    debugPrint("HELLO!!!!!!!!");
    return delegate.send(request);
  }

  void close() => delegate.close();
  void _logRequest(BaseRequest request) => debugPrint(request.toString());
}

But one can only override the send method in the HttpClient.

And I feel the GraphQL client uses the send method just once when it performs the first request maybe?
And in other queries, it uses the request method to perform a query or mutation.

How can I add my metrics to it?

Below is the code snippet from query_manager.dart that performs the request.

/// Resolve the query on the network,
  /// negotiating any necessary cache edits / optimistic cleanup
  Future<QueryResult<TParsed>> _resolveQueryOnNetwork<TParsed>(
    Request request,
    String queryId,
    BaseOptions<TParsed> options,
  ) async {
    Response response;
    QueryResult<TParsed>? queryResult;

    bool rereadFromCache = false;

    try {
      // execute the request through the provided link(s)
      response = await link.request(request).first;

      queryResult = mapFetchResultToQueryResult(
        response,
        options,
        source: QueryResultSource.network,
      );

      rereadFromCache = attemptCacheWriteFromResponse(
        options.policies,
        request,
        response,
        queryResult,
      );
    } catch (failure, trace) {
      // we set the source to indicate where the source of failure
      queryResult ??= QueryResult(
        source: QueryResultSource.network,
        parserFn: options.parserFn,
      );

      queryResult.exception = coalesceErrors(
        exception: queryResult.exception,
        linkException: translateFailure(failure, trace),
      );
    }

    // cleanup optimistic results
    cache.removeOptimisticPatch(queryId);

    if (rereadFromCache) {
      // normalize results if previously written
      attempCacheRereadIntoResult(request, queryResult);
    }

    // one off operations do not have an ObservableQuery to add to
    if (queryId != _oneOffOpId) {
      addQueryResult(request, queryId, queryResult);
    }

    return queryResult;
  }

So how can we log/instrument every request (basically get the start and end time) ?

[vincenzopalazzo]

This is a vey good question and sorry for delay, I'm not sure how to perform this also because all the work that we done is performed by the Link that we currently we do not manage.

Maybe creating your own Link solve your problem?

BTW, I'm not sure about the answer, so if you want we can look into it.