Integrate with the OkHttp's analytics API

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Following the analytics API that is being build within okhttp (https://github.com/square/okhttp/issues/270), I would like to capture metrics per mapped path / route.

tl;dr

Currently it is not possible to have metrics per route in OkHttp’s EventListener without parsing the URL against a known list of path (that has to populated from the interface or somewhere else. This inefficient on several aspects.

I would like retrofit to communicate the route context to OkHttp, inorder to access the in the EventListener.

Example

That is for the following interface.

interface FakeRest {
    @GET("/posts")
    Call<ResponseBody> posts();
    @GET("/posts/{post-id}")
    Call<ResponseBody> post(@Path("post-id") int postId);
    @GET("/posts/{post-id}/comments")
    Call<ResponseBody> postComments(@Path("post-id") int postId);
}

I would like to access the method or a pre-built request/call context that the EventListener can access. I’ve played around with the Retrofit builder using Call.Factory, CallAdapter.Factory but unfortunately I didn’t find a way to capture this information and to pass it in the HTTP Call Request.

I noticed the tag field in OkHttp’s Request, I know it’s not documented for this kind of usage, but it would helped me to bootstrap the idea.

What I tried (and it’s currently ugly and inelegant) :

Have a built retrofit.

Retrofit retrofit = new Retrofit.Builder().baseUrl("https://jsonplaceholder.typicode.com/").build();

Decorate each CallAdapter.Factory in a new Retrofit created form the original one, and capture path information from annotations (possibly use baseUrl as well).

Retrofit.Builder newBuilder = retrofit.newBuilder();
for (Factory callAdapterFactory : retrofit.callAdapterFactories()) {
    newBuilder.addCallAdapterFactory(new Factory() {
        @Override
        public CallAdapter<Object, Object> get(Type returnType, Annotation[] annotations, Retrofit retrofit) {
            String normalizedPath = normalizedPathFrom(annotations);
            CallAdapter<Object, Object> callAdapter = (CallAdapter<Object, Object>) callAdapterFactory.get(returnType, annotations, retrofit);
            return new CallAdapter<Object, Object>() {
                ...
                @Override
                public Object adapt(Call<Object> call) {
                    return callAdapter.adapt(wrapCall(call));
                }
            };
        }
    });
}
retrofit = newBuilder.build();

But the thing here is that I don’t get how to pass it to an OkHttp Request. The Call received in the adapt method cannot be modified, wrapping it won’t work, because internally (in OkHttpCall) retrofit will build his own immutable request that will be used for executing or enqueuing the actual request. Cloning is of course out of question, and duplicating it appears impossible because the constructors are not public.

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Using the Call.Factory is no help, because the this interface receives a pre-built request, so I cannot introduce a Call.Factory decorator that capture the necessary annotations and pass them in the request tag.

To be able to customize request, I believe that either RequestBuilder could be made an interface (and making the according modifications), or that RequestBuilder accept some sort of RequestCustomizer that can access the route context, either headers, path, query param names, interface method name, etc. and pass it to the OkHttp Request.

[nicktrav]

Just adding in my two cents here. We’d also love to be able to get at the method that was called on the interface.

Talking to @swankjesse about this internally, it sounds like he has some ideas for this that might involve being able to add a retrofit.Call into the okhttp.Response tags, and then being able to pluck that metadata back out for use later.

[JakeWharton]

Will be released in 2.5.0 soon.