Code demonstrating how to measure API performance using Answers and OkHttp 2.2+.

ApiMetricsInterceptor.java

import com.crashlytics.android.answers.Answers;
import com.crashlytics.android.answers.CustomEvent;
import com.squareup.okhttp.Interceptor;
import com.squareup.okhttp.MediaType;
import com.squareup.okhttp.Request;
import com.squareup.okhttp.RequestBody;
import com.squareup.okhttp.Response;
import com.squareup.okhttp.ResponseBody;

import java.io.IOException;
import java.net.URL;
import java.util.concurrent.TimeUnit;

public class ApiMetricsInterceptor implements Interceptor {
    private final Answers answers;

    public ApiMetricsInterceptor(Answers answers) {
        this.answers = answers;
    }

    @Override
    public Response intercept(Chain chain) throws IOException {
        // Execute the request and measure the elapsed time
        final long start = System.nanoTime();
        final Response response = chain.proceed(chain.request());
        final float elapsed = TimeUnit.NANOSECONDS.toMillis(System.nanoTime() - start) / 1000.0f;

        final CustomEvent customEvent = new CustomEvent("HTTPRequest");
        final Request request = response.request();
        final RequestBody requestBody = request.body();
        final URL url = request.url();
        final ResponseBody responseBody = response.body();

        // Set request attributes
        customEvent.putCustomAttribute("Host", url.getHost());
        customEvent.putCustomAttribute("URL Scheme", url.getProtocol());
        customEvent.putCustomAttribute("Sanitized URL", sanitizedUrl(url.getPath()));
        customEvent.putCustomAttribute("HTTP Method", request.method());
        if (requestBody != null && requestBody.contentLength() != -1) {
            customEvent.putCustomAttribute("Data Size", requestBody.contentLength());
        }

        // Set response attributes
        customEvent.putCustomAttribute("Status Code", Integer.toString(response.code()));
        customEvent.putCustomAttribute("Elapsed Time", elapsed);
        final long contentLength = responseBody.contentLength();
        if (contentLength != -1) {
            customEvent.putCustomAttribute("Expected Content Length", contentLength);
        }
        final MediaType contentType = responseBody.contentType();
        if (contentType != null) {
            customEvent.putCustomAttribute("Content-Type", contentType.toString());
        }

        // Log custom event
        answers.logCustom(customEvent);
        return response;
    }

    String  sanitizedUrl (String path) {
        // Make sure path is less than 100 chars
        // Remove sensitive data
        return path;
    }
}