FEATURE: Allow registration of detailed request logger

Detailed request loggers can be used to gather rich timing info
from all requests (which in turn can be forwarded to monitoring solution)

Middleware::RequestTracker.detailed_request_logger(->|env, data| do
   # do stuff with env and data
end

spec/components/middleware/request_tracker_spec.rb

@@ -21,7 +21,7 @@ describe Middleware::RequestTracker do
     def log_tracked_view(val)
       data = Middleware::RequestTracker.get_data(env(
         "HTTP_DISCOURSE_TRACK_VIEW" => val
-      ), ["200", { "Content-Type" => 'text/html' }])
+      ), ["200", { "Content-Type" => 'text/html' }], 0.2)
 
       Middleware::RequestTracker.log_request(data)
     end
@@ -40,19 +40,19 @@ describe Middleware::RequestTracker do
 
       data = Middleware::RequestTracker.get_data(env(
         "HTTP_USER_AGENT" => "AdsBot-Google (+http://www.google.com/adsbot.html)"
-      ), ["200", { "Content-Type" => 'text/html' }])
+      ), ["200", { "Content-Type" => 'text/html' }], 0.1)
 
       Middleware::RequestTracker.log_request(data)
 
       data = Middleware::RequestTracker.get_data(env(
         "HTTP_DISCOURSE_TRACK_VIEW" => "1"
-      ), ["200", {}])
+      ), ["200", {}], 0.1)
 
       Middleware::RequestTracker.log_request(data)
 
       data = Middleware::RequestTracker.get_data(env(
         "HTTP_USER_AGENT" => "Mozilla/5.0 (iPhone; CPU iPhone OS 8_1 like Mac OS X) AppleWebKit/600.1.4 (KHTML, like Gecko) Version/8.0 Mobile/12B410 Safari/600.1.4"
-      ), ["200", { "Content-Type" => 'text/html' }])
+      ), ["200", { "Content-Type" => 'text/html' }], 0.1)
 
       Middleware::RequestTracker.log_request(data)
 
@@ -65,5 +65,49 @@ describe Middleware::RequestTracker do
       expect(ApplicationRequest.page_view_crawler.first.count).to eq(1)
       expect(ApplicationRequest.page_view_anon_mobile.first.count).to eq(1)
     end
+
+  end
+
+  context "callbacks" do
+    def app(result, sql_calls: 0, redis_calls: 0)
+      lambda do |env|
+        sql_calls.times do
+          User.where(id: -100).first
+        end
+        redis_calls.times do
+          $redis.get("x")
+        end
+        result
+      end
+    end
+
+    let :logger do
+      ->(env, data) do
+        @env = env
+        @data = data
+      end
+    end
+
+    before do
+      Middleware::RequestTracker.register_detailed_request_logger(logger)
+    end
+
+    after do
+      Middleware::RequestTracker.register_detailed_request_logger(logger)
+    end
+
+    it "can correctly log detailed data" do
+      tracker = Middleware::RequestTracker.new(app([200, {}, []], sql_calls: 2, redis_calls: 2))
+      tracker.call(env)
+
+      timing = @data[:timing]
+      expect(timing[:total_duration]).to be > 0
+
+      expect(timing[:sql][:duration]).to be > 0
+      expect(timing[:sql][:calls]).to eq 2
+
+      expect(timing[:redis][:duration]).to be > 0
+      expect(timing[:redis][:calls]).to eq 2
+    end
   end
 end