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

lib/method_profiler.rb

@@ -0,0 +1,43 @@
+# see https://samsaffron.com/archive/2017/10/18/fastest-way-to-profile-a-method-in-ruby
+class MethodProfiler
+  def self.patch(klass, methods, name)
+    patches = methods.map do |method_name|
+      <<~RUBY
+      unless defined?(#{method_name}__mp_unpatched)
+        alias_method :#{method_name}__mp_unpatched, :#{method_name}
+        def #{method_name}(*args, &blk)
+          unless prof = Thread.current[:_method_profiler]
+            return #{method_name}__mp_unpatched(*args, &blk)
+          end
+          begin
+            start = Process.clock_gettime(Process::CLOCK_MONOTONIC)
+            #{method_name}__mp_unpatched(*args, &blk)
+          ensure
+            data = (prof[:#{name}] ||= {duration: 0.0, calls: 0})
+            data[:duration] += Process.clock_gettime(Process::CLOCK_MONOTONIC) - start
+            data[:calls] += 1
+          end
+        end
+      end
+      RUBY
+    end.join("\n")
+
+    klass.class_eval patches
+  end
+
+  def self.start
+    Thread.current[:_method_profiler] = {
+      __start: Process.clock_gettime(Process::CLOCK_MONOTONIC)
+    }
+  end
+
+  def self.stop
+    finish = Process.clock_gettime(Process::CLOCK_MONOTONIC)
+    if data = Thread.current[:_method_profiler]
+      Thread.current[:_method_profiler] = nil
+      start = data.delete(:__start)
+      data[:total_duration] = finish - start
+    end
+    data
+  end
+end