Added Sherlock, a custom profiling tool for GitLab

Sherlock will be a new GitLab specific tool for measuring the
performance of Rails requests (and SideKiq jobs at some point). Some of
the things that are currently tracked:

* SQL queries along with their timings, backtraces and query plans
  (using "EXPLAIN ANALYZE" for PostgreSQL and regular "EXPLAIN" for
  MySQL)
* Timings of application files (including views) on a per line basis
* Some meta data such as the request method, path, total duration, etc

More tracking (e.g. Rugged or gitlab-shell timings) might be added in
the future.

Sherlock will replace any existing tools we have used so far (e.g.
active_record_query_trace and rack-mini-profiler), hence the
corresponding Gems have been removed from the Gemfile.

Sherlock can be enabled by starting Rails as following:

    ENABLE_SHERLOCK=1 bundle exec rails s

Recorded transactions can be found at `/sherlock/transactions`.

4 files changed, 54 insertions, 10 deletions

diff --git a/config/initializers/rack_profiler.rb b/config/initializers/rack_profiler.rb
deleted file mode 100644
index 7710eeac453..00000000000
--- a/config/initializers/rack_profiler.rb
+++ /dev/null
@@ -1,10 +0,0 @@
-if Rails.env.development?
-  require 'rack-mini-profiler'
-
-  # initialization is skipped so trigger it
-  Rack::MiniProfilerRails.initialize!(Gitlab::Application)
-
-  Rack::MiniProfiler.config.position = 'right'
-  Rack::MiniProfiler.config.start_hidden = false
-  Rack::MiniProfiler.config.skip_paths << '/teaspoon'
-end
diff --git a/config/initializers/sherlock.rb b/config/initializers/sherlock.rb
new file mode 100644
index 00000000000..42b0d78c85f
--- /dev/null
+++ b/config/initializers/sherlock.rb
@@ -0,0 +1,5 @@
+if Gitlab::Sherlock.enabled?
+  Gitlab::Application.configure do |config|
+    config.middleware.use(Gitlab::Sherlock::Middleware)
+  end
+end
diff --git a/config/locales/sherlock.en.yml b/config/locales/sherlock.en.yml
new file mode 100644
index 00000000000..5c146b172b1
--- /dev/null
+++ b/config/locales/sherlock.en.yml
@@ -0,0 +1,36 @@
+en:
+  sherlock:
+    title: Sherlock
+    delete_all_transactions: Delete All Transactions
+    introduction: >
+      Below is a list of all transactions recorded by Sherlock. Requests to
+      Sherlock's own routes are ignored.
+    no_transactions: No transactions to show
+    no_queries: No queries to show
+    no_file_samples: No file samples to show
+    all_transactions: All Transactions
+    transaction: Transaction
+    query: Query
+    file_sample: File Sample
+    type: Type
+    path: Path
+    time: Time
+    queries: Queries
+    finished_at: Finished at
+    ago: ago
+    view: View
+    seconds: seconds
+    milliseconds: ms
+    general: General
+    id: ID
+    time_inclusive: Time (inclusive)
+    backtrace: Backtrace
+    application_backtrace: Application Backtrace
+    full_backtrace: Full Backtrace
+    origin: Origin
+    line: line
+    line_capitalized: Line
+    copy_to_clipboard: Copy to clipboard
+    query_plan: Query Plan
+    events: Events
+    percent: '%'
diff --git a/config/routes.rb b/config/routes.rb
index 990a00e3d0b..7d8a546a64c 100644
--- a/config/routes.rb
+++ b/config/routes.rb
@@ -2,6 +2,19 @@ require 'sidekiq/web'
 require 'api/api'
 
 Gitlab::Application.routes.draw do
+  if Gitlab::Sherlock.enabled?
+    namespace :sherlock do
+      resources :transactions, only: [:index, :show] do
+        resources :queries, only: [:show]
+        resources :file_samples, only: [:show]
+
+        collection do
+          delete :destroy_all
+        end
+      end
+    end
+  end
+
   namespace :ci do
     # CI API
     Ci::API::API.logger Rails.logger