Merge branch 'optimize_ldap' into 'master'

Optimize LDAP and add a search timeout

Related to #4282 

This merge request arranges some things in `access.rb` to facilitate some optimizations in EE (to come later). It also adds a 10 second timeout to all LDAP searches so the entire worker is not blocked if some query doesn't return in a reasonable amount of time. This timeout is configurable per LDAP server.

See merge request !2267

lib/gitlab/ldap/access.rb

@@ -5,7 +5,7 @@
 module Gitlab
   module LDAP
     class Access
-      attr_reader :adapter, :provider, :user
+      attr_reader :provider, :user
 
       def self.open(user, &block)
         Gitlab::LDAP::Adapter.open(user.ldap_identity.provider) do |adapter|
@@ -32,7 +32,7 @@ module Gitlab
       end
 
       def allowed?
-        if Gitlab::LDAP::Person.find_by_dn(user.ldap_identity.extern_uid, adapter)
+        if ldap_user
           return true unless ldap_config.active_directory
 
           # Block user in GitLab if he/she was blocked in AD
@@ -59,6 +59,10 @@ module Gitlab
       def ldap_config
         Gitlab::LDAP::Config.new(provider)
       end
+
+      def ldap_user
+        @ldap_user ||= Gitlab::LDAP::Person.find_by_dn(user.ldap_identity.extern_uid, adapter)
+      end
     end
   end
 end

lib/gitlab/ldap/adapter.rb

@@ -70,19 +70,25 @@ module Gitlab
       end
 
       def ldap_search(*args)
-        results = ldap.search(*args)
+        # Net::LDAP's `time` argument doesn't work. Use Ruby `Timeout` instead.
+        Timeout.timeout(config.timeout) do
+          results = ldap.search(*args)
 
-        if results.nil?
-          response = ldap.get_operation_result
+          if results.nil?
+            response = ldap.get_operation_result
 
-          unless response.code.zero?
-            Rails.logger.warn("LDAP search error: #{response.message}")
+            unless response.code.zero?
+              Rails.logger.warn("LDAP search error: #{response.message}")
+            end
+
+            []
+          else
+            results
           end
-
-          []
-        else
-          results
         end
+      rescue Timeout::Error
+        Rails.logger.warn("LDAP search timed out after #{config.timeout} seconds")
+        []
       end
     end
   end

lib/gitlab/ldap/config.rb

@@ -88,6 +88,10 @@ module Gitlab
         options['attributes']
       end
 
+      def timeout
+        options['timeout'].to_i
+      end
+
       protected
       def base_config
         Gitlab.config.ldap