Document site statistics APIce-6064-geo-sql-query-for-counting-projects-with-wikis-is-very-slow

1 files changed, 21 insertions, 0 deletions

diff --git a/app/models/site_statistic.rb b/app/models/site_statistic.rb
index c07233c48ed..9c9c3172fe6 100644
--- a/app/models/site_statistic.rb
+++ b/app/models/site_statistic.rb
@@ -5,18 +5,28 @@ class SiteStatistic < ActiveRecord::Base
   COUNTER_ATTRIBUTES = %w(repositories_count wikis_count).freeze
   REQUIRED_SCHEMA_VERSION = 20180629153018
 
+  # Tracks specific attribute
+  #
+  # @param [String] raw_attribute must be one of the values listed in COUNTER_ATTRIBUTES
   def self.track(raw_attribute)
     with_statistics_available(raw_attribute) do |attribute|
       SiteStatistic.update_all(["#{attribute} = #{attribute}+1"])
     end
   end
 
+  # Untracks specific attribute
+  #
+  # @param [String] raw_attribute must be one of the values listed in COUNTER_ATTRIBUTES
   def self.untrack(raw_attribute)
     with_statistics_available(raw_attribute) do |attribute|
       SiteStatistic.update_all(["#{attribute} = #{attribute}-1 WHERE #{attribute} > 0"])
     end
   end
 
+  # Wrapper for track/untrack operations with basic validations and enforced requirements
+  #
+  # @param [String] raw_attribute must be one of the values listed in COUNTER_ATTRIBUTES
+  # @yield [String] attribute quoted to be used inside SQL / Arel query
   def self.with_statistics_available(raw_attribute)
     unless raw_attribute.in?(COUNTER_ATTRIBUTES)
       raise ArgumentError, "Invalid attribute: '#{raw_attribute}' to '#{caller_locations(1, 1)[0].label}' method. " \
@@ -33,6 +43,9 @@ class SiteStatistic < ActiveRecord::Base
     yield(attribute)
   end
 
+  # Returns a site statistic record with tracked information
+  #
+  # @return [SiteStatistic] record with tracked information
   def self.fetch
     SiteStatistic.transaction(requires_new: true) do
       SiteStatistic.first_or_create!
@@ -41,10 +54,18 @@ class SiteStatistic < ActiveRecord::Base
     retry
   end
 
+  # Return whether required schema change is available
+  #
+  # This is needed in order to degrade gracefully when testing schema migrations
+  #
+  # @return [Boolean] whether schema is available
   def self.available?
     @available_flag ||= ActiveRecord::Migrator.current_version >= REQUIRED_SCHEMA_VERSION
   end
 
+  # Resets cached column information
+  #
+  # This is called during schema migration specs, in order to reset internal cache state
   def self.reset_column_information
     @available_flag = nil