Added cache for application settings (Setting model).

Once the values are cached, only one database query is done at each user request (to check if the cache is still valid). git-svn-id: http://redmine.rubyforge.org/svn/trunk@685 e93f8b46-1217-0410-a6f0-8f06a7374b81

Added cache for application settings (Setting model).
Once the values are cached, only one database query is done at each user request (to check if the cache is still valid). git-svn-id: http://redmine.rubyforge.org/svn/trunk@685 e93f8b46-1217-0410-a6f0-8f06a7374b81
6bdc13b3 · Jean-Philippe Lang · 404bfce4 · 6bdc13b3 · 6bdc13b3 · 6bdc13b3
Commit 6bdc13b3 authored Aug 31, 2007 by Jean-Philippe Lang
Showing with 47 additions and 10 deletions

application.rb app/controllers/application.rb +1 -0

setting.rb app/models/setting.rb +35 -10

065_add_settings_updated_on.rb db/migrate/065_add_settings_updated_on.rb +11 -0

No files found.
--- a/app/controllers/application.rb
+++ b/app/controllers/application.rb
@@ -32,6 +32,7 @@ class ApplicationController < ActionController::Base
  end
  
  def user_setup
+    Setting.check_cache
    if session[:user_id]
      # existing session
      User.current = User.find(session[:user_id])

--- a/app/models/setting.rb
+++ b/app/models/setting.rb
@@ -23,25 +23,28 @@ class Setting < ActiveRecord::Base
  validates_uniqueness_of :name
  validates_inclusion_of :name, :in => @@available_settings.keys
  validates_numericality_of :value, :only_integer => true, :if => Proc.new { |setting| @@available_settings[setting.name]['format'] == 'int' }  
-  
-  def self.get(name)
-    name = name.to_s
-    setting = find_by_name(name)
-    setting ||= new(:name => name, :value => @@available_settings[name]['default']) if @@available_settings.has_key? name
-    setting
-  end
-  
+
+  # Hash used to cache setting values
+  @cached_settings = {}
+  @cached_cleared_on = Time.now
+    
+  # Returns the value of the setting named name
  def self.[](name)
-    get(name).value
+    value = @cached_settings[name]
+    value ? value : (@cached_settings[name] = find_or_default(name).value)
  end
  
  def self.[]=(name, value)
-    setting = get(name)
+    setting = find_or_default(name)
    setting.value = (value ? value.to_s : "")
+    @cached_settings[name] = nil
    setting.save
    setting.value
  end
  
+  # Defines getter and setter for each setting
+  # Then setting values can be read using: Setting.some_setting_name
+  # or set using Setting.some_setting_name = "some value"
  @@available_settings.each do |name, params|
    src = <<-END_SRC
    def self.#{name}
@@ -58,4 +61,26 @@ class Setting < ActiveRecord::Base
    END_SRC
    class_eval src, __FILE__, __LINE__
  end
+  
+  # Checks if settings have changed since the values were read
+  # and clears the cache hash if it's the case
+  # Called once per request
+  def self.check_cache
+    settings_updated_on = Setting.maximum(:updated_on)
+    if settings_updated_on && @cached_cleared_on <= settings_updated_on
+      @cached_settings.clear
+      @cached_cleared_on = Time.now
+      logger.info "Settings cache cleared." if logger
+    end
+  end
+  
+private
+  # Returns the Setting instance for the setting named name
+  # (record found in database or new record with default value)
+  def self.find_or_default(name)
+    name = name.to_s
+    raise "There's no setting named #{name}" unless @@available_settings.has_key?(name)    
+    setting = find_by_name(name)
+    setting ||= new(:name => name, :value => @@available_settings[name]['default']) if @@available_settings.has_key? name
+  end
 end
--- a/db/migrate/065_add_settings_updated_on.rb
+++ b/db/migrate/065_add_settings_updated_on.rb
+class AddSettingsUpdatedOn < ActiveRecord::Migration
+  def self.up
+    add_column :settings, :updated_on, :timestamp
+    # set updated_on
+    Setting.find(:all).each(&:save)
+  end
+
+  def self.down
+    remove_column :settings, :updated_on
+  end
+end