masochism
=========
 
The masochism plugin provides an easy solution for Ruby on Rails applications to
work in a replicated database environment. Connection proxy sends some database
queries (those in a transaction, update statements, and ActiveRecord::Base#reload) 
to a master database, and the rest to the slave database. 
 
The ActiveReload::MasterDatabase model uses a 'master_database' setting that
can either be defined for all of your environments, or for each environment as
a nested declaration:
 
  # config/database.yml
  login: &login
    adapter: postgresql
    host: localhost
    port: 5432
 
  production:
    database: production_slave_database_name
    <<: *login
 
  master_database:
    database: production_master_database_name
    <<: *login
 
  staging:
    database: staging_database_name
    host: slave-db-pool.local
    <<: *login
    master_database: 
      database: staging_database_name
      host: master-db-server.local
      <<: *login
 
  development: # Does not use masochism
    database: development_database_name
    <<: *login
 
To setup:
 
Whether you want this in production only, or maybe just your deployment server, 
is up to you. Just call the following method in your desired environment file.
 
  ActiveReload::ConnectionProxy.setup!
 
Some suggestions:
 
  * in a config/initializer
  * config.after_initialize block
 
If you are using the Litespeed web server, child processes are initialized on 
creation, which means any setup done in an environment file will be effectively 
ignored. A brief discussion of the problem is posted here:
http://litespeedtech.com/support/wiki/doku.php?id=litespeed_wiki:rails:memcache
 
One solution for Litespeed users is to check the connection at your first request
and do the setup! call if your connection hasn't been initialized, like:
 
class ApplicationController < ActionController::Base
  prepend_before_filter do |controller|
    ActiveReload::ConnectionProxy.setup! unless ActiveRecord::Base.connection.is_a? ActiveReload::ConnectionProxy
  end
  ...
end
 
 
If you want a model to always use the Master database, you can inherit 
ActiveRelaod::MasterDatabase.  Any models with their own database connection
will not be affected.
 
Setting up your own proxies:
 
  # Sets up MyMaster's connection as the master database connection for User.
  ActiveReload::ConnectionProxy.setup_for MyMaster, User
  
Using the MasterFilter class is quite simple. If you have any actions you know require 
the Master DB for both reads and writes simply do the following:
 
class RandomController < ApplicationController
  around_filter MasterFilter, :only => [:show, :edit, :update]
  
  ...
end