== SmartSessionStore

A session store that avoids the pitfalls usually associated with concurrent access to the session (see 
http://www.texperts.com/2007/05/01/race-conditions-in-rails-sessions-and-how-to-fix-them/)

Derived from SqlSessionStore, see http://railsexpress.de/blog/articles/2005/12/19/roll-your-own-sql-session-store

== Step 1

Generate your sessions table using rake db:sessions:create

== Step 2

Add the code below in an initializer
  ActionController::Base.session_store = :smart_session_store

Finally, depending on your database type, add

    SmartSessionStore.session_class = MysqlSession
or

    SmartSessionStore.session_class = PostgresqlSession
or
    SmartSessionStore.session_class = SqliteSession

after the initializer section in environment.rb

== Step 3 (optional)

If you want to use a database separate from your default one to store
your sessions, specify a configuration in your database.yml file (say
sessions), and establish the connection on SqlSession in
environment.rb:

   SqlSession.establish_connection :sessions

== Testing

To run tests with a certain database, set the DATABASE attribute.
You may need to configure the database.yml or your database server.

For example:

   rake test    # defaults to mysql
   rake test DATABASE=postgresql


== Performance Implications

There's no such thing as a free lunch. Whenever you make changes to the session you'll incur a small extra hit: we lock 
the current session row, we reload it to determine if there is updated data and we merge the changes before doing the 
actual save. On the flipside, we only save the session at all if changes have been made.

== IMPORTANT NOTES

1. You will need the binary drivers for Mysql or Postgresql.
   These have been verified to work:

   * ruby-postgres (0.7.1.2005.12.21) with PostgreSQL 8.1
   * postgres (0.7.9.2008.01.28) with PostgreSQL 8.3
   * pg (0.7.9.2008.10.13) with PostgreSQL 8.3
   * ruby-mysql 2.7.1 with Mysql 4.1
   * ruby-mysql 2.7.2 with Mysql 5.0

2. Tests have been done with SqlLiteSession, SqlSession, PostgresqlSession
   and MysqlSession. Feedback would be very much appreciated.