class Rack::Session::Memcache

Rack::Session::Memcache provides simple cookie based session management. Session data is stored in memcached. The corresponding session key is maintained in the cookie. You may treat Session::Memcache as you would Session::Pool with the following caveats.

Note that memcache does drop data before it may be listed to expire. For a full description of behaviour, please see memcache's documentation.

Constants

DEFAULT_OPTIONS

Attributes

mutex[R]
pool[R]

Public Class Methods

new(app, options={}) click to toggle source
Calls superclass method Rack::Session::Abstract::ID.new
# File lib/rack/session/memcache.rb, line 29
def initialize(app, options={})
  super

  @mutex = Mutex.new
  mserv = @default_options[:memcache_server]
  mopts = @default_options.reject{|k,v| !MemCache::DEFAULT_OPTIONS.include? k }

  @pool = options[:cache] || MemCache.new(mserv, mopts)
  unless @pool.active? and @pool.servers.any?{|c| c.alive? }
    raise 'No memcache servers'
  end
end

Public Instance Methods

destroy_session(env, session_id, options) click to toggle source
# File lib/rack/session/memcache.rb, line 71
def destroy_session(env, session_id, options)
  with_lock(env) do
    @pool.delete(session_id)
    generate_sid unless options[:drop]
  end
end
generate_sid() click to toggle source
# File lib/rack/session/memcache.rb, line 42
def generate_sid
  loop do
    sid = super
    break sid unless @pool.get(sid, true)
  end
end
get_session(env, sid) click to toggle source
# File lib/rack/session/memcache.rb, line 49
def get_session(env, sid)
  with_lock(env) do
    unless sid and session = @pool.get(sid)
      sid, session = generate_sid, {}
      unless /^STORED/ =~ @pool.add(sid, session)
        raise "Session collision on '#{sid.inspect}'"
      end
    end
    [sid, session]
  end
end
set_session(env, session_id, new_session, options) click to toggle source
# File lib/rack/session/memcache.rb, line 61
def set_session(env, session_id, new_session, options)
  expiry = options[:expire_after]
  expiry = expiry.nil? ? 0 : expiry + 1

  with_lock(env) do
    @pool.set session_id, new_session, expiry
    session_id
  end
end
with_lock(env) { || ... } click to toggle source
# File lib/rack/session/memcache.rb, line 78
def with_lock(env)
  @mutex.lock if env['rack.multithread']
  yield
rescue MemCache::MemCacheError, Errno::ECONNREFUSED
  if $VERBOSE
    warn "#{self} is unable to find memcached server."
    warn $!.inspect
  end
  raise
ensure
  @mutex.unlock if @mutex.locked?
end