# AUTHOR: blink <blinketje@gmail.com>; blink#ruby-lang@irc.freenode.net
require 'rack/session/abstract/id'
require 'memcache'
module Rack
module Session
# 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.
#
# * Setting :expire_after to 0 would note to the Memcache server to hang
# onto the session data until it would drop it according to it's own
# specifications. However, the cookie sent to the client would expire
# immediately.
#
# Note that memcache does drop data before it may be listed to expire. For
# a full description of behaviour, please see memcache's documentation.
class Memcache < Abstract::ID
attr_reader :mutex, :pool
DEFAULT_OPTIONS = Abstract::ID::DEFAULT_OPTIONS.merge({
:namespace => 'rack:session',
:memcache_server => 'localhost:11211'
})
def initialize(app, options={})
super
@pool = MemCache.new @default_options[:memcache_server], @default_options
unless @pool.servers.any?{|s|s.alive?}
raise "#{self} unable to find server during initialization."
end
@mutex = Mutex.new
end
private
def get_session(env, sid)
session = sid && @pool.get(sid)
unless session and session.is_a?(Hash)
session = {}
lc = 0
@mutex.synchronize do
begin
raise RuntimeError, 'Unique id finding looping excessively' if (lc+=1) > 1000
sid = "%08x" % rand(0xffffffff)
ret = @pool.add(sid, session)
end until /^STORED/ =~ ret
end
end
class << session
@deleted = []
def delete key
(@deleted||=[]) << key
super
end
end
[sid, session]
rescue MemCache::MemCacheError, Errno::ECONNREFUSED # MemCache server cannot be contacted
warn "#{self} is unable to find server."
warn $!.inspect
return [ nil, {} ]
end
def set_session(env, sid)
session = env['rack.session']
options = env['rack.session.options']
expiry = options[:expire_after] || 0
o, s = @mutex.synchronize do
old_session = @pool.get(sid)
unless old_session.is_a?(Hash)
warn 'Session not properly initialized.' if $DEBUG
old_session = {}
@pool.add sid, old_session, expiry
end
session.instance_eval do
@deleted.each{|k| old_session.delete(k) } if defined? @deleted
end
@pool.set sid, old_session.merge(session), expiry
[old_session, session]
end
s.each do |k,v|
next unless o.has_key?(k) and v != o[k]
warn "session value assignment collision at #{k.inspect}:"+
"\n\t#{o[k].inspect}\n\t#{v.inspect}"
end if $DEBUG and env['rack.multithread']
return true
rescue MemCache::MemCacheError, Errno::ECONNREFUSED # MemCache server cannot be contacted
warn "#{self} is unable to find server."
warn $!.inspect
return false
end
end
end
end
