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# 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
@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?(&:alive?)
raise 'No memcache servers'
end
end
def generate_sid
loop do
sid = super
break sid unless @pool.get(sid, true)
end
end
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
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
def destroy_session(env, session_id, options)
with_lock(env) do
@pool.delete(session_id)
generate_sid unless options[:drop]
end
end
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
end
end
end