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.
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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.
Constants
- DEFAULT_OPTIONS
Attributes
mutex[R]
pool[R]
Public Class Methods
new(app, options={})
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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)
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# 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()
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Calls superclass method
Rack::Session::Abstract::ID#generate_sid
# 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)
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# File lib/rack/session/memcache.rb, line 49 def get_session(env, sid) with_lock(env, [nil, {}]) 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)
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# 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, false) do @pool.set session_id, new_session, expiry session_id end end
with_lock(env, default=nil) { || ... }
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# File lib/rack/session/memcache.rb, line 78 def with_lock(env, default=nil) @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 default ensure @mutex.unlock if @mutex.locked? end