def multi
      old, Thread.current[:dalli_multi] = Thread.current[:dalli_multi], true
      yield
    ensure
      Thread.current[:dalli_multi] = old
    end
def multi
      old, Thread.current[:dalli_multi] = Thread.current[:dalli_multi], true
      yield
    ensure
      Thread.current[:dalli_multi] = old
    end
Dalli::Client is the main class which developers will use to interact with
 the memcached server.  Usage:

   Dalli::Client.new(['localhost:11211:10', 'cache-2.example.com:11211:5', '192.168.0.1:22122:5', '/var/run/memcached/socket'],
                   :threadsafe => true, :failover => true, :expires_in => 300)

 servers is an Array of "host:port:weight" where weight allows you to distribute cache unevenly.
 Both weight and port are optional.  If you pass in nil, Dalli will use the <tt>MEMCACHE_SERVERS</tt>
 environment variable or default to 'localhost:11211' if it is not present.  Dalli also supports
 the ability to connect to Memcached on localhost through a UNIX socket.  To use this functionality,
 use a full pathname (beginning with a slash character '/') in place of the "host:port" pair in
 the server configuration.

 Options:
 - :namespace - prepend each key with this value to provide simple namespacing.
 - :failover - if a server is down, look for and store values on another server in the ring.  Default: true.
 - :threadsafe - ensure that only one thread is actively using a socket at a time. Default: true.
 - :expires_in - default TTL in seconds if you do not pass TTL as a parameter to an individual operation, defaults to 0 or forever
 - :compress - defaults to false, if true Dalli will compress values larger than 1024 bytes before sending them to memcached.
 - :serializer - defaults to Marshal
 - :compressor - defaults to zlib
 - :cache_nils - defaults to false, if true Dalli will not treat cached nil values as 'not found' for #fetch operations.


 The standard memcached instruction set


 Turn on quiet aka noreply support.
 All relevant operations within this block will be effectively
 pipelined as Dalli will use 'quiet' operations where possible.
 Currently supports the set, add, replace and delete operations.