Introducing Cacheismo

Cacheismo is scriptable object cache which can be used as a replacement for memcached. It supports memcache protocol (tcp and ascii only). It   automatically manages slab sizes, no user configuration is required.    Slabs are intelligently managed and they reconfigure themselves as per  the usage. PUT never ever fails. Details follow:     
- Efficient use of memory 

  Slab allocator used in memcached would waste memory if slab sizes
  and object sizes are not in sync. For example when using slab sizes
  of 64/128/256/512/1024 bytes object with size 513 is stored in 1024
  bytes slab, wasting almost half the memory. Cacheismo tries to 
  maintain memory used by object as close as possible to the object size

- Reclaimable Memory 

  Every byte is reclaimable in cacheismo. PUT never fails. You will
  never have slab full issues. More on memory management.

- True LRU support. Dependable cache

  Memcached will evict items from the slab in which object will be        placed. Cacheismo  will always use the LRU, irrespective of the size.   This ensures that the most  important data is always in the cache. No   surprises. If something is not in the cache, it either expired or was   least used.

- Server Side Scriptable objects

  The best part of using cacheismo is that is it fully scriptable
  in lua. Instead of cluttering your code with workarounds for 
  memcached read/write semantics, you can move that logic inside 
  cacheismo. 
  See Use cases for cacheismo 
      Rate Limiting Quota With Cacheismo
      Using Cacheismo Cluster For Real-time Analytics

  Sample objects map, set, quota and sliding window counters
  written in lua can be found in scripts directory. You could create 
  your own objects and place them in the scripts directory. 
  
  The interface for accessing scriptable objects is implemented via
  memcached get requests. For example: 
  get set:new:mykey     
  would create a new set object refered via myKey
  get set:put:myKey:a   
  would put key a in the set myKey
  get set:count:myKey   
  would return number of elements in the set
  get set:union:myKey1:myKey2   
  would return union of sets myKey1 and myKey2
  
  See scripts/set.lua for other functions.  
  
  I call this approach virtual keys. Reason for using it ...
  You can use existing memcached libraries to access cacheismo. 
  
Building - cacheismo depends on libevent and lua (luagit can 
also be used). Complete implementation is in about 5000 lines 
of code and fairly organised. 



Blue line is (memcachedTPS-cacheismoTPS)/memcachedTPS. This           essentially measures how much faster is memcached compared to         cacheismo. As you can see at max it is 20% faster.

Black line is (cacheismoHitRATE-memcachedHitRATE)/cacheismoHitRATE.   This essentially means how much memory efficient is cacheismo compared to memcached. For the first half of the test case we don't see any   difference. But in the second half cacheismo is at max about 80%      efficient. The reason for this behavior is that memcached can't       reassign slabs once they are used whereas cacheismo continues to      adjust with changing object sizes. Over time memcached commits memory to some slabs and hence its hit rate decreases over time.

Get source from GitHub

Google Group

UPDATE: Cacheismo Next Steps