LRU queue or heap data structure implementation?

Jay Nelson <>
Wed Nov 23 16:56:42 CET 2005


I have wanted to write a similar thing for a while now.  I would do it 
with processes:

1) Create a server to manage the ets table (eventually you would want 
this distributed), which handles the following messages:
    - New: create a new process and insert in ets with key
    - Locate: see if a key leads to an existing process
    - Reap: remove key and process from ets

2) Each process has a receive which does the following:
    - GetData: returns the state and loops
    - after LRU_Timeout: calls ets manager with Reap(SelfKey) then dies


Creating a new process causes it to read data from DB, construct 
corresponding internal data representation and then wait for callers to 
request the reformatted data.  Once it is idle for a long enough period 
of time it dies.  If there is a request prior to expiration, the 
LRU_Timeout starts over so every request is a new lease on life.


Variations:

a) Vary the LRU_Timeout based on the difficulty of restart.

b) Add supervisors to organize processes into hierarchies of related 
data (or just link the related processes as they are created by 
cascading spawns).  Kill the supervisor (or one of the networked 
processes) to remove all dependencies from memory.

c) Use a reaper process which monitors total memory consumption.  Have 
it broadcast a message to hasten the demise of any process which deems 
it can time out early in a memory pinch.

jay




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