Finding Keys In Cacheismo

In the last post I talked about how to do map-reduce like stuff with cacheimso. It occurred to me that their is no method to get all the keys. The global hashmap object now supports new method getPrefixMatchingKeys which as the name implies returns keys which match a certain prefix. Typically objects are stored with following template objectType$objectKey. Thus an object created by file quota.lua with key myKey will be stored with key quota$myKey. To do something with all the quota objects:
   
local keys = getHashMap():getPrefixMatchingKeys("quota$")
for k,v in pairs(keys) do 
   print(v)
end

If you would like the quota object itself to support say getAllKeys method then ...add this to quota.lua in scripts directory.



function getAllKeys() 

    local keys = getHashMap():getPrefixMatchingKeys("quota$")
    local result = ""
    for k,v in pairs(keys) do 
       result..v.."\n"  
    end
end

Now a get request with key quota:getAllKeys would return a new line separated list of all active quota objects in the map.

This is good enough but probably not very interesting. I am planning to support indexes as first class objects to make it faster to reach interesting objects in quick time. These indexes will automatically remove objects which are deleted or forced to expire because of LRU caching. So if you need to find all the quota objects that are close to quota limit, create an index on quota used value.