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-- Lua script to perform cache checking for bayes classification
-- This script accepts the following parameters:
-- key1 - cache id
-- key3 - is spam (1 or 0)
-- key3 - configuration table in message pack
local cache_id = KEYS[1]
local is_spam = KEYS[2]
local conf = cmsgpack.unpack(KEYS[3])
cache_id = string.sub(cache_id, 1, conf.cache_elt_len)
-- Try each prefix that is in Redis (as some other instance might have set it)
for i = 0, conf.cache_max_keys do
local prefix = conf.cache_prefix .. string.rep("X", i)
local have = redis.call('HGET', prefix, cache_id)
if have then
-- Already in cache, but is_spam changes when relearning
redis.call('HSET', prefix, cache_id, is_spam)
return false
end
end
local added = false
local lim = conf.cache_max_elt
for i = 0, conf.cache_max_keys do
if not added then
local prefix = conf.cache_prefix .. string.rep("X", i)
local count = redis.call('HLEN', prefix)
if count < lim then
-- We can add it to this prefix
redis.call('HSET', prefix, cache_id, is_spam)
added = true
end
end
end
if not added then
-- Need to expire some keys
local expired = false
for i = 0, conf.cache_max_keys do
local prefix = conf.cache_prefix .. string.rep("X", i)
local exists = redis.call('EXISTS', prefix)
if exists then
if not expired then
redis.call('DEL', prefix)
redis.call('HSET', prefix, cache_id, is_spam)
-- Do not expire anything else
expired = true
elseif i > 0 then
-- Move key to a shorter prefix, so we will rotate them eventually from lower to upper
local new_prefix = conf.cache_prefix .. string.rep("X", i - 1)
redis.call('RENAME', prefix, new_prefix)
end
end
end
end
return true
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