Re: Lua Performance, IO / Regexp
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- Subject: Re: Lua Performance, IO / Regexp
- From: Mariano Kamp <mariano.kamp@...>
- Date: 2007年10月23日 08:53:10 +0200
Thanks everyone for the tips and tricks.
I changed all the uses of global variables to local variables, got
rid of the metatable and substituted table.insert with the table
[#table+1] = value - syntax. Combined this resulted in a roughly 10%
better performance.
A huge help was to preliminary check the current line with
string.find. That reduced the time from about 5 to 3 seconds.
I have not been able to compile lpeg yet, but will have a look at it
later.
Quick follow up question to the use of local variables to store
functions: When I use local s_find = string.find can I still use the
"object oriented" syntax like line ="abc"; hit = line:find("xyz")??
Cheers,
Mariano
local PATTERN = "GET /ongoing/When/%d%d%dx/(%d%d%d%d/%d%d/%d%d/[^ .]+) "
local hits = {}
local s_match = string.match
local s_find = string.find
for line in io.lines("o100k.ap") do
if s_find( line, 'GET /ongoing/When/200x/' ) then
local article_key = s_match(line, PATTERN)
if (article_key) then hits[article_key] = (hits[article_key] or 0)
+ 1 end
end
end
local hits_index = {}
for article_key in pairs(hits) do
hits_index[#hits_index+1] = article_key
end
table.sort(hits_index, function(x,y) return hits[x] > hits[y] end)
for i, article_key in ipairs(hits_index) do
print(i .. ". " .. article_key .. " : " .. hits[article_key])
if i == 10 then break end
end