test_gc.lua

-- luajit test_gc.lua 20000000 cast
-- luajit test_gc.lua 20000000 coat
local n, m = ...
n = n and tonumber(n) or 20000000
m = m or 'cast'

print(n, m)

local ffi = require 'ffi'
ffi.cdef"struct tst{ int64_t i, j, k, h; }"
ffi.cdef"struct tsts{ struct tst*p; }"
ffi.cdef"void *malloc(int i); void free(void *);"
local tst=ffi.typeof("struct tst")
local tstp=ffi.typeof("struct tst*")
local tsts=ffi.typeof("struct tsts")
local mtt = {__gc=function(t) ffi.C.free(t.p) end}
ffi.metatype(tsts, mtt)

local t = {}
for i=1,n do
    local g
    if m == 'cast' then
        local p = ffi.C.malloc(ffi.sizeof(tst))
        local s = ffi.cast(tstp, p)
        g = ffi.gc(s, ffi.C.free)
    elseif m == 'coat' then
        local p = ffi.C.malloc(ffi.sizeof(tst))
        g = ffi.new(tsts)
        g.p = p
    end
end