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local M = {} -- the module
local ffi = require('ffi')
-- Beware that the timeout is only considered at certain points in time;
-- approximately at multiples of KR_CONN_RTT_MAX.
M.timeout = 3*sec
M.callback = ffi.cast("kr_stale_cb",
function (ttl) --, name, type, qry)
--log('[ ][stal] => called back with TTL: ' .. tostring(ttl))
if ttl + 3600 * 24 > 0 then -- at most one day stale
return 1
else
return -1
end
end)
M.layer = {
produce = function (state, req)
req = kres.request_t(req)
local qry = req:current()
-- Don't do anything for priming, prefetching, etc.
-- TODO: not all cases detected ATM.
if qry.flags.NO_CACHE then return state end
local now = ffi.C.kr_now()
local deadline = qry.creation_time_mono + M.timeout
if now > deadline or qry.flags.NO_NS_FOUND then
if verbose() then
log('[ ][stal] => no reachable NS, using stale data')
end
qry.stale_cb = M.callback
-- TODO: probably start the same request that doesn't stale-serve,
-- but first we need some detection of non-interactive / internal requests.
-- resolve(kres.dname2str(qry.sname), qry.stype, qry.sclass)
end
return state
end,
}
return M
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