1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
|
-- SPDX-License-Identifier: GPL-3.0-or-later
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_debug(ffi.C.SRVSTALE, ' => 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)
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
log_debug(ffi.C.LOG_GRP_SRVSTALE, ' => no reachable NS, using stale data')
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
|
