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Diffstat (limited to '')
| -rw-r--r-- | modules/serve_stale/serve_stale.lua | 44 |
1 files changed, 44 insertions, 0 deletions
diff --git a/modules/serve_stale/serve_stale.lua b/modules/serve_stale/serve_stale.lua new file mode 100644 index 0000000..cf19be1 --- /dev/null +++ b/modules/serve_stale/serve_stale.lua @@ -0,0 +1,44 @@ +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 + |