Add entry source, either cache or query #63
Merged
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When adding instrumentation around DNS lookups, it would be very helpful to be able to distinguish if an entry came from the cache or a fresh query. This would allow to compute the cache hit rate and to calculate stats on the duration of DNS queries, ignoring when the cache is hit.
The
source
is eithercache
orquery
. It is returned with the entry fromlookupAsync
and it is added as an extra parameter to the callback fromlookup
.I didn't add the
source
parameter to the callback type definitions in https://github.com/szmarczak/cacheable-lookup/blob/master/index.d.ts#L102-L105 since theexpires
andttl
were already omitted. I wasn't sure if that was on purpose or if it was an omission.