Always use the stored timestamp when checking for updates

Rely on the timestamp stored in the filesystem before updating
with a new value: the in-memory hash map could be stale and
it may risk to push back the latest updated timestamp for the indexed
values.

Example: you want to manually change the filesystem time-stamp value
for triggering some ad-hoc auto-reindexing. The in-memory value won't
be current anymore and risk to create more damage than benefit.

Before this change, FlusherRunner::store kept storing a null timestamp,
and was doing so for each call to the latter method, unexpectedly. With
this change, a new timestamp gets stored only if it is later than the
current one, or if it is the first known one.

Change-Id: Ib7ac06bdba25b6b0a24ada282c78cf123e3d6529
1 file changed