Hi Igniters,
I'd like to share a case which was implemented in the previous version of
TC Bot. It is a kind of REST responses cache <RestParms, Response>:
Response {
Long tsRefreshed; // timestamp of the last call to real service
List<Build> builds; // a huge list of builds, most times it is not
changed.
}
And it seems timestamp (ts) offset in all entries pages is constant and it
requires 8 bytes. Data in builds storage will require a number of pages in
the durable memory, probably >10-20 pages.
So if REST (real service) responds with the same builds content only TS is
updated. After that, I did cache.put(restParms, reponse).
So my question is, will such update, which affects only 1 field causes mark
dirty for 1 page or for 20? I feel according to checkpoints amount that we
mark all pages as dirty even if the content is not modified. If so, I would
like to suggest a slight change to Ignite: for data pages mark as only that
pages, which has a modification in its content.
I understand that previous implementation in the Bot was quite naive (now
it is changed), but still, what if we will check for modifications by
mem-compare before marking? Mark dirty now seems to cause additional data
to be flushed to disk on next checkpoint.
I would appreciate if Native Persistence Experts can help me to find a
place in the code, where such updates are performed? (Maybe I miss
something).
Sincerely,
Dmitriy Pavlov
