Hi, On Wed, Sep 04, 2024 at 02:05:46PM +0900, Kyotaro Horiguchi wrote: > At Tue, 3 Sep 2024 13:48:59 +0900, Michael Paquier <mich...@paquier.xyz> > wrote in > > Hi all, > > > > The last TODO item I had in my bucket about the generalization of > > pgstats is the option to a better control on the flush of the stats > > depending on the kind for fixed-numbered stats. Currently, this is > > controlled by pgstat_report_stat(), that includes special handling for > > WAL, IO and SLRU stats, with two generic concepts: > > - Check if there are pending entries, allowing a fast-path exit. > > - Do the actual flush, with a recheck on pending entries. > > > > SLRU and IO control that with one variable each, and WAL uses a > > routine for the same called pgstat_have_pending_wal(). Please find > > attached a patch to generalize the concept, with two new callbacks > > that can be used for fixed-numbered stats. SLRU, IO and WAL are > > switched to use these (the two pgstat_flush_* routines have been kept > > on purpose). This brings some clarity in the code, by making > > have_iostats and have_slrustats static in their respective files. The > > two pgstat_flush_* wrappers do not need a boolean as return result. > > The generalization sounds good to me, and hiding the private flags in > private places also seems good.
+1 on the idea. > Regarding pgstat_io_flush_cb, I think it no longer needs to check the > have_iostats variable, and that check should be moved to the new > pgstat_flush_io(). The same applies to pgstat_wal_flush_cb() (and > pgstat_flush_wal()). As for pgstat_slru_flush_cb, it simply doesn't > need the check anymore. Agree. Another option could be to add only one callback (the flush_fixed_cb one) and get rid of the have_fixed_pending_cb one. Then add an extra parameter to the flush_fixed_cb that would only check if there is pending stats (without flushing them). I think those 2 callbacks are highly related that's why I think we could "merge" them, thoughts? Regards, -- Bertrand Drouvot PostgreSQL Contributors Team RDS Open Source Databases Amazon Web Services: https://aws.amazon.com
