Fix and simplify some usages of TimestampDifference().
Introduce TimestampDifferenceMilliseconds() to simplify callers
that would rather have the difference in milliseconds, instead of
the select()-oriented seconds-and-microseconds format. This gets
rid of at least one integer division per call, and it eliminates
some apparently-easy-to-mess-up arithmetic.
Two of these call sites were in fact wrong:
* pg_prewarm's autoprewarm_main() forgot to multiply the seconds
by 1000, thus ending up with a delay 1000X shorter than intended.
That doesn't quite make it a busy-wait, but close.
* postgres_fdw's pgfdw_get_cleanup_result() thought it needed to compute
microseconds not milliseconds, thus ending up with a delay 1000X longer
than intended. Somebody along the way had noticed this problem but
misdiagnosed the cause, and imposed an ad-hoc 60-second limit rather
than fixing the units. This was relatively harmless in context, because
we don't care that much about exactly how long this delay is; still,
it's wrong.
There are a few more callers of TimestampDifference() that don't
have a direct need for seconds-and-microseconds, but can't use
TimestampDifferenceMilliseconds() either because they do need
microsecond precision or because they might possibly deal with
intervals long enough to overflow 32-bit milliseconds. It might be
worth inventing another API to improve that, but that seems outside
the scope of this patch; so those callers are untouched here.
Given the fact that we are fixing some bugs, and the likelihood
that future patches might want to back-patch code that uses this
new API, back-patch to all supported branches.
Alexey Kondratov and Tom Lane
Discussion: https://postgr.es/m/3b1c053a21c07c1ed5e00be3b2b855ef@postgrespro.ru
Branch
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master
Details
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https://git.postgresql.org/pg/commitdiff/ec29427ce2a451e7fef7a22de6db8147d8a80994
Modified Files
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contrib/pg_prewarm/autoprewarm.c | 12 ++---
contrib/postgres_fdw/connection.c | 9 +---
src/backend/access/transam/xlog.c | 85 +++++++++++-------------------
src/backend/replication/walreceiverfuncs.c | 25 ++-------
src/backend/replication/walsender.c | 8 +--
src/backend/utils/adt/timestamp.c | 38 +++++++++++--
src/include/utils/timestamp.h | 2 +
7 files changed, 80 insertions(+), 99 deletions(-)