From 05329213c873dea69cbea2021e048eb814e00b4b Mon Sep 17 00:00:00 2001 From: Alexey Kondratov Date: Mon, 9 Nov 2020 22:29:48 +0300 Subject: [PATCH v3 1/3] Implement TimestampDifferenceMilliseconds() Many callers of TimestampDifference() actually want a difference in milliseconds. This new function allows them to get rid of unnecessary (and frequently unsafe) calculations of milliseconds from seconds and microseconds. --- src/backend/utils/adt/timestamp.c | 32 +++++++++++++++++++++++++++++++ src/include/utils/timestamp.h | 2 ++ 2 files changed, 34 insertions(+) diff --git a/src/backend/utils/adt/timestamp.c b/src/backend/utils/adt/timestamp.c index ea0ada704f..893fd467ba 100644 --- a/src/backend/utils/adt/timestamp.c +++ b/src/backend/utils/adt/timestamp.c @@ -1666,6 +1666,38 @@ TimestampDifference(TimestampTz start_time, TimestampTz stop_time, } } +/* + * TimestampDifferenceMilliseconds -- convert the difference between two + * timestamps into integer milliseconds. + * + * Both inputs must be ordinary finite timestamps (in current usage, + * they'll be results from GetCurrentTimestamp()). + * + * We expect start_time <= stop_time. If not, we return zero. We also + * always round up result in ms, since many callers may use this function + * to decide whether it is time to do something on timeout or not. + * That way, let them do it just in time or 1 ms later instead of 1 ms + * earlier. + */ +long +TimestampDifferenceMilliseconds(TimestampTz start_time, TimestampTz stop_time) +{ + TimestampTz diff = stop_time - start_time; + + if (diff <= 0) + return 0; + else + { + long msecs = (long) (diff / 1000); + + /* Round up if there is a reminder */ + if (diff % 1000 > 0) + msecs += 1; + + return msecs; + } +} + /* * TimestampDifferenceExceeds -- report whether the difference between two * timestamps is >= a threshold (expressed in milliseconds) diff --git a/src/include/utils/timestamp.h b/src/include/utils/timestamp.h index 16c3fd8ec9..d45bf2bb7b 100644 --- a/src/include/utils/timestamp.h +++ b/src/include/utils/timestamp.h @@ -72,6 +72,8 @@ extern TimestampTz GetSQLCurrentTimestamp(int32 typmod); extern Timestamp GetSQLLocalTimestamp(int32 typmod); extern void TimestampDifference(TimestampTz start_time, TimestampTz stop_time, long *secs, int *microsecs); +extern long TimestampDifferenceMilliseconds(TimestampTz start_time, + TimestampTz stop_time); extern bool TimestampDifferenceExceeds(TimestampTz start_time, TimestampTz stop_time, int msec); base-commit: 3f16cb505d1d734674da2a2cbf2104ceae22f9b4 -- 2.19.1