diff options
| author | Tom Lane | 2023-01-26 22:09:12 +0000 |
|---|---|---|
| committer | Tom Lane | 2023-01-26 22:09:12 +0000 |
| commit | 3a28d78089289794fda86cdbd275fc4756c6c6aa (patch) | |
| tree | e7a3e527c46c57d272a7a67ef3d353f33a16e5de /src/backend/replication | |
| parent | 24ff700f6aee2e8b915399e03934c6fe9b593d3f (diff) | |
Improve TimestampDifferenceMilliseconds to cope with overflow sanely.
We'd like to use TimestampDifferenceMilliseconds with the stop_time
possibly being TIMESTAMP_INFINITY, but up to now it's disclaimed
responsibility for overflow cases. Define it to clamp its output to
the range [0, INT_MAX], handling overflow correctly. (INT_MAX rather
than LONG_MAX seems appropriate, because the function is already
described as being intended for calculating wait times for WaitLatch
et al, and that infrastructure only handles waits up to INT_MAX.
Also, this choice gets rid of cross-platform behavioral differences.)
Having done that, we can replace some ad-hoc code in walreceiver.c
with a simple call to TimestampDifferenceMilliseconds.
While at it, fix some buglets in existing callers of
TimestampDifferenceMilliseconds: basebackup_copy.c had not read the
memo about TimestampDifferenceMilliseconds never returning a negative
value, and postmaster.c had not read the memo about Min() and Max()
being macros with multiple-evaluation hazards. Neither of these
quite seem worth back-patching.
Patch by me; thanks to Nathan Bossart for review.
Discussion: https://postgr.es/m/3126727.1674759248@sss.pgh.pa.us
Diffstat (limited to 'src/backend/replication')
| -rw-r--r-- | src/backend/replication/walreceiver.c | 12 |
1 files changed, 3 insertions, 9 deletions
diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c index e95398db05..b0cfddd548 100644 --- a/src/backend/replication/walreceiver.c +++ b/src/backend/replication/walreceiver.c @@ -445,7 +445,7 @@ WalReceiverMain(void) pgsocket wait_fd = PGINVALID_SOCKET; int rc; TimestampTz nextWakeup; - int nap; + long nap; /* * Exit walreceiver if we're not in recovery. This should not @@ -528,15 +528,9 @@ WalReceiverMain(void) for (int i = 0; i < NUM_WALRCV_WAKEUPS; ++i) nextWakeup = Min(wakeup[i], nextWakeup); - /* - * Calculate the nap time. WaitLatchOrSocket() doesn't accept - * timeouts longer than INT_MAX milliseconds, so we limit the - * result accordingly. Also, we round up to the next - * millisecond to avoid waking up too early and spinning until - * one of the wakeup times. - */ + /* Calculate the nap time, clamping as necessary. */ now = GetCurrentTimestamp(); - nap = (int) Min(INT_MAX, Max(0, (nextWakeup - now + 999) / 1000)); + nap = TimestampDifferenceMilliseconds(now, nextWakeup); /* * Ideally we would reuse a WaitEventSet object repeatedly |