From af72b0889441e5ece199f782511d84d72fa6b88c Mon Sep 17 00:00:00 2001 From: Tom Lane Date: Tue, 12 Jul 2022 16:30:36 -0400 Subject: Invent qsort_interruptible(). Justin Pryzby reported that some scenarios could cause gathering of extended statistics to spend many seconds in an un-cancelable qsort() operation. To fix, invent qsort_interruptible(), which is just like qsort_arg() except that it will also do CHECK_FOR_INTERRUPTS every so often. This bloats the backend by a couple of kB, which seems like a good investment. (We considered just enabling CHECK_FOR_INTERRUPTS in the existing qsort and qsort_arg functions, but there are some callers for which that'd demonstrably be unsafe. Opt-in seems like a better way.) For now, just apply qsort_interruptible() in statistics collection. There's probably more places where it could be useful, but we can always change other call sites as we find problems. Back-patch to v14. Before that we didn't have extended stats on expressions, so that the problem was less severe. Also, this patch depends on the sort_template infrastructure introduced in v14. Tom Lane and Justin Pryzby Discussion: https://postgr.es/m/20220509000108.GQ28830@telsasoft.com --- src/include/port.h | 3 +++ 1 file changed, 3 insertions(+) (limited to 'src/include') diff --git a/src/include/port.h b/src/include/port.h index 82f63de3250..b405d0e7403 100644 --- a/src/include/port.h +++ b/src/include/port.h @@ -508,6 +508,9 @@ typedef int (*qsort_arg_comparator) (const void *a, const void *b, void *arg); extern void qsort_arg(void *base, size_t nel, size_t elsize, qsort_arg_comparator cmp, void *arg); +extern void qsort_interruptible(void *base, size_t nel, size_t elsize, + qsort_arg_comparator cmp, void *arg); + extern void *bsearch_arg(const void *key, const void *base, size_t nmemb, size_t size, int (*compar) (const void *, const void *, void *), -- cgit v1.2.3