patch 8.2.5028: syntax regexp matching can be slow
Problem: Syntax regexp matching can be slow.
Solution: Adjust the counters for checking the timeout to check about once
per msec. (closes #10487, closes #2712)
diff --git a/src/regexp_nfa.c b/src/regexp_nfa.c
index 511b904..1e7cd9b 100644
--- a/src/regexp_nfa.c
+++ b/src/regexp_nfa.c
@@ -5649,11 +5649,27 @@
static int
nfa_did_time_out()
{
- if (nfa_time_limit != NULL && profile_passed_limit(nfa_time_limit))
+ static int tm_count = 0;
+
+ // Check for timeout once in 800 times to avoid excessive overhead from
+ // reading the clock. The value has been picked to check about once per
+ // msec on a modern CPU.
+ if (nfa_time_limit != NULL)
{
- if (nfa_timed_out != NULL)
- *nfa_timed_out = TRUE;
- return TRUE;
+ if (tm_count == 800)
+ {
+ if (profile_passed_limit(nfa_time_limit))
+ {
+ if (nfa_timed_out != NULL)
+ *nfa_timed_out = TRUE;
+ return TRUE;
+ }
+ // Only reset the count when not timed out, so that when it did
+ // timeout it keeps timing out until the time limit is changed.
+ tm_count = 0;
+ }
+ else
+ ++tm_count;
}
return FALSE;
}