3 files changed, 36 insertions, 0 deletions
diff --git a/src/backend/regex/regc_nfa.c b/src/backend/regex/regc_nfa.c
index ae2dbe43fe8..f6dad013b54 100644
--- a/src/backend/regex/regc_nfa.c
+++ b/src/backend/regex/regc_nfa.c
@@ -174,11 +174,23 @@ newstate(struct nfa * nfa)
 {
 	struct state *s;
 
+	/*
+	 * This is a handy place to check for operation cancel during regex
+	 * compilation, since no code path will go very long without making a new
+	 * state.
+	 */
+	if (CANCEL_REQUESTED(nfa->v->re))
+	{
+		NERR(REG_CANCEL);
+		return NULL;
+	}
+
 	if (TooManyStates(nfa))
 	{
 		NERR(REG_ETOOBIG);
 		return NULL;
 	}
+
 	if (nfa->free != NULL)
 	{
 		s = nfa->free;
diff --git a/src/backend/regex/regcomp.c b/src/backend/regex/regcomp.c
index ca1ccc52023..d31d7f7b727 100644
--- a/src/backend/regex/regcomp.c
+++ b/src/backend/regex/regcomp.c
@@ -34,6 +34,8 @@
 
 #include "regex/regguts.h"
 
+#include "miscadmin.h"			/* needed by rcancelrequested() */
+
 /*
  * forward declarations, up here so forward datatypes etc. are defined early
  */
@@ -67,6 +69,7 @@ static long nfanode(struct vars *, struct subre *, FILE *);
 static int	newlacon(struct vars *, struct state *, struct state *, int);
 static void freelacons(struct subre *, int);
 static void rfree(regex_t *);
+static int	rcancelrequested(void);
 
 #ifdef REG_DEBUG
 static void dump(regex_t *, FILE *);
@@ -276,6 +279,7 @@ struct vars
 /* static function list */
 static const struct fns functions = {
 	rfree,						/* regfree insides */
+	rcancelrequested			/* check for cancel request */
 };
 
 
@@ -1893,6 +1897,22 @@ rfree(regex_t *re)
 	}
 }
 
+/*
+ * rcancelrequested - check for external request to cancel regex operation
+ *
+ * Return nonzero to fail the operation with error code REG_CANCEL,
+ * zero to keep going
+ *
+ * The current implementation is Postgres-specific.  If we ever get around
+ * to splitting the regex code out as a standalone library, there will need
+ * to be some API to let applications define a callback function for this.
+ */
+static int
+rcancelrequested(void)
+{
+	return InterruptPending && (QueryCancelPending || ProcDiePending);
+}
+
 #ifdef REG_DEBUG
 
 /*
diff --git a/src/backend/regex/regexec.c b/src/backend/regex/regexec.c
index 78ebdee39e4..0edb83c1099 100644
--- a/src/backend/regex/regexec.c
+++ b/src/backend/regex/regexec.c
@@ -595,6 +595,10 @@ cdissect(struct vars * v,
 	assert(t != NULL);
 	MDEBUG(("cdissect %ld-%ld %c\n", LOFF(begin), LOFF(end), t->op));
 
+	/* handy place to check for operation cancel */
+	if (CANCEL_REQUESTED(v->re))
+		return REG_CANCEL;
+
 	switch (t->op)
 	{
 		case '=':				/* terminal node */