In client and leafnode results cache, populate new entry after pruning (

#5760)

Otherwise we might add the entry into the cache and then immediately
prune it afterwards, depending on luck/map iteration order.

Signed-off-by: Neil Twigg <neil@nats.io>

server/client.go

@@ -4016,9 +4016,8 @@ func (c *client) processInboundClientMsg(msg []byte) (bool, bool) {
 		// Match may use the subject here to populate a cache, so can not use bytesToString here.
 		r = acc.sl.Match(string(c.pa.subject))
 		if len(r.psubs)+len(r.qsubs) > 0 {
-			c.in.results[string(c.pa.subject)] = r
 			// Prune the results cache. Keeps us from unbounded growth. Random delete.
-			if len(c.in.results) > maxResultCacheSize {
+			if len(c.in.results) >= maxResultCacheSize {
 				n := 0
 				for subject := range c.in.results {
 					delete(c.in.results, subject)
@@ -4027,6 +4026,8 @@ func (c *client) processInboundClientMsg(msg []byte) (bool, bool) {
 					}
 				}
 			}
+			// Then add the new cache entry.
+			c.in.results[string(c.pa.subject)] = r
 		}
 	}
 

server/leafnode.go

@@ -2698,9 +2698,8 @@ func (c *client) processInboundLeafMsg(msg []byte) {
 	// Go back to the sublist data structure.
 	if !ok {
 		r = c.acc.sl.Match(subject)
-		c.in.results[subject] = r
 		// Prune the results cache. Keeps us from unbounded growth. Random delete.
-		if len(c.in.results) > maxResultCacheSize {
+		if len(c.in.results) >= maxResultCacheSize {
 			n := 0
 			for subj := range c.in.results {
 				delete(c.in.results, subj)
@@ -2709,6 +2708,8 @@ func (c *client) processInboundLeafMsg(msg []byte) {
 				}
 			}
 		}
+		// Then add the new cache entry.
+		c.in.results[subject] = r
 	}
 
 	// Collect queue names if needed.