Merge pull request #5 from vemneyy/copilot/conduct-code-review

nfq: remove O(n) delayed-queue length scans from packet hot path

mdig/Makefile

@@ -1,6 +1,6 @@
 CC ?= cc
 OPTIMIZE ?= -Os
-CFLAGS += -std=gnu99 $(OPTIMIZE)
+CFLAGS += -std=gnu99 $(OPTIMIZE) -flto=auto
 CFLAGS_BSD = -Wno-address-of-packed-member
 CFLAGS_WIN = -static
 LIBS = -lpthread

nfq/packet_queue.c

@@ -6,7 +6,8 @@
 
 void rawpacket_queue_init(struct rawpacket_tailhead *q)
 {
-	TAILQ_INIT(q);
+	TAILQ_INIT(&q->head);
+	q->cached_count = 0;
 }
 void rawpacket_free(struct rawpacket *rp)
 {
@@ -16,8 +17,12 @@ void rawpacket_free(struct rawpacket *rp)
 struct rawpacket *rawpacket_dequeue(struct rawpacket_tailhead *q)
 {
 	struct rawpacket *rp;
-	rp = TAILQ_FIRST(q);
-	if (rp)	TAILQ_REMOVE(q, rp, next);
+	rp = TAILQ_FIRST(&q->head);
+	if (rp)
+	{
+		TAILQ_REMOVE(&q->head, rp, next);
+		q->cached_count--;
+	}
 	return rp;
 }
 void rawpacket_queue_destroy(struct rawpacket_tailhead *q)
@@ -52,19 +57,17 @@ struct rawpacket *rawpacket_queue(struct rawpacket_tailhead *q,const struct sock
 	rp->len=len;
 	rp->len_payload=len_payload;
 	
-	TAILQ_INSERT_TAIL(q, rp, next);
+	TAILQ_INSERT_TAIL(&q->head, rp, next);
+	q->cached_count++;
 	
 	return rp;
 }
 
 unsigned int rawpacket_queue_count(const struct rawpacket_tailhead *q)
 {
-	const struct rawpacket *rp;
-	unsigned int ct=0;
-	TAILQ_FOREACH(rp, q, next) ct++;
-	return ct;
+	return q->cached_count;
 }
 bool rawpacket_queue_empty(const struct rawpacket_tailhead *q)
 {
-	return !TAILQ_FIRST(q);
+	return !TAILQ_FIRST(&q->head);
 }

nfq/packet_queue.h

@@ -15,7 +15,11 @@ struct rawpacket
 	uint8_t *packet;
 	TAILQ_ENTRY(rawpacket) next;
 };
-TAILQ_HEAD(rawpacket_tailhead, rawpacket);
+TAILQ_HEAD(rawpacket_tailq, rawpacket);
+struct rawpacket_tailhead {
+	struct rawpacket_tailq head;
+	unsigned int cached_count;
+};
 
 void rawpacket_queue_init(struct rawpacket_tailhead *q);
 void rawpacket_queue_destroy(struct rawpacket_tailhead *q);