Speed up appending of sigs to a sig group head by using a tail ptr.

src/detect-siggroup.c

@@ -81,14 +81,11 @@ int SigGroupAppend(DetectAddressGroup *ag, Signature *s) {
     if (ag->sh->head == NULL) {
         /* put it as first in the list */
         ag->sh->head = sg;
+        ag->sh->tail = sg;
     } else {
         /* append to the list */
-        tmp_sg = ag->sh->head;
-        while (tmp_sg->next != NULL) {
-            tmp_sg = tmp_sg->next;
-        }
-
-        tmp_sg->next = sg;
+        tmp_sg = ag->sh->tail;
+        ag->sh->tail = tmp_sg->next = sg;
     }
     ag->sh->sig_cnt++;
     return 0;

src/detect.h

@@ -109,6 +109,7 @@ typedef struct _SigGroupHead {
 
     /* list of signature containers */
     SigGroupContainer *head;
+    SigGroupContainer *tail;
     u_int32_t sig_cnt;
     u_int32_t refcnt;
 
@@ -138,9 +139,9 @@ enum {
     DETECT_METADATA,
     DETECT_REFERENCE,
     DETECT_MSG,
-    DETECT_CONTENT,
-    DETECT_URICONTENT,
-    DETECT_PCRE,
+    DETECT_CONTENT,    /* 8 */
+    DETECT_URICONTENT, /* 9 */
+    DETECT_PCRE,       /* 10 */
     DETECT_DEPTH,
     DETECT_DISTANCE,
     DETECT_WITHIN,