Early return from LatestMap merge loop

If we run out of things to look at in the other map, return quickly.
Also move the equal-key case above the less-than case, since maps with
equal keys are the common case when merging.

extras/generate_latest_map

@@ -96,14 +96,16 @@ function generate_latest_map() {
     loop:
         for i < len(m) {
             switch {
-            case j >= len(n) || m[i].key < n[j].key:
-                i++
+            case j >= len(n):
+                return m
             case m[i].key == n[j].key:
                 if m[i].Timestamp.Before(n[j].Timestamp) {
                     break loop
                 }
                 i++
                 j++
+            case m[i].key < n[j].key:
+                i++
             default:
                 break loop
             }
@@ -117,9 +119,9 @@ function generate_latest_map() {
 
         for i < len(m) {
             switch {
-            case j >= len(n) || m[i].key < n[j].key:
-                out = append(out, m[i])
-                i++
+            case j >= len(n):
+                out = append(out, m[i:]...)
+                return out
             case m[i].key == n[j].key:
                 if m[i].Timestamp.Before(n[j].Timestamp) {
                     out = append(out, n[j])
@@ -128,6 +130,9 @@ function generate_latest_map() {
                 }
                 i++
                 j++
+            case m[i].key < n[j].key:
+                out = append(out, m[i])
+                i++
             default:
                 out = append(out, n[j])
                 j++

report/latest_map_generated.go

@@ -64,14 +64,16 @@ func (m StringLatestMap) Merge(n StringLatestMap) StringLatestMap {
 loop:
 	for i < len(m) {
 		switch {
-		case j >= len(n) || m[i].key < n[j].key:
-			i++
+		case j >= len(n):
+			return m
 		case m[i].key == n[j].key:
 			if m[i].Timestamp.Before(n[j].Timestamp) {
 				break loop
 			}
 			i++
 			j++
+		case m[i].key < n[j].key:
+			i++
 		default:
 			break loop
 		}
@@ -85,9 +87,9 @@ loop:
 
 	for i < len(m) {
 		switch {
-		case j >= len(n) || m[i].key < n[j].key:
-			out = append(out, m[i])
-			i++
+		case j >= len(n):
+			out = append(out, m[i:]...)
+			return out
 		case m[i].key == n[j].key:
 			if m[i].Timestamp.Before(n[j].Timestamp) {
 				out = append(out, n[j])
@@ -96,6 +98,9 @@ loop:
 			}
 			i++
 			j++
+		case m[i].key < n[j].key:
+			out = append(out, m[i])
+			i++
 		default:
 			out = append(out, n[j])
 			j++
@@ -311,14 +316,16 @@ func (m NodeControlDataLatestMap) Merge(n NodeControlDataLatestMap) NodeControlD
 loop:
 	for i < len(m) {
 		switch {
-		case j >= len(n) || m[i].key < n[j].key:
-			i++
+		case j >= len(n):
+			return m
 		case m[i].key == n[j].key:
 			if m[i].Timestamp.Before(n[j].Timestamp) {
 				break loop
 			}
 			i++
 			j++
+		case m[i].key < n[j].key:
+			i++
 		default:
 			break loop
 		}
@@ -332,9 +339,9 @@ loop:
 
 	for i < len(m) {
 		switch {
-		case j >= len(n) || m[i].key < n[j].key:
-			out = append(out, m[i])
-			i++
+		case j >= len(n):
+			out = append(out, m[i:]...)
+			return out
 		case m[i].key == n[j].key:
 			if m[i].Timestamp.Before(n[j].Timestamp) {
 				out = append(out, n[j])
@@ -343,6 +350,9 @@ loop:
 			}
 			i++
 			j++
+		case m[i].key < n[j].key:
+			out = append(out, m[i])
+			i++
 		default:
 			out = append(out, n[j])
 			j++