snapshot: Move 'newest' logic out of main compilation loop and evaluate the reflist afterward.

deb/reflist.go

@@ -226,10 +226,6 @@ func (l *PackageRefList) Diff(r *PackageRefList, packageCollection *PackageColle
 func (l *PackageRefList) Merge(r *PackageRefList, overrideMatching bool,
 	newestWins bool) (result *PackageRefList) {
 
-	// A running tab of packages observed during a merge. Used when -newest is
-	// passed to make sure only the newest version is carried into the snapshot.
-	var seen []string
-
 	// pointer to left and right reflists
 	il, ir := 0, 0
 	// length of reflists
@@ -238,7 +234,6 @@ func (l *PackageRefList) Merge(r *PackageRefList, overrideMatching bool,
 	result = &PackageRefList{}
 	result.Refs = make([][]byte, 0, ll+lr)
 
-OUTER:
 	// until we reached end of both lists
 	for il < ll || ir < lr {
 		// if we've exhausted left list, pull the rest from the right
@@ -278,34 +273,6 @@ OUTER:
 					continue
 				}
 			}
-			if newestWins {
-				partsL := bytes.Split(rl, []byte(" "))
-				nameL, archL, verL := partsL[0][1:], partsL[1], partsL[2]
-				pkgL := string(nameL) + "." + string(archL)
-
-				partsR := bytes.Split(rr, []byte(" "))
-				verR := partsR[2]
-
-				// If we've already seen this package, regardless of version,
-				// just skip it.
-				for _, s := range seen {
-					if s == pkgL {
-						il++
-						ir++
-						continue OUTER
-					}
-				}
-
-				seen = append(seen, pkgL)
-
-				vres := CompareVersions(string(verL), string(verR))
-				if vres <= 0 {
-					result.Refs = append(result.Refs, r.Refs[ir])
-					il++
-					ir++
-					continue
-				}
-			}
 
 			// otherwise append smallest of two
 			if rel < 0 {
@@ -318,5 +285,37 @@ OUTER:
 		}
 	}
 
+	if newestWins {
+		// A running tab of packages observed during a merge. Used when -newest
+		// is passed to ensure the newest version is carried into the snapshot.
+		refs := make(map[string][]byte)
+
+	OUTER:
+		for _, ref := range result.Refs {
+			partsL := bytes.Split(ref, []byte(" "))
+			nameL, archL, verL := partsL[0][1:], partsL[1], partsL[2]
+			pkgL := string(nameL) + "." + string(archL)
+
+			// If we've already seen this package, regardless of version,
+			// just skip it.
+			if _, ok := refs[pkgL]; ok {
+				vres := CompareVersions(string(verL), string(refs[pkgL]))
+				if vres <= 0 {
+					refs[pkgL] = ref
+					il++
+					ir++
+					continue OUTER
+				}
+			}
+
+			refs[pkgL] = ref
+		}
+
+		result.Refs = [][]byte{}
+		for _, ref := range refs {
+			result.Refs = append(result.Refs, ref)
+		}
+	}
+
 	return
 }