fix(gitter): Update affected commit logic when introduced=0

go/cmd/gitter/repository.go

@@ -509,50 +509,120 @@ func (r *Repository) expandByCherrypick(commits []int) []int {
 	return cherrypicked
 }
 
-// Affected returns a list of commits that are affected by the given introduced, fixed and last_affected events.
-// It also returns two slices of hex hashes for newly identified cherry-picked introduced and fixed commits.
-// A commit is affected when: from at least one introduced that is an ancestor of the commit, there is no path between them that passes through a fix.
-// A fix can either be a fixed commit, or the children of a lastAffected commit.
-func (r *Repository) Affected(ctx context.Context, se *SeparatedEvents, cherrypickIntro, cherrypickFixed bool) ([]*Commit, []string, []string) {
-	logger.InfoContext(ctx, "Starting affected commit walking")
-	start := time.Now()
+// findAncestorRoots returns the subset of r.rootCommits that are ancestors of any of the input commits.
+// It performs a BFS from the input fix commits to find reachable roots.
+func (r *Repository) findAncestorRoots(from []int) []int {
+	visited := make([]bool, len(r.commits))
+	queue := make([]int, 0, len(from))
+	foundRoots := make([]int, 0, len(r.rootCommits))
 
-	introduced := r.parseHashes(ctx, se.Introduced)
+	for _, idx := range from {
+		if !visited[idx] {
+			visited[idx] = true
+			queue = append(queue, idx)
+		}
+	}
+
+	for len(queue) > 0 {
+		if len(foundRoots) == len(r.rootCommits) {
+			// All roots are found, we can terminate early
+			break
+		}
+
+		curr := queue[0]
+		queue = queue[1:]
+
+		if len(r.commits[curr].Parents) == 0 {
+			foundRoots = append(foundRoots, curr)
+		}
+
+		for _, pIdx := range r.commits[curr].Parents {
+			if !visited[pIdx] {
+				visited[pIdx] = true
+				queue = append(queue, pIdx)
+			}
+		}
+	}
+
+	return foundRoots
+}
+
+// resolveEvents parses and expands SeparatedEvents into lists of introduced and fixed commits
+// In case of intro=0, it will not include root commits that are not ancestors of any fixed commits
+func (r *Repository) resolveEvents(ctx context.Context, se *SeparatedEvents, cherrypickIntro, cherrypickFixed bool) ([]int, []int, []string, []string) {
+	// Parsing and expanding fixed events first because we need them to find relevant roots for intro=0
 	fixed := r.parseHashes(ctx, se.Fixed)
 	lastAffected := r.parseHashes(ctx, se.LastAffected)
 
-	var newIntroHashes []string
-	var newFixedHashes []string
-
-	// Expands the introduced and fixed commits to include cherrypick equivalents
+	// Hash strings of commits cherrypicked from fixed commits (excluding the original commits)
+	var cherrypickedFixedHashes []string
 	// lastAffected should not be expanded because it does not imply a "fix" commit that can be cherrypicked to other branches
-	if cherrypickIntro {
-		newIntro := r.expandByCherrypick(introduced)
-		newIntroHashes = r.hexHashes(newIntro)
-		introduced = append(introduced, newIntro...)
-	}
 	if cherrypickFixed {
 		newFixed := r.expandByCherrypick(fixed)
-		newFixedHashes = r.hexHashes(newFixed)
+		cherrypickedFixedHashes = r.hexHashes(newFixed)
 		fixed = append(fixed, newFixed...)
 	}
 
-	// Fixed commits and children of last affected are both in this set
+	// Fixed commits and children of last affected are both in this list
 	// For graph traversal sake they are both considered the fix
-	fixedMap := make([]bool, len(r.commits))
+	allFixes := make([]int, 0, len(se.Fixed)+len(se.LastAffected))
+	allFixes = append(allFixes, fixed...)
+	for _, idx := range lastAffected {
+		if idx < len(r.commitGraph) {
+			allFixes = append(allFixes, r.commitGraph[idx]...)
+		}
+	}
 
-	for _, idx := range fixed {
-		fixedMap[idx] = true
+	hasIntroZero := false
+	filteredIntro := make([]string, 0, len(se.Introduced))
+	for _, s := range se.Introduced {
+		if s == "0" {
+			hasIntroZero = true
+		} else {
+			filteredIntro = append(filteredIntro, s)
+		}
 	}
 
-	for _, idx := range lastAffected {
-		if idx < len(r.commitGraph) {
-			for _, childIdx := range r.commitGraph[idx] {
-				fixedMap[childIdx] = true
-			}
+	introduced := r.parseHashes(ctx, filteredIntro)
+
+	if hasIntroZero {
+		if len(allFixes) > 0 {
+			// If there are fixes, introduced=0 should only include root commits that are ancestors of the fixes
+			introduced = append(introduced, r.findAncestorRoots(allFixes)...)
+		} else {
+			// If there are no fixes, then introduced=0 means all root commits
+			introduced = append(introduced, r.rootCommits...)
 		}
 	}
 
+	// Hash strings of commits cherrypicked from introduced commits (excluding the original commits)
+	var cherrypickedIntroHashes []string
+	if cherrypickIntro {
+		newIntro := r.expandByCherrypick(introduced)
+		cherrypickedIntroHashes = r.hexHashes(newIntro)
+		introduced = append(introduced, newIntro...)
+	}
+
+	return introduced, allFixes, cherrypickedIntroHashes, cherrypickedFixedHashes
+}
+
+// Affected returns a list of commits that are affected by the given introduced, fixed and last_affected events.
+// It also returns two slices of hex hashes for newly identified cherry-picked introduced and fixed commits.
+// A commit is affected when: from at least one introduced that is an ancestor of the commit, there is no path between them that passes through a fix.
+// A fix can either be a fixed commit, or the children of a lastAffected commit.
+func (r *Repository) Affected(ctx context.Context, se *SeparatedEvents, cherrypickIntro, cherrypickFixed bool) ([]*Commit, []string, []string) {
+	logger.InfoContext(ctx, "Starting affected commit walking")
+	start := time.Now()
+
+	introduced, allFixes, cherrypickedIntroHashes, cherrypickedFixedHashes := r.resolveEvents(ctx, se, cherrypickIntro, cherrypickFixed)
+
+	logger.DebugContext(ctx, "Resolved affected commit events to walk", slog.Any("introduced", introduced), slog.Any("allFixes", allFixes))
+
+	fixedMap := make([]bool, len(r.commits))
+	for _, idx := range allFixes {
+		fixedMap[idx] = true
+	}
+
 	// The graph traversal
 	// affectedMap deduplicates the affected commits from the graph walk from each introduced commit
 	affectedMap := make([]bool, len(r.commits))
@@ -643,7 +713,7 @@ func (r *Repository) Affected(ctx context.Context, se *SeparatedEvents, cherrypi
 
 	logger.InfoContext(ctx, "Affected commit walking completed", slog.Duration("duration", time.Since(start)))
 
-	return affectedCommits, newIntroHashes, newFixedHashes
+	return affectedCommits, cherrypickedIntroHashes, cherrypickedFixedHashes
 }
 
 // Limit walks and returns the commits that are strictly between introduced (inclusive) and limit (exclusive).
@@ -652,17 +722,17 @@ func (r *Repository) Limit(ctx context.Context, se *SeparatedEvents, cherrypickI
 	introduced := r.parseHashes(ctx, se.Introduced)
 	limit := r.parseHashes(ctx, se.Limit)
 
-	var newIntroHashes []string
-	var newLimitHashes []string
+	var cherrypickedIntroHashes []string
+	var cherrypickedLimitHashes []string
 
 	if cherrypickIntro {
 		newIntro := r.expandByCherrypick(introduced)
-		newIntroHashes = r.hexHashes(newIntro)
+		cherrypickedIntroHashes = r.hexHashes(newIntro)
 		introduced = append(introduced, newIntro...)
 	}
 	if cherrypickLimit {
 		newLimit := r.expandByCherrypick(limit)
-		newLimitHashes = r.hexHashes(newLimit)
+		cherrypickedLimitHashes = r.hexHashes(newLimit)
 		limit = append(limit, newLimit...)
 	}
 
@@ -709,5 +779,5 @@ func (r *Repository) Limit(ctx context.Context, se *SeparatedEvents, cherrypickI
 		}
 	}
 
-	return affectedCommits, newIntroHashes, newLimitHashes
+	return affectedCommits, cherrypickedIntroHashes, cherrypickedLimitHashes
 }