feat(cli): implement delta-push object reachability pruning

Author: Patel230

internal/cli/push.go

@@ -85,8 +85,23 @@ func Push(repoPath, daemonURL, repoID string, refNames ...string) error {
 		return nil
 	}
 
-	// Collect all reachable objects
-	gitObjects, err := collectObjects(repo, commitHashes)
+	// Build map of commits and trees already present on the remote to prune the walk (delta push)
+	remoteCommits := make(map[string]bool)
+	remoteTrees := make(map[string]bool)
+	for _, remoteHashStr := range remoteRefs {
+		remoteHash := plumbing.NewHash(remoteHashStr)
+		if commit, err := repo.CommitObject(remoteHash); err == nil {
+			commitIter := object.NewCommitPreorderIter(commit, nil, nil)
+			_ = commitIter.ForEach(func(c *object.Commit) error {
+				remoteCommits[c.Hash.String()] = true
+				remoteTrees[c.TreeHash.String()] = true
+				return nil
+			})
+		}
+	}
+
+	// Collect all reachable objects (excluding remote ones)
+	gitObjects, err := collectObjects(repo, commitHashes, remoteCommits, remoteTrees)
 	if err != nil {
 		return fmt.Errorf("collecting objects: %w", err)
 	}
@@ -155,8 +170,8 @@ func createPackfile(objects []GitObject) ([]byte, error) {
 	return writer.WritePackfile(gitObjects)
 }
 
-// collectObjects walks the git graph from the given commits and collects all reachable objects
-func collectObjects(repo *git.Repository, hashes []plumbing.Hash) ([]GitObject, error) {
+// collectObjects walks the git graph from the given commits and collects all reachable objects (excluding remote ones)
+func collectObjects(repo *git.Repository, hashes []plumbing.Hash, remoteCommits map[string]bool, remoteTrees map[string]bool) ([]GitObject, error) {
 	seen := make(map[string]bool)
 	var objects []GitObject
 
@@ -168,7 +183,7 @@ func collectObjects(repo *git.Repository, hashes []plumbing.Hash) ([]GitObject,
 		// Walk commits
 		commitIter := object.NewCommitPreorderIter(commit, nil, nil)
 		commitIter.ForEach(func(c *object.Commit) error {
-			if seen[c.Hash.String()] {
+			if remoteCommits[c.Hash.String()] || seen[c.Hash.String()] {
 				return nil
 			}
 			seen[c.Hash.String()] = true
@@ -182,7 +197,7 @@ func collectObjects(repo *git.Repository, hashes []plumbing.Hash) ([]GitObject,
 			// Add tree and blobs
 			tree, err := repo.TreeObject(c.TreeHash)
 			if err == nil {
-				treeObjs, err := collectTreeObjects(repo, tree, seen)
+				treeObjs, err := collectTreeObjects(repo, tree, seen, remoteTrees)
 				if err == nil {
 					objects = append(objects, treeObjs...)
 				}
@@ -195,10 +210,10 @@ func collectObjects(repo *git.Repository, hashes []plumbing.Hash) ([]GitObject,
 }
 
 // collectTreeObjects recursively collects tree and blob objects
-func collectTreeObjects(repo *git.Repository, tree *object.Tree, seen map[string]bool) ([]GitObject, error) {
+func collectTreeObjects(repo *git.Repository, tree *object.Tree, seen map[string]bool, remoteTrees map[string]bool) ([]GitObject, error) {
 	var objects []GitObject
 
-	if seen[tree.Hash.String()] {
+	if remoteTrees[tree.Hash.String()] || seen[tree.Hash.String()] {
 		return objects, nil
 	}
 	seen[tree.Hash.String()] = true
@@ -223,7 +238,7 @@ func collectTreeObjects(repo *git.Repository, tree *object.Tree, seen map[string
 		case filemode.Dir:
 			subtree, err := repo.TreeObject(entry.Hash)
 			if err == nil {
-				subObjs, err := collectTreeObjects(repo, subtree, seen)
+				subObjs, err := collectTreeObjects(repo, subtree, seen, remoteTrees)
 				if err == nil {
 					objects = append(objects, subObjs...)
 				}