Make prune object walker generic

2 files changed, 107 insertions, 91 deletions

diff --git a/object_walker.go b/object_walker.go
new file mode 100644
index 0000000..8bae1fa
--- /dev/null
+++ b/object_walker.go
@@ -0,0 +1,105 @@
+package git
+
+import (
+	"fmt"
+
+	"gopkg.in/src-d/go-git.v4/plumbing"
+	"gopkg.in/src-d/go-git.v4/plumbing/filemode"
+	"gopkg.in/src-d/go-git.v4/plumbing/object"
+	"gopkg.in/src-d/go-git.v4/storage"
+)
+
+type objectWalker struct {
+	Storer storage.Storer
+	// seen is the set of objects seen in the repo.
+	// seen map can become huge if walking over large
+	// repos. Thus using struct{} as the value type.
+	seen map[plumbing.Hash]struct{}
+}
+
+func newObjectWalker(s storage.Storer) *objectWalker {
+	return &objectWalker{s, map[plumbing.Hash]struct{}{}}
+}
+
+// walkAllRefs walks all (hash) refererences from the repo.
+func (p *objectWalker) walkAllRefs() error {
+	// Walk over all the references in the repo.
+	it, err := p.Storer.IterReferences()
+	if err != nil {
+		return err
+	}
+	defer it.Close()
+	err = it.ForEach(func(ref *plumbing.Reference) error {
+		// Exit this iteration early for non-hash references.
+		if ref.Type() != plumbing.HashReference {
+			return nil
+		}
+		return p.walkObjectTree(ref.Hash())
+	})
+	if err != nil {
+		return err
+	}
+	return nil
+}
+
+func (p *objectWalker) isSeen(hash plumbing.Hash) bool {
+	_, seen := p.seen[hash]
+	return seen
+}
+
+func (p *objectWalker) add(hash plumbing.Hash) {
+	p.seen[hash] = struct{}{}
+}
+
+// walkObjectTree walks over all objects and remembers references
+// to them in the objectWalker. This is used instead of the revlist
+// walks because memory usage is tight with huge repos.
+func (p *objectWalker) walkObjectTree(hash plumbing.Hash) error {
+	// Check if we have already seen, and mark this object
+	if p.isSeen(hash) {
+		return nil
+	}
+	p.add(hash)
+	// Fetch the object.
+	obj, err := object.GetObject(p.Storer, hash)
+	if err != nil {
+		return fmt.Errorf("Getting object %s failed: %v", hash, err)
+	}
+	// Walk all children depending on object type.
+	switch obj := obj.(type) {
+	case *object.Commit:
+		err = p.walkObjectTree(obj.TreeHash)
+		if err != nil {
+			return err
+		}
+		for _, h := range obj.ParentHashes {
+			err = p.walkObjectTree(h)
+			if err != nil {
+				return err
+			}
+		}
+	case *object.Tree:
+		for i := range obj.Entries {
+			// Shortcut for blob objects:
+			// 'or' the lower bits of a mode and check that it
+			// it matches a filemode.Executable. The type information
+			// is in the higher bits, but this is the cleanest way
+			// to handle plain files with different modes.
+			// Other non-tree objects are somewhat rare, so they
+			// are not special-cased.
+			if obj.Entries[i].Mode|0755 == filemode.Executable {
+				p.add(obj.Entries[i].Hash)
+				continue
+			}
+			// Normal walk for sub-trees (and symlinks etc).
+			err = p.walkObjectTree(obj.Entries[i].Hash)
+			if err != nil {
+				return err
+			}
+		}
+	default:
+		// Error out on unhandled object types.
+		return fmt.Errorf("Unknown object %X %s %T\n", obj.ID(), obj.Type(), obj)
+	}
+	return nil
+}
diff --git a/prune.go b/prune.go
index 9c3c4ff..fce3bfd 100644
--- a/prune.go
+++ b/prune.go
@@ -1,13 +1,9 @@
 package git
 
 import (
-	"fmt"
 	"time"
 
 	"gopkg.in/src-d/go-git.v4/plumbing"
-	"gopkg.in/src-d/go-git.v4/plumbing/filemode"
-	"gopkg.in/src-d/go-git.v4/plumbing/object"
-	"gopkg.in/src-d/go-git.v4/storage"
 )
 
 type PruneHandler func(unreferencedObjectHash plumbing.Hash) error
@@ -26,23 +22,8 @@ func (r *Repository) DeleteObject(hash plumbing.Hash) error {
 }
 
 func (r *Repository) Prune(opt PruneOptions) error {
-	pw := &pruneWalker{
-		Storer: r.Storer,
-		seen:   map[plumbing.Hash]struct{}{},
-	}
-	// Walk over all the references in the repo.
-	it, err := r.Storer.IterReferences()
-	if err != nil {
-		return nil
-	}
-	defer it.Close()
-	err = it.ForEach(func(ref *plumbing.Reference) error {
-		// Exit this iteration early for non-hash references.
-		if ref.Type() != plumbing.HashReference {
-			return nil
-		}
-		return pw.walkObjectTree(ref.Hash())
-	})
+	pw := newObjectWalker(r.Storer)
+	err := pw.walkAllRefs()
 	if err != nil {
 		return err
 	}
@@ -73,73 +54,3 @@ func (r *Repository) Prune(opt PruneOptions) error {
 	}
 	return nil
 }
-
-type pruneWalker struct {
-	Storer storage.Storer
-	// seen is the set of objects seen in the repo.
-	// seen map can become huge if walking over large
-	// repos. Thus using struct{} as the value type.
-	seen map[plumbing.Hash]struct{}
-}
-
-func (p *pruneWalker) isSeen(hash plumbing.Hash) bool {
-	_, seen := p.seen[hash]
-	return seen
-}
-
-func (p *pruneWalker) add(hash plumbing.Hash) {
-	p.seen[hash] = struct{}{}
-}
-
-// walkObjectTree walks over all objects and remembers references
-// to them in the pruneWalker. This is used instead of the revlist
-// walks because memory usage is tight with huge repos.
-func (p *pruneWalker) walkObjectTree(hash plumbing.Hash) error {
-	// Check if we have already seen, and mark this object
-	if p.isSeen(hash) {
-		return nil
-	}
-	p.add(hash)
-	// Fetch the object.
-	obj, err := object.GetObject(p.Storer, hash)
-	if err != nil {
-		return fmt.Errorf("Getting object %s failed: %v", hash, err)
-	}
-	// Walk all children depending on object type.
-	switch obj := obj.(type) {
-	case *object.Commit:
-		err = p.walkObjectTree(obj.TreeHash)
-		if err != nil {
-			return err
-		}
-		for _, h := range obj.ParentHashes {
-			err = p.walkObjectTree(h)
-			if err != nil {
-				return err
-			}
-		}
-	case *object.Tree:
-		for i := range obj.Entries {
-			// Shortcut for blob objects:
-			// 'or' the lower bits of a mode and check that it
-			// it matches a filemode.Executable. The type information
-			// is in the higher bits, but this is the cleanest way
-			// to handle plain files with different modes.
-			// Other non-tree objects are somewhat rare, so they
-			// are not special-cased.
-			if obj.Entries[i].Mode|0755 == filemode.Executable {
-				p.add(obj.Entries[i].Hash)
-				continue
-			}
-			// Normal walk for sub-trees (and symlinks etc).
-			err = p.walkObjectTree(obj.Entries[i].Hash)
-			if err != nil {
-				return err
-			}
-		}
-	default:
-		// Error out on unhandled object types.
-		return fmt.Errorf("Unknown object %X %s %T\n", obj.ID(), obj.Type(), obj)
-	}
-	return nil
-}