bundles: add 'bundle.heuristic' to bundle list

Include the 'bundle.heuristic' config (value "creationToken" to denote use
of the creation token heuristic [1]) in the bundle list. Without this, Git
will not use the creation token heuristic to apply incremental bundle
updates on fetches after an initial clone.

Signed-off-by: Victoria Dye <vdye@github.com>

Author: vdye

internal/bundles/bundles.go

@@ -59,9 +59,19 @@ func NewBundle(repo *core.Repository, timestamp int64) Bundle {
 }
 
 type BundleList struct {
-	Version int
-	Mode    string
-	Bundles map[int64]Bundle
+	Version   int
+	Mode      string
+	Heuristic string
+	Bundles   map[int64]Bundle
+}
+
+func NewBundleList() *BundleList {
+	return &BundleList{
+		Version:   1,
+		Mode:      "any",
+		Heuristic: "creationToken",
+		Bundles:   make(map[int64]Bundle),
+	}
 }
 
 func (list *BundleList) addBundle(bundle Bundle) {
@@ -125,11 +135,9 @@ func (b *bundleProvider) createDistinctBundle(repo *core.Repository, list *Bundl
 }
 
 func (b *bundleProvider) CreateSingletonList(ctx context.Context, bundle Bundle) *BundleList {
-	list := BundleList{1, "all", make(map[int64]Bundle)}
-
+	list := NewBundleList()
 	list.addBundle(bundle)
-
-	return &list
+	return list
 }
 
 // Given a BundleList, write the bundle list content to the web directory.
@@ -161,8 +169,8 @@ func (b *bundleProvider) WriteBundleList(ctx context.Context, list *BundleList,
 		defer out.Flush()
 
 		fmt.Fprintf(
-			out, "[bundle]\n\tversion = %d\n\tmode = %s\n\n",
-			list.Version, list.Mode)
+			out, "[bundle]\n\tversion = %d\n\tmode = %s\n\theuristic = %s\n\n",
+			list.Version, list.Mode, list.Heuristic)
 
 		uriBase := path.Dir(requestUri) + "/"
 		for _, token := range keys {

internal/bundles/bundles_test.go

@@ -31,9 +31,10 @@ var writeBundleListTests = []struct {
 	{
 		"Empty bundle list",
 		&bundles.BundleList{
-			Version: 1,
-			Mode:    "all",
-			Bundles: map[int64]bundles.Bundle{},
+			Version:   1,
+			Mode:      "all",
+			Heuristic: "creationToken",
+			Bundles:   map[int64]bundles.Bundle{},
 		},
 		&core.Repository{
 			Route:   "test/repo",
@@ -44,21 +45,24 @@ var writeBundleListTests = []struct {
 			`[bundle]`,
 			`	version = 1`,
 			`	mode = all`,
+			`	heuristic = creationToken`,
 			``,
 		},
 		[]string{
 			`[bundle]`,
 			`	version = 1`,
 			`	mode = all`,
+			`	heuristic = creationToken`,
 			``,
 		},
 		false,
 	},
 	{
 		"Single bundle list",
 		&bundles.BundleList{
-			Version: 1,
-			Mode:    "all",
+			Version:   1,
+			Mode:      "all",
+			Heuristic: "creationToken",
 			Bundles: map[int64]bundles.Bundle{
 				1: {
 					URI:           "/test/myrepo/bundle-1.bundle",
@@ -76,6 +80,7 @@ var writeBundleListTests = []struct {
 			`[bundle]`,
 			`	version = 1`,
 			`	mode = all`,
+			`	heuristic = creationToken`,
 			``,
 			`[bundle "1"]`,
 			`	uri = bundle-1.bundle`,
@@ -86,6 +91,7 @@ var writeBundleListTests = []struct {
 			`[bundle]`,
 			`	version = 1`,
 			`	mode = all`,
+			`	heuristic = creationToken`,
 			``,
 			`[bundle "1"]`,
 			`	uri = myrepo/bundle-1.bundle`,
@@ -97,8 +103,9 @@ var writeBundleListTests = []struct {
 	{
 		"Multi-bundle list is sorted by creationToken",
 		&bundles.BundleList{
-			Version: 1,
-			Mode:    "all",
+			Version:   1,
+			Mode:      "all",
+			Heuristic: "creationToken",
 			Bundles: map[int64]bundles.Bundle{
 				2: {
 					URI:           "/test/myrepo/bundle-2.bundle",
@@ -126,6 +133,7 @@ var writeBundleListTests = []struct {
 			`[bundle]`,
 			`	version = 1`,
 			`	mode = all`,
+			`	heuristic = creationToken`,
 			``,
 			`[bundle "1"]`,
 			`	uri = bundle-1.bundle`,
@@ -144,6 +152,7 @@ var writeBundleListTests = []struct {
 			`[bundle]`,
 			`	version = 1`,
 			`	mode = all`,
+			`	heuristic = creationToken`,
 			``,
 			`[bundle "1"]`,
 			`	uri = myrepo/bundle-1.bundle`,