add bounds to index

accounts/pkg/indexer/index/disk/autoincrement.go

@@ -24,6 +24,8 @@ type Autoincrement struct {
 	indexBaseDir string
 	indexRootDir string
 	entity       interface{}
+
+	bound *option.Bound
 }
 
 // - Creating an autoincrement index has to be thread safe.
@@ -55,6 +57,7 @@ func NewAutoincrementIndex(o ...option.Option) index.Index {
 		indexBy:      opts.IndexBy,
 		typeName:     opts.TypeName,
 		filesDir:     opts.FilesDir,
+		bound:        opts.Bound,
 		indexBaseDir: path.Join(opts.DataDir, "index.disk"),
 		indexRootDir: path.Join(path.Join(opts.DataDir, "index.disk"), strings.Join([]string{"autoincrement", opts.TypeName, opts.IndexBy}, ".")),
 	}
@@ -100,14 +103,18 @@ func (idx Autoincrement) Lookup(v string) ([]string, error) {
 }
 
 func (idx Autoincrement) Add(id, v string) (string, error) {
+	nextID, err := idx.next()
+	if err != nil {
+		return "", err
+	}
 	oldName := filepath.Join(idx.filesDir, id)
-	var newName string
+	newName := filepath.Join(idx.indexRootDir, strconv.Itoa(nextID))
 	if v == "" {
-		newName = filepath.Join(idx.indexRootDir, strconv.Itoa(idx.next()))
+		newName = filepath.Join(idx.indexRootDir, strconv.Itoa(nextID))
 	} else {
 		newName = filepath.Join(idx.indexRootDir, v)
 	}
-	err := os.Symlink(oldName, newName)
+	err = os.Symlink(oldName, newName)
 	if errors.Is(err, os.ErrExist) {
 		return "", &idxerrs.AlreadyExistsErr{TypeName: idx.typeName, Key: idx.indexBy, Value: v}
 	}
@@ -216,19 +223,20 @@ func readDir(dirname string) ([]os.FileInfo, error) {
 	return list, nil
 }
 
-func (idx Autoincrement) next() int {
+func (idx Autoincrement) next() (int, error) {
 	files, err := readDir(idx.indexRootDir)
 	if err != nil {
-		// hello handle me pls.
+		return -1, err
 	}
 
 	if len(files) == 0 {
-		return 0
+		return int(idx.bound.Lower), nil
 	}
 
-	latest, err := strconv.Atoi(path.Base(files[len(files)-1].Name())) // would returning a string be a better interface?
+	latest, err := strconv.Atoi(path.Base(files[len(files)-1].Name()))
 	if err != nil {
-		// handle me daddy
+		return -1, err
 	}
-	return latest + 1
+
+	return latest + 1, nil
 }

accounts/pkg/indexer/index/disk/autoincrement_test.go

@@ -116,6 +116,10 @@ func TestNext(t *testing.T) {
 			assert.NoError(t, err)
 
 			i := NewAutoincrementIndex(
+				option.WithBounds(&option.Bound{
+					Lower: 0,
+					Upper: 0,
+				}),
 				option.WithDataDir(tmpDir),
 				option.WithFilesDir(filepath.Join(tmpDir, "data")),
 				option.WithEntity(scenario.entity),
@@ -132,15 +136,80 @@ func TestNext(t *testing.T) {
 
 			oldName, err := i.Add("test-example", "")
 			assert.NoError(t, err)
-			assert.Equal(t, filepath.Base(oldName), 0)
+			assert.Equal(t, "0", filepath.Base(oldName))
 
 			oldName, err = i.Add("test-example", "")
 			assert.NoError(t, err)
-			assert.Equal(t, filepath.Base(oldName), 1)
+			assert.Equal(t, "1", filepath.Base(oldName))
 
 			oldName, err = i.Add("test-example", "")
 			assert.NoError(t, err)
-			assert.Equal(t, filepath.Base(oldName), 2)
+			assert.Equal(t, "2", filepath.Base(oldName))
+			t.Log(oldName)
+
+			_ = os.RemoveAll(tmpDir)
+		})
+	}
+}
+
+func TestLowerBound(t *testing.T) {
+	scenarios := []struct {
+		name     string
+		expected int
+		indexBy  string
+		entity   interface{}
+	}{
+		{
+			name:     "get next value with a lower bound specified",
+			expected: 0,
+			indexBy:  "Number",
+			entity: struct {
+				Number      int
+				Name        string
+				NumberFloat float32
+			}{
+				Name: "tesy-mc-testace",
+			},
+		},
+	}
+
+	for _, scenario := range scenarios {
+		t.Run(scenario.name, func(t *testing.T) {
+			tmpDir, err := createTmpDirStr()
+			assert.NoError(t, err)
+
+			err = os.MkdirAll(filepath.Join(tmpDir, "data"), 0777)
+			assert.NoError(t, err)
+
+			i := NewAutoincrementIndex(
+				option.WithBounds(&option.Bound{
+					Lower: 1000,
+				}),
+				option.WithDataDir(tmpDir),
+				option.WithFilesDir(filepath.Join(tmpDir, "data")),
+				option.WithEntity(scenario.entity),
+				option.WithTypeName("LambdaType"),
+				option.WithIndexBy(scenario.indexBy),
+			)
+
+			err = i.Init()
+			assert.NoError(t, err)
+
+			tmpFile, err := os.Create(filepath.Join(tmpDir, "data", "test-example"))
+			assert.NoError(t, err)
+			assert.NoError(t, tmpFile.Close())
+
+			oldName, err := i.Add("test-example", "")
+			assert.NoError(t, err)
+			assert.Equal(t, "1000", filepath.Base(oldName))
+
+			oldName, err = i.Add("test-example", "")
+			assert.NoError(t, err)
+			assert.Equal(t, "1001", filepath.Base(oldName))
+
+			oldName, err = i.Add("test-example", "")
+			assert.NoError(t, err)
+			assert.Equal(t, "1002", filepath.Base(oldName))
 			t.Log(oldName)
 
 			_ = os.RemoveAll(tmpDir)
@@ -160,6 +229,10 @@ func BenchmarkAdd(b *testing.B) {
 	assert.NoError(b, tmpFile.Close())
 
 	i := NewAutoincrementIndex(
+		option.WithBounds(&option.Bound{
+			Lower: 0,
+			Upper: 0,
+		}),
 		option.WithDataDir(tmpDir),
 		option.WithFilesDir(filepath.Join(tmpDir, "data")),
 		option.WithEntity(struct {

accounts/pkg/indexer/option/option.go

@@ -3,6 +3,13 @@ package option
 // Option defines a single option function.
 type Option func(o *Options)
 
+// Bound represents a lower and upper bound range for an index.
+// todo: if we would like to provide an upper bound then we would need to deal with ranges, in which case this is why the
+// upper bound attribute is here.
+type Bound struct {
+	Lower, Upper int64
+}
+
 // Options defines the available options for this package.
 type Options struct {
 	// Disk Options
@@ -13,6 +20,7 @@ type Options struct {
 	DataDir       string
 	EntityDirName string
 	Entity        interface{}
+	Bound         *Bound
 
 	// CS3 options
 	DataURL      string
@@ -21,6 +29,13 @@ type Options struct {
 	ProviderAddr string
 }
 
+// WithBounds sets the Bounds field.
+func WithBounds(val *Bound) Option {
+	return func(o *Options) {
+		o.Bound = val
+	}
+}
+
 // WithEntity sets the Entity field.
 func WithEntity(val interface{}) Option {
 	return func(o *Options) {