Remove unused backend.Batch interface (#31941)

Only two backends implemented the interface and it was only being
used by tests.

lib/backend/backend.go

@@ -139,14 +139,6 @@ func StreamRange(ctx context.Context, bk Backend, startKey, endKey []byte, pageS
 	})
 }
 
-// Batch implements some batch methods
-// that are not mandatory for all interfaces,
-// only the ones used in bulk operations.
-type Batch interface {
-	// PutRange puts range of items in one transaction
-	PutRange(ctx context.Context, items []Item) error
-}
-
 // Lease represents a lease on the item that can be used
 // to extend item's TTL without updating its contents.
 //

lib/backend/lite/lite.go

@@ -100,7 +100,7 @@ type Config struct {
 	// Journal sets the journal_mode pragma
 	Journal string `json:"journal,omitempty"`
 	// Mirror turns on mirror mode for the backend,
-	// which will use record IDs for Put and PutRange passed from
+	// which will use record IDs for Put passed from
 	// the resources, not generate a new one
 	Mirror bool `json:"mirror"`
 }
@@ -583,23 +583,6 @@ func (l *Backend) Import(ctx context.Context, items []backend.Item) error {
 	return nil
 }
 
-// PutRange puts range of items into backend (creates if items doe not
-// exists, updates it otherwise)
-func (l *Backend) PutRange(ctx context.Context, items []backend.Item) error {
-	for i := range items {
-		if items[i].Key == nil {
-			return trace.BadParameter("missing parameter key in item %v", i)
-		}
-	}
-	err := l.inTransaction(ctx, func(tx *sql.Tx) error {
-		return l.putRangeInTransaction(ctx, tx, items, false)
-	})
-	if err != nil {
-		return trace.Wrap(err)
-	}
-	return nil
-}
-
 func (l *Backend) putRangeInTransaction(ctx context.Context, tx *sql.Tx, items []backend.Item, forceEventsOff bool) error {
 	var eventsStmt *sql.Stmt
 	var err error

lib/backend/memory/memory.go

@@ -61,7 +61,7 @@ type Config struct {
 	// BufferSize sets up event buffer size
 	BufferSize int
 	// Mirror mode is used when the memory backend is used for caching. In mirror
-	// mode, record IDs for Put and PutRange requests are re-used (instead of
+	// mode, record IDs for Put requests are re-used (instead of
 	// generating fresh ones) and expiration is turned off.
 	Mirror bool
 }
@@ -243,33 +243,6 @@ func (m *Memory) Put(ctx context.Context, i backend.Item) (*backend.Lease, error
 	return m.newLease(i), nil
 }
 
-// PutRange puts range of items into backend (creates if items do not
-// exist, updates it otherwise)
-func (m *Memory) PutRange(ctx context.Context, items []backend.Item) error {
-	for i := range items {
-		if items[i].Key == nil {
-			return trace.BadParameter("missing parameter key in item %v", i)
-		}
-	}
-	m.Lock()
-	defer m.Unlock()
-	m.removeExpired()
-	for _, item := range items {
-		event := backend.Event{
-			Type: types.OpPut,
-			Item: item,
-		}
-		if !m.Mirror {
-			event.Item.ID = m.generateID()
-		}
-		m.processEvent(event)
-		if !m.EventsOff {
-			m.buf.Emit(event)
-		}
-	}
-	return nil
-}
-
 // Delete deletes item by key, returns NotFound error
 // if item does not exist
 func (m *Memory) Delete(ctx context.Context, key []byte) error {

lib/backend/test/suite.go

@@ -141,10 +141,6 @@ func RunBackendComplianceSuite(t *testing.T, newBackend Constructor) {
 		testDeleteRange(t, newBackend)
 	})
 
-	t.Run("PutRange", func(t *testing.T) {
-		testPutRange(t, newBackend)
-	})
-
 	t.Run("CompareAndSwap", func(t *testing.T) {
 		testCompareAndSwap(t, newBackend)
 	})
@@ -362,32 +358,6 @@ func testDeleteRange(t *testing.T, newBackend Constructor) {
 	RequireItems(t, []backend.Item{a, b}, result.Items)
 }
 
-// testPutRange tests scenarios with put range
-func testPutRange(t *testing.T, newBackend Constructor) {
-	uut, _, err := newBackend()
-	require.NoError(t, err)
-	defer func() { require.NoError(t, uut.Close()) }()
-
-	batchUut, ok := uut.(backend.Batch)
-	if !ok {
-		t.Skip("Backend should support Batch interface for this test")
-	}
-
-	ctx := context.Background()
-	prefix := MakePrefix()
-	a := backend.Item{Key: prefix("/prefix/a"), Value: []byte("val a")}
-	b := backend.Item{Key: prefix("/prefix/b"), Value: []byte("val b")}
-
-	// add one element that should not show up (i.e. a duplicate `a`)
-	err = batchUut.PutRange(ctx, []backend.Item{a, b, a})
-	require.NoError(t, err)
-
-	// prefix range fetch
-	result, err := uut.GetRange(ctx, prefix("/prefix"), backend.RangeEnd(prefix("/prefix")), backend.NoLimit)
-	require.NoError(t, err)
-	RequireItems(t, []backend.Item{a, b}, result.Items)
-}
-
 // testCompareAndSwap tests compare and swap functionality
 func testCompareAndSwap(t *testing.T, newBackend Constructor) {
 	uut, _, err := newBackend()