Allow nil Snapshot for most ops, CRUD for collection

mdb/collection.go

@@ -108,33 +108,6 @@ type indexConfig[T any] struct {
 	Include func(item *T) bool
 }
 
-// A shortcut for c.ByID.Get(tx, &Item{ID:id}).
-func (c *Collection[T]) Get(tx *Snapshot, id uint64) (*T, bool) {
-	x := new(T)
-	c.setID(x, id)
-	return c.ByID.Get(tx, x)
-}
-
-func (c *Collection[T]) GetList(tx *Snapshot, ids []uint64, out []*T) []*T {
-	if len(ids) == 0 {
-		return out[:0]
-	}
-
-	if cap(out) < len(ids) {
-		out = make([]*T, len(ids))
-	}
-	out = out[:0]
-
-	for _, id := range ids {
-		item, ok := c.Get(tx, id)
-		if ok {
-			out = append(out, item)
-		}
-	}
-
-	return out
-}
-
 // AddIndex: Add an index to the collection.
 func (c *Collection[T]) addIndex(conf indexConfig[T]) *Index[T] {
 	var less func(*T, *T) bool
@@ -161,6 +134,7 @@ func (c *Collection[T]) addIndex(conf indexConfig[T]) *Index[T] {
 	}
 
 	index := &Index[T]{
+		db:           c.db,
 		collectionID: c.collectionID,
 		name:         conf.Name,
 		indexID:      c.getState(c.db.Snapshot()).addIndex(indexState),
@@ -176,7 +150,26 @@ func (c *Collection[T]) addIndex(conf indexConfig[T]) *Index[T] {
 	return index
 }
 
+func (c *Collection[T]) Get(tx *Snapshot, id uint64) *T {
+	if tx == nil {
+		tx = c.db.Snapshot()
+	}
+	item := new(T)
+	c.setID(item, id)
+	return c.ByID.Get(tx, item)
+}
+
 func (c *Collection[T]) Insert(tx *Snapshot, userItem *T) error {
+	if tx == nil {
+		return c.db.Update(func(tx *Snapshot) error {
+			return c.insert(tx, userItem)
+		})
+	}
+
+	return c.insert(tx, userItem)
+}
+
+func (c *Collection[T]) insert(tx *Snapshot, userItem *T) error {
 	if err := c.ensureMutable(tx); err != nil {
 		return err
 	}
@@ -204,6 +197,15 @@ func (c *Collection[T]) Insert(tx *Snapshot, userItem *T) error {
 }
 
 func (c *Collection[T]) Update(tx *Snapshot, userItem *T) error {
+	if tx == nil {
+		return c.db.Update(func(tx *Snapshot) error {
+			return c.update(tx, userItem)
+		})
+	}
+	return c.update(tx, userItem)
+}
+
+func (c *Collection[T]) update(tx *Snapshot, userItem *T) error {
 	if err := c.ensureMutable(tx); err != nil {
 		return err
 	}
@@ -235,19 +237,16 @@ func (c *Collection[T]) Update(tx *Snapshot, userItem *T) error {
 	return nil
 }
 
-func (c *Collection[T]) UpdateFunc(tx *Snapshot, id uint64, update func(item *T) error) error {
+func (c *Collection[T]) Upsert(tx *Snapshot, item *T) error {
-	item, ok := c.getByID(tx, id)
+	if tx == nil {
-	if !ok {
+		return c.db.Update(func(tx *Snapshot) error {
-		return errs.NotFound
+			return c.upsert(tx, item)
+		})
 	}
-	itemCopy := c.copy(item)
+	return c.upsert(tx, item)
-	if err := update(itemCopy); err != nil {
-		return err
-	}
-	return c.Update(tx, itemCopy)
 }
 
-func (c *Collection[T]) Upsert(tx *Snapshot, item *T) error {
+func (c *Collection[T]) upsert(tx *Snapshot, item *T) error {
 	err := c.Insert(tx, item)
 	if err == nil {
 		return nil
@@ -258,21 +257,16 @@ func (c *Collection[T]) Upsert(tx *Snapshot, item *T) error {
 	return err
 }
 
-func (c *Collection[T]) UpsertFunc(tx *Snapshot, id uint64, update func(item *T) error) error {
+func (c *Collection[T]) Delete(tx *Snapshot, itemID uint64) error {
-	item, ok := c.getByID(tx, id)
+	if tx == nil {
-	if !ok {
+		return c.db.Update(func(tx *Snapshot) error {
-		item = new(T)
+			return c.delete(tx, itemID)
-		c.setID(item, id)
+		})
 	}
-
+	return c.delete(tx, itemID)
-	itemCopy := c.copy(item)
-	if err := update(itemCopy); err != nil {
-		return err
-	}
-	return c.Upsert(tx, itemCopy)
 }
 
-func (c *Collection[T]) Delete(tx *Snapshot, itemID uint64) error {
+func (c *Collection[T]) delete(tx *Snapshot, itemID uint64) error {
 	if err := c.ensureMutable(tx); err != nil {
 		return err
 	}

mdb/db-testcases_test.go

@@ -54,8 +54,8 @@ var testDBTestCases = []DBTestCase{{
 		Name: "Update",
 
 		Update: func(t *testing.T, db TestDB, tx *Snapshot) error {
-			user, ok := db.Users.ByID.Get(tx, &User{ID: 1})
+			user := db.Users.ByID.Get(tx, &User{ID: 1})
-			if !ok {
+			if user == nil {
 				return errs.NotFound
 			}
 			user.Name = "Bob"
@@ -323,8 +323,8 @@ var testDBTestCases = []DBTestCase{{
 		Name: "Update",
 
 		Update: func(t *testing.T, db TestDB, tx *Snapshot) error {
-			user, ok := db.Users.ByID.Get(tx, &User{ID: 1})
+			user := db.Users.ByID.Get(tx, &User{ID: 1})
-			if !ok {
+			if user == nil {
 				return errs.NotFound
 			}
 			user.Name = "Bob"
@@ -493,8 +493,8 @@ var testDBTestCases = []DBTestCase{{
 		Name: "Update",
 
 		Update: func(t *testing.T, db TestDB, tx *Snapshot) error {
-			u, ok := db.Users.ByID.Get(tx, &User{ID: 2})
+			u := db.Users.ByID.Get(tx, &User{ID: 2})
-			if !ok {
+			if u == nil {
 				return errs.NotFound
 			}
 
@@ -609,16 +609,16 @@ var testDBTestCases = []DBTestCase{{
 		Update: func(t *testing.T, db TestDB, tx *Snapshot) error {
 			expected := &User{ID: 1, Name: "Alice", Email: "a@b.com"}
 
-			u, ok := db.Users.ByID.Get(tx, &User{ID: 1})
+			u := db.Users.ByID.Get(tx, &User{ID: 1})
-			if !ok {
+			if u == nil {
 				return errs.NotFound
 			}
 			if !reflect.DeepEqual(u, expected) {
 				return errors.New("Not equal (id)")
 			}
 
-			u, ok = db.Users.ByEmail.Get(tx, &User{Email: "a@b.com"})
+			u = db.Users.ByEmail.Get(tx, &User{Email: "a@b.com"})
-			if !ok {
+			if u == nil {
 				return errs.NotFound
 			}
 			if !reflect.DeepEqual(u, expected) {
@@ -637,11 +637,11 @@ var testDBTestCases = []DBTestCase{{
 		Name: "Get not found",
 
 		Update: func(t *testing.T, db TestDB, tx *Snapshot) error {
-			if _, ok := db.Users.ByID.Get(tx, &User{ID: 2}); ok {
+			if u := db.Users.ByID.Get(tx, &User{ID: 2}); u != nil {
 				return errors.New("Found (id)")
 			}
 
-			if _, ok := db.Users.ByEmail.Get(tx, &User{Email: "x@b.com"}); ok {
+			if u := db.Users.ByEmail.Get(tx, &User{Email: "x@b.com"}); u != nil {
 				return errors.New("Found (email)")
 			}
 
@@ -753,8 +753,8 @@ var testDBTestCases = []DBTestCase{{
 					return true
 				}
 
-				prev, ok := db.Users.ByID.Get(tx, &User{ID: u.ID - 1})
+				prev := db.Users.ByID.Get(tx, &User{ID: u.ID - 1})
-				if !ok {
+				if prev == nil {
 					err = errors.New("Previous user not found")
 					return false
 				}
@@ -811,8 +811,8 @@ var testDBTestCases = []DBTestCase{{
 					return true
 				}
 
-				prev, ok := db.Users.ByID.Get(tx, &User{ID: u.ID + 1})
+				prev := db.Users.ByID.Get(tx, &User{ID: u.ID + 1})
-				if !ok {
+				if prev == nil {
 					err = errors.New("Previous user not found")
 					return false
 				}

mdb/db-testlist_test.go

@@ -123,7 +123,7 @@ func TestDBList(t *testing.T) {
 	for _, tc := range cases {
 		t.Run(tc.Name, func(t *testing.T) {
 			tx := db.Snapshot()
-			l := db.UserData.ByName.List(tx, tc.Args, nil)
+			l := db.UserData.ByName.List(tx, &tc.Args, nil)
 			if len(l) != len(tc.Expected) {
 				t.Fatal(tc.Name, l)
 			}

mdb/db-testrunner_test.go

@@ -136,21 +136,21 @@ func checkSlicesEqual[T any](t *testing.T, name string, actual, expected []T) {
 
 func checkMinMaxEqual[T any](t *testing.T, name string, tx *Snapshot, index *Index[T], expected []T) {
 	if len(expected) == 0 {
-		if min, ok := index.Min(tx); ok {
+		if min := index.Min(tx); min != nil {
 			t.Fatal(min)
 		}
-		if max, ok := index.Max(tx); ok {
+		if max := index.Max(tx); max != nil {
 			t.Fatal(max)
 		}
 		return
 	}
 
-	min, ok := index.Min(tx)
+	min := index.Min(tx)
-	if !ok {
+	if min == nil {
 		t.Fatal("No min")
 	}
-	max, ok := index.Max(tx)
+	max := index.Max(tx)
-	if !ok {
+	if max == nil {
 		t.Fatal("No max")
 	}
 

mdb/equality_test.go

@@ -21,8 +21,8 @@ func (i Index[T]) AssertEqual(t *testing.T, tx1, tx2 *Snapshot) {
 
 	errStr := ""
 	i.Ascend(tx1, func(item1 *T) bool {
-		item2, ok := i.Get(tx2, item1)
+		item2 := i.Get(tx2, item1)
-		if !ok {
+		if item2 == nil {
 			errStr = fmt.Sprintf("Indices don't match. %v not found.", item1)
 			return false
 		}

mdb/index.go

@@ -63,6 +63,7 @@ func NewUniquePartialIndex[T any](
 // ----------------------------------------------------------------------------
 
 type Index[T any] struct {
+	db           *Database
 	name         string
 	collectionID uint64
 	indexID      uint64
@@ -70,12 +71,19 @@ type Index[T any] struct {
 	copy         func(*T) *T
 }
 
-func (i *Index[T]) Get(tx *Snapshot, in *T) (item *T, ok bool) {
+func (i *Index[T]) ensureSnapshot(tx *Snapshot) *Snapshot {
-	tPtr, ok := i.get(tx, in)
+	if tx == nil {
-	if !ok {
+		tx = i.db.Snapshot()
-		return item, false
 	}
-	return i.copy(tPtr), true
+	return tx
+}
+
+func (i *Index[T]) Get(tx *Snapshot, in *T) *T {
+	tx = i.ensureSnapshot(tx)
+	if tPtr, ok := i.get(tx, in); ok {
+		return i.copy(tPtr)
+	}
+	return nil
 }
 
 func (i *Index[T]) get(tx *Snapshot, in *T) (*T, bool) {
@@ -83,44 +91,49 @@ func (i *Index[T]) get(tx *Snapshot, in *T) (*T, bool) {
 }
 
 func (i *Index[T]) Has(tx *Snapshot, in *T) bool {
+	tx = i.ensureSnapshot(tx)
 	return i.btree(tx).Has(in)
 }
 
-func (i *Index[T]) Min(tx *Snapshot) (item *T, ok bool) {
+func (i *Index[T]) Min(tx *Snapshot) *T {
-	tPtr, ok := i.btree(tx).Min()
+	tx = i.ensureSnapshot(tx)
-	if !ok {
+	if tPtr, ok := i.btree(tx).Min(); ok {
-		return item, false
+		return i.copy(tPtr)
 	}
-	return i.copy(tPtr), true
+	return nil
 }
 
-func (i *Index[T]) Max(tx *Snapshot) (item *T, ok bool) {
+func (i *Index[T]) Max(tx *Snapshot) *T {
-	tPtr, ok := i.btree(tx).Max()
+	tx = i.ensureSnapshot(tx)
-	if !ok {
+	if tPtr, ok := i.btree(tx).Max(); ok {
-		return item, false
+		return i.copy(tPtr)
 	}
-	return i.copy(tPtr), true
+	return nil
 }
 
 func (i *Index[T]) Ascend(tx *Snapshot, each func(*T) bool) {
+	tx = i.ensureSnapshot(tx)
 	i.btreeForIter(tx).Ascend(func(t *T) bool {
 		return each(i.copy(t))
 	})
 }
 
 func (i *Index[T]) AscendAfter(tx *Snapshot, after *T, each func(*T) bool) {
+	tx = i.ensureSnapshot(tx)
 	i.btreeForIter(tx).AscendGreaterOrEqual(after, func(t *T) bool {
 		return each(i.copy(t))
 	})
 }
 
 func (i *Index[T]) Descend(tx *Snapshot, each func(*T) bool) {
+	tx = i.ensureSnapshot(tx)
 	i.btreeForIter(tx).Descend(func(t *T) bool {
 		return each(i.copy(t))
 	})
 }
 
 func (i *Index[T]) DescendAfter(tx *Snapshot, after *T, each func(*T) bool) {
+	tx = i.ensureSnapshot(tx)
 	i.btreeForIter(tx).DescendLessOrEqual(after, func(t *T) bool {
 		return each(i.copy(t))
 	})
@@ -133,7 +146,12 @@ type ListArgs[T any] struct {
 	Limit int           // Maximum number of items to return. 0 => All.
 }
 
-func (i *Index[T]) List(tx *Snapshot, args ListArgs[T], out []*T) []*T {
+func (i *Index[T]) List(tx *Snapshot, args *ListArgs[T], out []*T) []*T {
+	tx = i.ensureSnapshot(tx)
+	if args == nil {
+		args = &ListArgs[T]{}
+	}
+
 	if args.Limit < 0 {
 		return nil
 	}

mdb/testdb_test.go

@@ -133,8 +133,8 @@ func (db DataDB) modifyOnce() {
 func (db DataDB) ComputeCRC(tx *Snapshot) uint32 {
 	h := crc32.NewIEEE()
 	for dataID := uint64(1); dataID < 10; dataID++ {
-		d, ok := db.Datas.ByID.Get(tx, &DataItem{ID: dataID})
+		d := db.Datas.ByID.Get(tx, &DataItem{ID: dataID})
-		if !ok {
+		if d == nil {
 			continue
 		}
 		h.Write(d.Data)
@@ -143,8 +143,8 @@ func (db DataDB) ComputeCRC(tx *Snapshot) uint32 {
 }
 
 func (db DataDB) ReadCRC(tx *Snapshot) uint32 {
-	r, ok := db.CRCs.ByID.Get(tx, &CRCItem{ID: 1})
+	r := db.CRCs.ByID.Get(tx, &CRCItem{ID: 1})
-	if !ok {
+	if r == nil {
 		return 0
 	}
 	return r.CRC32

mdb/testing/crashconsistency/main.go

@@ -136,8 +136,8 @@ func (db DataDB) modifyOnce() {
 func (db DataDB) ComputeCRC(tx *mdb.Snapshot) uint32 {
 	h := crc32.NewIEEE()
 	for dataID := uint64(1); dataID < 10; dataID++ {
-		d, ok := db.Datas.ByID.Get(tx, &DataItem{ID: dataID})
+		d := db.Datas.ByID.Get(tx, &DataItem{ID: dataID})
-		if !ok {
+		if d == nil {
 			continue
 		}
 		h.Write(d.Data)
@@ -146,8 +146,8 @@ func (db DataDB) ComputeCRC(tx *mdb.Snapshot) uint32 {
 }
 
 func (db DataDB) ReadCRC(tx *mdb.Snapshot) uint32 {
-	r, ok := db.CRCs.ByID.Get(tx, &CRCItem{ID: 1})
+	r := db.CRCs.ByID.Get(tx, &CRCItem{ID: 1})
-	if !ok {
+	if r == nil {
 		return 0
 	}
 	return r.CRC32