(v27) support empty key/values: 1. as valid dupsort key/values 2. as …

…valid Set/SetRange/GetBoth/GetBothRange arguments (#124)
erigontech · Nov 1, 2023 · e364f0a · e364f0a
1 parent 9206bf3
commit e364f0a
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Showing 4 changed files with 150 additions and 1 deletion.
diff --git a/mdbx/cursor.go b/mdbx/cursor.go
@@ -148,8 +148,10 @@ func (c *Cursor) DBI() DBI {
 // See mdb_cursor_get.
 func (c *Cursor) Get(setkey, setval []byte, op uint) (key, val []byte, err error) {
 	switch {
-	case len(setkey) == 0:
+	case len(setkey) == 0 && len(setval) == 0:
 		err = c.getVal0(op)
+	case len(setkey) == 0:
+		err = c.getVal01(setval, op)
 	case len(setval) == 0:
 		err = c.getVal1(setkey, op)
 	default:
@@ -209,6 +211,20 @@ func (c *Cursor) getVal1(setkey []byte, op uint) error {
 	)
 	return operrno("mdbx_cursor_get", ret)
 }
+func (c *Cursor) getVal01(setval []byte, op uint) error {
+	var v *C.char
+	if len(setval) > 0 {
+		v = (*C.char)(unsafe.Pointer(&setval[0]))
+	}
+	ret := C.mdbxgo_cursor_get01(
+		c._c,
+		v, C.size_t(len(setval)),
+		c.txn.key,
+		c.txn.val,
+		C.MDBX_cursor_op(op),
+	)
+	return operrno("mdbx_cursor_get", ret)
+}
 
 // getVal2 retrieves items from the database using key and value data for
 // reference (GetBoth, GetBothRange, etc).

diff --git a/mdbx/cursor_test.go b/mdbx/cursor_test.go
@@ -729,6 +729,133 @@ func TestCursor_Del(t *testing.T) {
 	}
 }
 
+func TestDupCursor_EmptyKeyValues(t *testing.T) {
+	env := setup(t)
+
+	var db DBI
+	err := env.Update(func(txn *Txn) (err error) {
+		db, err = txn.OpenDBI("testingdup", Create|DupSort, nil, nil)
+		if err != nil {
+			return err
+		}
+		cur, err := txn.OpenCursor(db)
+		if err != nil {
+			return err
+		}
+		defer cur.Close()
+
+		// empty value - must function as valid dupsort value
+		if err = txn.Put(db, []byte{1}, []byte{}, 0); err != nil {
+			panic(err)
+		}
+		if err = txn.Put(db, []byte{1}, []byte{8}, 0); err != nil {
+			panic(err)
+		}
+
+		_, v, err := cur.Get([]byte{1}, []byte{}, GetBothRange)
+		if err != nil {
+			panic(err)
+		}
+		if !bytes.Equal(v, []byte{}) {
+			panic(v)
+		}
+		_, v, err = cur.Get([]byte{1}, []byte{0}, GetBothRange)
+		if err != nil {
+			panic(err)
+		}
+		if !bytes.Equal(v, []byte{8}) {
+			panic(v)
+		}
+		_, v, err = cur.Get([]byte{}, []byte{0}, GetBoth)
+		if err == nil {
+			panic("expecting 'not found' error")
+		}
+		if v != nil {
+			panic(v)
+		}
+
+		// can use empty key as valid key in non-dupsort operations
+		k, v, err := cur.Get([]byte{}, nil, SetRange)
+		if err != nil {
+			panic(err)
+		}
+		if k == nil {
+			panic("nil")
+		}
+		if !bytes.Equal(k, []byte{1}) {
+			panic(fmt.Sprintf("%x", k))
+		}
+		if !bytes.Equal(v, []byte{}) {
+			panic(fmt.Sprintf("%x", v))
+		}
+		k, v, err = cur.Get([]byte{}, nil, Set)
+		if err == nil {
+			panic("expected 'not found' error")
+		}
+		if k != nil {
+			panic("nil")
+		}
+
+		// empty key - must function as valid dupsort key
+		if err = txn.Put(db, []byte{}, []byte{}, 0); err != nil {
+			panic(err)
+		}
+		if err = txn.Put(db, []byte{}, []byte{2}, 0); err != nil {
+			panic(err)
+		}
+		_, v, err = cur.Get([]byte{}, []byte{}, GetBothRange)
+		if err != nil {
+			panic(err)
+		}
+		if !bytes.Equal(v, []byte{}) {
+			panic(v)
+		}
+		_, v, err = cur.Get([]byte{}, []byte{0}, GetBothRange)
+		if err != nil {
+			panic(err)
+		}
+		if !bytes.Equal(v, []byte{2}) {
+			panic(v)
+		}
+		_, v, err = cur.Get([]byte{}, []byte{0}, GetBoth)
+		if err == nil {
+			panic("expecting 'not found' error ")
+		}
+		if v != nil {
+			panic(v)
+		}
+
+		// non-existing key
+		_, v, err = cur.Get([]byte{7}, []byte{}, GetBoth)
+		if err == nil {
+			panic("expecting 'not found' error")
+		}
+		if v != nil {
+			panic(v)
+		}
+
+		// sub-db doesn't have empty value, but we must be able to search from it
+		if err = txn.Put(db, []byte{2}, []byte{1}, 0); err != nil {
+			return err
+		}
+		if err = txn.Put(db, []byte{2}, []byte{3}, 0); err != nil {
+			return err
+		}
+		_, v, err = cur.Get([]byte{2}, []byte{}, GetBothRange)
+		if err != nil {
+			panic(err)
+		}
+		if !bytes.Equal(v, []byte{1}) {
+			panic(v)
+		}
+
+		return nil
+	})
+	if err != nil {
+		t.Error(err)
+	}
+}
+
 // This test verifies the behavior of Cursor.Count when DupSort is provided.
 func TestCursor_Count_DupSort(t *testing.T) {
 	env := setup(t)

diff --git a/mdbx/mdbxgo.c b/mdbx/mdbxgo.c
@@ -60,6 +60,11 @@ int mdbxgo_cursor_putmulti(MDBX_cursor *cur, char *kdata, size_t kn, char *vdata
     return mdbx_cursor_put(cur, &key, &val[0], flags);
 }
 
+int mdbxgo_cursor_get01(MDBX_cursor *cur, char *vdata, size_t vn, MDBX_val *key, MDBX_val *val, MDBX_cursor_op op) {
+    MDBXGO_SET_VAL(val, vn, vdata);
+    return mdbx_cursor_get(cur, key, val, op);
+}
+
 int mdbxgo_cursor_get1(MDBX_cursor *cur, char *kdata, size_t kn, MDBX_val *key, MDBX_val *val, MDBX_cursor_op op) {
     MDBXGO_SET_VAL(key, kn, kdata);
     return mdbx_cursor_get(cur, key, val, op);

diff --git a/mdbx/mdbxgo.h b/mdbx/mdbxgo.h
@@ -24,6 +24,7 @@ int mdbxgo_put2(MDBX_txn *txn, MDBX_dbi dbi, char *kdata, size_t kn, char *vdata
 int mdbxgo_cursor_put1(MDBX_cursor *cur, char *kdata, size_t kn, MDBX_val *val, MDBX_put_flags_t flags);
 int mdbxgo_cursor_put2(MDBX_cursor *cur, char *kdata, size_t kn, char *vdata, size_t vn, MDBX_put_flags_t flags);
 int mdbxgo_cursor_putmulti(MDBX_cursor *cur, char *kdata, size_t kn, char *vdata, size_t vn, size_t vstride, MDBX_put_flags_t flags);
+int mdbxgo_cursor_get01(MDBX_cursor *cur, char *vdata, size_t vn, MDBX_val *key, MDBX_val *val, MDBX_cursor_op op);
 int mdbxgo_cursor_get1(MDBX_cursor *cur, char *kdata, size_t kn, MDBX_val *key, MDBX_val *val, MDBX_cursor_op op);
 int mdbxgo_cursor_get2(MDBX_cursor *cur, char *kdata, size_t kn, char *vdata, size_t vn, MDBX_val *key, MDBX_val *val, MDBX_cursor_op op);