No pointer optimisation txn (#142)

* added valNP (no pointer value) argument to Txn obj tp increase performance (see GetFast for more details)

* replace txn.Get with txn.GetFast realization

* change type of txn.val from *C.MDBX_val to C.MDBX_val

* no longer takes pointer from env val

---------

Co-authored-by: Ilya Miheev <[email protected]>

mdbx/cursor.go

@@ -159,7 +159,7 @@ func (c *Cursor) Get(setkey, setval []byte, op uint) (key, val []byte, err error
 	}
 	if err != nil {
 		*c.txn.key = C.MDBX_val{}
-		*c.txn.val = C.MDBX_val{}
+		c.txn.val = C.MDBX_val{}
 		return nil, nil, err
 	}
 
@@ -174,12 +174,12 @@ func (c *Cursor) Get(setkey, setval []byte, op uint) (key, val []byte, err error
 			key = castToBytes(c.txn.key)
 		}
 	}
-	val = castToBytes(c.txn.val)
+	val = castToBytes(&c.txn.val)
 
 	// Clear transaction storage record storage area for future use and to
 	// prevent dangling references.
 	*c.txn.key = C.MDBX_val{}
-	*c.txn.val = C.MDBX_val{}
+	c.txn.val = C.MDBX_val{}
 
 	return key, val, nil
 }
@@ -189,7 +189,7 @@ func (c *Cursor) Get(setkey, setval []byte, op uint) (key, val []byte, err error
 //
 // See mdb_cursor_get.
 func (c *Cursor) getVal0(op uint) error {
-	ret := C.mdbx_cursor_get(c._c, c.txn.key, c.txn.val, C.MDBX_cursor_op(op))
+	ret := C.mdbx_cursor_get(c._c, c.txn.key, &c.txn.val, C.MDBX_cursor_op(op))
 	return operrno("mdbx_cursor_get", ret)
 }
 
@@ -206,7 +206,7 @@ func (c *Cursor) getVal1(setkey []byte, op uint) error {
 		c._c,
 		k, C.size_t(len(setkey)),
 		c.txn.key,
-		c.txn.val,
+		&c.txn.val,
 		C.MDBX_cursor_op(op),
 	)
 	return operrno("mdbx_cursor_get", ret)
@@ -220,7 +220,7 @@ func (c *Cursor) getVal01(setval []byte, op uint) error {
 		c._c,
 		v, C.size_t(len(setval)),
 		c.txn.key,
-		c.txn.val,
+		&c.txn.val,
 		C.MDBX_cursor_op(op),
 	)
 	return operrno("mdbx_cursor_get", ret)
@@ -242,7 +242,7 @@ func (c *Cursor) getVal2(setkey, setval []byte, op uint) error {
 		c._c,
 		k, C.size_t(len(setkey)),
 		v, C.size_t(len(setval)),
-		c.txn.key, c.txn.val,
+		c.txn.key, &c.txn.val,
 		C.MDBX_cursor_op(op),
 	)
 	return operrno("mdbx_cursor_get", ret)
@@ -280,16 +280,16 @@ func (c *Cursor) PutReserve(key []byte, n int, flags uint) ([]byte, error) {
 	ret := C.mdbxgo_cursor_put1(
 		c._c,
 		k, C.size_t(len(key)),
-		c.txn.val,
+		&c.txn.val,
 		C.MDBX_put_flags_t(flags|C.MDBX_RESERVE),
 	)
 	err := operrno("mdbx_cursor_put", ret)
 	if err != nil {
-		*c.txn.val = C.MDBX_val{}
+		c.txn.val = C.MDBX_val{}
 		return nil, err
 	}
-	b := castToBytes(c.txn.val)
-	*c.txn.val = C.MDBX_val{}
+	b := castToBytes(&c.txn.val)
+	c.txn.val = C.MDBX_val{}
 	return b, nil
 }
 

mdbx/txn.go

@@ -60,7 +60,7 @@ type Txn struct {
 	env  *Env
 	_txn *C.MDBX_txn
 	key  *C.MDBX_val
-	val  *C.MDBX_val
+	val  C.MDBX_val
 
 	errLogf func(format string, v ...interface{})
 
@@ -93,14 +93,12 @@ func beginTxn(env *Env, parent *Txn, flags uint) (*Txn, error) {
 			// In a write Txn we can use the shared, C-allocated key and value
 			// allocated by env, and freed when it is closed.
 			txn.key = env.ckey
-			txn.val = env.cval
 		} else {
 			// It is not easy to share C.MDBX_val values in this scenario unless
 			// there is a synchronized pool involved, which will increase
 			// overhead.  Further, allocating these values with C will add
 			// overhead both here and when the values are freed.
 			txn.key = new(C.MDBX_val)
-			txn.val = new(C.MDBX_val)
 		}
 	} else {
 		// Because parent Txn objects cannot be used while a sub-Txn is active
@@ -593,15 +591,15 @@ func (txn *Txn) Get(dbi DBI, key []byte) ([]byte, error) {
 	ret := C.mdbxgo_get(
 		txn._txn, C.MDBX_dbi(dbi),
 		k, C.size_t(len(key)),
-		txn.val,
+		&txn.val,
 	)
 	err := operrno("mdbx_get", ret)
 	if err != nil {
-		*txn.val = C.MDBX_val{}
+		txn.val = C.MDBX_val{}
 		return nil, err
 	}
-	b := castToBytes(txn.val)
-	*txn.val = C.MDBX_val{}
+	b := castToBytes(&txn.val)
+	txn.val = C.MDBX_val{}
 	return b, nil
 }
 
@@ -637,16 +635,16 @@ func (txn *Txn) PutReserve(dbi DBI, key []byte, n int, flags uint) ([]byte, erro
 	ret := C.mdbxgo_put1(
 		txn._txn, C.MDBX_dbi(dbi),
 		k, C.size_t(len(key)),
-		txn.val,
+		&txn.val,
 		C.MDBX_put_flags_t(flags|C.MDBX_RESERVE),
 	)
 	err := operrno("mdbx_put", ret)
 	if err != nil {
-		*txn.val = C.MDBX_val{}
+		txn.val = C.MDBX_val{}
 		return nil, err
 	}
-	b := castToBytes(txn.val)
-	*txn.val = C.MDBX_val{}
+	b := castToBytes(&txn.val)
+	txn.val = C.MDBX_val{}
 	return b, nil
 }