GODRIVER-2025 Stop replacing the bsonrw.valueWriter buffer when given a SliceWriter destination. (#679)

Author: matthewdale

bson/bsonrw/value_writer.go

@@ -47,11 +47,9 @@ func NewBSONValueWriterPool() *BSONValueWriterPool {
 // Get retrieves a BSON ValueWriter from the pool and resets it to use w as the destination.
 func (bvwp *BSONValueWriterPool) Get(w io.Writer) ValueWriter {
 	vw := bvwp.pool.Get().(*valueWriter)
-	if writer, ok := w.(*SliceWriter); ok {
-		vw.reset(*writer)
-		vw.w = writer
-		return vw
-	}
+
+	// TODO: Having to call reset here with the same buffer doesn't really make sense.
+	vw.reset(vw.buf)
 	vw.buf = vw.buf[:0]
 	vw.w = w
 	return vw
@@ -72,11 +70,6 @@ func (bvwp *BSONValueWriterPool) Put(vw ValueWriter) (ok bool) {
 		return false
 	}
 
-	if _, ok := bvw.w.(*SliceWriter); ok {
-		bvw.buf = nil
-	}
-	bvw.w = nil
-
 	bvwp.pool.Put(bvw)
 	return true
 }
@@ -549,10 +542,6 @@ func (vw *valueWriter) Flush() error {
 		return nil
 	}
 
-	if sw, ok := vw.w.(*SliceWriter); ok {
-		*sw = vw.buf
-		return nil
-	}
 	if _, err := vw.w.Write(vw.buf); err != nil {
 		return err
 	}

bson/marshal.go

@@ -52,14 +52,14 @@ func MarshalAppend(dst []byte, val interface{}) ([]byte, error) {
 // MarshalWithRegistry returns the BSON encoding of val as a BSON document. If val is not a type that can be transformed
 // into a document, MarshalValueWithRegistry should be used instead.
 func MarshalWithRegistry(r *bsoncodec.Registry, val interface{}) ([]byte, error) {
-	dst := make([]byte, 0, 256) // TODO: make the default cap a constant
+	dst := make([]byte, 0)
 	return MarshalAppendWithRegistry(r, dst, val)
 }
 
 // MarshalWithContext returns the BSON encoding of val as a BSON document using EncodeContext ec. If val is not a type
 // that can be transformed into a document, MarshalValueWithContext should be used instead.
 func MarshalWithContext(ec bsoncodec.EncodeContext, val interface{}) ([]byte, error) {
-	dst := make([]byte, 0, 256) // TODO: make the default cap a constant
+	dst := make([]byte, 0)
 	return MarshalAppendWithContext(ec, dst, val)
 }
 
@@ -115,13 +115,13 @@ func MarshalValueAppend(dst []byte, val interface{}) (bsontype.Type, []byte, err
 
 // MarshalValueWithRegistry returns the BSON encoding of val using Registry r.
 func MarshalValueWithRegistry(r *bsoncodec.Registry, val interface{}) (bsontype.Type, []byte, error) {
-	dst := make([]byte, 0, defaultDstCap)
+	dst := make([]byte, 0)
 	return MarshalValueAppendWithRegistry(r, dst, val)
 }
 
 // MarshalValueWithContext returns the BSON encoding of val using EncodeContext ec.
 func MarshalValueWithContext(ec bsoncodec.EncodeContext, val interface{}) (bsontype.Type, []byte, error) {
-	dst := make([]byte, 0, defaultDstCap)
+	dst := make([]byte, 0)
 	return MarshalValueAppendWithContext(ec, dst, val)
 }