[#276] Merge repo with frostfs-api-go

Signed-off-by: Pavel Pogodaev <p.pogodaev@yadro.com>

api/rpc/client/flows.go

@@ -0,0 +1,124 @@
+package client
+
+import (
+	"errors"
+	"io"
+	"sync"
+
+	"git.frostfs.info/TrueCloudLab/frostfs-sdk-go/api/rpc/common"
+	"git.frostfs.info/TrueCloudLab/frostfs-sdk-go/api/rpc/message"
+)
+
+// SendUnary initializes communication session by RPC info, performs unary RPC
+// and closes the session.
+func SendUnary(cli *Client, info common.CallMethodInfo, req, resp message.Message, opts ...CallOption) error {
+	rw, err := cli.Init(info, opts...)
+	if err != nil {
+		return err
+	}
+
+	err = rw.WriteMessage(req)
+	if err != nil {
+		return err
+	}
+
+	err = rw.ReadMessage(resp)
+	if err != nil {
+		return err
+	}
+
+	return rw.Close()
+}
+
+// MessageWriterCloser wraps MessageWriter
+// and io.Closer interfaces.
+type MessageWriterCloser interface {
+	MessageWriter
+	io.Closer
+}
+
+type clientStreamWriterCloser struct {
+	MessageReadWriter
+
+	resp message.Message
+}
+
+func (c *clientStreamWriterCloser) Close() error {
+	err := c.MessageReadWriter.Close()
+	if err != nil {
+		return err
+	}
+
+	return c.ReadMessage(c.resp)
+}
+
+// OpenClientStream initializes communication session by RPC info, opens client-side stream
+// and returns its interface.
+//
+// All stream writes must be performed before the closing. Close must be called once.
+func OpenClientStream(cli *Client, info common.CallMethodInfo, resp message.Message, opts ...CallOption) (MessageWriterCloser, error) {
+	rw, err := cli.Init(info, opts...)
+	if err != nil {
+		return nil, err
+	}
+
+	return &clientStreamWriterCloser{
+		MessageReadWriter: rw,
+		resp:              resp,
+	}, nil
+}
+
+// MessageReaderCloser wraps MessageReader
+// and io.Closer interface.
+type MessageReaderCloser interface {
+	MessageReader
+	io.Closer
+}
+
+type serverStreamReaderCloser struct {
+	rw MessageReadWriter
+
+	once sync.Once
+
+	req message.Message
+}
+
+func (s *serverStreamReaderCloser) ReadMessage(msg message.Message) error {
+	var err error
+
+	s.once.Do(func() {
+		err = s.rw.WriteMessage(s.req)
+	})
+
+	if err != nil {
+		return err
+	}
+
+	err = s.rw.ReadMessage(msg)
+	if !errors.Is(err, io.EOF) {
+		return err
+	}
+
+	err = s.rw.Close()
+	if err != nil {
+		return err
+	}
+
+	return io.EOF
+}
+
+// OpenServerStream initializes communication session by RPC info, opens server-side stream
+// and returns its interface.
+//
+// All stream reads must be performed before the closing. Close must be called once.
+func OpenServerStream(cli *Client, info common.CallMethodInfo, req message.Message, opts ...CallOption) (MessageReader, error) {
+	rw, err := cli.Init(info, opts...)
+	if err != nil {
+		return nil, err
+	}
+
+	return &serverStreamReaderCloser{
+		rw:  rw,
+		req: req,
+	}, nil
+}