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

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

api/rpc/client/init.go

@@ -0,0 +1,69 @@
+package client
+
+import (
+	"context"
+	"io"
+
+	"git.frostfs.info/TrueCloudLab/frostfs-sdk-go/api/rpc/common"
+	"git.frostfs.info/TrueCloudLab/frostfs-sdk-go/api/rpc/message"
+	"google.golang.org/grpc"
+)
+
+// MessageReader is an interface of the Message reader.
+type MessageReader interface {
+	// ReadMessage reads the next Message.
+	//
+	// Returns io.EOF if there are no more messages to read.
+	// ReadMessage should not be called after io.EOF occasion.
+	ReadMessage(message.Message) error
+}
+
+// MessageWriter is an interface of the Message writer.
+type MessageWriter interface {
+	// WriteMessage writers the next Message.
+	//
+	// WriteMessage should not be called after any error.
+	WriteMessage(message.Message) error
+}
+
+// MessageReadWriter is a component interface
+// for transmitting raw Protobuf messages.
+type MessageReadWriter interface {
+	MessageReader
+	MessageWriter
+
+	// Closes the communication session.
+	//
+	// All calls to send/receive messages must be done before closing.
+	io.Closer
+}
+
+// Init initiates a messaging session and returns the interface for message transmitting.
+func (c *Client) Init(info common.CallMethodInfo, opts ...CallOption) (MessageReadWriter, error) {
+	prm := defaultCallParameters()
+
+	for _, opt := range opts {
+		opt(prm)
+	}
+
+	if err := c.openGRPCConn(prm.ctx, prm.dialer); err != nil {
+		return nil, err
+	}
+
+	ctx, cancel := context.WithCancel(prm.ctx)
+	stream, err := c.conn.NewStream(ctx, &grpc.StreamDesc{
+		StreamName:    info.Name,
+		ServerStreams: info.ServerStream(),
+		ClientStreams: info.ClientStream(),
+	}, toMethodName(info))
+	if err != nil {
+		cancel()
+		return nil, err
+	}
+
+	return &streamWrapper{
+		ClientStream: stream,
+		cancel:       cancel,
+		timeout:      c.rwTimeout,
+	}, nil
+}