From df67791c6ffc96331f75aec7d3addfe2efca7739 Mon Sep 17 00:00:00 2001
From: Ondrej Fabry <ofabry@cisco.com>
Date: Thu, 25 Jun 2020 11:55:58 +0200
Subject: Introduce Stream - experimental API for low-level access to VPP API

Change-Id: I2698e11b76ff55d9730b47d4fee990be93349516
Signed-off-by: Ondrej Fabry <ofabry@cisco.com>
---
 core/stream.go | 124 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 124 insertions(+)
 create mode 100644 core/stream.go

(limited to 'core/stream.go')

diff --git a/core/stream.go b/core/stream.go
new file mode 100644
index 0000000..edc3f2b
--- /dev/null
+++ b/core/stream.go
@@ -0,0 +1,124 @@
+//  Copyright (c) 2020 Cisco and/or its affiliates.
+//
+//  Licensed under the Apache License, Version 2.0 (the "License");
+//  you may not use this file except in compliance with the License.
+//  You may obtain a copy of the License at:
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+//  Unless required by applicable law or agreed to in writing, software
+//  distributed under the License is distributed on an "AS IS" BASIS,
+//  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+//  See the License for the specific language governing permissions and
+//  limitations under the License.
+
+package core
+
+import (
+	"context"
+	"errors"
+	"fmt"
+	"reflect"
+	"sync/atomic"
+
+	"git.fd.io/govpp.git/api"
+)
+
+type Stream struct {
+	id      uint32
+	conn    *Connection
+	ctx     context.Context
+	channel *Channel
+}
+
+func (c *Connection) NewStream(ctx context.Context) (api.Stream, error) {
+	if c == nil {
+		return nil, errors.New("nil connection passed in")
+	}
+	// TODO: add stream options as variadic parameters for customizing:
+	// - request/reply channel size
+	// - reply timeout
+	// - retries
+	// - ???
+
+	// create new channel
+	chID := uint16(atomic.AddUint32(&c.maxChannelID, 1) & 0x7fff)
+	channel := newChannel(chID, c, c.codec, c, 10, 10)
+
+	// store API channel within the client
+	c.channelsLock.Lock()
+	c.channels[chID] = channel
+	c.channelsLock.Unlock()
+
+	// Channel.watchRequests are not started here intentionally, because
+	// requests are sent directly by SendMsg.
+
+	return &Stream{
+		id:      uint32(chID),
+		conn:    c,
+		ctx:     ctx,
+		channel: channel,
+	}, nil
+}
+
+func (c *Connection) Invoke(ctx context.Context, req api.Message, reply api.Message) error {
+	// TODO: implement invoke
+	panic("not implemented")
+}
+
+func (s *Stream) Context() context.Context {
+	return s.ctx
+}
+
+func (s *Stream) Close() error {
+	if s.conn == nil {
+		return errors.New("stream closed")
+	}
+	s.conn.releaseAPIChannel(s.channel)
+	s.conn = nil
+	return nil
+}
+
+func (s *Stream) SendMsg(msg api.Message) error {
+	if s.conn == nil {
+		return errors.New("stream closed")
+	}
+	req := s.channel.newRequest(msg, false)
+	if err := s.conn.processRequest(s.channel, req); err != nil {
+		return err
+	}
+	return nil
+}
+
+func (s *Stream) RecvMsg() (api.Message, error) {
+	if s.conn == nil {
+		return nil, errors.New("stream closed")
+	}
+	select {
+	case reply, ok := <-s.channel.replyChan:
+		if !ok {
+			return nil, fmt.Errorf("reply channel closed")
+		}
+		if reply.err != nil {
+			// this case should actually never happen for stream
+			// since reply.err is only filled in watchRequests
+			// and stream does not use it
+			return nil, reply.err
+		}
+		// resolve message type
+		msg, err := s.channel.msgIdentifier.LookupByID(reply.msgID)
+		if err != nil {
+			return nil, err
+		}
+		// allocate message instance
+		msg = reflect.New(reflect.TypeOf(msg).Elem()).Interface().(api.Message)
+		// decode message data
+		if err := s.channel.msgCodec.DecodeMsg(reply.data, msg); err != nil {
+			return nil, err
+		}
+		return msg, nil
+
+	case <-s.ctx.Done():
+		return nil, s.ctx.Err()
+	}
+}
-- 
cgit 1.2.3-korg