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// 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"
"time"
"git.fd.io/govpp.git/api"
)
type Stream struct {
id uint32
conn *Connection
ctx context.Context
channel *Channel
// available options
requestSize int
replySize int
replyTimeout time.Duration
}
func (c *Connection) NewStream(ctx context.Context, options ...api.StreamOption) (api.Stream, error) {
if c == nil {
return nil, errors.New("nil connection passed in")
}
s := &Stream{
conn: c,
ctx: ctx,
// default options
requestSize: RequestChanBufSize,
replySize: ReplyChanBufSize,
replyTimeout: DefaultReplyTimeout,
}
// parse custom options
for _, option := range options {
option(s)
}
// create and store a new channel
s.id = atomic.AddUint32(&c.maxChannelID, 1) & 0x7fff
s.channel = newChannel(uint16(s.id), c, c.codec, c, s.requestSize, s.replySize)
s.channel.SetReplyTimeout(s.replyTimeout)
// store API channel within the client
c.channelsLock.Lock()
c.channels[uint16(s.id)] = s.channel
c.channelsLock.Unlock()
// Channel.watchRequests are not started here intentionally, because
// requests are sent directly by SendMsg.
return s, nil
}
func (c *Connection) Invoke(ctx context.Context, req api.Message, reply api.Message) error {
stream, err := c.NewStream(ctx)
if err != nil {
return err
}
if err := stream.SendMsg(req); err != nil {
return err
}
s := stream.(*Stream)
rep, err := s.recvReply()
if err != nil {
return err
}
if err := s.channel.msgCodec.DecodeMsg(rep.data, reply); err != nil {
return err
}
return nil
}
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) {
reply, err := s.recvReply()
if err != nil {
return nil, 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
}
func WithRequestSize(size int) api.StreamOption {
return func(stream api.Stream) {
stream.(*Stream).requestSize = size
}
}
func WithReplySize(size int) api.StreamOption {
return func(stream api.Stream) {
stream.(*Stream).replySize = size
}
}
func WithReplyTimeout(timeout time.Duration) api.StreamOption {
return func(stream api.Stream) {
stream.(*Stream).replyTimeout = timeout
}
}
func (s *Stream) recvReply() (*vppReply, 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
}
return reply, nil
case <-s.ctx.Done():
return nil, s.ctx.Err()
}
}
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