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stream.go
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stream.go
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// Copyright 2019-present Open Networking Foundation.
//
// 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 service
import (
"container/list"
streams "github.com/atomix/go-framework/pkg/atomix/stream"
"github.com/atomix/go-framework/pkg/atomix/util"
"github.com/gogo/protobuf/proto"
)
// sessionStream manages a single stream for a session
type sessionStream struct {
ID uint64
Type string
session *Session
responseID uint64
completeID uint64
lastIndex uint64
ctx Context
stream streams.WriteStream
results *list.List
}
// sessionStreamResult contains a single stream result
type sessionStreamResult struct {
id uint64
index uint64
result streams.Result
}
// open opens the stream
func (s *sessionStream) open() {
s.updateClock()
bytes, err := proto.Marshal(&SessionResponse{
Response: &SessionResponse_Command{
Command: &SessionCommandResponse{
Context: &SessionResponseContext{
StreamID: s.ID,
Index: s.lastIndex,
Sequence: s.responseID,
Type: SessionResponseType_OPEN_STREAM,
},
},
},
})
result := streams.Result{
Value: bytes,
Error: err,
}
out := sessionStreamResult{
id: s.responseID,
index: s.ctx.Index(),
result: result,
}
s.results.PushBack(out)
util.StreamEntry(s.ctx.Node(), s.session.ID, s.ID).
Tracef("Sending stream open %d %v", s.responseID, out.result)
s.stream.Send(out.result)
}
func (s *sessionStream) updateClock() {
// If the client acked a sequence number greater than the current event sequence number since we know the
// client must have received it from another server.
s.responseID++
if s.completeID > s.responseID {
util.StreamEntry(s.ctx.Node(), s.session.ID, s.ID).
Debugf("Skipped completed result %d", s.responseID)
return
}
// Record the last index sent on the stream
s.lastIndex = s.ctx.Index()
}
func (s *sessionStream) Send(result streams.Result) {
s.updateClock()
// Create the stream result and add it to the results list.
if result.Succeeded() {
bytes, err := proto.Marshal(&SessionResponse{
Response: &SessionResponse_Command{
Command: &SessionCommandResponse{
Context: &SessionResponseContext{
StreamID: s.ID,
Index: s.lastIndex,
Sequence: s.responseID,
},
Response: &ServiceCommandResponse{
Response: &ServiceCommandResponse_Operation{
Operation: &ServiceOperationResponse{
result.Value.([]byte),
},
},
},
},
},
})
result = streams.Result{
Value: bytes,
Error: err,
}
}
out := sessionStreamResult{
id: s.responseID,
index: s.ctx.Index(),
result: result,
}
s.results.PushBack(out)
util.StreamEntry(s.ctx.Node(), s.session.ID, s.ID).
Tracef("Cached response %d", s.responseID)
// If the out channel is set, send the result
util.StreamEntry(s.ctx.Node(), s.session.ID, s.ID).
Tracef("Sending response %d %v", s.responseID, out.result)
s.stream.Send(out.result)
}
func (s *sessionStream) Result(value interface{}, err error) {
s.Send(streams.Result{
Value: value,
Error: err,
})
}
func (s *sessionStream) Value(value interface{}) {
s.Result(value, nil)
}
func (s *sessionStream) Error(err error) {
s.Result(nil, err)
}
func (s *sessionStream) Close() {
util.StreamEntry(s.ctx.Node(), s.session.ID, s.ID).
Trace("Stream closed")
s.updateClock()
bytes, err := proto.Marshal(&SessionResponse{
Response: &SessionResponse_Command{
Command: &SessionCommandResponse{
Context: &SessionResponseContext{
StreamID: s.ID,
Index: s.lastIndex,
Sequence: s.responseID,
Type: SessionResponseType_CLOSE_STREAM,
},
},
},
})
result := streams.Result{
Value: bytes,
Error: err,
}
out := sessionStreamResult{
id: s.responseID,
index: s.ctx.Index(),
result: result,
}
s.results.PushBack(out)
util.StreamEntry(s.ctx.Node(), s.session.ID, s.ID).
Tracef("Sending stream close %d %v", s.responseID, out.result)
s.stream.Send(out.result)
s.stream.Close()
}
// LastIndex returns the last index in the stream
func (s *sessionStream) LastIndex() uint64 {
if s.results.Len() > 0 {
return s.lastIndex
}
return s.ctx.Index()
}
// ack acknowledges results up to the given ID
func (s *sessionStream) ack(id uint64) {
if id > s.completeID {
event := s.results.Front()
for event != nil && event.Value.(sessionStreamResult).id <= id {
next := event.Next()
s.results.Remove(event)
s.completeID = event.Value.(sessionStreamResult).id
event = next
}
util.StreamEntry(s.ctx.Node(), s.session.ID, s.ID).
Tracef("Discarded cached responses up to %d", id)
}
}
// replay resends results on the given channel
func (s *sessionStream) replay(stream streams.WriteStream) {
result := s.results.Front()
for result != nil {
response := result.Value.(sessionStreamResult)
util.StreamEntry(s.ctx.Node(), s.session.ID, s.ID).
Tracef("Sending response %d %v", response.id, response.result)
stream.Send(response.result)
result = result.Next()
}
s.stream = stream
}