Refacor routines to reduce duplication

blockchain/v2/routines.go

@@ -6,32 +6,15 @@ import (
 )
 
 /*
-# Message passing between components
-	* output of one routine becomes input for all other routines
-	* avoid loops somehow
-	* Message priority
-
-# Components have isolated lifecycle management
-	* Lifecycle management
-		* Setup
-		* Teardown
-# Individual
-			* message passing should be non blocking
-		* backpressure between components
-		* Lifecycle management of components
-		* Observable behavior:
-			* progress
-			* blocking components
-	What would look a test look like?
-		Lifecycle management
-			Start/Stop
-
-	How to make this non blocking?
-
-	How to avoid Thread saturation
-	How to handle concurrency
+TODO:
+	* Look at refactoring routines
+		* single struct, paramterize the handle function
+	* introduce an sendError and seperate error channel
+	* How could this be tested?
+		* Ensure Start/Stopping
+		* Ensure all messages sent are processed
+		* Ensure that errors can be processed depsite outstanding messages
 */
-
 type testEvent struct {
 	msg  string
 	time time.Time
@@ -46,50 +29,65 @@ type timeCheck struct {
 	time time.Time
 }
 
-// scheduler
+type handleFunc = func(event Event) Events
 
-type scheduler struct {
+// Routine
+type Routine struct {
+	name    string
 	input   chan Event
 	output  chan Event
 	stopped chan struct{}
+	handle  handleFunc
 }
 
-func newScheduler(output chan Event) *scheduler {
-	return &scheduler{
+func newRoutine(name string, output chan Event, handleFunc handleFunc) *Routine {
+	return &Routine{
+		name:    name,
 		input:   make(chan Event, 1),
 		output:  output,
 		stopped: make(chan struct{}, 1),
+		handle:  handleFunc,
 	}
 }
 
-func (sc *scheduler) run() {
-	fmt.Println("scheduler run")
+// XXX: what about error handling?
+// we need an additional error channel here which will ensure
+// errors get processed as soon as possible
+// XXX: what about state here, we need per routine state
+func (rt *Routine) run() {
+	fmt.Printf("%s: run\n", rt.name)
 	for {
-		iEvent, ok := <-sc.input // stuckhere
+		iEvent, ok := <-rt.input
 		if !ok {
-			fmt.Println("stopping scheduler")
-			sc.stopped <- struct{}{}
+			fmt.Printf("%s: stopping\n", rt.name)
+			rt.stopped <- struct{}{}
 			break
 		}
-		oEvents := sc.handle(iEvent)
+		oEvents := rt.handle(iEvent)
 		for _, event := range oEvents {
-			sc.output <- event
+			rt.output <- event
 		}
 	}
 }
 
-func (fs *scheduler) send(event Event) bool {
-	fmt.Println("scheduler send")
+func (rt *Routine) send(event Event) bool {
+	fmt.Printf("%s: send\n", rt.name)
 	select {
-	case fs.input <- event:
+	case rt.input <- event:
 		return true
 	default:
-		fmt.Println("scheduler channel was full")
+		fmt.Printf("%s: channel was full\n", rt.name)
 		return false
 	}
 }
 
-func (sc *scheduler) handle(event Event) Events {
+func (rt *Routine) stop() {
+	fmt.Printf("%s: stop\n", rt.name)
+	close(rt.input)
+	<-rt.stopped
+}
+
+func schedulerHandle(event Event) Events {
 	switch event.(type) {
 	case timeCheck:
 		fmt.Println("scheduler handle timeCheck")
@@ -99,56 +97,7 @@ func (sc *scheduler) handle(event Event) Events {
 	return Events{}
 }
 
-func (sc *scheduler) stop() {
-	fmt.Println("scheduler stop")
-	close(sc.input)
-	<-sc.stopped
-}
-
-// processor
-type processor struct {
-	input   chan Event
-	output  chan Event
-	stopped chan struct{}
-}
-
-func newProcessor(output chan Event) *processor {
-	return &processor{
-		input:   make(chan Event, 1),
-		output:  output,
-		stopped: make(chan struct{}, 1),
-	}
-}
-
-func (pc *processor) run() {
-	fmt.Println("processor run")
-	for {
-		iEvent, ok := <-pc.input
-		if !ok {
-			fmt.Println("stopping processor")
-			pc.stopped <- struct{}{}
-			break
-		}
-
-		oEvents := pc.handle(iEvent)
-		for _, event := range oEvents {
-			pc.output <- event
-		}
-	}
-}
-
-func (pc *processor) send(event Event) bool {
-	fmt.Println("processor send")
-	select {
-	case pc.input <- event:
-		return true
-	default:
-		fmt.Println("processor channel was full")
-		return false
-	}
-}
-
-func (pc *processor) handle(event Event) Events {
+func processorHandle(event Event) Events {
 	switch event.(type) {
 	case timeCheck:
 		fmt.Println("processor handle timeCheck")
@@ -158,80 +107,29 @@ func (pc *processor) handle(event Event) Events {
 	return Events{}
 }
 
-func (pc *processor) stop() {
-	fmt.Println("processor stop")
-	close(pc.input)
-	<-pc.stopped
-}
-
-// demuxer
-type demuxer struct {
-	input     chan Event
-	output    chan Event
-	scheduler *scheduler
-	processor *processor
-	stopped   chan struct{}
-}
-
-func newDemuxer(output chan Event, scheduler *scheduler, processor *processor) *demuxer {
-	return &demuxer{
-		input:     make(chan Event, 1),
-		output:    output,
-		stopped:   make(chan struct{}, 1),
-		scheduler: scheduler,
-		processor: processor,
-	}
-}
-
-func (dm *demuxer) run() {
-	fmt.Println("Running demuxer")
-	for {
-		// so now we need a way to flush
-		event, ok := <-dm.input
-		if !ok {
-			fmt.Println("demuxer stopping")
-			dm.stopped <- struct{}{}
-			break
-		}
-		// event.time = time.Now()
-		received := dm.scheduler.send(event)
+func genDemuxerHandle(scheduler *Routine, processor *Routine) handleFunc {
+	return func(event Event) Events {
+		received := scheduler.send(event)
 		if !received {
 			panic("couldn't send to scheduler")
 		}
 
-		received = dm.processor.send(event)
+		received = processor.send(event)
 		if !received {
 			panic("couldn't send to the processor")
 		}
-	}
-}
 
-func (dm *demuxer) send(event Event) bool {
-	fmt.Println("demuxer send")
-	// we need to close if this is closed first
-	select {
-	case dm.input <- event:
-		return true
-	default:
-		fmt.Println("demuxer channel was full")
-		return false
+		// XXX: think about emitting backpressure if !received
+		return Events{}
 	}
 }
 
-func (dm *demuxer) stop() {
-	fmt.Println("demuxer stop")
-	close(dm.input)
-	<-dm.stopped
-	fmt.Println("demuxer stopped")
-}
-
 // reactor
-
 type DummyReactor struct {
 	events        chan Event
-	demuxer       *demuxer
-	scheduler     *scheduler
-	processor     *processor
+	demuxer       *Routine
+	scheduler     *Routine
+	processor     *Routine
 	ticker        *time.Ticker
 	tickerStopped chan struct{}
 }
@@ -240,9 +138,10 @@ func (dr *DummyReactor) Start() {
 	bufferSize := 10
 	events := make(chan Event, bufferSize)
 
-	dr.scheduler = newScheduler(events)
-	dr.processor = newProcessor(events)
-	dr.demuxer = newDemuxer(events, dr.scheduler, dr.processor)
+	dr.scheduler = newRoutine("scheduler", events, schedulerHandle)
+	dr.processor = newRoutine("processor", events, processorHandle)
+	demuxerHandle := genDemuxerHandle(dr.scheduler, dr.processor)
+	dr.demuxer = newRoutine("demuxer", events, demuxerHandle)
 	dr.tickerStopped = make(chan struct{})
 
 	go dr.scheduler.run()
@@ -267,7 +166,6 @@ func (dr *DummyReactor) Stop() {
 	fmt.Println("reactor stopping")
 	// this should be synchronous
 	dr.tickerStopped <- struct{}{}
-	fmt.Println("waiting for ticker")
 	dr.demuxer.stop()
 	dr.scheduler.stop()
 	dr.processor.stop()