Mega patch
This is still a dirty prototype, so please excuse the mess. Please excuse the fact that this is a mega patch. Once things settle down this won't happen any more. Some of the changes squashed into here include: * Merge vertex loop with type loop (The file watcher seems to cache events anyways) * Improve pgraph library * Add indegree, outdegree, and topological sort with tests * Add reverse function for vertex list * Tons of additional cleanup! Amazingly, on my first successful compile, this seemed to run! A special thanks to Ira Cooper who helped me talk through some of the algorithmic decisions and for his help in finding better ones!
This commit is contained in:
James Shubin
223
types.go
223
types.go
@@ -18,56 +18,231 @@
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package main
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import (
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"code.google.com/p/go-uuid/uuid"
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"fmt"
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"log"
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"time"
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)
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type Type interface {
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//Name() string
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Watch(*Vertex)
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Init()
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GetName() string // can't be named "Name()" because of struct field
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Watch()
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StateOK() bool // TODO: can we rename this to something better?
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Apply() bool
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Exit() bool
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SetVertex(*Vertex)
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Compare(Type) bool
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SendEvent(eventName, bool)
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GetTimestamp() int64
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UpdateTimestamp() int64
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//Process()
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}
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type BaseType struct {
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Name string `yaml:"name"`
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timestamp int64 // last updated timestamp ?
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events chan Event
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vertex *Vertex
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}
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type NoopType struct {
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uuid string
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Type string // always "noop"
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Name string // name variable
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Events chan string // FIXME: eventually a struct for the event?
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BaseType `yaml:",inline"`
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Comment string `yaml:"comment"` // extra field for example purposes
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}
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func NewNoopType(name string) *NoopType {
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// FIXME: we could get rid of this New constructor and use raw object creation with a required Init()
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return &NoopType{
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uuid: uuid.New(),
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Type: "noop",
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Name: name,
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Events: make(chan string, 1), // XXX: chan size?
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BaseType: BaseType{
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Name: name,
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events: make(chan Event), // unbuffered chan size to avoid stale events
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vertex: nil,
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},
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Comment: "",
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}
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}
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func (obj NoopType) Watch(v *Vertex) {
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select {
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case exit := <-obj.Events:
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if exit == "exit" {
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// initialize structures like channels if created without New constructor
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func (obj *BaseType) Init() {
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obj.events = make(chan Event)
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}
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// this method gets used by all the types, if we have one of (obj NoopType) it would get overridden in that case!
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func (obj *BaseType) GetName() string {
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return obj.Name
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}
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func (obj *BaseType) GetVertex() *Vertex {
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return obj.vertex
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}
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func (obj *BaseType) SetVertex(v *Vertex) {
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obj.vertex = v
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}
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// get timestamp of a vertex
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func (obj *BaseType) GetTimestamp() int64 {
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return obj.timestamp
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}
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// update timestamp of a vertex
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func (obj *BaseType) UpdateTimestamp() int64 {
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obj.timestamp = time.Now().UnixNano() // update
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return obj.timestamp
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}
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// can this element run right now?
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func (obj *BaseType) OKTimestamp() bool {
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v := obj.GetVertex()
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g := v.GetGraph()
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// these are all the vertices pointing TO v, eg: ??? -> v
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for _, n := range g.IncomingGraphEdges(v) {
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// if the vertex has a greater timestamp than any pre-req (n)
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// then we can't run right now...
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if obj.GetTimestamp() > n.Type.GetTimestamp() {
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return false
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}
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}
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return true
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}
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func (obj *BaseType) Poke() bool { // XXX: how can this ever fail and return false? eg: when is a poke not possible and should be rescheduled?
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v := obj.GetVertex()
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g := v.GetGraph()
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// these are all the vertices pointing AWAY FROM v, eg: v -> ???
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for _, n := range g.OutgoingGraphEdges(v) {
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n.SendEvent(eventPoke, false) // XXX: should this be sync or not? XXX: try it as async for now, but switch to sync and see if we deadlock -- maybe it's possible, i don't know for sure yet
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}
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return true
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}
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// push an event into the message queue for a particular type vertex
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func (obj *BaseType) SendEvent(event eventName, sync bool) {
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if !sync {
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obj.events <- Event{event, nil, ""}
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return
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}
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resp := make(chan bool)
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obj.events <- Event{event, resp, ""}
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for {
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value := <-resp
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// wait until true value
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if value {
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return
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} else {
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log.Fatal("Unknown event: %v\n", exit)
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}
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}
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}
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func (obj NoopType) Exit() bool {
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obj.Events <- "exit"
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return true
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// process events when a select gets one
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// this handles the pause code too!
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func (obj *BaseType) ReadEvent(event *Event) bool {
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event.ACK()
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switch event.Name {
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case eventStart:
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return true
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case eventPoke:
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return true
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case eventExit:
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return false
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case eventPause:
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// wait for next event to continue
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select {
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case e := <-obj.events:
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e.ACK()
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if e.Name == eventExit {
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return false
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} else if e.Name == eventContinue {
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return true
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} else {
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log.Fatal("Unknown event: ", e)
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}
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}
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default:
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log.Fatal("Unknown event: ", event)
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}
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return false // required to keep the stupid go compiler happy
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}
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func (obj NoopType) StateOK() bool {
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// XXX: rename this function
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func (obj *BaseType) Process(typ Type) {
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var ok bool
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ok = true
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// is it okay to run dependency wise right now?
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// if not, that's okay because when the dependency runs, it will poke
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// us back and we will run if needed then!
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if obj.OKTimestamp() {
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// XXX XXX: why does this have to be typ instead of just obj! "obj.StateOK undefined (type *BaseType has no field or method StateOK)"
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if !typ.StateOK() { // TODO: can we rename this to something better?
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// throw an error if apply fails...
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// if this fails, don't UpdateTimestamp()
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if !typ.Apply() { // check for error
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ok = false
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}
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}
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if ok {
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// if poke fails, don't update timestamp
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// since we didn't propagate the pokes!
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if obj.Poke() {
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obj.UpdateTimestamp() // this was touched...
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}
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}
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}
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}
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func (obj *NoopType) Watch() {
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//vertex := obj.vertex // stored with SetVertex
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var send = false // send event?
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for {
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select {
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case event := <-obj.events:
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if ok := obj.ReadEvent(&event); !ok {
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return // exit
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}
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send = true
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}
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// do all our event sending all together to avoid duplicate msgs
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if send {
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send = false
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obj.Process(obj) // XXX: rename this function
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}
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}
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}
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func (obj *NoopType) StateOK() bool {
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return true // never needs updating
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}
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func (obj NoopType) Apply() bool {
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fmt.Printf("Apply->%v[%v]\n", obj.Type, obj.Name)
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func (obj *NoopType) Apply() bool {
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fmt.Printf("Apply->Noop[%v]\n", obj.Name)
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return true
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}
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func (obj *NoopType) Compare(typ Type) bool {
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switch typ.(type) {
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// we can only compare NoopType to others of the same type
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case *NoopType:
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return obj.compare(typ.(*NoopType))
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default:
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return false
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}
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}
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func (obj *NoopType) compare(typ *NoopType) bool {
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if obj.Name != typ.Name {
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return false
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}
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return true
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}
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