resources: Remove SetWatching/IsWatching code from Watch

This removes some boilerplate from the Watch methods which can be baked
into the engine instead.

This code should be checked for races and locks to make sure we only
start resources when it makes sense to.

pgraph/actions.go

@@ -289,6 +289,9 @@ func (g *Graph) Worker(v *Vertex) error {
 	// the Watch() function about which graph it is
 	// running on, which isolates things nicely...
 	obj := v.Res
+	// TODO: is there a better system for the `Watching` flag?
+	obj.SetWatching(true)
+	defer obj.SetWatching(false)
 	processChan := make(chan event.Event)
 	go func() {
 		running := false

resources/exec.go

@@ -110,11 +110,6 @@ func (obj *ExecRes) BufioChanScanner(scanner *bufio.Scanner) (chan string, chan
 
 // Watch is the primary listener for this resource and it outputs events.
 func (obj *ExecRes) Watch(processChan chan event.Event) error {
-	if obj.IsWatching() {
-		return nil
-	}
-	obj.SetWatching(true)
-	defer obj.SetWatching(false)
 	cuid := obj.Converger() // get the converger uid used to report status
 
 	var send = false // send event?

resources/file.go

@@ -141,11 +141,6 @@ func (obj *FileRes) Validate() error {
 // must be restarted. On a clean exit it returns nil.
 // FIXME: Also watch the source directory when using obj.Source !!!
 func (obj *FileRes) Watch(processChan chan event.Event) error {
-	if obj.IsWatching() {
-		return nil // TODO: should this be an error?
-	}
-	obj.SetWatching(true)
-	defer obj.SetWatching(false)
 	cuid := obj.Converger() // get the converger uid used to report status
 
 	var err error

resources/hostname.go

@@ -108,11 +108,6 @@ func (obj *HostnameRes) Validate() error {
 
 // Watch is the primary listener for this resource and it outputs events.
 func (obj *HostnameRes) Watch(processChan chan event.Event) error {
-	if obj.IsWatching() {
-		return nil // TODO: should this be an error?
-	}
-	obj.SetWatching(true)
-	defer obj.SetWatching(false)
 	cuid := obj.Converger() // get the converger uid used to report status
 
 	// if we share the bus with others, we will get each others messages!!

resources/msg.go

@@ -135,11 +135,6 @@ func (obj *MsgRes) journalPriority() journal.Priority {
 
 // Watch is the primary listener for this resource and it outputs events.
 func (obj *MsgRes) Watch(processChan chan event.Event) error {
-	if obj.IsWatching() {
-		return nil
-	}
-	obj.SetWatching(true)
-	defer obj.SetWatching(false)
 	cuid := obj.Converger() // get the converger uid used to report status
 
 	// notify engine that we're running

resources/noop.go

@@ -59,11 +59,6 @@ func (obj *NoopRes) Validate() error {
 
 // Watch is the primary listener for this resource and it outputs events.
 func (obj *NoopRes) Watch(processChan chan event.Event) error {
-	if obj.IsWatching() {
-		return nil // TODO: should this be an error?
-	}
-	obj.SetWatching(true)
-	defer obj.SetWatching(false)
 	cuid := obj.Converger() // get the converger uid used to report status
 
 	// notify engine that we're running

resources/nspawn.go

@@ -95,11 +95,6 @@ func (obj *NspawnRes) Validate() error {
 
 // Watch for state changes and sends a message to the bus if there is a change
 func (obj *NspawnRes) Watch(processChan chan event.Event) error {
-	if obj.IsWatching() {
-		return nil
-	}
-	obj.SetWatching(true)
-	defer obj.SetWatching(false)
 	cuid := obj.Converger() // get the converger uid used to report status
 
 	// this resource depends on systemd ensure that it's running

resources/password.go

@@ -168,11 +168,6 @@ Loop:
 
 // Watch is the primary listener for this resource and it outputs events.
 func (obj *PasswordRes) Watch(processChan chan event.Event) error {
-	if obj.IsWatching() {
-		return nil // TODO: should this be an error?
-	}
-	obj.SetWatching(true)
-	defer obj.SetWatching(false)
 	cuid := obj.Converger() // get the converger uid used to report status
 
 	var err error

resources/pkg.go

@@ -109,11 +109,6 @@ func (obj *PkgRes) Validate() error {
 // TODO: https://github.com/hughsie/PackageKit/issues/109
 // TODO: https://github.com/hughsie/PackageKit/issues/110
 func (obj *PkgRes) Watch(processChan chan event.Event) error {
-	if obj.IsWatching() {
-		return nil
-	}
-	obj.SetWatching(true)
-	defer obj.SetWatching(false)
 	cuid := obj.Converger() // get the converger uid used to report status
 
 	bus := packagekit.NewBus()

resources/resources.go

@@ -280,12 +280,12 @@ func (obj *BaseRes) AssociateData(data *Data) {
 	obj.debug = data.Debug
 }
 
-// IsWatching tells us if the Watch() function is running.
+// IsWatching tells us if the Worker() function is running.
 func (obj *BaseRes) IsWatching() bool {
 	return obj.watching
 }
 
-// SetWatching stores the status of if the Watch() function is running.
+// SetWatching stores the status of if the Worker() function is running.
 func (obj *BaseRes) SetWatching(b bool) {
 	obj.watching = b
 }

resources/svc.go

@@ -75,11 +75,6 @@ func (obj *SvcRes) Validate() error {
 
 // Watch is the primary listener for this resource and it outputs events.
 func (obj *SvcRes) Watch(processChan chan event.Event) error {
-	if obj.IsWatching() {
-		return nil
-	}
-	obj.SetWatching(true)
-	defer obj.SetWatching(false)
 	cuid := obj.Converger() // get the converger uid used to report status
 
 	// obj.Name: svc name

resources/timer.go

@@ -74,11 +74,6 @@ func (obj *TimerRes) newTicker() *time.Ticker {
 
 // Watch is the primary listener for this resource and it outputs events.
 func (obj *TimerRes) Watch(processChan chan event.Event) error {
-	if obj.IsWatching() {
-		return nil
-	}
-	obj.SetWatching(true)
-	defer obj.SetWatching(false)
 	cuid := obj.Converger() // get the converger uid used to report status
 
 	// create a time.Ticker for the given interval

resources/virt.go

@@ -132,11 +132,6 @@ func (obj *VirtRes) connect() (conn libvirt.VirConnection, err error) {
 
 // Watch is the primary listener for this resource and it outputs events.
 func (obj *VirtRes) Watch(processChan chan event.Event) error {
-	if obj.IsWatching() {
-		return nil
-	}
-	obj.SetWatching(true)
-	defer obj.SetWatching(false)
 	cuid := obj.Converger() // get the converger uid used to report status
 
 	conn, err := obj.connect()