Push mini-reports when container's state changes.

probe/docker/registry.go

@@ -31,14 +31,19 @@ type Registry interface {
 	LockedPIDLookup(f func(func(int) Container))
 	WalkContainers(f func(Container))
 	WalkImages(f func(*docker_client.APIImages))
+	WatchContainerUpdates(ContainerUpdateWatcher)
 }
 
+// ContainerUpdateWatcher is the type of functions that get called when containers are updated.
+type ContainerUpdateWatcher func(c Container)
+
 type registry struct {
 	sync.RWMutex
 	quit     chan chan struct{}
 	interval time.Duration
 	client   Client
 
+	watchers        []ContainerUpdateWatcher
 	containers      map[string]Container
 	containersByPID map[int]Container
 	images          map[string]*docker_client.APIImages
@@ -91,6 +96,14 @@ func (r *registry) Stop() {
 	<-ch
 }
 
+// WatchContainerUpdates registers a callback to be called
+// whenever a container is updated.
+func (r *registry) WatchContainerUpdates(f ContainerUpdateWatcher) {
+	r.Lock()
+	defer r.Unlock()
+	r.watchers = append(r.watchers, f)
+}
+
 func (r *registry) loop() {
 	for {
 		// NB listenForEvents blocks.
@@ -244,6 +257,11 @@ func (r *registry) updateContainerState(containerID string) {
 		c.UpdateState(dockerContainer)
 	}
 
+	// Trigger anyone watching for updates
+	for _, f := range r.watchers {
+		f(c)
+	}
+
 	// And finally, ensure we gather stats for it
 	if dockerContainer.State.Running {
 		if err := c.StartGatheringStats(); err != nil {

probe/docker/reporter.go

@@ -1,10 +1,12 @@
 package docker
 
 import (
+	"log"
 	"net"
 
 	docker_client "github.com/fsouza/go-dockerclient"
 
+	"github.com/weaveworks/scope/probe"
 	"github.com/weaveworks/scope/report"
 )
 
@@ -18,16 +20,32 @@ const (
 type Reporter struct {
 	registry Registry
 	hostID   string
+	probe    *probe.Probe
 }
 
 // NewReporter makes a new Reporter
-func NewReporter(registry Registry, hostID string) *Reporter {
+func NewReporter(registry Registry, hostID string, probe *probe.Probe) *Reporter {
 	return &Reporter{
 		registry: registry,
 		hostID:   hostID,
+		probe:    probe,
 	}
 }
 
+// ContainerUpdated should be called whenever a container is updated.
+func (r *Reporter) ContainerUpdated(c Container) {
+	localAddrs, err := report.LocalAddresses()
+	if err != nil {
+		log.Printf("Error getting local address: %v", err)
+		return
+	}
+
+	// Publish a 'short cut' report container just this container
+	rpt := report.MakeReport()
+	rpt.Container.AddNode(report.MakeContainerNodeID(r.hostID, c.ID()), c.GetNode(r.hostID, localAddrs))
+	r.probe.Publish(rpt)
+}
+
 // Report generates a Report containing Container and ContainerImage topologies
 func (r *Reporter) Report() (report.Report, error) {
 	localAddrs, err := report.LocalAddresses()

probe/docker/reporter_test.go

@@ -36,6 +36,8 @@ func (r *mockRegistry) WalkImages(f func(*client.APIImages)) {
 	}
 }
 
+func (r *mockRegistry) WatchContainerUpdates(_ docker.ContainerUpdateWatcher) {}
+
 var (
 	mockRegistryInstance = &mockRegistry{
 		containersByPID: map[int]docker.Container{
@@ -95,7 +97,7 @@ func TestReporter(t *testing.T) {
 		Controls: report.Controls{},
 	}
 
-	reporter := docker.NewReporter(mockRegistryInstance, "")
+	reporter := docker.NewReporter(mockRegistryInstance, "", nil)
 	have, _ := reporter.Report()
 	if !reflect.DeepEqual(want, have) {
 		t.Errorf("%s", test.Diff(want, have))

probe/probe.go

@@ -9,6 +9,10 @@ import (
 	"github.com/weaveworks/scope/xfer"
 )
 
+const (
+	reportBufferSize = 16
+)
+
 // Probe sits there, generating and publishing reports.
 type Probe struct {
 	spyInterval, publishInterval time.Duration
@@ -20,7 +24,9 @@ type Probe struct {
 
 	quit chan struct{}
 	done sync.WaitGroup
-	rpt  syncReport
+
+	spiedReports    chan report.Report
+	shortcutReports chan report.Report
 }
 
 // Tagger tags nodes with value-add node metadata.
@@ -47,8 +53,9 @@ func New(spyInterval, publishInterval time.Duration, publisher xfer.Publisher) *
 		publishInterval: publishInterval,
 		publisher:       publisher,
 		quit:            make(chan struct{}),
+		spiedReports:    make(chan report.Report, reportBufferSize),
+		shortcutReports: make(chan report.Report, reportBufferSize),
 	}
-	result.rpt.swap(report.MakeReport())
 	return result
 }
 
@@ -80,6 +87,12 @@ func (p *Probe) Stop() {
 	p.done.Wait()
 }
 
+// Publish will queue a report for immediate publication,
+// bypassing the spy tick
+func (p *Probe) Publish(rpt report.Report) {
+	p.shortcutReports <- rpt
+}
+
 func (p *Probe) spyLoop() {
 	defer p.done.Done()
 	spyTick := time.Tick(p.spyInterval)
@@ -94,10 +107,9 @@ func (p *Probe) spyLoop() {
 				}
 			}
 
-			localReport := p.rpt.copy()
-			localReport = localReport.Merge(p.report())
-			localReport = p.tag(localReport)
-			p.rpt.swap(localReport)
+			rpt := p.report()
+			rpt = p.tag(rpt)
+			p.spiedReports <- rpt
 
 			if took := time.Since(start); took > p.spyInterval {
 				log.Printf("report generation took too long (%s)", took)
@@ -140,6 +152,17 @@ func (p *Probe) tag(r report.Report) report.Report {
 	return r
 }
 
+func condense(rpt report.Report, rs chan report.Report) report.Report {
+	for {
+		select {
+		case r := <-rs:
+			rpt = rpt.Merge(r)
+		default:
+			return rpt
+		}
+	}
+}
+
 func (p *Probe) publishLoop() {
 	defer p.done.Done()
 	var (
@@ -150,8 +173,14 @@ func (p *Probe) publishLoop() {
 	for {
 		select {
 		case <-pubTick:
-			localReport := p.rpt.swap(report.MakeReport())
-			if err := rptPub.Publish(localReport); err != nil {
+			rpt := condense(report.MakeReport(), p.spiedReports)
+			if err := rptPub.Publish(rpt); err != nil {
+				log.Printf("publish: %v", err)
+			}
+
+		case rpt := <-p.shortcutReports:
+			rpt = condense(rpt, p.shortcutReports)
+			if err := rptPub.Publish(rpt); err != nil {
 				log.Printf("publish: %v", err)
 			}
 

prog/probe/main.go

@@ -134,7 +134,10 @@ func main() {
 		if registry, err := docker.NewRegistry(*dockerInterval); err == nil {
 			defer registry.Stop()
 			p.AddTagger(docker.NewTagger(registry, processCache))
-			p.AddReporter(docker.NewReporter(registry, hostID))
+
+			reporter := docker.NewReporter(registry, hostID, p)
+			registry.WatchContainerUpdates(reporter.ContainerUpdated)
+			p.AddReporter(reporter)
 		} else {
 			log.Printf("Docker: failed to start registry: %v", err)
 		}