Kill the curation state channel.

The use of the channels for curation state were always unidiomatic.

Change-Id: I1cb1d7175ebfb4faf28dff84201066278d6a0d92

main.go

@@ -80,7 +80,6 @@ type prometheus struct {
 	deletionTimer       *time.Ticker
 
 	curationMutex            sync.Mutex
-	curationState            chan metric.CurationState
 	stopBackgroundOperations chan bool
 
 	unwrittenSamples chan *extraction.Result
@@ -88,6 +87,8 @@ type prometheus struct {
 	ruleManager   rules.RuleManager
 	notifications chan notification.NotificationReqs
 	storage       *metric.TieredStorage
+
+	curationState metric.CurationStateUpdater
 }
 
 func (p *prometheus) interruptHandler() {
@@ -157,7 +158,6 @@ func (p *prometheus) close() {
 
 	close(p.notifications)
 	close(p.stopBackgroundOperations)
-	close(p.curationState)
 }
 
 func main() {
@@ -189,7 +189,6 @@ func main() {
 
 		Ingester: retrieval.ChannelIngester(unwrittenSamples),
 	}
-	curationState := make(chan metric.CurationState, 1)
 	// Coprime numbers, fool!
 	headCompactionTimer := time.NewTicker(*headCompactInterval)
 	bodyCompactionTimer := time.NewTicker(*bodyCompactInterval)
@@ -219,16 +218,13 @@ func main() {
 		flags[f.Name] = f.Value.String()
 	})
 
-	statusHandler := &web.StatusHandler{
-		PrometheusStatus: &web.PrometheusStatus{
-			BuildInfo:   BuildInfo,
-			Config:      conf.String(),
-			RuleManager: ruleManager,
-			TargetPools: targetManager.Pools(),
-			Flags:       flags,
-			Birth:       time.Now(),
-		},
-		CurationState: curationState,
+	prometheusStatus := &web.PrometheusStatusHandler{
+		BuildInfo:   BuildInfo,
+		Config:      conf.String(),
+		RuleManager: ruleManager,
+		TargetPools: targetManager.Pools(),
+		Flags:       flags,
+		Birth:       time.Now(),
 	}
 
 	alertsHandler := &web.AlertsHandler{
@@ -247,7 +243,7 @@ func main() {
 	}
 
 	webService := &web.WebService{
-		StatusHandler:    statusHandler,
+		StatusHandler:    prometheusStatus,
 		MetricsHandler:   metricsService,
 		DatabasesHandler: databasesHandler,
 		AlertsHandler:    alertsHandler,
@@ -260,7 +256,7 @@ func main() {
 
 		deletionTimer: deletionTimer,
 
-		curationState: curationState,
+		curationState: prometheusStatus,
 
 		unwrittenSamples: unwrittenSamples,
 

storage/metric/curator.go

@@ -31,6 +31,11 @@ import (
 	dto "github.com/prometheus/prometheus/model/generated"
 )
 
+// CurationStateUpdater receives updates about the curation state.
+type CurationStateUpdater interface {
+	UpdateCurationState(*CurationState)
+}
+
 // CurationState contains high-level curation state information for the
 // heads-up-display.
 type CurationState struct {
@@ -83,7 +88,7 @@ type watermarkScanner struct {
 	// stop functions as the global stop channel for all future operations.
 	stop chan bool
 	// status is the outbound channel for notifying the status page of its state.
-	status chan CurationState
+	status CurationStateUpdater
 }
 
 // run facilitates the curation lifecycle.
@@ -92,7 +97,7 @@ type watermarkScanner struct {
 // curated.
 // curationState is the on-disk store where the curation remarks are made for
 // how much progress has been made.
-func (c *Curator) Run(ignoreYoungerThan time.Duration, instant time.Time, processor Processor, curationState CurationRemarker, samples *leveldb.LevelDBPersistence, watermarks HighWatermarker, status chan CurationState) (err error) {
+func (c *Curator) Run(ignoreYoungerThan time.Duration, instant time.Time, processor Processor, curationState CurationRemarker, samples *leveldb.LevelDBPersistence, watermarks HighWatermarker, status CurationStateUpdater) (err error) {
 	defer func(t time.Time) {
 		duration := float64(time.Since(t) / time.Millisecond)
 
@@ -108,13 +113,8 @@ func (c *Curator) Run(ignoreYoungerThan time.Duration, instant time.Time, proces
 		curationDuration.IncrementBy(labels, duration)
 		curationDurations.Add(labels, duration)
 	}(time.Now())
-	defer func() {
-		select {
-		case status <- CurationState{Active: false}:
-		case <-status:
-		default:
-		}
-	}()
+
+	defer status.UpdateCurationState(&CurationState{Active: false})
 
 	iterator := samples.NewIterator(true)
 	defer iterator.Close()
@@ -201,16 +201,12 @@ func (w *watermarkScanner) Filter(key, value interface{}) (r storage.FilterResul
 
 		curationFilterOperations.Increment(labels)
 
-		select {
-		case w.status <- CurationState{
+		w.status.UpdateCurationState(&CurationState{
 			Active:      true,
 			Name:        w.processor.Name(),
 			Limit:       w.ignoreYoungerThan,
 			Fingerprint: fingerprint,
-		}:
-		case <-w.status:
-		default:
-		}
+		})
 	}()
 
 	if w.shouldStop() {

storage/metric/processor_test.go

@@ -112,6 +112,10 @@ func (s sampleGroup) Get() (key, value proto.Message) {
 	return k, v
 }
 
+type noopUpdater bool
+
+func (noopUpdater) UpdateCurationState(*CurationState) {}
+
 func TestCuratorCompactionProcessor(t *testing.T) {
 	scenarios := []struct {
 		in  in
@@ -872,8 +876,7 @@ func TestCuratorCompactionProcessor(t *testing.T) {
 		}
 		defer samples.Close()
 
-		updates := make(chan CurationState, 100)
-		defer close(updates)
+		updates := new(noopUpdater)
 
 		stop := make(chan bool)
 		defer close(stop)
@@ -1396,8 +1399,7 @@ func TestCuratorDeletionProcessor(t *testing.T) {
 		}
 		defer samples.Close()
 
-		updates := make(chan CurationState, 100)
-		defer close(updates)
+		updates := new(noopUpdater)
 
 		stop := make(chan bool)
 		defer close(stop)

web/status.go

@@ -14,15 +14,18 @@
 package web
 
 import (
-	"github.com/prometheus/prometheus/retrieval"
-	"github.com/prometheus/prometheus/rules"
-	"github.com/prometheus/prometheus/storage/metric"
 	"net/http"
 	"sync"
 	"time"
+
+	"github.com/prometheus/prometheus/retrieval"
+	"github.com/prometheus/prometheus/rules"
+	"github.com/prometheus/prometheus/storage/metric"
 )
 
-type PrometheusStatus struct {
+type PrometheusStatusHandler struct {
+	mu sync.RWMutex
+
 	BuildInfo   map[string]string
 	Config      string
 	Curation    metric.CurationState
@@ -33,23 +36,16 @@ type PrometheusStatus struct {
 	Birth time.Time
 }
 
-type StatusHandler struct {
-	CurationState    chan metric.CurationState
-	PrometheusStatus *PrometheusStatus
+func (h *PrometheusStatusHandler) UpdateCurationState(c *metric.CurationState) {
+	h.mu.Lock()
+	defer h.mu.Unlock()
 
-	mutex sync.RWMutex
+	h.Curation = *c
 }
 
-func (h *StatusHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
-	select {
-	case curationState := <-h.CurationState:
-		h.mutex.Lock()
-		defer h.mutex.Unlock()
-		h.PrometheusStatus.Curation = curationState
-	default:
-		h.mutex.RLock()
-		defer h.mutex.RUnlock()
-	}
+func (h *PrometheusStatusHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
+	h.mu.RLock()
+	defer h.mu.RUnlock()
 
-	executeTemplate(w, "status", h.PrometheusStatus)
+	executeTemplate(w, "status", h)
 }

web/web.go

@@ -39,7 +39,7 @@ var (
 )
 
 type WebService struct {
-	StatusHandler    *StatusHandler
+	StatusHandler    *PrometheusStatusHandler
 	DatabasesHandler *DatabasesHandler
 	MetricsHandler   *api.MetricsService
 	AlertsHandler    *AlertsHandler