lib/promscrape: remove ID field from ScrapeWork struct. Use a pointer to ScrapeWork as a key in targetStatusMap

This simplifies the code a bit.

lib/promscrape/config.go

@@ -8,7 +8,6 @@ import (
 	"path/filepath"
 	"strings"
 	"sync"
-	"sync/atomic"
 	"time"
 
 	"github.com/VictoriaMetrics/VictoriaMetrics/lib/envtemplate"
@@ -744,7 +743,6 @@ func appendScrapeWork(dst []*ScrapeWork, swc *scrapeWorkConfig, target string, e
 	// Reduce memory usage by interning all the strings in labels.
 	internLabelStrings(labels)
 	dst = append(dst, &ScrapeWork{
-		ID:                   atomic.AddUint64(&nextScrapeWorkID, 1),
 		ScrapeURL:            scrapeURL,
 		ScrapeInterval:       swc.scrapeInterval,
 		ScrapeTimeout:        swc.scrapeTimeout,
@@ -764,9 +762,6 @@ func appendScrapeWork(dst []*ScrapeWork, swc *scrapeWorkConfig, target string, e
 	return dst, nil
 }
 
-// Each ScrapeWork has an ID, which is used for locating it when updating its status.
-var nextScrapeWorkID uint64
-
 func internLabelStrings(labels []prompbmarshal.Label) {
 	for i := range labels {
 		label := &labels[i]

lib/promscrape/config_test.go

@@ -442,7 +442,6 @@ scrape_configs:
 
 func resetNonEssentialFields(sws []*ScrapeWork) {
 	for i := range sws {
-		sws[i].ID = 0
 		sws[i].OriginalLabels = nil
 	}
 }

lib/promscrape/scraper.go

@@ -355,7 +355,7 @@ func newScraper(sw *ScrapeWork, group string, pushData func(wr *prompbmarshal.Wr
 		stopCh: make(chan struct{}),
 	}
 	c := newClient(sw)
-	sc.sw.Config = *sw
+	sc.sw.Config = sw
 	sc.sw.ScrapeGroup = group
 	sc.sw.ReadData = c.ReadData
 	sc.sw.GetStreamReader = c.GetStreamReader

lib/promscrape/scrapework.go

@@ -27,10 +27,9 @@ var (
 )
 
 // ScrapeWork represents a unit of work for scraping Prometheus metrics.
+//
+// It must be immutable during its lifetime, since it is read from concurrently running goroutines.
 type ScrapeWork struct {
-	// Unique ID for the ScrapeWork.
-	ID uint64
-
 	// Full URL (including query args) for the scrape.
 	ScrapeURL string
 
@@ -144,7 +143,7 @@ func promLabelsString(labels []prompbmarshal.Label) string {
 
 type scrapeWork struct {
 	// Config for the scrape.
-	Config ScrapeWork
+	Config *ScrapeWork
 
 	// ReadData is called for reading the data.
 	ReadData func(dst []byte) ([]byte, error)
@@ -308,7 +307,7 @@ func (sw *scrapeWork) scrapeInternal(scrapeTimestamp, realTimestamp int64) error
 	// body must be released only after wc is released, since wc refers to body.
 	sw.prevBodyLen = len(body.B)
 	leveledbytebufferpool.Put(body)
-	tsmGlobal.Update(&sw.Config, sw.ScrapeGroup, up == 1, realTimestamp, int64(duration*1000), err)
+	tsmGlobal.Update(sw.Config, sw.ScrapeGroup, up == 1, realTimestamp, int64(duration*1000), err)
 	return err
 }
 
@@ -369,7 +368,7 @@ func (sw *scrapeWork) scrapeStream(scrapeTimestamp, realTimestamp int64) error {
 	sw.prevRowsLen = len(wc.rows.Rows)
 	wc.reset()
 	writeRequestCtxPool.Put(wc)
-	tsmGlobal.Update(&sw.Config, sw.ScrapeGroup, up == 1, realTimestamp, int64(duration*1000), err)
+	tsmGlobal.Update(sw.Config, sw.ScrapeGroup, up == 1, realTimestamp, int64(duration*1000), err)
 	return nil
 }
 

lib/promscrape/scrapework_test.go

@@ -49,6 +49,7 @@ func TestScrapeWorkScrapeInternalFailure(t *testing.T) {
 	timeseriesExpected := parseData(dataExpected)
 
 	var sw scrapeWork
+	sw.Config = &ScrapeWork{}
 
 	readDataCalls := 0
 	sw.ReadData = func(dst []byte) ([]byte, error) {
@@ -87,7 +88,7 @@ func TestScrapeWorkScrapeInternalSuccess(t *testing.T) {
 		timeseriesExpected := parseData(dataExpected)
 
 		var sw scrapeWork
-		sw.Config = *cfg
+		sw.Config = cfg
 
 		readDataCalls := 0
 		sw.ReadData = func(dst []byte) ([]byte, error) {

lib/promscrape/scrapework_timing_test.go

@@ -37,6 +37,7 @@ vm_tcplistener_write_calls_total{name="https", addr=":443"} 132356
 	b.SetBytes(int64(len(data)))
 	b.RunParallel(func(pb *testing.PB) {
 		var sw scrapeWork
+		sw.Config = &ScrapeWork{}
 		sw.ReadData = readDataFunc
 		sw.PushData = func(wr *prompbmarshal.WriteRequest) {}
 		timestamp := int64(0)

lib/promscrape/targetstatus.go

@@ -59,45 +59,49 @@ func WriteAPIV1Targets(w io.Writer, state string) {
 
 type targetStatusMap struct {
 	mu sync.Mutex
-	m  map[uint64]*targetStatus
+	m  map[*ScrapeWork]*targetStatus
 }
 
 func newTargetStatusMap() *targetStatusMap {
 	return &targetStatusMap{
-		m: make(map[uint64]*targetStatus),
+		m: make(map[*ScrapeWork]*targetStatus),
 	}
 }
 
 func (tsm *targetStatusMap) Reset() {
 	tsm.mu.Lock()
-	tsm.m = make(map[uint64]*targetStatus)
+	tsm.m = make(map[*ScrapeWork]*targetStatus)
 	tsm.mu.Unlock()
 }
 
 func (tsm *targetStatusMap) Register(sw *ScrapeWork) {
 	tsm.mu.Lock()
-	tsm.m[sw.ID] = &targetStatus{
+	tsm.m[sw] = &targetStatus{
-		sw: *sw,
+		sw: sw,
 	}
 	tsm.mu.Unlock()
 }
 
 func (tsm *targetStatusMap) Unregister(sw *ScrapeWork) {
 	tsm.mu.Lock()
-	delete(tsm.m, sw.ID)
+	delete(tsm.m, sw)
 	tsm.mu.Unlock()
 }
 
 func (tsm *targetStatusMap) Update(sw *ScrapeWork, group string, up bool, scrapeTime, scrapeDuration int64, err error) {
 	tsm.mu.Lock()
-	tsm.m[sw.ID] = &targetStatus{
+	ts := tsm.m[sw]
-		sw:             *sw,
+	if ts == nil {
-		up:             up,
+		ts = &targetStatus{
-		scrapeGroup:    group,
+			sw: sw,
-		scrapeTime:     scrapeTime,
-		scrapeDuration: scrapeDuration,
-		err:            err,
 		}
+		tsm.m[sw] = ts
+	}
+	ts.up = up
+	ts.scrapeGroup = group
+	ts.scrapeTime = scrapeTime
+	ts.scrapeDuration = scrapeDuration
+	ts.err = err
 	tsm.mu.Unlock()
 }
 
@@ -123,8 +127,8 @@ func (tsm *targetStatusMap) WriteActiveTargetsJSON(w io.Writer) {
 		st  targetStatus
 	}
 	kss := make([]keyStatus, 0, len(tsm.m))
-	for _, st := range tsm.m {
+	for sw, st := range tsm.m {
-		key := promLabelsString(st.sw.OriginalLabels)
+		key := promLabelsString(sw.OriginalLabels)
 		kss = append(kss, keyStatus{
 			key: key,
 			st:  *st,
@@ -176,7 +180,7 @@ func writeLabelsJSON(w io.Writer, labels []prompbmarshal.Label) {
 }
 
 type targetStatus struct {
-	sw             ScrapeWork
+	sw             *ScrapeWork
 	up             bool
 	scrapeGroup    string
 	scrapeTime     int64