Count the take-ins and every other background work in the serving group, so serve's stop waits for them too (issue 1945)

inBackground ran the take-ins of done keys (now in #463's slots), the start's
look, the given values' replacement and the announced reads beside serve without
serve waiting for them: a take-in could outlive its controller as the loops did.
It now takes the context and is counted in its serving group as well, and a
serve that is stopping starts none.

cmd/mesh-controller/composed_keys.go

@@ -307,7 +307,7 @@ func watchDoneKeys(ctx context.Context, open *stores) {
 		return
 	}
 	if err := builderkeys.Watch(ctx, keys.JS, func(module string) {
-		inBackground(func() { takeDoneKey(ctx, open, module) })
+		inBackground(ctx, func() { takeDoneKey(ctx, open, module) })
 	}); err != nil {
 		closeKeys()
 		fmt.Printf("done keys: the builder's keys are not watched: %v\n", err)
@@ -318,7 +318,7 @@ func watchDoneKeys(ctx context.Context, open *stores) {
 		closeKeys()
 	})
 	// And every module once now, after the watch is open so no write falls between the two.
-	inBackground(func() {
+	inBackground(ctx, func() {
 		doneKeysAtStart(ctx, catalogedModules(open), func(module string) { takeDoneKeyAtStart(ctx, open, module) })
 	})
 }
@@ -389,7 +389,7 @@ func takeDoneKeyAtStart(ctx context.Context, open *stores, module string) {
 	_, again := doneKeysLookAgain.LoadAndDelete(module)
 	if err != nil || again {
 		// A failure, a wait or a wake meanwhile is followed by takeDoneKey, which says it and looks again.
-		inBackground(func() { takeDoneKey(ctx, open, module) })
+		inBackground(ctx, func() { takeDoneKey(ctx, open, module) })
 	}
 }
 

cmd/mesh-controller/composed_rejudge.go

@@ -152,7 +152,7 @@ func watchHavesForJudgement(ctx context.Context, open *stores) {
 				if err != nil || isNode {
 					continue
 				}
-				inBackground(func() {
+				inBackground(ctx, func() {
 					if err := rejudgeOn(ctx, open, []string{node}, module); err != nil {
 						fmt.Printf("compositions: %s on %s is not judged again: %v\n", module, node, err)
 					}

cmd/mesh-controller/given.go

@@ -195,7 +195,7 @@ func watchHavesForGiven(ctx context.Context, open *stores) {
 				if at.IsZero() {
 					continue
 				}
-				inBackground(func() { replaceGiven(ctx, open, node, map[string]time.Time{module: at}) })
+				inBackground(ctx, func() { replaceGiven(ctx, open, node, map[string]time.Time{module: at}) })
 			}
 		}
 	})

cmd/mesh-controller/new_modules.go

@@ -200,13 +200,13 @@ func newModuleObservations(now time.Time) []conditions.Observation {
 // watchNewModules wakes the take-in of new modules for each module the builder or the indexer writes, until ctx ends, and
 // looks at every module once now. A bucket not there yet is said: the look at start and a first merge's word still work.
 func watchNewModules(ctx context.Context, open *stores) {
-	inBackground(func() {
+	inBackground(ctx, func() {
 		takeNewModules(ctx, open)
 	})
 	// And, beside it, the start's pass of release 6 and the take-in of each registered module's new done key (novox/hq
 	// ADR 0539 clauses 5, 7, 10 and 13; composed_start.go, composed_keys.go): the plans' buckets deleted, every node
 	// composed, the replaced controller composed, and from now on each new fingerprint registered, composed and granted.
-	inBackground(func() { composeAtStart(ctx, open) })
+	inBackground(ctx, func() { composeAtStart(ctx, open) })
 	watchDoneKeys(ctx, open)
 	watchHavesForJudgement(ctx, open)
 	// And the keep set keeps the builds every want names (ADR 0539 clause 1), with no plan left to name them.
@@ -232,7 +232,7 @@ func watchNewModules(ctx context.Context, open *stores) {
 // wakeNewModule takes module in when the catalogue does not hold it: never on the watch's own goroutine, which must keep
 // draining.
 func wakeNewModule(ctx context.Context, open *stores, module string) {
-	inBackground(func() {
+	inBackground(ctx, func() {
 		entries, err := open.inventory.Catalogued(ctx)
 		if err != nil {
 			return
@@ -250,14 +250,17 @@ func wakeNewModule(ctx context.Context, open *stores, module string) {
 // ends only once the work its mesh started has.
 var background sync.WaitGroup
 
-// inBackground runs work beside the caller, counted in background. A variable so a test of what a walk does around a
-// take-in may run it in the caller's turn and need not wait for it.
-var inBackground = func(work func()) {
+// inBackground runs work beside the caller, counted in background and, under a serving controller, in its serving group,
+// so serve's stop waits for it and a serve that is stopping starts none (serving_group.go). A variable so a test of what a
+// walk does around a take-in may run it in the caller's turn and need not wait for it.
+var inBackground = func(ctx context.Context, work func()) {
 	background.Add(1)
-	go func() {
+	if !goServing(ctx, func() {
 		defer background.Done()
 		work()
-	}()
+	}) {
+		background.Done()
+	}
 }
 
 // newModulesOf are the modules the indexer holds in a repository: what a first merge's word wakes.

cmd/mesh-controller/serving_group.go

@@ -29,17 +29,17 @@ func withServingGroup(ctx context.Context) (context.Context, *servingGroup) {
 
 // goServing runs work beside the caller, counted in the group ctx carries, so serve's stop waits for it. Under a group
 // whose stop began it runs nothing; under a context with no group (a part run alone, by a test or a verb) it is a plain
-// goroutine, as before.
-func goServing(ctx context.Context, work func()) {
+// goroutine, as before. It says whether it started work.
+func goServing(ctx context.Context, work func()) bool {
 	g, _ := ctx.Value(servingGroupKey{}).(*servingGroup)
 	if g == nil {
 		go work()
-		return
+		return true
 	}
 	g.mu.Lock()
 	if g.stopped {
 		g.mu.Unlock()
-		return
+		return false
 	}
 	g.wg.Add(1)
 	g.mu.Unlock()
@@ -47,6 +47,7 @@ func goServing(ctx context.Context, work func()) {
 		defer g.wg.Done()
 		work()
 	}()
+	return true
 }
 
 // stop starts nothing more and waits for what was started; the caller ends their context first. A second stop waits

cmd/mesh-controller/states_announced.go

@@ -67,7 +67,7 @@ func keepAnnouncements(ctx context.Context, js *broker.JetStream, open *stores)
 			return
 		}
 		if changed {
-			inBackground(func() { composeAnnouncedReads(context.WithoutCancel(ctx), open) })
+			inBackground(ctx, func() { composeAnnouncedReads(context.WithoutCancel(ctx), open) })
 		}
 	})
 	if err != nil {