Golang Stopper.RunTask方法代碼示例

// startUser simulates a stream of user events until the stopper
// indicates it's time to exit.
func startUser(ctx Context, stopper *stop.Stopper) {
	for {
		userID := 1 + int(rand.ExpFloat64()/rate)
		op := randomOp()

		if err := stopper.RunTask(func() {
			err := runUserOp(ctx, userID, op.typ)
			stats.Lock()
			_ = stats.hist.RecordValue(int64(userID))
			stats.totalOps++
			stats.opCounts[op.typ]++
			switch {
			case err == errNoUser:
				stats.noUserOps++
			case err == errNoPhoto:
				stats.noPhotoOps++
			case err != nil:
				stats.failedOps++
				log.Printf("failed to run %s op for %d: %s", op.name, userID, err)
			}
			stats.Unlock()
		}); err != nil {
			return
		}
	}
}

// processLoop processes the entries in the queue until the provided
// stopper signals exit.
//
// TODO(spencer): current load should factor into replica processing timer.
func (bq *baseQueue) processLoop(clock *hlc.Clock, stopper *stop.Stopper) {
	stopper.RunWorker(func() {
		ctx := bq.AnnotateCtx(context.Background())
		defer func() {
			bq.mu.Lock()
			bq.mu.stopped = true
			bq.mu.Unlock()
			bq.AmbientContext.FinishEventLog()
		}()

		// nextTime is initially nil; we don't start any timers until the queue
		// becomes non-empty.
		var nextTime <-chan time.Time

		immediately := make(chan time.Time)
		close(immediately)

		for {
			select {
			// Exit on stopper.
			case <-stopper.ShouldStop():
				return

			// Incoming signal sets the next time to process if there were previously
			// no replicas in the queue.
			case <-bq.incoming:
				if nextTime == nil {
					// When a replica is added, wake up immediately. This is mainly
					// to facilitate testing without unnecessary sleeps.
					nextTime = immediately

					// In case we're in a test, still block on the impl.
					bq.impl.timer()
				}
			// Process replicas as the timer expires.
			case <-nextTime:
				repl := bq.pop()
				if repl != nil {
					if stopper.RunTask(func() {
						annotatedCtx := repl.AnnotateCtx(ctx)
						if err := bq.processReplica(annotatedCtx, repl, clock); err != nil {
							// Maybe add failing replica to purgatory if the queue supports it.
							bq.maybeAddToPurgatory(annotatedCtx, repl, err, clock, stopper)
						}
					}) != nil {
						return
					}
				}
				if bq.Length() == 0 {
					nextTime = nil
				} else {
					nextTime = time.After(bq.impl.timer())
				}
			}
		}
	})
}

// scanLoop loops endlessly, scanning through replicas available via
// the replica set, or until the scanner is stopped. The iteration
// is paced to complete a full scan in approximately the scan interval.
func (rs *replicaScanner) scanLoop(clock *hlc.Clock, stopper *stop.Stopper) {
	stopper.RunWorker(func() {
		ctx := rs.AnnotateCtx(context.Background())
		start := timeutil.Now()

		// waitTimer is reset in each call to waitAndProcess.
		defer rs.waitTimer.Stop()

		for {
			if rs.GetDisabled() {
				if done := rs.waitEnabled(stopper); done {
					return
				}
				continue
			}
			var shouldStop bool
			count := 0
			rs.replicas.Visit(func(repl *Replica) bool {
				count++
				shouldStop = rs.waitAndProcess(ctx, start, clock, stopper, repl)
				return !shouldStop
			})
			if count == 0 {
				// No replicas processed, just wait.
				shouldStop = rs.waitAndProcess(ctx, start, clock, stopper, nil)
			}

			shouldStop = shouldStop || nil != stopper.RunTask(func() {
				// Increment iteration count.
				rs.mu.Lock()
				defer rs.mu.Unlock()
				rs.mu.scanCount++
				rs.mu.total += timeutil.Since(start)
				if log.V(6) {
					log.Infof(ctx, "reset replica scan iteration")
				}

				// Reset iteration and start time.
				start = timeutil.Now()
			})
			if shouldStop {
				return
			}
		}
	})
}

// maybeAddToPurgatory possibly adds the specified replica to the
// purgatory queue, which holds replicas which have failed
// processing. To be added, the failing error must implement
// purgatoryError and the queue implementation must have its own
// mechanism for signaling re-processing of replicas held in
// purgatory.
func (bq *baseQueue) maybeAddToPurgatory(
	ctx context.Context, repl *Replica, triggeringErr error, clock *hlc.Clock, stopper *stop.Stopper,
) {
	// Increment failures metric here to capture all error returns from
	// process().
	bq.failures.Inc(1)

	// Check whether the failure is a purgatory error and whether the queue supports it.
	if _, ok := triggeringErr.(purgatoryError); !ok || bq.impl.purgatoryChan() == nil {
		log.Error(ctx, triggeringErr)
		return
	}
	bq.mu.Lock()
	defer bq.mu.Unlock()

	// First, check whether the replica has already been re-added to queue.
	if _, ok := bq.mu.replicas[repl.RangeID]; ok {
		return
	}

	log.Error(ctx, errors.Wrap(triggeringErr, "purgatory"))

	item := &replicaItem{value: repl.RangeID}
	bq.mu.replicas[repl.RangeID] = item

	defer func() {
		bq.purgatory.Update(int64(len(bq.mu.purgatory)))
	}()

	// If purgatory already exists, just add to the map and we're done.
	if bq.mu.purgatory != nil {
		bq.mu.purgatory[repl.RangeID] = triggeringErr
		return
	}

	// Otherwise, create purgatory and start processing.
	bq.mu.purgatory = map[roachpb.RangeID]error{
		repl.RangeID: triggeringErr,
	}

	stopper.RunWorker(func() {
		ctx := bq.AnnotateCtx(context.Background())
		ticker := time.NewTicker(purgatoryReportInterval)
		for {
			select {
			case <-bq.impl.purgatoryChan():
				// Remove all items from purgatory into a copied slice.
				bq.mu.Lock()
				ranges := make([]roachpb.RangeID, 0, len(bq.mu.purgatory))
				for rangeID := range bq.mu.purgatory {
					item := bq.mu.replicas[rangeID]
					ranges = append(ranges, item.value)
					bq.remove(item)
				}
				bq.mu.Unlock()
				for _, id := range ranges {
					repl, err := bq.store.GetReplica(id)
					if err != nil {
						log.Errorf(ctx, "range %s no longer exists on store: %s", id, err)
						return
					}
					if stopper.RunTask(func() {
						annotatedCtx := repl.AnnotateCtx(ctx)
						if err := bq.processReplica(annotatedCtx, repl, clock); err != nil {
							bq.maybeAddToPurgatory(annotatedCtx, repl, err, clock, stopper)
						}
					}) != nil {
						return
					}
				}
				bq.mu.Lock()
				if len(bq.mu.purgatory) == 0 {
					log.Infof(ctx, "purgatory is now empty")
					bq.mu.purgatory = nil
					bq.mu.Unlock()
					return
				}
				bq.mu.Unlock()
			case <-ticker.C:
				// Report purgatory status.
				bq.mu.Lock()
				errMap := map[string]int{}
				for _, err := range bq.mu.purgatory {
					errMap[err.Error()]++
				}
				bq.mu.Unlock()
				for errStr, count := range errMap {
					log.Errorf(ctx, "%d replicas failing with %q", count, errStr)
				}
			case <-stopper.ShouldStop():
				return
			}
		}
	})
//.........這裏部分代碼省略.........