Kubernetes源码学习笔记------api-server的请求调度（2）

// WorkEstimate carries three of the four parameters that determine the work in a request.
// The fourth parameter is the duration of the initial phase of execution.
type WorkEstimate struct {
	// InitialSeats is the number of seats occupied while the server is
	// executing this request.
	InitialSeats uint64

	// FinalSeats is the number of seats occupied at the end,
	// during the AdditionalLatency.
	FinalSeats uint64

	// AdditionalLatency specifies the additional duration the seats allocated
	// to this request must be reserved after the given request had finished.
	// AdditionalLatency should not have any impact on the user experience, the
	// caller must not experience this additional latency.
	AdditionalLatency time.Duration
}

func (e *listWorkEstimator) estimate(r *http.Request, flowSchemaName, priorityLevelName string) WorkEstimat {
    // ........
    isListFromCache := requestInfo.Verb == "watch" || !shouldListFromStorage(query, &listOptions)

    numStored, err := e.countGetterFn(key(requestInfo))
    // ........
    switch {
	case isListFromCache:
		// TODO: For resources that implement indexes at the watchcache level,
		//  we need to adjust the cost accordingly
		estimatedObjectsToBeProcessed = numStored
	case listOptions.FieldSelector != "" || listOptions.LabelSelector != "":
		estimatedObjectsToBeProcessed = numStored + limit
	default:
		estimatedObjectsToBeProcessed = 2 * limit
	}

    seats := uint64(math.Ceil(float64(estimatedObjectsToBeProcessed) / e.config.ObjectsPerSeat))
     // ........
    return WorkEstimate{InitialSeats: seats}
}

func (e *mutatingWorkEstimator) estimate(r *http.Request, flowSchemaName, priorityLevelName string) WorkEstimate {
	minSeats := e.config.MinimumSeats
	maxSeats := e.maxSeatsFn(priorityLevelName)
	if maxSeats == 0 || maxSeats > e.config.MaximumSeatsLimit {
		maxSeats = e.config.MaximumSeatsLimit
	}

	if !e.config.Enabled {
		return WorkEstimate{
			InitialSeats: minSeats,
		}
	}

	requestInfo, ok := apirequest.RequestInfoFrom(r.Context())
	if !ok {
		return WorkEstimate{
			InitialSeats:      minSeats,
			FinalSeats:        maxSeats,
			AdditionalLatency: e.config.eventAdditionalDuration(),
		}
	}

	if isRequestExemptFromWatchEvents(requestInfo) {
		return WorkEstimate{
			InitialSeats:      minSeats,
			FinalSeats:        0,
			AdditionalLatency: time.Duration(0),
		}
	}

	watchCount := e.countFn(requestInfo)
	metrics.ObserveWatchCount(r.Context(), priorityLevelName, flowSchemaName, watchCount)

	var finalSeats uint64
	var additionalLatency time.Duration


	if watchCount >= int(e.config.WatchesPerSeat) {
		finalSeats = uint64(math.Ceil(float64(watchCount) / e.config.WatchesPerSeat))
		finalWork := SeatsTimesDuration(float64(finalSeats), e.config.eventAdditionalDuration())

		if finalSeats > maxSeats {
			finalSeats = maxSeats
		}
		additionalLatency = finalWork.DurationPerSeat(float64(finalSeats))
	}

	return WorkEstimate{
		InitialSeats:      1,
		FinalSeats:        finalSeats,
		AdditionalLatency: additionalLatency,
	}
}