Refactor qos package

Signed-off-by: Buddha Prakash <buddhap@google.com>

pkg/kubelet/qos/qos.go

@@ -0,0 +1,140 @@
+/*
+Copyright 2015 The Kubernetes Authors All rights reserved.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package qos
+
+import (
+	"k8s.io/kubernetes/pkg/api"
+	"k8s.io/kubernetes/pkg/api/resource"
+)
+
+// isResourceGuaranteed returns true if the container's resource requirements are Guaranteed.
+func isResourceGuaranteed(container *api.Container, resource api.ResourceName) bool {
+	// A container resource is guaranteed if its request == limit.
+	// If request == limit, the user is very confident of resource consumption.
+	req, hasReq := container.Resources.Requests[resource]
+	limit, hasLimit := container.Resources.Limits[resource]
+	if !hasReq || !hasLimit {
+		return false
+	}
+	return req.Cmp(limit) == 0 && req.Value() != 0
+}
+
+// isResourceBestEffort returns true if the container's resource requirements are best-effort.
+func isResourceBestEffort(container *api.Container, resource api.ResourceName) bool {
+	// A container resource is best-effort if its request is unspecified or 0.
+	// If a request is specified, then the user expects some kind of resource guarantee.
+	req, hasReq := container.Resources.Requests[resource]
+	return !hasReq || req.Value() == 0
+}
+
+// GetPodQos returns the QoS class of a pod.
+// A pod is besteffort if none of its containers have specified any requests or limits.
+// A pod is guaranteed only when requests and limits are specified for all the containers and they are equal.
+// A pod is burstable if limits and requests do not match across all containers.
+func GetPodQos(pod *api.Pod) QOSClass {
+	requests := api.ResourceList{}
+	limits := api.ResourceList{}
+	zeroQuantity := resource.MustParse("0")
+	isGuaranteed := true
+	for _, container := range pod.Spec.Containers {
+		// process requests
+		for name, quantity := range container.Resources.Requests {
+			if quantity.Cmp(zeroQuantity) == 1 {
+				delta := quantity.Copy()
+				if _, exists := requests[name]; !exists {
+					requests[name] = *delta
+				} else {
+					delta.Add(requests[name])
+					requests[name] = *delta
+				}
+			}
+		}
+		// process limits
+		for name, quantity := range container.Resources.Limits {
+			if quantity.Cmp(zeroQuantity) == 1 {
+				delta := quantity.Copy()
+				if _, exists := limits[name]; !exists {
+					limits[name] = *delta
+				} else {
+					delta.Add(limits[name])
+					limits[name] = *delta
+				}
+			}
+		}
+		if len(container.Resources.Limits) != len(supportedComputeResources) {
+			isGuaranteed = false
+		}
+	}
+	if len(requests) == 0 && len(limits) == 0 {
+		return BestEffort
+	}
+	// Check is requests match limits for all resources.
+	if isGuaranteed {
+		for name, req := range requests {
+			if lim, exists := limits[name]; !exists || lim.Cmp(req) != 0 {
+				isGuaranteed = false
+				break
+			}
+		}
+	}
+	if isGuaranteed &&
+		len(requests) == len(limits) &&
+		len(limits) == len(supportedComputeResources) {
+		return Guaranteed
+	}
+	return Burstable
+}
+
+// QoSList is a set of (resource name, QoS class) pairs.
+type QoSList map[api.ResourceName]QOSClass
+
+// GetQoS returns a mapping of resource name to QoS class of a container
+func GetQoS(container *api.Container) QoSList {
+	resourceToQoS := QoSList{}
+	for resource := range allResources(container) {
+		switch {
+		case isResourceGuaranteed(container, resource):
+			resourceToQoS[resource] = Guaranteed
+		case isResourceBestEffort(container, resource):
+			resourceToQoS[resource] = BestEffort
+		default:
+			resourceToQoS[resource] = Burstable
+		}
+	}
+	return resourceToQoS
+}
+
+// supportedComputeResources is the list of supported compute resources
+var supportedComputeResources = []api.ResourceName{
+	api.ResourceCPU,
+	api.ResourceMemory,
+}
+
+// allResources returns a set of all possible resources whose mapped key value is true if present on the container
+func allResources(container *api.Container) map[api.ResourceName]bool {
+	resources := map[api.ResourceName]bool{}
+	for _, resource := range supportedComputeResources {
+		resources[resource] = false
+	}
+	for resource := range container.Resources.Requests {
+		resources[resource] = true
+	}
+	for resource := range container.Resources.Limits {
+		resources[resource] = true
+	}
+	return resources
+}