improve gpu integration

Signed-off-by: Vishnu kannan <vishnuk@google.com>

pkg/kubelet/gpu/nvidia/helpers.go

@@ -0,0 +1,59 @@
+/*
+Copyright 2017 The Kubernetes Authors.
+
+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 nvidia
+
+import "k8s.io/apimachinery/pkg/util/sets"
+
+// podGPUs represents a list of pod to GPU mappings.
+type podGPUs struct {
+	podGPUMapping map[string]sets.String
+}
+
+func newPodGpus() *podGPUs {
+	return &podGPUs{
+		podGPUMapping: map[string]sets.String{},
+	}
+}
+func (pgpu *podGPUs) pods() sets.String {
+	ret := sets.NewString()
+	for k := range pgpu.podGPUMapping {
+		ret.Insert(k)
+	}
+	return ret
+}
+
+func (pgpu *podGPUs) insert(podUID string, device string) {
+	if _, exists := pgpu.podGPUMapping[podUID]; !exists {
+		pgpu.podGPUMapping[podUID] = sets.NewString(device)
+	} else {
+		pgpu.podGPUMapping[podUID].Insert(device)
+	}
+}
+
+func (pgpu *podGPUs) delete(pods []string) {
+	for _, uid := range pods {
+		delete(pgpu.podGPUMapping, uid)
+	}
+}
+
+func (pgpu *podGPUs) devices() sets.String {
+	ret := sets.NewString()
+	for _, devices := range pgpu.podGPUMapping {
+		ret.Union(devices)
+	}
+	return ret
+}