Add "reserve" and "prebind" plugin interfaces for the scheduling framework.

pkg/scheduler/plugins/examples/multipoint.go

@@ -0,0 +1,62 @@
+/*
+Copyright 2018 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 examples
+
+import (
+	"fmt"
+
+	"k8s.io/api/core/v1"
+	plugins "k8s.io/kubernetes/pkg/scheduler/plugins/v1alpha1"
+)
+
+// MultipointCommunicatingPlugin is an example of a plugin that implements two
+// extension points. It communicates through pluginContext with another function.
+type MultipointCommunicatingPlugin struct{}
+
+var _ = plugins.ReservePlugin(MultipointCommunicatingPlugin{})
+
+// Name returns name of the plugin. It is used in logs, etc.
+func (mc MultipointCommunicatingPlugin) Name() string {
+	return "multipoint-communicating-plugin"
+}
+
+// Reserve is the functions invoked by the framework at "reserve" extension point.
+func (mc MultipointCommunicatingPlugin) Reserve(ps plugins.PluginSet, pod *v1.Pod, nodeName string) error {
+	if pod == nil {
+		return fmt.Errorf("pod cannot be nil")
+	}
+	if pod.Name == "my-test-pod" {
+		ps.Data().Ctx.SyncWrite(plugins.ContextKey(pod.Name), "never bind")
+	}
+	return nil
+}
+
+// Prebind is the functions invoked by the framework at "prebind" extension point.
+func (mc MultipointCommunicatingPlugin) Prebind(ps plugins.PluginSet, pod *v1.Pod, nodeName string) (bool, error) {
+	if pod == nil {
+		return false, fmt.Errorf("pod cannot be nil")
+	}
+	if v, e := ps.Data().Ctx.SyncRead(plugins.ContextKey(pod.Name)); e == nil && v == "never bind" {
+		return false, nil
+	}
+	return true, nil
+}
+
+// NewMultipointCommunicatingPlugin initializes a new plugin and returns it.
+func NewMultipointCommunicatingPlugin() *MultipointCommunicatingPlugin {
+	return &MultipointCommunicatingPlugin{}
+}