forked from yamt/midonet-kubernetes
/
controller.go
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/
controller.go
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// Copyright (C) 2018 Midokura SARL.
// 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 controller
import (
log "github.com/sirupsen/logrus"
"k8s.io/apimachinery/pkg/runtime/schema"
"k8s.io/client-go/tools/cache"
"k8s.io/client-go/util/workqueue"
)
// Handler is a set of callbacks to process events on the queue.
type Handler interface {
Update(string, schema.GroupVersionKind, interface{}) error
Delete(string) error
}
// Controller describes a controller to watch the given GVK events.
type Controller struct {
informer cache.SharedIndexInformer
queue workqueue.RateLimitingInterface
handler Handler
gvk schema.GroupVersionKind
}
// NewController creates a controller.
func NewController(gvk schema.GroupVersionKind, informer cache.SharedIndexInformer, handler Handler) *Controller {
queue := AddHandler(informer, gvk.String())
return &Controller{
informer: informer,
queue: queue,
handler: handler,
gvk: gvk,
}
}
// Run executes the controller.
func (c *Controller) Run() {
for c.processNextItem() {
}
}
func (c *Controller) processNextItem() bool {
queue := c.queue
key, quit := queue.Get()
if quit {
return false
}
defer queue.Done(key)
clog := log.WithFields(log.Fields{
"key": key,
})
clog.Debug("Start processing.")
err := c.processItem(key.(string), c.informer)
if err == nil {
clog.Debug("Done.")
queue.Forget(key)
return true
}
clog.WithError(err).Error("Failed. Retrying.")
queue.AddRateLimited(key)
return true
}
func (c *Controller) processItem(key string, informer cache.SharedIndexInformer) error {
clog := log.WithField("key", key)
clog.Debug("Processing")
obj, exists, err := informer.GetIndexer().GetByKey(key)
if err != nil {
clog.WithError(err).Fatal("GetBykey")
}
if !exists {
clog.Debug("Deleted.")
return c.handler.Delete(key)
}
clog.WithField("obj", obj).Debug("Updated.")
return c.handler.Update(key, c.gvk, obj)
}
// GetQueue returns the event queue used by the controller.
// It can be useful to inject extra events for the controller.
// See pkg/converter/endpoints/controller.go for an example.
func (c *Controller) GetQueue() workqueue.Interface {
return c.queue
}