Add base controller

Signed-off-by: Michael Tsang <michael.tsang@jetstack.io>

pkg/controller/BUILD.bazel

@@ -3,6 +3,7 @@ load("@io_bazel_rules_go//go:def.bzl", "go_library", "go_test")
 go_library(
     name = "go_default_library",
     srcs = [
+        "base_controller.go",
         "context.go",
         "helper.go",
         "register.go",
@@ -14,8 +15,10 @@ go_library(
         "//pkg/apis/certmanager/v1alpha1:go_default_library",
         "//pkg/client/clientset/versioned:go_default_library",
         "//pkg/client/informers/externalversions:go_default_library",
+        "//pkg/logs:go_default_library",
         "//vendor/k8s.io/apimachinery/pkg/api/resource:go_default_library",
         "//vendor/k8s.io/apimachinery/pkg/util/runtime:go_default_library",
+        "//vendor/k8s.io/apimachinery/pkg/util/wait:go_default_library",
         "//vendor/k8s.io/client-go/informers:go_default_library",
         "//vendor/k8s.io/client-go/kubernetes:go_default_library",
         "//vendor/k8s.io/client-go/rest:go_default_library",

pkg/controller/base_controller.go

@@ -0,0 +1,128 @@
+/*
+Copyright 2019 The Jetstack cert-manager contributors.
+
+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 (
+	"context"
+	"fmt"
+	"sync"
+	"time"
+
+	"k8s.io/apimachinery/pkg/util/wait"
+	"k8s.io/client-go/tools/cache"
+	"k8s.io/client-go/util/workqueue"
+
+	logf "github.com/jetstack/cert-manager/pkg/logs"
+)
+
+type BaseController struct {
+	// the controllers root context, containing a controller scoped logger
+	Ctx context.Context
+	*Context
+
+	// To allow injection for testing.
+	syncHandler func(ctx context.Context, key string) error
+
+	watchedInformers []cache.InformerSynced
+	Queue            workqueue.RateLimitingInterface
+}
+
+func New(ctx *Context, controllerName string, syncHandler func(ctx context.Context, key string) error) *BaseController {
+	bctrl := &BaseController{Context: ctx}
+	bctrl.syncHandler = syncHandler
+	bctrl.Ctx = logf.NewContext(ctx.RootContext, nil, controllerName)
+	return bctrl
+}
+
+func (bctrl *BaseController) AddQueuing(rateLimiter workqueue.RateLimiter, name string, informer cache.SharedIndexInformer) {
+	bctrl.Queue = workqueue.NewNamedRateLimitingQueue(rateLimiter, name)
+	informer.AddEventHandler(&QueuingEventHandler{Queue: bctrl.Queue})
+	bctrl.watchedInformers = append(bctrl.watchedInformers, informer.HasSynced)
+}
+
+func (bctrl *BaseController) AddHandled(informer cache.SharedIndexInformer, handler cache.ResourceEventHandler) {
+	informer.AddEventHandler(handler)
+	bctrl.watchedInformers = append(bctrl.watchedInformers, informer.HasSynced)
+}
+
+func (bctrl *BaseController) AddWatched(informers ...cache.SharedIndexInformer) {
+	for _, informer := range informers {
+		bctrl.watchedInformers = append(bctrl.watchedInformers, informer.HasSynced)
+	}
+}
+
+func (bc *BaseController) Run(workers int, stopCh <-chan struct{}) error {
+	ctx, cancel := context.WithCancel(bc.Ctx)
+	defer cancel()
+	log := logf.FromContext(ctx)
+
+	log.Info("starting control loop")
+	// wait for all the informer caches we depend on are synced
+	if !cache.WaitForCacheSync(stopCh, bc.watchedInformers...) {
+		// TODO: replace with Errorf call to glog
+		return fmt.Errorf("error waiting for informer caches to sync")
+	}
+
+	var wg sync.WaitGroup
+	for i := 0; i < workers; i++ {
+		wg.Add(1)
+		// TODO (@munnerz): make time.Second duration configurable
+		go wait.Until(func() {
+			defer wg.Done()
+			bc.worker(ctx)
+		}, time.Second, stopCh)
+	}
+	<-stopCh
+	log.Info("shutting down queue as workqueue signaled shutdown")
+	bc.Queue.ShutDown()
+	log.V(logf.DebugLevel).Info("waiting for workers to exit...")
+	wg.Wait()
+	log.V(logf.DebugLevel).Info("workers exited")
+	return nil
+}
+
+func (bc *BaseController) worker(ctx context.Context) {
+	log := logf.FromContext(bc.Ctx)
+
+	log.V(logf.DebugLevel).Info("starting worker")
+	for {
+		obj, shutdown := bc.Queue.Get()
+		if shutdown {
+			break
+		}
+
+		var key string
+		// use an inlined function so we can use defer
+		func() {
+			defer bc.Queue.Done(obj)
+			var ok bool
+			if key, ok = obj.(string); !ok {
+				return
+			}
+			log := log.WithValues("key", key)
+			log.Info("syncing item")
+			if err := bc.syncHandler(ctx, key); err != nil {
+				log.Error(err, "re-queuing item  due to error processing")
+				bc.Queue.AddRateLimited(obj)
+				return
+			}
+			log.Info("finished processing work item")
+			bc.Queue.Forget(obj)
+		}()
+	}
+	log.V(logf.DebugLevel).Info("exiting worker loop")
+}