refactor(zfspv): renamed watcher to mgmt package

as it does the management task also corrected few logs
and renamed zvol to zfs(as we support zvol and dataset both)

Signed-off-by: Pawan <pawan@mayadata.io>

pkg/mgmt/mgmt.go

@@ -0,0 +1,254 @@
+/*
+Copyright 2019 The OpenEBS 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 mgmt
+
+import (
+	"fmt"
+	"time"
+
+	"github.com/Sirupsen/logrus"
+
+	apis "github.com/openebs/zfs-localpv/pkg/apis/openebs.io/core/v1alpha1"
+	zfs "github.com/openebs/zfs-localpv/pkg/zfs"
+	k8serror "k8s.io/apimachinery/pkg/api/errors"
+	"k8s.io/apimachinery/pkg/util/runtime"
+	"k8s.io/apimachinery/pkg/util/wait"
+	"k8s.io/client-go/tools/cache"
+)
+
+// isDeletionCandidate checks if a zfs volume is a deletion candidate.
+func (c *ZVController) isDeletionCandidate(zv *apis.ZFSVolume) bool {
+	return zv.ObjectMeta.DeletionTimestamp != nil
+}
+
+// syncHandler compares the actual state with the desired, and attempts to
+// converge the two. It then updates the Status block of the spcPoolUpdated resource
+// with the current status of the resource.
+func (c *ZVController) syncHandler(key string) error {
+	// Convert the namespace/name string into a distinct namespace and name
+	namespace, name, err := cache.SplitMetaNamespaceKey(key)
+	if err != nil {
+		runtime.HandleError(fmt.Errorf("invalid resource key: %s", key))
+		return nil
+	}
+
+	// Get the zv resource with this namespace/name
+	zv, err := c.zvLister.ZFSVolumes(namespace).Get(name)
+	if k8serror.IsNotFound(err) {
+		runtime.HandleError(fmt.Errorf("zfsvolume '%s' has been deleted", key))
+		return nil
+	}
+	if err != nil {
+		return err
+	}
+	zvCopy := zv.DeepCopy()
+	err = c.syncZV(zvCopy)
+	return err
+}
+
+// enqueueZV takes a ZFSVolume resource and converts it into a namespace/name
+// string which is then put onto the work queue. This method should *not* be
+// passed resources of any type other than ZFSVolume.
+func (c *ZVController) enqueueZV(obj interface{}) {
+	var key string
+	var err error
+	if key, err = cache.MetaNamespaceKeyFunc(obj); err != nil {
+		runtime.HandleError(err)
+		return
+	}
+	c.workqueue.Add(key)
+
+}
+
+// synZV is the function which tries to converge to a desired state for the
+// ZFSVolume
+func (c *ZVController) syncZV(zv *apis.ZFSVolume) error {
+	var err error
+	// ZFS Volume should be deleted. Check if deletion timestamp is set
+	if c.isDeletionCandidate(zv) {
+		err = zfs.DestroyVolume(zv)
+		if err == nil {
+			zfs.RemoveZvolFinalizer(zv)
+		}
+	} else {
+		// if finalizer is not set then it means we are creating
+		// the volume. And if it is set then volume has already been
+		// created and this event is for property change only.
+		if zv.Finalizers != nil {
+			err = zfs.SetZvolProp(zv)
+		} else {
+			err = zfs.CreateVolume(zv)
+			if err == nil {
+				err = zfs.UpdateZvolInfo(zv)
+			}
+		}
+	}
+	return err
+}
+
+// addZV is the add event handler for ZFSVolume
+func (c *ZVController) addZV(obj interface{}) {
+	zv, ok := obj.(*apis.ZFSVolume)
+	if !ok {
+		runtime.HandleError(fmt.Errorf("Couldn't get zv object %#v", obj))
+		return
+	}
+
+	if zfs.NodeID != zv.Spec.OwnerNodeID {
+		return
+	}
+	logrus.Infof("Got add event for ZV %s/%s", zv.Spec.PoolName, zv.Name)
+	c.enqueueZV(zv)
+}
+
+// updateZV is the update event handler for ZFSVolume
+func (c *ZVController) updateZV(oldObj, newObj interface{}) {
+
+	newZV, ok := newObj.(*apis.ZFSVolume)
+	if !ok {
+		runtime.HandleError(fmt.Errorf("Couldn't get zv object %#v", newZV))
+		return
+	}
+
+	if zfs.NodeID != newZV.Spec.OwnerNodeID {
+		return
+	}
+
+	oldZV, ok := oldObj.(*apis.ZFSVolume)
+	if zfs.PropertyChanged(oldZV, newZV) ||
+		c.isDeletionCandidate(newZV) {
+		logrus.Infof("Got update event for ZV %s/%s", newZV.Spec.PoolName, newZV.Name)
+		c.enqueueZV(newZV)
+	}
+}
+
+// deleteZV is the delete event handler for ZFSVolume
+func (c *ZVController) deleteZV(obj interface{}) {
+	zv, ok := obj.(*apis.ZFSVolume)
+	if !ok {
+		tombstone, ok := obj.(cache.DeletedFinalStateUnknown)
+		if !ok {
+			runtime.HandleError(fmt.Errorf("Couldn't get object from tombstone %#v", obj))
+			return
+		}
+		zv, ok = tombstone.Obj.(*apis.ZFSVolume)
+		if !ok {
+			runtime.HandleError(fmt.Errorf("Tombstone contained object that is not a zfsvolume %#v", obj))
+			return
+		}
+	}
+
+	if zfs.NodeID != zv.Spec.OwnerNodeID {
+		return
+	}
+
+	logrus.Infof("Got delete event for ZV %s/%s", zv.Spec.PoolName, zv.Name)
+	c.enqueueZV(zv)
+}
+
+// Run will set up the event handlers for types we are interested in, as well
+// as syncing informer caches and starting workers. It will block until stopCh
+// is closed, at which point it will shutdown the workqueue and wait for
+// workers to finish processing their current work items.
+func (c *ZVController) Run(threadiness int, stopCh <-chan struct{}) error {
+	defer runtime.HandleCrash()
+	defer c.workqueue.ShutDown()
+
+	// Start the informer factories to begin populating the informer caches
+	logrus.Info("Starting ZV controller")
+
+	// Wait for the k8s caches to be synced before starting workers
+	logrus.Info("Waiting for informer caches to sync")
+	if ok := cache.WaitForCacheSync(stopCh, c.zvSynced); !ok {
+		return fmt.Errorf("failed to wait for caches to sync")
+	}
+	logrus.Info("Starting ZV workers")
+	// Launch worker to process ZV resources
+	// Threadiness will decide the number of workers you want to launch to process work items from queue
+	for i := 0; i < threadiness; i++ {
+		go wait.Until(c.runWorker, time.Second, stopCh)
+	}
+
+	logrus.Info("Started ZV workers")
+	<-stopCh
+	logrus.Info("Shutting down ZV workers")
+
+	return nil
+}
+
+// runWorker is a long-running function that will continually call the
+// processNextWorkItem function in order to read and process a message on the
+// workqueue.
+func (c *ZVController) runWorker() {
+	for c.processNextWorkItem() {
+	}
+}
+
+// processNextWorkItem will read a single work item off the workqueue and
+// attempt to process it, by calling the syncHandler.
+func (c *ZVController) processNextWorkItem() bool {
+	obj, shutdown := c.workqueue.Get()
+
+	if shutdown {
+		return false
+	}
+
+	// We wrap this block in a func so we can defer c.workqueue.Done.
+	err := func(obj interface{}) error {
+		// We call Done here so the workqueue knows we have finished
+		// processing this item. We also must remember to call Forget if we
+		// do not want this work item being re-queued. For example, we do
+		// not call Forget if a transient error occurs, instead the item is
+		// put back on the workqueue and attempted again after a back-off
+		// period.
+		defer c.workqueue.Done(obj)
+		var key string
+		var ok bool
+		// We expect strings to come off the workqueue. These are of the
+		// form namespace/name. We do this as the delayed nature of the
+		// workqueue means the items in the informer cache may actually be
+		// more up to date that when the item was initially put onto the
+		// workqueue.
+		if key, ok = obj.(string); !ok {
+			// As the item in the workqueue is actually invalid, we call
+			// Forget here else we'd go into a loop of attempting to
+			// process a work item that is invalid.
+			c.workqueue.Forget(obj)
+			runtime.HandleError(fmt.Errorf("expected string in workqueue but got %#v", obj))
+			return nil
+		}
+		// Run the syncHandler, passing it the namespace/name string of the
+		// ZV resource to be synced.
+		if err := c.syncHandler(key); err != nil {
+			// Put the item back on the workqueue to handle any transient errors.
+			c.workqueue.AddRateLimited(key)
+			return fmt.Errorf("error syncing '%s': %s, requeuing", key, err.Error())
+		}
+		// Finally, if no error occurs we Forget this item so it does not
+		// get queued again until another change happens.
+		c.workqueue.Forget(obj)
+		logrus.Infof("Successfully synced '%s'", key)
+		return nil
+	}(obj)
+
+	if err != nil {
+		runtime.HandleError(err)
+		return true
+	}
+
+	return true
+}