libcontainer: client.processEventStream: use locally scoped variables

- use local variables and remove some intermediate variables
- handle the events inside the switch itself; this makes all the
  switch branches use the same logic, instead of "some" using
  a `continue`, and others falling through to have the event handled
  outside of the switch.

Signed-off-by: Sebastiaan van Stijn <github@gone.nl>

libcontainerd/remote/client.go

@@ -20,7 +20,6 @@ import (
 	"github.com/containerd/containerd/cio"
 	"github.com/containerd/containerd/content"
 	cerrdefs "github.com/containerd/containerd/errdefs"
-	"github.com/containerd/containerd/events"
 	"github.com/containerd/containerd/images"
 	"github.com/containerd/containerd/log"
 	v2runcoptions "github.com/containerd/containerd/runtime/v2/runc/options"
@@ -614,13 +613,6 @@ func (c *client) waitServe(ctx context.Context) bool {
 }
 
 func (c *client) processEventStream(ctx context.Context, ns string) {
-	var (
-		err error
-		ev  *events.Envelope
-		et  libcontainerdtypes.EventType
-		ei  libcontainerdtypes.EventInfo
-	)
-
 	// Create a new context specifically for this subscription.
 	// The context must be cancelled to cancel the subscription.
 	// In cases where we have to restart event stream processing,
@@ -636,7 +628,7 @@ func (c *client) processEventStream(ctx context.Context, ns string) {
 
 	for {
 		select {
-		case err = <-errC:
+		case err := <-errC:
 			if err != nil {
 				errStatus, ok := status.FromError(err)
 				if !ok || errStatus.Code() != codes.Canceled {
@@ -650,7 +642,7 @@ func (c *client) processEventStream(ctx context.Context, ns string) {
 				c.logger.WithError(ctx.Err()).Info("stopping event stream following graceful shutdown")
 			}
 			return
-		case ev = <-eventStream:
+		case ev := <-eventStream:
 			if ev.Event == nil {
 				c.logger.WithField("event", ev).Warn("invalid event")
 				continue
@@ -666,74 +658,60 @@ func (c *client) processEventStream(ctx context.Context, ns string) {
 
 			switch t := v.(type) {
 			case *apievents.TaskCreate:
-				et = libcontainerdtypes.EventCreate
+				c.processEvent(ctx, libcontainerdtypes.EventCreate, libcontainerdtypes.EventInfo{
-				ei = libcontainerdtypes.EventInfo{
 					ContainerID: t.ContainerID,
 					ProcessID:   t.ContainerID,
 					Pid:         t.Pid,
-				}
+				})
 			case *apievents.TaskStart:
-				et = libcontainerdtypes.EventStart
+				c.processEvent(ctx, libcontainerdtypes.EventStart, libcontainerdtypes.EventInfo{
-				ei = libcontainerdtypes.EventInfo{
 					ContainerID: t.ContainerID,
 					ProcessID:   t.ContainerID,
 					Pid:         t.Pid,
-				}
+				})
 			case *apievents.TaskExit:
-				et = libcontainerdtypes.EventExit
+				c.processEvent(ctx, libcontainerdtypes.EventExit, libcontainerdtypes.EventInfo{
-				ei = libcontainerdtypes.EventInfo{
 					ContainerID: t.ContainerID,
 					ProcessID:   t.ID,
 					Pid:         t.Pid,
 					ExitCode:    t.ExitStatus,
 					ExitedAt:    t.ExitedAt,
-				}
+				})
 			case *apievents.TaskOOM:
-				et = libcontainerdtypes.EventOOM
+				c.processEvent(ctx, libcontainerdtypes.EventOOM, libcontainerdtypes.EventInfo{
-				ei = libcontainerdtypes.EventInfo{
 					ContainerID: t.ContainerID,
-				}
+				})
 			case *apievents.TaskExecAdded:
-				et = libcontainerdtypes.EventExecAdded
+				c.processEvent(ctx, libcontainerdtypes.EventExecAdded, libcontainerdtypes.EventInfo{
-				ei = libcontainerdtypes.EventInfo{
 					ContainerID: t.ContainerID,
 					ProcessID:   t.ExecID,
-				}
+				})
 			case *apievents.TaskExecStarted:
-				et = libcontainerdtypes.EventExecStarted
+				c.processEvent(ctx, libcontainerdtypes.EventExecStarted, libcontainerdtypes.EventInfo{
-				ei = libcontainerdtypes.EventInfo{
 					ContainerID: t.ContainerID,
 					ProcessID:   t.ExecID,
 					Pid:         t.Pid,
-				}
+				})
 			case *apievents.TaskPaused:
-				et = libcontainerdtypes.EventPaused
+				c.processEvent(ctx, libcontainerdtypes.EventPaused, libcontainerdtypes.EventInfo{
-				ei = libcontainerdtypes.EventInfo{
 					ContainerID: t.ContainerID,
-				}
+				})
 			case *apievents.TaskResumed:
-				et = libcontainerdtypes.EventResumed
+				c.processEvent(ctx, libcontainerdtypes.EventResumed, libcontainerdtypes.EventInfo{
-				ei = libcontainerdtypes.EventInfo{
 					ContainerID: t.ContainerID,
-				}
+				})
 			case *apievents.TaskDelete:
 				c.logger.WithFields(log.Fields{
 					"topic":     ev.Topic,
 					"type":      reflect.TypeOf(t),
 					"container": t.ContainerID,
-				},
+				}).Info("ignoring event")
-				).Info("ignoring event")
-				continue
 			default:
 				c.logger.WithFields(log.Fields{
 					"topic": ev.Topic,
 					"type":  reflect.TypeOf(t),
-				},
+				}).Info("ignoring event")
-				).Info("ignoring event")
-				continue
 			}
-
-			c.processEvent(ctx, et, ei)
 		}
 	}
 }