sensors: allow listing policies after removal

Instead of destroying the sensors of a policy and then removing them
from the collection, remove them first and then destroy them. Once we
remove them, we can release the collection lock that allows listing of
the policies.

Signed-off-by: Kornilios Kourtis <kornilios@isovalent.com>

pkg/sensors/handler.go

@@ -152,13 +152,16 @@ func (h *handler) addTracingPolicy(op *tracingPolicyAdd) error {
 
 func (h *handler) deleteTracingPolicy(op *tracingPolicyDelete) error {
 	h.collections.mu.Lock()
-	defer h.collections.mu.Unlock()
 	collections := h.collections.c
 	col, exists := collections[op.ck]
 	if !exists {
+		h.collections.mu.Unlock()
 		return fmt.Errorf("tracing policy %s does not exist", op.ck)
 	}
-	defer delete(collections, op.ck)
+	delete(collections, op.ck)
+	// we have removed the collection, so unlock the map so that the lister can quickly view
+	// that the collection is gone
+	h.collections.mu.Unlock()
 
 	col.destroy()