Treat actor creation like a regular task. (#1668)

* Treat actor creation like a regular task.

* Small cleanups.

* Change semantics of actor resource handling.

* Bug fix.

* Minor linting

* Bug fix

* Fix jenkins test.

* Fix actor tests

* Some cleanups

* Bug fix

* Fix bug.

* Remove cached actor tasks when a driver is removed.

* Add more info to taskspec in global state API.

* Fix cyclic import bug in tune.

* Fix

* Fix linting.

* Fix linting.

* Don't schedule any tasks (especially actor creaiton tasks) on local schedulers with 0 CPUs.

* Bug fix.

* Add test for 0 CPU case

* Fix linting

* Address comments.

* Fix typos and add comment.

* Add assertion and fix test.

src/common/format/common.fbs

@@ -29,6 +29,10 @@ table TaskInfo {
   parent_task_id: string;
   // A count of the number of tasks submitted by the parent task before this one.
   parent_counter: int;
+  // The ID of the actor to create if this is an actor creation task.
+  actor_creation_id: string;
+  // The dummy object ID of the actor creation task if this is an actor method.
+  actor_creation_dummy_object_id: string;
   // Actor ID of the task. This is the actor that this task is executed on
   // or NIL_ACTOR_ID if the task is just a normal task.
   actor_id: string;
@@ -162,3 +166,12 @@ table DriverTableMessage {
   // The driver ID of the driver that died.
   driver_id: string;
 }
+
+table ActorCreationNotification {
+  // The ID of the actor that was created.
+  actor_id: string;
+  // The ID of the driver that created the actor.
+  driver_id: string;
+  // The ID of the local scheduler that created the actor.
+  local_scheduler_id: string;
+}