Implement actor checkpointing (#3839)

* Implement Actor checkpointing

* docs

* fix

* fix

* fix

* move restore-from-checkpoint to HandleActorStateTransition

* Revert "move restore-from-checkpoint to HandleActorStateTransition"

This reverts commit 9aa4447c1e3e321f42a1d895d72f17098b72de12.

* resubmit waiting tasks when actor frontier restored

* add doc about num_actor_checkpoints_to_keep=1

* add num_actor_checkpoints_to_keep to Cython

* add checkpoint_expired api

* check if actor class is abstract

* change checkpoint_ids to long string

* implement java

* Refactor to delay actor creation publish until checkpoint is resumed

* debug, lint

* Erase from checkpoints to restore if task fails

* fix lint

* update comments

* avoid duplicated actor notification log

* fix unintended change

* add actor_id to checkpoint_expired

* small java updates

* make checkpoint info per actor

* lint

* Remove logging

* Remove old actor checkpointing Python code, move new checkpointing code to FunctionActionManager

* Replace old actor checkpointing tests

* Fix test and lint

* address comments

* consolidate kill_actor

* Remove __ray_checkpoint__

* fix non-ascii char

* Loosen test checks

* fix java

* fix sphinx-build

python/ray/includes/ray_config.pxd

@@ -1,4 +1,4 @@
-from libc.stdint cimport int64_t, uint64_t
+from libc.stdint cimport int64_t, uint64_t, uint32_t
 from libcpp.string cimport string as c_string
 from libcpp.unordered_map cimport unordered_map
 
@@ -80,4 +80,6 @@ cdef extern from "ray/ray_config.h" nogil:
 
         int64_t max_task_lease_timeout_ms() const
 
+        uint32_t num_actor_checkpoints_to_keep() const
+
         void initialize(const unordered_map[c_string, int] &config_map)