Revert state compaction (#1259) (#1275)

## Summary

Reverts the state compaction feature (#1259) to investigate issues with
nodes staying as "unknown" after joining a cluster.

## Test plan

- [ ] Verify nodes properly show up after joining cluster
- [ ] Verify state catchup works correctly without compaction

🤖 Generated with [Claude Code](https://claude.com/claude-code)

src/exo/main.py

@@ -53,7 +53,6 @@ class Node:
         await router.register_topic(topics.COMMANDS)
         await router.register_topic(topics.ELECTION_MESSAGES)
         await router.register_topic(topics.CONNECTION_MESSAGES)
-        await router.register_topic(topics.STATE_CATCHUP)
         await router.register_topic(topics.DOWNLOAD_COMMANDS)
 
         logger.info(f"Starting node {node_id}")
@@ -83,7 +82,6 @@ class Node:
                 command_sender=router.sender(topics.COMMANDS),
                 download_command_sender=router.sender(topics.DOWNLOAD_COMMANDS),
                 election_receiver=router.receiver(topics.ELECTION_MESSAGES),
-                state_catchup_receiver=router.receiver(topics.STATE_CATCHUP),
             )
         else:
             api = None
@@ -96,7 +94,6 @@ class Node:
                 global_event_receiver=router.receiver(topics.GLOBAL_EVENTS),
                 local_event_sender=router.sender(topics.LOCAL_EVENTS),
                 command_sender=router.sender(topics.COMMANDS),
-                state_catchup_receiver=router.receiver(topics.STATE_CATCHUP),
                 download_command_sender=router.sender(topics.DOWNLOAD_COMMANDS),
                 event_index_counter=event_index_counter,
             )
@@ -110,7 +107,6 @@ class Node:
             global_event_sender=router.sender(topics.GLOBAL_EVENTS),
             local_event_receiver=router.receiver(topics.LOCAL_EVENTS),
             command_receiver=router.receiver(topics.COMMANDS),
-            state_catchup_sender=router.sender(topics.STATE_CATCHUP),
         )
 
         er_send, er_recv = channel[ElectionResult]()
@@ -193,7 +189,6 @@ class Node:
                         global_event_sender=self.router.sender(topics.GLOBAL_EVENTS),
                         local_event_receiver=self.router.receiver(topics.LOCAL_EVENTS),
                         command_receiver=self.router.receiver(topics.COMMANDS),
-                        state_catchup_sender=self.router.sender(topics.STATE_CATCHUP),
                     )
                     self._tg.start_soon(self.master.run)
                 elif (
@@ -240,9 +235,6 @@ class Node:
                             ),
                             local_event_sender=self.router.sender(topics.LOCAL_EVENTS),
                             command_sender=self.router.sender(topics.COMMANDS),
-                            state_catchup_receiver=self.router.receiver(
-                                topics.STATE_CATCHUP
-                            ),
                             download_command_sender=self.router.sender(
                                 topics.DOWNLOAD_COMMANDS
                             ),

src/exo/master/api.py

@@ -166,7 +166,6 @@ class API:
         download_command_sender: Sender[ForwarderDownloadCommand],
         # This lets us pause the API if an election is running
         election_receiver: Receiver[ElectionMessage],
-        state_catchup_receiver: Receiver[State],
     ) -> None:
         self.state = State()
         self._event_log: list[Event] = []
@@ -174,7 +173,6 @@ class API:
         self.download_command_sender = download_command_sender
         self.global_event_receiver = global_event_receiver
         self.election_receiver = election_receiver
-        self.state_catchup_receiver = state_catchup_receiver
         self.event_buffer: OrderedBuffer[Event] = OrderedBuffer[Event]()
         self.node_id: NodeId = node_id
         self.session_id: SessionId = session_id
@@ -1251,7 +1249,6 @@ class API:
             tg.start_soon(self._apply_state)
             tg.start_soon(self._pause_on_new_election)
             tg.start_soon(self._cleanup_expired_images)
-            tg.start_soon(self._state_catchup)
             print_startup_banner(self.port)
             await serve(
                 cast(ASGIFramework, self.app),
@@ -1262,22 +1259,6 @@ class API:
         self.command_sender.close()
         self.global_event_receiver.close()
 
-    async def _state_catchup(self):
-        with self.state_catchup_receiver as states:
-            async for state in states:
-                if (
-                    self.state.last_event_applied_idx == -1
-                    and state.last_event_applied_idx > self.state.last_event_applied_idx
-                ):
-                    logger.info(
-                        f"API catching up state to idx {state.last_event_applied_idx}"
-                    )
-                    self.event_buffer.store = {}
-                    self.event_buffer.next_idx_to_release = (
-                        state.last_event_applied_idx + 1
-                    )
-                    self.state = state
-
     async def _apply_state(self):
         with self.global_event_receiver as events:
             async for f_event in events:

src/exo/master/main.py

@@ -68,8 +68,6 @@ class Master:
         # Send events to the forwarder to be indexed (usually from command processing)
         # Ideally these would be MasterForwarderEvents but type system says no :(
         global_event_sender: Sender[ForwarderEvent],
-        # not a fan but - send the entire state to a node so it can catchup without the whole event log.
-        state_catchup_sender: Sender[State],
     ):
         self.state = State()
         self._tg: TaskGroup = anyio.create_task_group()
@@ -79,7 +77,6 @@ class Master:
         self.command_receiver = command_receiver
         self.local_event_receiver = local_event_receiver
         self.global_event_sender = global_event_sender
-        self.state_catchup_sender = state_catchup_sender
         send, recv = channel[Event]()
         self.event_sender: Sender[Event] = send
         self._loopback_event_receiver: Receiver[Event] = recv
@@ -87,6 +84,7 @@ class Master:
             local_event_receiver.clone_sender()
         )
         self._multi_buffer = MultiSourceBuffer[NodeId, Event]()
+        # TODO: not have this
         self._event_log: list[Event] = []
 
     async def run(self):
@@ -293,17 +291,11 @@ class Master:
                                     command.finished_command_id
                                 ]
                         case RequestEventLog():
-                            if command.since_idx == 0:
-                                # This is an optimization, and should not be relied upon in theory.
-                                logger.info(
-                                    f"Master sending catchup state for index {self.state.last_event_applied_idx}"
+                            # We should just be able to send everything, since other buffers will ignore old messages
+                            for i in range(command.since_idx, len(self._event_log)):
+                                await self._send_event(
+                                    IndexedEvent(idx=i, event=self._event_log[i])
                                 )
-                                await self.state_catchup_sender.send(self.state)
-                            else:
-                                for i in range(command.since_idx, len(self._event_log)):
-                                    await self._send_event(
-                                        IndexedEvent(idx=i, event=self._event_log[i])
-                                    )
                     for event in generated_events:
                         await self.event_sender.send(event)
                 except ValueError as e:

src/exo/master/tests/test_master.py

@@ -27,7 +27,6 @@ from exo.shared.types.memory import Memory
 from exo.shared.types.profiling import (
     MemoryUsage,
 )
-from exo.shared.types.state import State
 from exo.shared.types.tasks import ChatCompletion as ChatCompletionTask
 from exo.shared.types.tasks import TaskStatus
 from exo.shared.types.worker.instances import (
@@ -48,7 +47,6 @@ async def test_master():
     ge_sender, global_event_receiver = channel[ForwarderEvent]()
     command_sender, co_receiver = channel[ForwarderCommand]()
     local_event_sender, le_receiver = channel[ForwarderEvent]()
-    st_s, _st_r = channel[State]()
 
     all_events: list[IndexedEvent] = []
 
@@ -69,7 +67,6 @@ async def test_master():
         global_event_sender=ge_sender,
         local_event_receiver=le_receiver,
         command_receiver=co_receiver,
-        state_catchup_sender=st_s,
     )
     logger.info("run the master")
     async with anyio.create_task_group() as tg:

src/exo/routing/topics.py

@@ -7,7 +7,6 @@ from exo.shared.types.commands import ForwarderCommand, ForwarderDownloadCommand
 from exo.shared.types.events import (
     ForwarderEvent,
 )
-from exo.shared.types.state import State
 from exo.utils.pydantic_ext import CamelCaseModel
 
 
@@ -46,7 +45,6 @@ ELECTION_MESSAGES = TypedTopic(
 CONNECTION_MESSAGES = TypedTopic(
     "connection_messages", PublishPolicy.Never, ConnectionMessage
 )
-STATE_CATCHUP = TypedTopic("state_catchup", PublishPolicy.Always, State)
 DOWNLOAD_COMMANDS = TypedTopic(
     "download_commands", PublishPolicy.Always, ForwarderDownloadCommand
 )

src/exo/worker/main.py

@@ -60,8 +60,9 @@ class Worker:
         connection_message_receiver: Receiver[ConnectionMessage],
         global_event_receiver: Receiver[ForwarderEvent],
         local_event_sender: Sender[ForwarderEvent],
+        # This is for requesting updates. It doesn't need to be a general command sender right now,
+        # but I think it's the correct way to be thinking about commands
         command_sender: Sender[ForwarderCommand],
-        state_catchup_receiver: Receiver[State],
         download_command_sender: Sender[ForwarderDownloadCommand],
         event_index_counter: Iterator[int],
     ):
@@ -70,8 +71,6 @@ class Worker:
 
         self.global_event_receiver = global_event_receiver
         self.local_event_sender = local_event_sender
-        self.state_catchup_receiver = state_catchup_receiver
-        self.local_event_index = 0
         self.event_index_counter = event_index_counter
         self.command_sender = command_sender
         self.download_command_sender = download_command_sender
@@ -111,7 +110,6 @@ class Worker:
             tg.start_soon(self._event_applier)
             tg.start_soon(self._forward_events)
             tg.start_soon(self._poll_connection_updates)
-            tg.start_soon(self._check_catchup_state)
 
         # Actual shutdown code - waits for all tasks to complete before executing.
         self.local_event_sender.close()
@@ -131,22 +129,6 @@ class Worker:
                     )
                 )
 
-    async def _check_catchup_state(self):
-        with self.state_catchup_receiver as states:
-            async for state in states:
-                if (
-                    self.state.last_event_applied_idx == -1
-                    and state.last_event_applied_idx > self.state.last_event_applied_idx
-                ):
-                    logger.info(
-                        f"Worker catching up state to idx {state.last_event_applied_idx}"
-                    )
-                    self.event_buffer.store = {}
-                    self.event_buffer.next_idx_to_release = (
-                        state.last_event_applied_idx + 1
-                    )
-                    self.state = state
-
     async def _event_applier(self):
         with self.global_event_receiver as events:
             async for f_event in events:
@@ -336,7 +318,10 @@ class Worker:
         # We request all events after (and including) the missing index.
         # This function is started whenever we receive an event that is out of sequence.
         # It is cancelled as soon as we receiver an event that is in sequence.
-        assert since_idx >= 0
+
+        if since_idx < 0:
+            logger.warning(f"Negative value encountered for nack request {since_idx=}")
+            since_idx = 0
 
         with CancelScope() as scope:
             self._nack_cancel_scope = scope