From bf7d169936f82d51e882cd781d74729214e910cb Mon Sep 17 00:00:00 2001
From: Niklas Fiekas <niklas.fiekas@backscattering.de>
Date: Fri, 20 Dec 2024 20:19:56 +0100
Subject: [PATCH] wip cancel engine commands

---
 chess/engine.py | 27 ++++++++++++---------------
 test.py         | 21 +++++++++++++++++++++
 2 files changed, 33 insertions(+), 15 deletions(-)

diff --git a/chess/engine.py b/chess/engine.py
index b979b278..e2ba1fcc 100644
--- a/chess/engine.py
+++ b/chess/engine.py
@@ -946,9 +946,7 @@ async def communicate(self, command_factory: Callable[[Self], BaseCommand[T]]) -
         assert command.state == CommandState.NEW, command.state
 
         if self.next_command is not None:
-            self.next_command.result.cancel()
-            self.next_command.finished.cancel()
-            self.next_command.set_finished()
+            self.next_command._cancel()
 
         self.next_command = command
 
@@ -957,20 +955,14 @@ def previous_command_finished() -> None:
             if self.command is not None:
                 cmd = self.command
 
-                def cancel_if_cancelled(result: asyncio.Future[T]) -> None:
-                    if result.cancelled():
-                        cmd._cancel()
-
-                cmd.result.add_done_callback(cancel_if_cancelled)
-                cmd._start()
+                if cmd.state == CommandState.NEW:
+                    cmd._start()
                 cmd.add_finished_callback(previous_command_finished)
 
-        if self.command is None:
-            previous_command_finished()
-        elif not self.command.result.done():
-            self.command.result.cancel()
-        elif not self.command.result.cancelled():
+        if self.command is not None:
             self.command._cancel()
+        else:
+            previous_command_finished()
 
         return await command.result
 
@@ -1233,7 +1225,12 @@ def set_finished(self) -> None:
         self._dispatch_finished()
 
     def _cancel(self) -> None:
-        if self.state != CommandState.CANCELLING and self.state != CommandState.DONE:
+        if self.state == CommandState.NEW:
+            self.state = CommandState.DONE
+            self.result.cancel()
+            self.finished.cancel()
+            self._dispatch_finished()
+        elif self.state != CommandState.CANCELLING and self.state != CommandState.DONE:
             assert self.state == CommandState.ACTIVE, self.state
             self.state = CommandState.CANCELLING
             self.cancel()
diff --git a/test.py b/test.py
index 6db84d25..024f80d7 100755
--- a/test.py
+++ b/test.py
@@ -3142,6 +3142,27 @@ def test_sf_quit(self):
         with self.assertRaises(chess.engine.EngineTerminatedError), engine:
             engine.ping()
 
+    @catchAndSkip(FileNotFoundError, "need stockfish")
+    def test_sf_cancel(self):
+        class TerminateTaskGroup(Exception):
+            pass
+
+        async def terminate_task_group():
+            await asyncio.sleep(0.001)
+            raise TerminateTaskGroup()
+
+        async def main():
+            try:
+                async with asyncio.TaskGroup() as group:
+                    _, engine = await chess.engine.popen_uci("stockfish")
+                    group.create_task(engine.analyse(chess.Board(), chess.engine.Limit()))
+                    group.create_task(engine.analyse(chess.Board(), chess.engine.Limit()))
+                    group.create_task(terminate_task_group())
+            except* TerminateTaskGroup:
+                pass
+
+        asyncio.run(main())
+
     @catchAndSkip(FileNotFoundError, "need fairy-stockfish")
     def test_fairy_sf_initialize(self):
         with chess.engine.SimpleEngine.popen_uci("fairy-stockfish", setpgrp=True, debug=True):