Extract game launching sequence

Author: Askaholic

server/ladder_service.py

@@ -31,12 +31,20 @@
 )
 from .decorators import with_logger
 from .game_service import GameService
-from .games import InitMode, LadderGame
+from .games import Game, InitMode, LadderGame
 from .matchmaker import MapPool, MatchmakerQueue, OnMatchedCallback, Search
 from .players import Player, PlayerState
+from .protocol import DisconnectedError
 from .types import GameLaunchOptions, Map, NeroxisGeneratedMap
 
 
+class GameLaunchError(Exception):
+    """When a game failed to launch because some players did not connect"""
+
+    def __init__(self, players: List[Player]):
+        self.players = players
+
+
 @with_logger
 class LadderService(Service):
     """
@@ -427,41 +435,7 @@ def get_player_mean(player):
                 game.set_player_option(player.id, "Army", slot)
                 game.set_player_option(player.id, "Color", slot)
 
-            self._logger.debug("Starting ladder game: %s", game)
-            # Options shared by all players
-            options = GameLaunchOptions(
-                mapname=game.map_name,
-                expected_players=len(all_players),
-            )
-
-            def game_options(player: Player) -> GameLaunchOptions:
-                return options._replace(
-                    team=game.get_player_option(player.id, "Team"),
-                    faction=player.faction,
-                    map_position=game.get_player_option(player.id, "StartSpot")
-                )
-
-            await host.lobby_connection.launch_game(
-                game, is_host=True, options=game_options(host)
-            )
-            try:
-                await game.wait_hosted(60)
-            finally:
-                # TODO: Once the client supports `match_cancelled`, don't
-                # send `launch_game` to the client if the host timed out. Until
-                # then, failing to send `launch_game` will cause the client to
-                # think it is searching for ladder, even though the server has
-                # already removed it from the queue.
-
-                await asyncio.gather(*[
-                    guest.lobby_connection.launch_game(
-                        game, is_host=False, options=game_options(guest)
-                    )
-                    for guest in all_guests
-                    if guest.lobby_connection is not None
-                ])
-            await game.wait_launched(60 + 10 * len(all_guests))
-            self._logger.debug("Ladder game launched successfully")
+            await self.launch_game(game, host, all_guests)
         except Exception:
             if game:
                 await game.on_game_end()
@@ -473,6 +447,74 @@ def game_options(player: Player) -> GameLaunchOptions:
                     player.state = PlayerState.IDLE
                 player.write_message(msg)
 
+    async def launch_game(
+        self,
+        game: Game,
+        host: Player,
+        guests: List[Player]
+    ) -> None:
+        self._logger.debug("Starting ladder game: %s", game)
+        all_players = (host, *guests)
+
+        # Options shared by all players
+        options = GameLaunchOptions(
+            mapname=game.map_name,
+            expected_players=len(all_players),
+        )
+
+        def game_options(player: Player) -> GameLaunchOptions:
+            return options._replace(
+                team=game.get_player_option(player.id, "Team"),
+                faction=player.faction,
+                map_position=game.get_player_option(player.id, "StartSpot")
+            )
+
+        # Check if anyone DC'd from the server entirely
+        disconnected_players = [
+            player for player in all_players
+            if player.lobby_connection is None
+        ]
+        if disconnected_players:
+            raise GameLaunchError(disconnected_players)
+
+        try:
+            await host.lobby_connection.launch_game(
+                game,
+                is_host=True,
+                options=game_options(host)
+            )
+            await game.wait_hosted(60)
+        except (asyncio.TimeoutError, DisconnectedError) as e:
+            raise GameLaunchError([host]) from e
+        finally:
+            # TODO: Once the client supports `match_cancelled`, don't
+            # send `launch_game` to the client if the host timed out. Until
+            # then, failing to send `launch_game` will cause the client to
+            # think it is searching for ladder, even though the server has
+            # already removed it from the queue.
+
+            await asyncio.gather(*[
+                guest.lobby_connection.launch_game(
+                    game,
+                    is_host=False,
+                    options=game_options(guest)
+                )
+                for guest in guests
+                if guest.lobby_connection is not None
+            ], return_exceptions=True)
+
+        try:
+            await game.wait_launched(60 + 10 * len(guests))
+        except asyncio.TimeoutError as e:
+            connected_players = game.players
+            disconnected_players = [
+                player for player in all_players
+                if player not in connected_players
+            ]
+            raise GameLaunchError(disconnected_players) from e
+
+        self._logger.debug("Ladder game launched successfully")
+
     async def get_game_history(
         self,
         players: List[Player],

tests/unit_tests/test_ladder_service.py

@@ -6,22 +6,35 @@
 from hypothesis import given, settings
 from hypothesis import strategies as st
 
-from server import LadderService, LobbyConnection
+from server import LobbyConnection
 from server.db.models import matchmaker_queue, matchmaker_queue_map_pool
-from server.games import LadderGame
-from server.ladder_service import game_name
+from server.games import GameState, LadderGame
+from server.ladder_service import GameLaunchError, LadderService, game_name
 from server.matchmaker import MapPool, MatchmakerQueue
 from server.players import PlayerState
+from server.protocol import DisconnectedError
 from server.rating import RatingType
 from server.types import Map, NeroxisGeneratedMap
 from tests.conftest import make_player
+from tests.unit_tests.conftest import add_connected_player
 from tests.utils import autocontext, fast_forward
 
 from .strategies import st_players
 
 pytestmark = pytest.mark.asyncio
 
 
+@pytest.fixture
+def game(database, game_service, game_stats_service):
+    return LadderGame(
+        42,
+        database,
+        game_service,
+        game_stats_service,
+        rating_type=RatingType.GLOBAL
+    )
+
+
 async def test_queue_initialization(database, game_service):
     ladder_service = LadderService(database, game_service)
 
@@ -176,6 +189,64 @@ async def test_start_game_timeout(
     # assert p2.state is PlayerState.IDLE
 
 
+async def test_launch_game_error_host(
+    ladder_service: LadderService,
+    game,
+    player_factory
+):
+    # Host disconnected before game launch
+    host = player_factory("Dostya", player_id=1, lobby_connection_spec=None)
+    guest = player_factory("Rhiza", player_id=2, lobby_connection_spec="auto")
+
+    with pytest.raises(GameLaunchError) as ex_info:
+        await ladder_service.launch_game(game, host, [guest])
+    assert ex_info.value.players == [host]
+
+    # Host disconnected during game launch
+    host = player_factory("Dostya", player_id=1, lobby_connection_spec="auto")
+    disconnected_error = DisconnectedError("Test")
+    host.lobby_connection.launch_game.side_effect = disconnected_error
+
+    with pytest.raises(GameLaunchError) as ex_info:
+        await ladder_service.launch_game(game, host, [guest])
+    assert ex_info.value.players == [host]
+    assert ex_info.value.__cause__ == disconnected_error
+
+
+async def test_launch_game_error_many_disconnected(
+    ladder_service: LadderService,
+    game,
+    player_factory
+):
+    # Multiple players disconnect before game launch
+    host = player_factory("Dostya", player_id=1, lobby_connection_spec=None)
+    p2 = player_factory("Rhiza", player_id=2, lobby_connection_spec="auto")
+    p3 = player_factory("QAI", player_id=3, lobby_connection_spec=None)
+    p4 = player_factory("Brackman", player_id=4, lobby_connection_spec="auto")
+
+    with pytest.raises(GameLaunchError) as ex_info:
+        await ladder_service.launch_game(game, host, [p2, p3, p4])
+    assert ex_info.value.players == [host, p3]
+
+    # Players 3 and 4 disconnect during game launch
+    host = player_factory("Dostya", player_id=1, lobby_connection_spec="auto")
+    p3 = player_factory("QAI", player_id=3, lobby_connection_spec="auto")
+    disconnected_error = DisconnectedError("Test")
+    timeout_error = asyncio.TimeoutError()
+    p3.lobby_connection.launch_game.side_effect = disconnected_error
+    p4.lobby_connection.launch_game.side_effect = disconnected_error
+    game.wait_hosted = CoroutineMock()
+    game.wait_launched = CoroutineMock(side_effect=timeout_error)
+    game.state = GameState.LOBBY
+    add_connected_player(game, host)
+    add_connected_player(game, p2)
+
+    with pytest.raises(GameLaunchError) as ex_info:
+        await ladder_service.launch_game(game, host, [p2, p3, p4])
+    assert ex_info.value.players == [p3, p4]
+    assert ex_info.value.__cause__ == timeout_error
+
+
 @given(
     player1=st_players("p1", player_id=1, lobby_connection_spec="mock"),
     player2=st_players("p2", player_id=2, lobby_connection_spec="mock"),