[Audio] Connect to lavalink in the background (#2335)

Also:
- restart and reconnect if connection settings change
  - shutdown and restart if not configured to use external
- show a message in [p]play et al. when the connection hasn't been made
- move the JAR download to manager so audio.py can access it
- only start if no process exists

Resolves #2306

redbot/cogs/audio/__init__.py

@@ -1,10 +1,8 @@
 from pathlib import Path
-from aiohttp import ClientSession
-import shutil
 import logging
 
 from .audio import Audio
-from .manager import start_lavalink_server
+from .manager import start_lavalink_server, maybe_download_lavalink
 from redbot.core import commands
 from redbot.core.data_manager import cog_data_path
 import redbot.core
@@ -22,30 +20,6 @@ APP_YML_FILE = LAVALINK_DOWNLOAD_DIR / "application.yml"
 BUNDLED_APP_YML_FILE = Path(__file__).parent / "data/application.yml"
 
 
-async def download_lavalink(session):
-    with LAVALINK_JAR_FILE.open(mode="wb") as f:
-        async with session.get(LAVALINK_DOWNLOAD_URL) as resp:
-            while True:
-                chunk = await resp.content.read(512)
-                if not chunk:
-                    break
-                f.write(chunk)
-
-
-async def maybe_download_lavalink(loop, cog):
-    jar_exists = LAVALINK_JAR_FILE.exists()
-    current_build = redbot.VersionInfo.from_json(await cog.config.current_version())
-
-    if not jar_exists or current_build < redbot.core.version_info:
-        log.info("Downloading Lavalink.jar")
-        LAVALINK_DOWNLOAD_DIR.mkdir(parents=True, exist_ok=True)
-        async with ClientSession(loop=loop) as session:
-            await download_lavalink(session)
-        await cog.config.current_version.set(redbot.core.version_info.to_json())
-
-    shutil.copyfile(str(BUNDLED_APP_YML_FILE), str(APP_YML_FILE))
-
-
 async def setup(bot: commands.Bot):
     cog = Audio(bot)
     if not await cog.config.use_external_lavalink():

redbot/cogs/audio/audio.py

@@ -25,7 +25,7 @@ from redbot.core.utils.menus import (
 )
 from redbot.core.utils.predicates import MessagePredicate, ReactionPredicate
 from urllib.parse import urlparse
-from .manager import shutdown_lavalink_server
+from .manager import shutdown_lavalink_server, start_lavalink_server, maybe_download_lavalink
 
 _ = Translator("Audio", __file__)
 
@@ -74,10 +74,29 @@ class Audio(commands.Cog):
         self.config.register_global(**default_global)
         self.skip_votes = {}
         self.session = aiohttp.ClientSession()
+        self._connect_task = None
         self._disconnect_task = None
         self._cleaned_up = False
 
     async def initialize(self):
+        self._restart_connect()
+        self._disconnect_task = self.bot.loop.create_task(self.disconnect_timer())
+        lavalink.register_event_listener(self.event_handler)
+
+    def _restart_connect(self):
+        if self._connect_task:
+            self._connect_task.cancel()
+
+        self._connect_task = self.bot.loop.create_task(self.attempt_connect())
+
+    async def attempt_connect(self, timeout: int = 30):
+        while True:  # run until success
+            external = await self.config.use_external_lavalink()
+            if not external:
+                shutdown_lavalink_server()
+                await maybe_download_lavalink(self.bot.loop, self)
+                await start_lavalink_server(self.bot.loop)
+            try:
                 host = await self.config.host()
                 password = await self.config.password()
                 rest_port = await self.config.rest_port()
@@ -89,11 +108,13 @@ class Audio(commands.Cog):
                     password=password,
                     rest_port=rest_port,
                     ws_port=ws_port,
-            timeout=60,
+                    timeout=timeout,
                 )
-        lavalink.register_event_listener(self.event_handler)
+                return  # break infinite loop
-
+            except Exception:
-        self._disconnect_task = self.bot.loop.create_task(self.disconnect_timer())
+                if not external:
+                    shutdown_lavalink_server()
+                await asyncio.sleep(1)  # prevent busylooping
 
     async def event_handler(self, player, event_type, extra):
         notify = await self.config.guild(player.channel.guild).notify()
@@ -903,6 +924,10 @@ class Audio(commands.Cog):
                 player.store("connect", datetime.datetime.utcnow())
             except AttributeError:
                 return await self._embed_msg(ctx, _("Connect to a voice channel first."))
+            except IndexError:
+                return await self._embed_msg(
+                    ctx, _("Connection to Lavalink has not yet been established.")
+                )
         if dj_enabled:
             if not await self._can_instaskip(ctx, ctx.author):
                 return await self._embed_msg(ctx, _("You need the DJ role to queue tracks."))
@@ -1416,6 +1441,10 @@ class Audio(commands.Cog):
             except AttributeError:
                 await self._embed_msg(ctx, _("Connect to a voice channel first."))
                 return False
+            except IndexError:
+                return await self._embed_msg(
+                    ctx, _("Connection to Lavalink has not yet been established.")
+                )
         player = lavalink.get_player(ctx.guild.id)
         player.store("channel", ctx.channel.id)
         player.store("guild", ctx.guild.id)
@@ -1793,6 +1822,10 @@ class Audio(commands.Cog):
                 player.store("connect", datetime.datetime.utcnow())
             except AttributeError:
                 return await self._embed_msg(ctx, _("Connect to a voice channel first."))
+            except IndexError:
+                return await self._embed_msg(
+                    ctx, _("Connection to Lavalink has not yet been established.")
+                )
         player = lavalink.get_player(ctx.guild.id)
         shuffle = await self.config.guild(ctx.guild).shuffle()
         player.store("channel", ctx.channel.id)
@@ -1877,6 +1910,10 @@ class Audio(commands.Cog):
                 player.store("connect", datetime.datetime.utcnow())
             except AttributeError:
                 return await self._embed_msg(ctx, _("Connect to a voice channel first."))
+            except IndexError:
+                return await self._embed_msg(
+                    ctx, _("Connection to Lavalink has not yet been established.")
+                )
         player = lavalink.get_player(ctx.guild.id)
         jukebox_price = await self.config.guild(ctx.guild).jukebox_price()
         shuffle = await self.config.guild(ctx.guild).shuffle()
@@ -1897,7 +1934,6 @@ class Audio(commands.Cog):
         except IndexError:
             search_choice = tracks[-1]
         try:
-            search_check = search_choice.uri
             if "localtracks" in search_choice.uri:
                 if search_choice.title == "Unknown title":
                     description = "**{} - {}**\n{}".format(
@@ -2333,6 +2369,7 @@ class Audio(commands.Cog):
         """Toggle using external lavalink servers."""
         external = await self.config.use_external_lavalink()
         await self.config.use_external_lavalink.set(not external)
+
         if external:
             await self.config.host.set("localhost")
             await self.config.password.set("youshallnotpass")
@@ -2345,13 +2382,15 @@ class Audio(commands.Cog):
                 ),
             )
             embed.set_footer(text=_("Defaults reset."))
-            return await ctx.send(embed=embed)
+            await ctx.send(embed=embed)
         else:
             await self._embed_msg(
                 ctx,
                 _("External lavalink server: {true_or_false}.").format(true_or_false=not external),
             )
 
+        self._restart_connect()
+
     @llsetup.command()
     async def host(self, ctx, host):
         """Set the lavalink server host."""
@@ -2365,6 +2404,8 @@ class Audio(commands.Cog):
         else:
             await self._embed_msg(ctx, _("Host set to {host}.").format(host=host))
 
+        self._restart_connect()
+
     @llsetup.command()
     async def password(self, ctx, password):
         """Set the lavalink server password."""
@@ -2381,6 +2422,8 @@ class Audio(commands.Cog):
                 ctx, _("Server password set to {password}.").format(password=password)
             )
 
+        self._restart_connect()
+
     @llsetup.command()
     async def restport(self, ctx, rest_port: int):
         """Set the lavalink REST server port."""
@@ -2395,6 +2438,8 @@ class Audio(commands.Cog):
         else:
             await self._embed_msg(ctx, _("REST port set to {port}.").format(port=rest_port))
 
+        self._restart_connect()
+
     @llsetup.command()
     async def wsport(self, ctx, ws_port: int):
         """Set the lavalink websocket server port."""
@@ -2409,6 +2454,8 @@ class Audio(commands.Cog):
         else:
             await self._embed_msg(ctx, _("Websocket port set to {port}.").format(port=ws_port))
 
+        self._restart_connect()
+
     async def _check_external(self):
         external = await self.config.use_external_lavalink()
         if not external:
@@ -2555,7 +2602,7 @@ class Audio(commands.Cog):
         try:
             query_url = urlparse(url)
             return all([query_url.scheme, query_url.netloc, query_url.path])
-        except:
+        except Exception:
             return False
 
     @staticmethod
@@ -2659,8 +2706,13 @@ class Audio(commands.Cog):
     def __unload(self):
         if not self._cleaned_up:
             self.session.detach()
+
             if self._disconnect_task:
                 self._disconnect_task.cancel()
+
+            if self._connect_task:
+                self._connect_task.cancel()
+
             lavalink.unregister_event_listener(self.event_handler)
             self.bot.loop.create_task(lavalink.close())
             shutdown_lavalink_server()

redbot/cogs/audio/manager.py

@@ -8,6 +8,10 @@ import re
 from subprocess import Popen, DEVNULL
 from typing import Optional, Tuple
 
+from aiohttp import ClientSession
+
+import redbot.core
+
 _JavaVersion = Tuple[int, int]
 
 log = logging.getLogger("red.audio.manager")
@@ -111,6 +115,10 @@ async def start_lavalink_server(loop):
     start_cmd = "java {} -jar {}".format(extra_flags, LAVALINK_JAR_FILE.resolve())
 
     global proc
+
+    if proc and proc.poll() is None:
+        return  # already running
+
     proc = Popen(
         shlex.split(start_cmd, posix=os.name == "posix"),
         cwd=str(LAVALINK_DOWNLOAD_DIR),
@@ -126,11 +134,39 @@ async def start_lavalink_server(loop):
 
 
 def shutdown_lavalink_server():
-    log.info("Shutting down lavalink server.")
     global shutdown
     shutdown = True
     global proc
     if proc is not None:
+        log.info("Shutting down lavalink server.")
         proc.terminate()
         proc.wait()
         proc = None
+
+
+async def download_lavalink(session):
+    from . import LAVALINK_DOWNLOAD_URL, LAVALINK_JAR_FILE
+
+    with LAVALINK_JAR_FILE.open(mode="wb") as f:
+        async with session.get(LAVALINK_DOWNLOAD_URL) as resp:
+            while True:
+                chunk = await resp.content.read(512)
+                if not chunk:
+                    break
+                f.write(chunk)
+
+
+async def maybe_download_lavalink(loop, cog):
+    from . import LAVALINK_DOWNLOAD_DIR, LAVALINK_JAR_FILE, BUNDLED_APP_YML_FILE, APP_YML_FILE
+
+    jar_exists = LAVALINK_JAR_FILE.exists()
+    current_build = redbot.VersionInfo.from_json(await cog.config.current_version())
+
+    if not jar_exists or current_build < redbot.core.version_info:
+        log.info("Downloading Lavalink.jar")
+        LAVALINK_DOWNLOAD_DIR.mkdir(parents=True, exist_ok=True)
+        async with ClientSession(loop=loop) as session:
+            await download_lavalink(session)
+        await cog.config.current_version.set(redbot.core.version_info.to_json())
+
+    shutil.copyfile(str(BUNDLED_APP_YML_FILE), str(APP_YML_FILE))