[Audio] Improve Lavalink download/connection exception handling (#2764)

- More errors will be logged to the console with clearer messages when something goes wrong
- Downloading the Lavalink Jar will abort after 5 failed attempts. The connect task will also abort if an unhandled exception occurs whilst downloading or connecting to Lavalink. After this occurs, instead of responding "Connection to Lavalink has not yet been established" to commands, the bot will respond "Connection to Lavalink has failed". This has no effect on other commands which don't involve connecting to Lavalink (e.g. settings commands).
- Logs this message when Lavalink jar is successfully downloaded: `Successfully downloaded Lavalink.jar (<x> bytes written)`
- Uses [`tqdm`](https://github.com/tqdm/tqdm/) to display a progress bar whilst downloading Lavalink.jar.

Signed-off-by: Toby Harradine <tobyharradine@gmail.com>

redbot/cogs/audio/manager.py

@@ -6,12 +6,15 @@ import asyncio
 import asyncio.subprocess  # disables for # https://github.com/PyCQA/pylint/issues/1469
 import logging
 import re
+import sys
 import tempfile
 from typing import Optional, Tuple, ClassVar, List
 
 import aiohttp
+from tqdm import tqdm
 
 from redbot.core import data_manager
+from .errors import LavalinkDownloadFailed
 
 JAR_VERSION = "3.2.0.3"
 JAR_BUILD = 796
@@ -200,22 +203,45 @@ class ServerManager:
         async with aiohttp.ClientSession() as session:
             async with session.get(LAVALINK_DOWNLOAD_URL) as response:
                 if response.status == 404:
-                    raise RuntimeError(
-                        f"Lavalink jar version {JAR_VERSION}_{JAR_BUILD} hasn't been published"
+                    # A 404 means our LAVALINK_DOWNLOAD_URL is invalid, so likely the jar version
+                    # hasn't been published yet
+                    raise LavalinkDownloadFailed(
+                        f"Lavalink jar version {JAR_VERSION}_{JAR_BUILD} hasn't been published "
+                        f"yet",
+                        response=response,
+                        should_retry=False,
                     )
+                elif 400 <= response.status < 600:
+                    # Other bad responses should be raised but we should retry just incase
+                    raise LavalinkDownloadFailed(response=response, should_retry=True)
                 fd, path = tempfile.mkstemp()
                 file = open(fd, "wb")
-                try:
-                    chunk = await response.content.read(1024)
-                    while chunk:
-                        file.write(chunk)
+                nbytes = 0
+                with tqdm(
+                    desc="Lavalink.jar",
+                    total=response.content_length,
+                    file=sys.stdout,
+                    unit="B",
+                    unit_scale=True,
+                    miniters=1,
+                    dynamic_ncols=True,
+                    leave=False,
+                ) as progress_bar:
+                    try:
                         chunk = await response.content.read(1024)
-                    file.flush()
-                finally:
-                    file.close()
+                        while chunk:
+                            chunk_size = file.write(chunk)
+                            nbytes += chunk_size
+                            progress_bar.update(chunk_size)
+                            chunk = await response.content.read(1024)
+                        file.flush()
+                    finally:
+                        file.close()
 
                 shutil.move(path, str(LAVALINK_JAR_FILE), copy_function=shutil.copyfile)
 
+        log.info("Successfully downloaded Lavalink.jar (%s bytes written)", format(nbytes, ","))
+
     @classmethod
     async def _is_up_to_date(cls):
         if cls._up_to_date is True: