Cache prefixes (#3150)

* Cache prefixes

 - This works towards #3148
 - Ends up centralizing some logic
   - Including that prefixes should be a reverse sorted list

* handle global prefix attempts at none

* fix prefix set for server

* cache using guild id

changelog.d/3148.misc.1.rst

@@ -0,0 +1 @@
+Cache prefixes rather than lookup from config each time

redbot/core/bot.py

@@ -36,6 +36,8 @@ from .dev_commands import Dev
 from .events import init_events
 from .global_checks import init_global_checks
 
+from .settings_caches import PrefixManager
+
 from .rpc import RPCMixin
 from .utils import common_filters
 
@@ -124,23 +126,13 @@ class RedBase(commands.GroupMixin, commands.bot.BotBase, RPCMixin):  # pylint: d
 
         self._config.init_custom(SHARED_API_TOKENS, 2)
         self._config.register_custom(SHARED_API_TOKENS)
+        self._prefix_cache = PrefixManager(self._config, cli_flags)
 
-        async def prefix_manager(bot, message):
+        async def prefix_manager(bot, message) -> List[str]:
-            if not cli_flags.prefix:
+            prefixes = await self._prefix_cache.get_prefixes(message.guild)
-                global_prefix = await bot._config.prefix()
-            else:
-                global_prefix = cli_flags.prefix
-            if message.guild is None:
-                return global_prefix
-            server_prefix = await bot._config.guild(message.guild).prefix()
             if cli_flags.mentionable:
-                return (
+                return when_mentioned_or(*prefixes)(bot, message)
-                    when_mentioned_or(*server_prefix)(bot, message)
+            return prefixes
-                    if server_prefix
-                    else when_mentioned_or(*global_prefix)(bot, message)
-                )
-            else:
-                return server_prefix if server_prefix else global_prefix
 
         if "command_prefix" not in kwargs:
             kwargs["command_prefix"] = prefix_manager
@@ -273,15 +265,15 @@ class RedBase(commands.GroupMixin, commands.bot.BotBase, RPCMixin):  # pylint: d
         """
         This checks if a user or member is allowed to run things,
         as considered by Red's whitelist and blacklist.
-        
+
         If given a user object, this function will check the global lists
-        
+
         If given a member, this will additionally check guild lists
-        
+
         If omiting a user or member, you must provide a value for ``who_id``
-        
+
         You may also provide a value for ``guild_id`` in this case
-        
+
         If providing a member by guild and member ids,
         you should supply ``role_ids`` as well
 
@@ -289,7 +281,7 @@ class RedBase(commands.GroupMixin, commands.bot.BotBase, RPCMixin):  # pylint: d
         ----------
         who : Optional[Union[discord.Member, discord.User]]
             The user or member object to check
-        
+
         Other Parameters
         ----------------
         who_id : Optional[int]
@@ -906,7 +898,7 @@ class RedBase(commands.GroupMixin, commands.bot.BotBase, RPCMixin):  # pylint: d
         This should realistically only be used for responding using user provided
         input. (unfortunately, including usernames)
         Manually crafted messages which dont take any user input have no need of this
-        
+
         Returns
         -------
         discord.Message

redbot/core/cli.py

@@ -135,7 +135,9 @@ def parse_cli_flags(args):
         "security implications if misused. Can be "
         "multiple.",
     )
-    parser.add_argument("--prefix", "-p", action="append", help="Global prefix. Can be multiple")
+    parser.add_argument(
+        "--prefix", "-p", action="append", help="Global prefix. Can be multiple", default=[]
+    )
     parser.add_argument(
         "--no-prompt",
         action="store_true",

redbot/core/core_commands.py

@@ -257,10 +257,9 @@ class CoreLogic:
             The current (or new) list of prefixes.
         """
         if prefixes:
-            prefixes = sorted(prefixes, reverse=True)
+            await self.bot._prefix_cache.set_prefixes(guild=None, prefixes=prefixes)
-            await self.bot._config.prefix.set(prefixes)
             return prefixes
-        return await self.bot._config.prefix()
+        return await self.bot._prefix_cache.get_prefixes(guild=None)
 
     @classmethod
     async def _version_info(cls) -> Dict[str, str]:
@@ -847,15 +846,13 @@ class Core(commands.Cog, CoreLogic):
                 mod_role_ids = await ctx.bot._config.guild(ctx.guild).mod_role()
                 mod_role_names = [r.name for r in guild.roles if r.id in mod_role_ids]
                 mod_roles_str = humanize_list(mod_role_names) if mod_role_names else "Not Set."
-                prefixes = await ctx.bot._config.guild(ctx.guild).prefix()
                 guild_settings = _("Admin roles: {admin}\nMod roles: {mod}\n").format(
                     admin=admin_roles_str, mod=mod_roles_str
                 )
             else:
                 guild_settings = ""
-                prefixes = None  # This is correct. The below can happen in a guild.
+
-            if not prefixes:
+            prefixes = await ctx.bot._prefix_cache.get_prefixes(ctx.guild)
-                prefixes = await ctx.bot._config.prefix()
             locale = await ctx.bot._config.locale()
 
             prefix_string = " ".join(prefixes)
@@ -1182,11 +1179,11 @@ class Core(commands.Cog, CoreLogic):
     async def serverprefix(self, ctx: commands.Context, *prefixes: str):
         """Sets Red's server prefix(es)"""
         if not prefixes:
-            await ctx.bot._config.guild(ctx.guild).prefix.set([])
+            await ctx.bot._prefix_cache.set_prefixes(guild=ctx.guild, prefixes=[])
             await ctx.send(_("Guild prefixes have been reset."))
             return
         prefixes = sorted(prefixes, reverse=True)
-        await ctx.bot._config.guild(ctx.guild).prefix.set(prefixes)
+        await ctx.bot._prefix_cache.set_prefixes(guild=ctx.guild, prefixes=prefixes)
         await ctx.send(_("Prefix set."))
 
     @_set.command()

redbot/core/settings_caches.py

@@ -0,0 +1,53 @@
+from __future__ import annotations
+
+from typing import Dict, List, Optional
+from argparse import Namespace
+
+import discord
+
+from .config import Config
+
+
+class PrefixManager:
+    def __init__(self, config: Config, cli_flags: Namespace):
+        self._config: Config = config
+        self._global_prefix_overide: Optional[List[str]] = sorted(
+            cli_flags.prefix, reverse=True
+        ) or None
+        self._cached: Dict[Optional[int], List[str]] = {}
+
+    async def get_prefixes(self, guild: Optional[discord.Guild] = None) -> List[str]:
+        ret: List[str]
+
+        gid: Optional[int] = guild.id if guild else None
+
+        if gid in self._cached:
+            ret = self._cached[gid].copy()
+        else:
+            if gid is not None:
+                ret = await self._config.guild_from_id(gid).prefix()
+                if not ret:
+                    ret = await self.get_prefixes(None)
+            else:
+                ret = self._global_prefix_overide or (await self._config.prefix())
+
+            self._cached[gid] = ret.copy()
+
+        return ret
+
+    async def set_prefixes(
+        self, guild: Optional[discord.Guild] = None, prefixes: Optional[List[str]] = None
+    ):
+        gid: Optional[int] = guild.id if guild else None
+        prefixes = prefixes or []
+        if not isinstance(prefixes, list) and not all(isinstance(pfx, str) for pfx in prefixes):
+            raise TypeError("Prefixes must be a list of strings")
+        prefixes = sorted(prefixes, reverse=True)
+        if gid is None:
+            if not prefixes:
+                raise ValueError("You must have at least one prefix.")
+            self._cached.clear()
+            await self._config.prefix.set(prefixes)
+        else:
+            del self._cached[gid]
+            await self._config.guild_from_id(gid).prefix.set(prefixes)