Add LRU support to Cache and message cache size option (#61)

disagreement/cache.py

@@ -2,6 +2,7 @@ from __future__ import annotations
 
 import time
 from typing import TYPE_CHECKING, Dict, Generic, Optional, TypeVar
+from collections import OrderedDict
 
 if TYPE_CHECKING:
     from .models import Channel, Guild, Member
@@ -11,15 +12,22 @@ T = TypeVar("T")
 
 
 class Cache(Generic[T]):
-    """Simple in-memory cache with optional TTL support."""
+    """Simple in-memory cache with optional TTL and max size support."""
 
-    def __init__(self, ttl: Optional[float] = None) -> None:
+    def __init__(
+        self, ttl: Optional[float] = None, maxlen: Optional[int] = None
+    ) -> None:
         self.ttl = ttl
-        self._data: Dict[str, tuple[T, Optional[float]]] = {}
+        self.maxlen = maxlen
+        self._data: "OrderedDict[str, tuple[T, Optional[float]]]" = OrderedDict()
 
     def set(self, key: str, value: T) -> None:
         expiry = time.monotonic() + self.ttl if self.ttl is not None else None
+        if key in self._data:
+            self._data.move_to_end(key)
         self._data[key] = (value, expiry)
+        if self.maxlen is not None and len(self._data) > self.maxlen:
+            self._data.popitem(last=False)
 
     def get(self, key: str) -> Optional[T]:
         item = self._data.get(key)
@@ -29,6 +37,7 @@ class Cache(Generic[T]):
         if expiry is not None and expiry < time.monotonic():
             self.invalidate(key)
             return None
+        self._data.move_to_end(key)
         return value
 
     def invalidate(self, key: str) -> None:

disagreement/client.py

@@ -82,6 +82,8 @@ class Client:
         http_options (Optional[Dict[str, Any]]): Extra options passed to
             :class:`HTTPClient` for creating the internal
             :class:`aiohttp.ClientSession`.
+        message_cache_maxlen (Optional[int]): Maximum number of messages to keep
+            in the cache. When ``None``, the cache size is unlimited.
     """
 
     def __init__(
@@ -99,6 +101,7 @@ class Client:
         gateway_max_retries: int = 5,
         gateway_max_backoff: float = 60.0,
         member_cache_flags: Optional[MemberCacheFlags] = None,
+        message_cache_maxlen: Optional[int] = None,
         http_options: Optional[Dict[str, Any]] = None,
     ):
         if not token:
@@ -108,6 +111,7 @@ class Client:
         self.member_cache_flags: MemberCacheFlags = (
             member_cache_flags if member_cache_flags is not None else MemberCacheFlags()
         )
+        self.message_cache_maxlen: Optional[int] = message_cache_maxlen
         self.intents: int = intents if intents is not None else GatewayIntent.default()
         if loop:
             self.loop: asyncio.AbstractEventLoop = loop
@@ -157,7 +161,7 @@ class Client:
         self._guilds: GuildCache = GuildCache()
         self._channels: ChannelCache = ChannelCache()
         self._users: Cache["User"] = Cache()
-        self._messages: Cache["Message"] = Cache(ttl=3600)  # Cache messages for an hour
+        self._messages: Cache["Message"] = Cache(ttl=3600, maxlen=message_cache_maxlen)
         self._views: Dict[Snowflake, "View"] = {}
         self._persistent_views: Dict[str, "View"] = {}
         self._voice_clients: Dict[Snowflake, VoiceClient] = {}
@@ -1514,35 +1518,35 @@ class Client:
         return [self.parse_invite(inv) for inv in data]
 
     def add_persistent_view(self, view: "View") -> None:
-       """
-       Registers a persistent view with the client.
+        """
+        Registers a persistent view with the client.
 
-       Persistent views have a timeout of `None` and their components must have a `custom_id`.
-       This allows the view to be re-instantiated across bot restarts.
+        Persistent views have a timeout of `None` and their components must have a `custom_id`.
+        This allows the view to be re-instantiated across bot restarts.
 
-       Args:
-           view (View): The view instance to register.
+        Args:
+            view (View): The view instance to register.
 
-       Raises:
-           ValueError: If the view is not persistent (timeout is not None) or if a component's
-                       custom_id is already registered.
-       """
-       if self.is_ready():
-           print(
-               "Warning: Adding a persistent view after the client is ready. "
-               "This view will only be available for interactions on this session."
-           )
+        Raises:
+            ValueError: If the view is not persistent (timeout is not None) or if a component's
+                        custom_id is already registered.
+        """
+        if self.is_ready():
+            print(
+                "Warning: Adding a persistent view after the client is ready. "
+                "This view will only be available for interactions on this session."
+            )
 
-       if view.timeout is not None:
-           raise ValueError("Persistent views must have a timeout of None.")
+        if view.timeout is not None:
+            raise ValueError("Persistent views must have a timeout of None.")
 
-       for item in view.children:
-           if item.custom_id:  # Ensure custom_id is not None
-               if item.custom_id in self._persistent_views:
-                   raise ValueError(
-                       f"A component with custom_id '{item.custom_id}' is already registered."
-                   )
-               self._persistent_views[item.custom_id] = view
+        for item in view.children:
+            if item.custom_id:  # Ensure custom_id is not None
+                if item.custom_id in self._persistent_views:
+                    raise ValueError(
+                        f"A component with custom_id '{item.custom_id}' is already registered."
+                    )
+                self._persistent_views[item.custom_id] = view
 
     # --- Application Command Methods ---
     async def process_interaction(self, interaction: Interaction) -> None:

tests/test_cache.py

@@ -15,3 +15,14 @@ def test_cache_ttl_expiry():
     assert cache.get("b") == 1
     time.sleep(0.02)
     assert cache.get("b") is None
+
+
+def test_cache_lru_eviction():
+    cache = Cache(maxlen=2)
+    cache.set("a", 1)
+    cache.set("b", 2)
+    assert cache.get("a") == 1
+    cache.set("c", 3)
+    assert cache.get("b") is None
+    assert cache.get("a") == 1
+    assert cache.get("c") == 3

tests/test_client_message_cache.py

@@ -0,0 +1,23 @@
+import pytest
+
+from disagreement.client import Client
+
+
+def _add_message(client: Client, message_id: str) -> None:
+    data = {
+        "id": message_id,
+        "channel_id": "c",
+        "author": {"id": "u", "username": "u", "discriminator": "0001"},
+        "content": "hi",
+        "timestamp": "t",
+    }
+    client.parse_message(data)
+
+
+def test_client_message_cache_size():
+    client = Client(token="t", message_cache_maxlen=1)
+    _add_message(client, "1")
+    assert client._messages.get("1").id == "1"
+    _add_message(client, "2")
+    assert client._messages.get("1") is None
+    assert client._messages.get("2").id == "2"