WIP

Author: mosquito

aiomisc/cache/base.py

@@ -1,73 +1,29 @@
-import asyncio
-import threading
 from abc import ABC, abstractmethod
-from typing import Any, Union, Hashable, Dict, Optional
-
-from llist import dllist, dllistnode
+from typing import Any, Hashable
 
 
 class CacheBase(ABC):
-    def __init__(self, max_size: int = 0):
-        self._max_size: int = max_size
-        self._loop: Optional[asyncio.AbstractEventLoop] = None
-        self.usages: dllist = dllist()
-        self.cache: Dict[Hashable, Any] = dict()
-        self.lock = threading.RLock()
-
-    @property
-    def is_overflow(self) -> bool:
-        if self._max_size == 0:
-            return False
-
-        if self._max_size < len(self.usages):
-            return True
+    __slots__ = "max_size",
 
-        return False
-
-    @property
-    def loop(self) -> asyncio.AbstractEventLoop:
-        if self._loop is None:
-            self._loop = asyncio.get_event_loop()
-        return self._loop
+    def __init__(self, max_size: int = 0):
+        self.max_size = max_size
 
     @abstractmethod
-    def _on_set(self, node: dllistnode) -> None:
-        pass
-
-    def _on_expires(self, node: dllistnode) -> None:
-        pass
+    def get(self, key: Hashable):
+        raise NotImplementedError
 
     @abstractmethod
-    def _on_get(self, node: dllistnode) -> Any:
-        pass
-
-    def __contains__(self, item: Hashable) -> bool:
-        return item in self.cache
+    def remove(self, key: Hashable):
+        raise NotImplementedError
 
-    def get(self, item: Hashable) -> Any:
-        with self.lock:
-            node: dllistnode = self.cache[item]
-        self.loop.call_soon(self._on_get, node)
-        return node.value[1]
-
-    def expire(self, node: dllistnode):
-        with self.lock:
-            item, value = node.value
-            node: Optional[dllistnode] = self.cache.pop(item, None)
-
-        if node is None:
-            return
-
-        self.loop.call_soon(self._on_expires, node)
-        self.usages.remove(node)
-
-    def set(self, item: Hashable, value: Any,
-            expiration: Union[int, float] = None) -> None:
-        with self.lock:
-            node: dllistnode = self.usages.append((item, value))
-            self.cache[item] = node
+    @abstractmethod
+    def set(self, key: Hashable, value: Any):
+        raise NotImplementedError
 
-        self.loop.call_soon(self._on_set, node)
+    @abstractmethod
+    def __contains__(self, key: Hashable):
+        raise NotImplementedError
 
-        if expiration is not None:
-            self.loop.call_later(expiration, self.expire, node)
+    @abstractmethod
+    def __len__(self):
+        raise NotImplementedError

aiomisc/cache/lfu.py

@@ -1,10 +1,11 @@
-from dataclasses import dataclass
 from threading import RLock
-from typing import Any, Hashable, Optional, Set
+from typing import Any, Hashable, Optional, Dict, Set
+from aiomisc.cache.base import CacheBase
 
 
+# noinspection PyShadowingBuiltins
 class Node:
-    __slots__ = ('prev', 'next', 'items')
+    __slots__ = 'prev', 'next', 'items'
 
     def __init__(self, prev: "Node" = None, next: "Node" = None,
                  items: Optional[Set["Item"]] = None):
@@ -13,14 +14,16 @@ def __init__(self, prev: "Node" = None, next: "Node" = None,
         self.items = items or set()
 
 
-@dataclass(frozen=True)
 class Item:
-    node: Node
-    key: Hashable
-    value: Any
+    __slots__ = 'node', 'key', 'value'
 
+    def __init__(self, node: Node, key: Hashable, value: Any):
+        self.node: Node = node
+        self.key: Hashable = key
+        self.value: Any = value
 
-class LFUCache:
+
+class LFUCache(CacheBase):
     """
     LFU cache implementation
 
@@ -29,20 +32,37 @@ class LFUCache:
     >>> assert "foo" in lfu
     >>> lfu.get('foo')
     'bar'
+
+    >>> lfu.remove('foo')
+    >>> assert "foo" not in lfu
+    >>> lfu.get("foo")
+    Traceback (most recent call last):
+    ...
+    KeyError: 'foo'
+    >>> lfu.remove("foo")
+
     >>> lfu.set("bar", "foo")
     >>> lfu.set("spam", "egg")
-
+    >>> lfu.set("foo", "bar")
+    >>> lfu.get("foo")
+    'bar'
+    >>> lfu.get("spam")
+    'egg'
+    >>> assert len(lfu) == 3
+    >>> lfu.set("egg", "spam")
+    >>> assert len(lfu) == 3
     """
 
-    def __init__(self, max_size: int = 0):
-        self.cache = dict()
-        self.usages: Node = Node(prev=None, next=None, items=set())
-        self.lock = RLock()
-        self.size = 0
-        self.max_size = max_size
+    __slots__ = "cache", "usages", "lock"
+
+    def __init__(self, max_size: int):
+        super().__init__(max_size)
+        self.cache: Dict[Hashable, Item] = dict()
+        self.usages: Node = Node(prev=None, next=None)
+        self.lock: RLock = RLock()
 
     def _create_node(self) -> Node:
-        node = Node(prev=self.usages, next=None, items=set())
+        node = Node(prev=self.usages, next=None)
         self.usages.next = node
         return node
 
@@ -55,11 +75,7 @@ def _update_usage(self, item: Item):
                 new_node = self._create_node()
 
             old_node.items.remove(item)
-            item = Item(
-                node=new_node,
-                key=item.key,
-                value=item.value,
-            )
+            item.node = new_node
             new_node.items.add(item)
             self.cache[item.key] = item
 
@@ -69,11 +85,29 @@ def _update_usage(self, item: Item):
                 self.usages = new_node
                 self.usages.prev = None
 
+    def _remove_item(self, item: Item):
+        with self.lock:
+            if item.key in self.cache:
+                self.cache.pop(item.key, None)
+
+            if item in item.node.items:
+                item.node.items.remove(item)
+
+            item.node = None
+
     def get(self, key: Hashable):
         item: Item = self.cache[key]
         self._update_usage(item)
         return item.value
 
+    def remove(self, key: Hashable):
+        with self.lock:
+            item: Optional[Item] = self.cache.pop(key, None)
+            if item is None:
+                return
+
+            self._remove_item(item)
+
     def set(self, key: Hashable, value: Any):
         with self.lock:
             node: Optional[Node] = self.usages
@@ -85,8 +119,30 @@ def set(self, key: Hashable, value: Any):
             node.items.add(item)
             self.cache[key] = item
 
-    def __contains__(self, key) -> Any:
+        if self._is_overflow():
+            self._on_overflow()
+
+    def _on_overflow(self):
+        with self.lock:
+            while self._is_overflow():
+                if not self.usages.items:
+                    if self.usages.next is not None:
+                        self.usages.next.prev = None
+                        self.usages = self.usages.next
+                    else:
+                        self.usages = Node(prev=None, next=None)
+
+                item = self.usages.items.pop()
+                self._remove_item(item)
+
+    def _is_overflow(self) -> bool:
+        return len(self.cache) > self.max_size
+
+    def __contains__(self, key: Hashable) -> Any:
         if key in self.cache:
             self._update_usage(self.cache[key])
             return True
         return False
+
+    def __len__(self):
+        return len(self.cache)