Add timeout mechaism for cache.

Author: ralgond

mybatis/cache.py

@@ -1,5 +1,6 @@
 import json
 import pickle
+import time
 from typing import Dict, Any, Optional
 
 from pympler import asizeof
@@ -9,18 +10,11 @@ def __init__(self, sql, param_list):
         self.sql = sql
         self.param_list = param_list
 
-    def __hash__(self):
-        return hash((self.sql, self.param_list))
-
-    def __eq__(self, other):
-        if not isinstance(other, CacheKey):
-            return False
-        return self.sql == other.sql and self.param_list == other.param_list
-
 class Cache(object):
-    def __init__(self, memory_limit:int):
+    def __init__(self, memory_limit:int, max_live_ms:int):
         self.memory_limit = memory_limit
         self.memory_used = 0
+        self.max_live_ms = max_live_ms
         self.table : Dict[str, CacheNode] = {}
         self.list = CacheList()
 
@@ -69,7 +63,15 @@ def get(self, raw_key: CacheKey) -> Optional[Any]:
         key = json.dumps(raw_key.__dict__)
         if key not in self.table:
             return None
+
         node = self.table[key]
+        current_time_ms = int(time.time() * 1000)
+        if current_time_ms - node.timestamp > self.max_live_ms:
+            del self.table[node.key]
+            self.list.remove(node)
+            self.memory_used -= node.memory_usage
+            return None
+
         self.list.move_to_head(node)
         return json.loads(node.value)
 
@@ -89,6 +91,7 @@ def __init__(self, key : Any, value : Any):
         self.memory_usage = asizeof.asizeof(key) + asizeof.asizeof(value)
         self.key = key
         self.value = value
+        self.timestamp = int(time.time() * 1000)
 
 class CacheList:
     def __init__(self):

mybatis/mybatis.py

@@ -6,14 +6,14 @@
 import os
 
 class Mybatis(object):
-    def __init__(self, conn, mapper_path:str, cache_memory_limit:Optional[int]=None):
+    def __init__(self, conn, mapper_path:str, cache_memory_limit:Optional[int]=None, cache_max_live_ms:int=5*1000):
         self.conn = conn
         self.mapper_manager = MapperManager()
 
         if cache_memory_limit is not None:
-            self.cache = Cache(cache_memory_limit)
+            self.cache = Cache(cache_memory_limit, cache_max_live_ms)
         else:
-            self.cache = Cache(0)
+            self.cache = Cache(0, cache_max_live_ms)
 
         mapper_file_name_l = [name for name in os.listdir(mapper_path) if name.endswith(".xml")]
         for file_name in mapper_file_name_l:

setup.py

@@ -2,7 +2,7 @@
 
 setup(
     name='mybatis',
-    version='0.0.6',
+    version='0.0.7',
     description='A python ORM like mybatis.',
     long_description=open('README.md').read(),
     long_description_content_type='text/markdown',  # 如果你使用的是Markdown格式的README

test/test_cache.py

@@ -1,8 +1,10 @@
+import time
+
 import pytest
 from mybatis import Cache, CacheKey
 
 def test_basic():
-    cache = Cache(memory_limit=555)  # 50MB
+    cache = Cache(memory_limit=555, max_live_ms=10*1000)  # 50MB, 10sec
     cache.put(CacheKey("a", [1, 'a', None]), [{"a1": 1}, {"a2": 2}])
     cache.put(CacheKey("b", [2, 'b', None]), "2")
     cache.put(CacheKey("c", [3, 'c', None]), "3")
@@ -42,3 +44,18 @@ def test_basic():
 
     assert l[2][0] == '{"sql": "d", "param_list": [4, "d", null]}'
     assert l[2][1] == None
+
+def test_timeout():
+    cache = Cache(memory_limit=555, max_live_ms=1 * 1000)  # 50MB, 10sec
+    cache.put(CacheKey("a", [1, 'a', None]), [{"a1": 1}, {"a2": 2}])
+    cache.put(CacheKey("b", [2, 'b', None]), "2")
+    cache.put(CacheKey("c", [3, 'c', None]), "3")
+    cache.put(CacheKey("d", [4, 'd', None]), None)
+
+    time.sleep(2)
+    assert cache.get(CacheKey("a", [1, 'a', None])) == None
+    assert cache.get(CacheKey("b", [2, 'b', None])) == None
+    assert cache.get(CacheKey("c", [3, 'c', None])) == None
+    assert cache.get(CacheKey("d", [4, 'd', None])) == None
+
+    assert cache.memory_used == 0