added cache expiration

python_requests/cache.py

@@ -1,10 +1,11 @@
+from typing import Optional
 from codecs import encode
 from hashlib import sha1
 from pathlib import Path
 import requests
 import pickle
 import sqlite3
-from datetime import datetime
+from datetime import datetime, timedelta
 
 from . import CACHE_DIRECTORY
 
@@ -18,7 +19,7 @@ def _init_db():
         conn.execute("""
         CREATE TABLE IF NOT EXISTS url_cache (
             url_hash TEXT PRIMARY KEY,
-            last_updated TIMESTAMP
+            expires_at TIMESTAMP
         )
         """)
         conn.commit()
@@ -36,16 +37,37 @@ def get_url_file(url: str) -> Path:
 
 
 def has_cache(url: str) -> bool:
-    cache_exists = get_url_file(url).exists()
-    if not cache_exists:
+    url_hash = get_url_hash(url)
+    cache_file = get_url_file(url)
+    
+    if not cache_file.exists():
         return False
     
-    # Check if the URL hash exists in the database
-    url_hash = get_url_hash(url)
+    # Check if the cache has expired
     with sqlite3.connect(DB_FILE) as conn:
         cursor = conn.cursor()
-        cursor.execute("SELECT 1 FROM url_cache WHERE url_hash = ?", (url_hash,))
-        return cursor.fetchone() is not None
+        cursor.execute(
+            "SELECT expires_at FROM url_cache WHERE url_hash = ?",
+            (url_hash,)
+        )
+        result = cursor.fetchone()
+        
+        if result is None:
+            return False  # No expiration record exists
+        
+        expires_at = datetime.fromisoformat(result[0])
+        if datetime.now() > expires_at:
+            # Cache expired, clean it up
+            cache_file.unlink(missing_ok=True)
+            cursor.execute(
+                "DELETE FROM url_cache WHERE url_hash = ?",
+                (url_hash,)
+            )
+            conn.commit()
+            return False
+    
+    return True
+
 
 
 def get_cache(url: str) -> requests.Response:
@@ -53,9 +75,18 @@ def get_cache(url: str) -> requests.Response:
         return pickle.load(cache_file)
 
 
-def write_cache(url: str, resp: requests.Response):
+def write_cache(
+    url: str,
+    resp: requests.Response,
+    expires_after: Optional[timedelta] = None
+):
     url_hash = get_url_hash(url)
-    current_time = datetime.now().isoformat()
+    
+    # Default expiration: 24 hours from now
+    if expires_after is None:
+        expires_after = timedelta(hours=1)
+    
+    expires_at = datetime.now() + expires_after
     
     # Write the cache file
     with get_url_file(url).open("wb") as url_file:
@@ -64,7 +95,7 @@ def write_cache(url: str, resp: requests.Response):
     # Update the database
     with sqlite3.connect(DB_FILE) as conn:
         conn.execute(
-            "INSERT OR REPLACE INTO url_cache (url_hash, last_updated) VALUES (?, ?)",
-            (url_hash, current_time)
+            "INSERT OR REPLACE INTO url_cache (url_hash, expires_at) VALUES (?, ?)",
+            (url_hash, expires_at.isoformat())
         )
         conn.commit()