added cache expiration

python_requests/cache.py

@@ -1,12 +1,33 @@
+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, timedelta
 
 from . import CACHE_DIRECTORY
 
 
+# SQLite database file path
+DB_FILE = Path(CACHE_DIRECTORY, "cache_metadata.db")
+
+# Initialize the database
+def _init_db():
+    with sqlite3.connect(DB_FILE) as conn:
+        conn.execute("""
+        CREATE TABLE IF NOT EXISTS url_cache (
+            url_hash TEXT PRIMARY KEY,
+            expires_at TIMESTAMP
+        )
+        """)
+        conn.commit()
+
+# Initialize the database when module is imported
+_init_db()
+
+
 def get_url_hash(url: str) -> str:
     return sha1(encode(url.strip(), "utf-8")).hexdigest()
 
@@ -16,7 +37,37 @@ def get_url_file(url: str) -> Path:
 
 
 def has_cache(url: str) -> bool:
-    return get_url_file(url).exists()
+    url_hash = get_url_hash(url)
+    cache_file = get_url_file(url)
+    
+    if not cache_file.exists():
+        return False
+    
+    # Check if the cache has expired
+    with sqlite3.connect(DB_FILE) as conn:
+        cursor = conn.cursor()
+        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:
@@ -24,6 +75,27 @@ 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)
+    
+    # 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:
         pickle.dump(resp, url_file)
+    
+    # Update the database
+    with sqlite3.connect(DB_FILE) as conn:
+        conn.execute(
+            "INSERT OR REPLACE INTO url_cache (url_hash, expires_at) VALUES (?, ?)",
+            (url_hash, expires_at.isoformat())
+        )
+        conn.commit()