Update write_cache, test

safety/safety.py

@@ -100,20 +100,26 @@ def write_to_cache(db_name, data):
             if exc.errno != errno.EEXIST:
                 raise
 
-    with open(DB_CACHE_FILE, "r") as f:
-        try:
-            cache = json.loads(f.read())
-        except json.JSONDecodeError:
-            LOG.debug('JSONDecodeError in the local cache, dumping the full cache file.')
+    cache_file_lock = f"{DB_CACHE_FILE}.lock"
+    lock = FileLock(cache_file_lock, timeout=10)
+    with lock:
+        if os.path.exists(DB_CACHE_FILE):
+            with open(DB_CACHE_FILE, "r") as f:
+                try:
+                    cache = json.loads(f.read())
+                except json.JSONDecodeError:
+                    LOG.debug('JSONDecodeError in the local cache, dumping the full cache file.')
+                    cache = {}
+        else:
             cache = {}
 
-    with open(DB_CACHE_FILE, "w") as f:
-        cache[db_name] = {
-            "cached_at": time.time(),
-            "db": data
-        }
-        f.write(json.dumps(cache))
-        LOG.debug('Safety updated the cache file for %s database.', db_name)
+        with open(DB_CACHE_FILE, "w") as f:
+            cache[db_name] = {
+                "cached_at": time.time(),
+                "db": data
+            }
+            f.write(json.dumps(cache))
+            LOG.debug('Safety updated the cache file for %s database.', db_name)
 
 
 def fetch_database_url(session, mirror, db_name, cached, telemetry=True,

tests/test_safety.py

@@ -171,6 +171,9 @@ def test_check_live(self):
     def test_check_live_cached(self):
         from safety.constants import DB_CACHE_FILE
 
+        # Ensure the cache directory and file exist
+        os.makedirs(os.path.dirname(DB_CACHE_FILE), exist_ok=True)
+
         # lets clear the cache first
         try:
             with open(DB_CACHE_FILE, 'w') as f: