try_delete() added

redis_cache/backends/base.py

@@ -284,8 +284,8 @@ class BaseRedisCache(BaseCache):
     @get_client(write=True)
     def delete(self, client, key):
         """Remove a key from the cache."""
-        client.delete("__fresh__" + key)
-        return client.delete(key)
+        all_keys = ["__fresh__" + key, key]
+        return client.delete(*all_keys)
 
     def _delete_many(self, client, keys):
         all_keys = keys.copy()
@@ -505,3 +505,19 @@ class BaseRedisCache(BaseCache):
         Returns True if successful and False if not.
         """
         return client.persist(key)
+
+    @get_client(write=True)
+    def try_delete(self, client, key):
+        """Remove a key from the cache if not locked."""
+        lock = cache.lock(key, timeout=5)
+        acquired = lock.acquire(blocking=False)
+        if acquired:
+            try:
+                all_keys = ["__fresh__" + key, key]
+                client.delete(*all_keys)
+            except Exception:
+                raise
+            finally:
+                lock.release()
+
+        return acquired