[HiCache] Clear kvcache in storage backend with fastAPI (#9750)

Co-authored-by: hzh0425 <hzh0425@apache.org>

python/sglang/srt/mem_cache/hicache_storage.py

@@ -102,6 +102,20 @@ class HiCacheStorage(ABC):
         """
         pass
 
+    @abstractmethod
+    def delete(self, key: str) -> bool:
+        """
+        Delete the entry associated with the given key.
+        """
+        pass
+
+    @abstractmethod
+    def clear(self) -> bool:
+        """
+        Clear all entries in the storage.
+        """
+        pass
+
     def batch_exists(self, keys: List[str]) -> int:
         """
         Check if the keys exist in the storage.
@@ -214,12 +228,14 @@ class HiCacheFile(HiCacheStorage):
             logger.warning(f"Key {key} does not exist. Cannot delete.")
             return
 
-    def clear(self) -> None:
+    def clear(self) -> bool:
         try:
             for filename in os.listdir(self.file_path):
                 file_path = os.path.join(self.file_path, filename)
                 if os.path.isfile(file_path):
                     os.remove(file_path)
             logger.info("Cleared all entries in HiCacheFile storage.")
+            return True
         except Exception as e:
             logger.error(f"Failed to clear HiCacheFile storage: {e}")
+            return False

python/sglang/srt/mem_cache/hiradix_cache.py

@@ -125,6 +125,15 @@ class HiRadixCache(RadixCache):
             height += 1
         return height
 
+    def clear_storage_backend(self):
+        if self.enable_storage:
+            self.cache_controller.storage_backend.clear()
+            logger.info("Hierarchical cache storage backend cleared successfully!")
+            return True
+        else:
+            logger.warning("Hierarchical cache storage backend is not enabled.")
+            return False
+
     def write_backup(self, node: TreeNode, write_back=False):
         host_indices = self.cache_controller.write(
             device_indices=node.value,

python/sglang/srt/mem_cache/storage/hf3fs/storage_hf3fs.py

@@ -393,8 +393,14 @@ class HiCacheHF3FS(HiCacheStorage):
 
         return len(keys)
 
-    def clear(self) -> None:
-        self.metadata_client.clear(self.rank)
+    def clear(self) -> bool:
+        try:
+            self.metadata_client.clear(self.rank)
+            logger.info(f"Cleared HiCacheHF3FS for rank {self.rank}")
+            return True
+        except Exception as e:
+            logger.error(f"Failed to clear HiCacheHF3FS: {e}")
+            return False
 
     def close(self) -> None:
         try:

python/sglang/srt/mem_cache/storage/mooncake_store/mooncake_store.py

@@ -254,7 +254,7 @@ class MooncakeStore(HiCacheStorage):
         pass
 
     def clear(self) -> None:
-        raise (NotImplementedError)
+        self.store.remove_all()
 
     def _put_batch_zero_copy_impl(
         self, key_strs: List[str], buffer_ptrs: List[int], buffer_sizes: List[int]