[Feature] [KVCache] support file_store kv cache backend (#6188)

* fix(examples): comment out stop.sh to avoid error when script is missing

* feat: add file_store support for cache manager

* [fix] fix multi gpu transfer

* [fix] fix global kvcache transfer

* [Feature] [KVCache] support file_store kv cache backend

* chore: update FileStore according to PR comments

* fix: remove comments

* fix: add swap_cache_layout for file store

* fix: remove rank key

* fix: Switch KV cache storage to pure file mode

* Temporarily disable support for Tensor types

* fix: remove args --kvcache_file_path & add envs FILE_BACKEND_STORAGE_DIR

* fixx: Simplify cache_transfer_manager.py

* fix: fix syntax bug

* fix: Simplify file_store.py

* fix: Use the key directly as the filename

* fix: Simplify set()

* fix: Simplify cache_transfer_manager.py & file_store.py

* fix: Only support load to cpu buffer

* feat: add FileStore backend for cache transfer

* fix: guard zmq import

fastdeploy/cache_manager/cache_transfer_manager.py

@@ -43,7 +43,11 @@ from fastdeploy.cache_manager.ops import (
     swap_cache_layout,
     unset_data_ipc,
 )
-from fastdeploy.cache_manager.transfer_factory import AttentionStore, MooncakeStore
+from fastdeploy.cache_manager.transfer_factory import (
+    AttentionStore,
+    FileStore,
+    MooncakeStore,
+)
 from fastdeploy.config import SpeculativeConfig
 from fastdeploy.inter_communicator import EngineCacheQueue, IPCSignal, KVCacheStatus
 from fastdeploy.platforms import current_platform
@@ -112,7 +116,7 @@ def parse_args():
         "--kvcache_storage_backend",
         type=str,
         default=None,
-        choices=["mooncake", "attention_store"],
+        choices=["mooncake", "attention_store", "file"],
         help="The storage backend for kvcache storage. If not set, storage backend is disabled.",
     )
     parser.add_argument(
@@ -289,6 +293,15 @@ class CacheTransferManager:
                     dp_id=self.local_data_parallel_id,
                 )
                 logger.info("Initialized attention store successfully!")
+            elif args.kvcache_storage_backend == "file":
+                logger.info("Start initialize file store...")
+                self.storage_backend = FileStore(
+                    namespace=self.model_id,
+                    tp_rank=self.rank,
+                    tp_size=self.n_ranks,
+                )
+                self._init_storage_buffer(args)
+                logger.info("Initialized file store successfully")
             else:
                 raise NotImplementedError(f"Unsupported storage backend: {self.storage_backend_type}")
         except Exception as e:
@@ -518,7 +531,7 @@ class CacheTransferManager:
         Read storage data from the given blocks to the corresponding cache tensors on the current rank's GPU.
         """
         try:
-            if self.storage_backend_type == "mooncake":
+            if self.storage_backend_type in ("mooncake", "file"):
                 block_num = len(gpu_block_ids)
                 keys = k_cache_keys + v_cache_keys
                 k_cache_ptrs = [
@@ -600,7 +613,7 @@ class CacheTransferManager:
             k_cache_keys = [f"prefix{self.key_prefix}_{key}_{self.rank}_key" for key in task.keys]
             v_cache_keys = [f"prefix{self.key_prefix}_{key}_{self.rank}_value" for key in task.keys]
             match_block_num = 0
-            if self.storage_backend_type == "mooncake":
+            if self.storage_backend_type in ("mooncake", "file"):
                 match_block_num = self.storage_backend.query(k_cache_keys, v_cache_keys)
             elif self.storage_backend_type == "attention_store":
                 match_block_num = self.storage_backend.query(
@@ -666,7 +679,7 @@ class CacheTransferManager:
         timeout,
     ):
         try:
-            if self.storage_backend_type == "mooncake":
+            if self.storage_backend_type in ("mooncake", "file"):
                 key_cache_size = [
                     self.key_cache_shape[0],
                     self.key_cache_shape[1],
@@ -747,7 +760,7 @@ class CacheTransferManager:
             v_cache_keys = [f"prefix{self.key_prefix}_{key}_{self.rank}_value" for key in task.keys]
 
             match_block_num = 0
-            if self.storage_backend_type == "mooncake":
+            if self.storage_backend_type == ("mooncake", "file"):
                 match_block_num = self.storage_backend.query(k_cache_keys, v_cache_keys, task.timeout)
             elif self.storage_backend_type == "attention_store":
                 match_block_num = self.storage_backend.query(task.task_id, task.token_ids, 0, task.timeout)