[Refactor] Remove Hicache Load & Write threads (#10127)

Co-authored-by: Zhiqiang Xie <xiezhq@stanford.edu>

python/sglang/srt/mem_cache/memory_pool.py

@@ -13,6 +13,8 @@ See the License for the specific language governing permissions and
 limitations under the License.
 """
 
+from __future__ import annotations
+
 from sglang.srt.torch_memory_saver_adapter import TorchMemorySaverAdapter
 
 """
@@ -27,7 +29,7 @@ KVCache actually holds the physical kv cache.
 import abc
 import logging
 from contextlib import nullcontext
-from typing import Dict, List, Optional, Tuple, Union
+from typing import TYPE_CHECKING, Dict, List, Optional, Tuple, Union
 
 import numpy as np
 import torch
@@ -38,6 +40,9 @@ from sglang.srt.constants import GPU_MEMORY_TYPE_KV_CACHE
 from sglang.srt.layers.radix_attention import RadixAttention
 from sglang.srt.utils import get_bool_env_var, is_cuda, is_npu, next_power_of_2
 
+if TYPE_CHECKING:
+    from sglang.srt.managers.cache_controller import LayerDoneCounter
+
 logger = logging.getLogger(__name__)
 
 GB = 1024 * 1024 * 1024
@@ -175,7 +180,7 @@ class KVCache(abc.ABC):
     ) -> None:
         raise NotImplementedError()
 
-    def register_layer_transfer_counter(self, layer_transfer_counter):
+    def register_layer_transfer_counter(self, layer_transfer_counter: LayerDoneCounter):
         self.layer_transfer_counter = layer_transfer_counter
 
     def get_cpu_copy(self, indices):