[Feat] Support chunked prefill for LMCache connector (#14505)

Signed-off-by: YaoJiayi <120040070@link.cuhk.edu.cn>

vllm/distributed/kv_transfer/kv_connector/lmcache_connector.py

@@ -38,7 +38,8 @@ class LMCacheConnector(KVConnectorBase):
         from lmcache.integration.vllm.utils import ENGINE_NAME
         from lmcache.integration.vllm.vllm_adapter import (
             RetrieveStatus, StoreStatus, init_lmcache_engine,
-            lmcache_retrieve_kv, lmcache_should_store, lmcache_store_kv)
+            lmcache_retrieve_kv, lmcache_should_retrieve, lmcache_should_store,
+            lmcache_store_kv)
         logger.info("Initializing LMCacheConfig under kv_transfer_config %s",
                     self.transfer_config)
 
@@ -54,6 +55,7 @@ class LMCacheConnector(KVConnectorBase):
         self.cache_config = config.cache_config
         self.lmcache_retrieve_kv = lmcache_retrieve_kv
         self.lmcache_store_kv = lmcache_store_kv
+        self.lmcache_should_retrieve = lmcache_should_retrieve
         self.lmcache_should_store = lmcache_should_store
         self.store_status = StoreStatus
         self.retrieve_status = RetrieveStatus
@@ -65,15 +67,11 @@ class LMCacheConnector(KVConnectorBase):
     ) -> Tuple[Union[torch.Tensor, IntermediateTensors], bool,
                "ModelInputForGPUWithSamplingMetadata"]:
 
-        hidden_or_intermediate_states = None
-
-        # TODO (Jiayi): Need to support chunked prefill
-        retrieve_status = self.retrieve_status.PREFILL
-
-        model_input, bypass_model_exec = self.lmcache_retrieve_kv(
-            model_executable, model_input, self.cache_config, kv_caches,
-            retrieve_status)
-
+        retrieve_status = self.lmcache_should_retrieve(model_input)
+        model_input, bypass_model_exec, hidden_or_intermediate_states =\
+            self.lmcache_retrieve_kv(
+                model_executable, model_input, self.cache_config, kv_caches,
+                retrieve_status)
         return hidden_or_intermediate_states, bypass_model_exec, model_input
 
     def send_kv_caches_and_hidden_states(
@@ -84,15 +82,7 @@ class LMCacheConnector(KVConnectorBase):
         hidden_or_intermediate_states: Union[torch.Tensor,
                                              IntermediateTensors],
     ) -> None:
-        num_reqs = 0
-        seq_group_list = model_input.sampling_metadata.seq_groups
-        assert seq_group_list is not None
-        for seq_group in seq_group_list:
-            seq_ids = seq_group.seq_ids
-            for seq_id in seq_ids:
-                num_reqs += 1
-
-        # TODO (Jiayi): Only normal prefill is supported for now
+
         store_status = self.lmcache_should_store(model_input)
         self.lmcache_store_kv(
             self.model_config,