[KVConnector][LMCache] Propagate cache_salt through MP connector for per-user...

[KVConnector][LMCache] Propagate cache_salt through MP connector for per-user cache isolation (#39837)
Signed-off-by: royyhuang <royyhuang@gmail.com>
Signed-off-by: royyhuang <roy.y.huang@gmail.com>

vllm/distributed/kv_transfer/kv_connector/v1/lmcache_mp_connector.py

@@ -215,8 +215,11 @@ class LMCacheMPRequestTracker:
     # Main state
     state: LMCacheMPRequestState = LMCacheMPRequestState.PREFETCHING
 
+    cache_salt: str = ""
+
     def __init__(self, request: "Request"):
         self.request_id = request.request_id
+        self.cache_salt: str = request.cache_salt or ""
         self.all_token_ids = request.all_token_ids
         self.block_hashes = ConstantList(request.block_hashes)
         self.allocated_block_ids = []
@@ -289,6 +292,7 @@ class LMCacheMPRequestMetadata:
     request_id: str
     direction: Literal["STORE", "RETRIEVE"]
     op: LoadStoreOp
+    cache_salt: str = ""
 
     @staticmethod
     def GetStoreMetadata(
@@ -355,6 +359,7 @@ class LMCacheMPRequestMetadata:
                 request_id=tracker.request_id,
                 direction="STORE",
                 op=op,
+                cache_salt=tracker.cache_salt,
             )
 
             # Update the request tracker
@@ -421,6 +426,7 @@ class LMCacheMPRequestMetadata:
                 request_id=tracker.request_id,
                 direction="RETRIEVE",
                 op=op,
+                cache_salt=tracker.cache_salt,
             )
             return ret
 
@@ -569,12 +575,14 @@ class LMCacheMPConnector(KVConnectorBase_V1):
 
         request_ids = []
         ops = []
+        cache_salts = []
 
         for meta in metadata.requests:
             if meta.direction != "RETRIEVE":
                 continue
             request_ids.append(meta.request_id)
             ops.append(meta.op)
+            cache_salts.append(meta.cache_salt)
 
         if len(request_ids) == 0:
             return
@@ -583,7 +591,9 @@ class LMCacheMPConnector(KVConnectorBase_V1):
             event = torch.cuda.Event(interprocess=True)
             event.record()
 
-        self.worker_adapter.batched_submit_retrieve_requests(request_ids, ops, event)
+        self.worker_adapter.batched_submit_retrieve_requests(
+            request_ids, ops, event, cache_salts=cache_salts
+        )
 
     def wait_for_layer_load(self, layer_name: str) -> None:
         """
@@ -640,11 +650,13 @@ class LMCacheMPConnector(KVConnectorBase_V1):
 
         request_ids = []
         ops = []
+        cache_salts = []
         for meta in metadata.requests:
             if meta.direction != "STORE":
                 continue
             request_ids.append(meta.request_id)
             ops.append(meta.op)
+            cache_salts.append(meta.cache_salt)
 
         if len(request_ids) == 0:
             return
@@ -653,7 +665,9 @@ class LMCacheMPConnector(KVConnectorBase_V1):
             event = torch.cuda.Event(interprocess=True)
             event.record()
 
-        self.worker_adapter.batched_submit_store_requests(request_ids, ops, event)
+        self.worker_adapter.batched_submit_store_requests(
+            request_ids, ops, event, cache_salts=cache_salts
+        )
 
     def get_finished(
         self, finished_req_ids: set[str]
@@ -755,6 +769,7 @@ class LMCacheMPConnector(KVConnectorBase_V1):
         self.scheduler_adapter.maybe_submit_lookup_request(
             request.request_id,
             token_ids=list(request.all_token_ids),
+            cache_salt=tracker.cache_salt,
         )
 
         ret = self.scheduler_adapter.check_lookup_result(request.request_id)