feat(hicache): Support passing prefix keys for l3 store. (#9045)

Co-authored-by: pansicheng <sicheng.pan.chn@gmail.com>
Co-authored-by: Zhiqiang Xie <xiezhq@stanford.edu>

python/sglang/srt/managers/scheduler.py

@@ -1491,8 +1491,18 @@ class Scheduler(
                 last_hash = req.last_host_node.get_last_hash_value()
                 matched_len = len(req.prefix_indices) + req.host_hit_length
                 new_input_tokens = req.fill_ids[matched_len:]
+
+                prefix_keys = (
+                    req.last_node.get_prefix_hash_values(req.last_node.parent)
+                    if self.tree_cache.hicache_storage_pass_prefix_keys
+                    else None
+                )
                 self.tree_cache.prefetch_from_storage(
-                    req.rid, req.last_host_node, new_input_tokens, last_hash
+                    req.rid,
+                    req.last_host_node,
+                    new_input_tokens,
+                    last_hash,
+                    prefix_keys,
                 )
 
     def _add_request_to_queue(self, req: Req, is_retracted: bool = False):