Add improvements from code review comments

Review comments:
- vllm-project#28309 (comment)
- vllm-project#28309 (comment)

Signed-off-by: Martin Hickey <martin.hickey@ie.ibm.com>

Author: hickeyma

vllm/distributed/kv_events.py

@@ -71,11 +71,11 @@ def combine_unique_ordered_events(self, other: "KVEventBatch") -> "KVEventBatch"
         """
         Combine non duplicated events with another `KVEventBatch` object.
         """
-        combined_events = self.events[:]
+        checked_events = set(self.events)
         for item in other.events:
-            if item not in combined_events:
-                combined_events.append(item)
-        self.events = combined_events
+            if item not in checked_events:
+                self.events.append(item)
+                checked_events.add(item)
         return self
 
 

vllm/v1/worker/kv_connector_model_runner_mixin.py

@@ -12,14 +12,12 @@
 )
 
 from vllm.config import VllmConfig
-from vllm.distributed.kv_events import KVEventBatch
 from vllm.distributed.kv_transfer import (
     ensure_kv_transfer_shutdown,
     get_kv_transfer_group,
     has_kv_transfer_group,
 )
 from vllm.distributed.kv_transfer.kv_connector.base import KVConnectorBase
-from vllm.distributed.kv_transfer.kv_connector.v1.metrics import KVConnectorStats
 from vllm.forward_context import get_forward_context, set_forward_context
 from vllm.logger import init_logger
 from vllm.v1.outputs import (
@@ -132,23 +130,13 @@ def _get_kv_connector_output(
                 kv_connector.get_finished(scheduler_output.finished_req_ids)
             )
             output.invalid_block_ids = kv_connector.get_block_ids_with_load_errors()
-
-            output.kv_connector_stats = (
-                KVConnectorModelRunnerMixin.get_kv_connector_stats()
-            )
-            output.kv_cache_events = (
-                KVConnectorModelRunnerMixin.get_kv_connector_kv_cache_events()
-            )
+            if has_kv_transfer_group():
+                output.kv_connector_stats = (
+                    get_kv_transfer_group().get_kv_connector_stats()
+                )
+                output.kv_cache_events = (
+                    get_kv_transfer_group().get_kv_connector_kv_cache_events()
+                )
+            else:
+                output.kv_connector_stats = output.kv_cache_events = None
             kv_connector.clear_connector_metadata()
-
-    @staticmethod
-    def get_kv_connector_stats() -> KVConnectorStats | None:
-        if has_kv_transfer_group():
-            return get_kv_transfer_group().get_kv_connector_stats()
-        return None
-
-    @staticmethod
-    def get_kv_connector_kv_cache_events() -> KVEventBatch | None:
-        if has_kv_transfer_group():
-            return get_kv_transfer_group().get_kv_connector_kv_cache_events()
-        return None