[BugFix] Fix mooncake bug in PCP scenario (#5055)

### What this PR does / why we need it?
The mooncake_connector.py file was importing the wrong arguments to the
file, which could cause errors when use PCP; this issue has been
corrected.

### Does this PR introduce _any_ user-facing change?
NO
### How was this patch tested?

- vLLM version: v0.12.0
- vLLM main:
ad32e3e19c

---------

Signed-off-by: daishixun <dsxsteven@sina.com>

tests/ut/kv_connector/test_mooncake_connector.py

@@ -22,6 +22,7 @@ sys.modules["mooncake.engine"] = fake_engine
 _mock_ascend_config = MagicMock(enable_kv_nz=False)
 _mock_pp_group = MagicMock(rank_in_group=0, world_size=1)
 _mock_tp_group = MagicMock(rank_in_group=0, world_size=4)
+_mock_pcp_group = MagicMock(rank_in_group=0, world_size=1)
 patch('vllm_ascend.distributed.mooncake_connector.get_pp_group',
       return_value=_mock_pp_group).start()
 patch('vllm_ascend.distributed.mooncake_connector.get_tp_group',
@@ -32,6 +33,8 @@ patch(
 patch(
     'vllm_ascend.distributed.mooncake_connector.get_tensor_model_parallel_rank',
     return_value=0).start()
+patch('vllm_ascend.distributed.mooncake_connector.get_pcp_group',
+      return_value=_mock_pcp_group).start()
 
 from vllm_ascend.distributed.mooncake_connector import (  # noqa: E402
     KVCacheRecvingThread, KVCacheSendingThread, KVCacheTaskTracker,

vllm_ascend/distributed/mooncake_connector.py

@@ -23,6 +23,7 @@ import zmq
 from mooncake.engine import TransferEngine  # type: ignore
 from vllm import envs
 from vllm.config import VllmConfig
+from vllm.distributed import get_pcp_group
 from vllm.distributed.kv_transfer.kv_connector.v1.base import (
     KVConnectorBase_V1, KVConnectorHandshakeMetadata, KVConnectorMetadata,
     KVConnectorRole)
@@ -43,13 +44,6 @@ from vllm_ascend.distributed.mooncake_transfer_engine import global_te
 from vllm_ascend.distributed.utils import get_transfer_timeout_value
 from vllm_ascend.utils import prefill_context_parallel_enable
 
-# isort: off
-if prefill_context_parallel_enable():
-    from vllm.distributed import (get_prefill_context_model_parallel_rank,
-                                  get_prefill_context_model_parallel_world_size
-                                  )
-# isort: on
-
 if TYPE_CHECKING:
     from vllm.attention.backends.abstract import AttentionMetadata
     from vllm.forward_context import ForwardContext
@@ -1003,13 +997,12 @@ class MooncakeConnectorWorker:
         self.pp_size = vllm_config.parallel_config.pipeline_parallel_size
         self.kv_caches: dict[str, torch.Tensor] = {}
         self.side_channel_host = get_ip()
-        self.pcp_size = get_prefill_context_model_parallel_world_size(
+        self.pcp_size = get_pcp_group().world_size
-        ) if prefill_context_parallel_enable() else 1
         # Assert that pp_size and pcp_size cannot both be greater than 1
         assert not (self.pp_size > 1 and self.pcp_size
                     > 1), "pp and pcp cannot open in same time"
-        self.pcp_rank = get_prefill_context_model_parallel_rank(
+        self.pcp_rank = get_pcp_group(
-        ) if self.pcp_size > 1 else 0
+        ).rank_in_group if self.pcp_size > 1 else 0
         self.dcp_size = get_decode_context_model_parallel_world_size()
         self.dcp_rank = get_decode_context_model_parallel_rank(
         ) if self.dcp_size > 1 else 0