[Feat][RL][1/2] Native Weight Syncing API: NCCL (#31943)

Signed-off-by: ahao-anyscale <ahao@anyscale.com>
Signed-off-by: Aaron Hao <ahao@anyscale.com>
Co-authored-by: SumanthRH <sumanthrh99@gmail.com>

vllm/engine/protocol.py

@@ -6,6 +6,10 @@ from collections.abc import AsyncGenerator, Iterable, Mapping
 from typing import Any
 
 from vllm.config import ModelConfig, VllmConfig
+from vllm.distributed.weight_transfer.base import (
+    WeightTransferInitRequest,
+    WeightTransferUpdateRequest,
+)
 from vllm.inputs.data import PromptType, StreamingInput
 from vllm.lora.request import LoRARequest
 from vllm.outputs import PoolingRequestOutput, RequestOutput
@@ -191,3 +195,13 @@ class EngineClient(ABC):
     async def get_supported_tasks(self) -> tuple[SupportedTask, ...]:
         """Get supported tasks"""
         raise NotImplementedError
+
+    async def init_weight_transfer_engine(
+        self, init_request: WeightTransferInitRequest
+    ) -> None:
+        """Initialize weight transfer for RL training."""
+        raise NotImplementedError
+
+    async def update_weights(self, request: WeightTransferUpdateRequest) -> None:
+        """Batched weight update for RL training."""
+        raise NotImplementedError