add _acall method to YandexGPT (#12029)

- **Description:** Add async support for YandexGPT LLM model

Co-authored-by: Dmitry Tyumentsev <dmitry.tyumentsev@raftds.com>

libs/langchain/langchain/llms/yandex.py

@@ -1,6 +1,9 @@
 from typing import Any, Dict, List, Mapping, Optional
 
-from langchain.callbacks.manager import CallbackManagerForLLMRun
+from langchain.callbacks.manager import (
+    AsyncCallbackManagerForLLMRun,
+    CallbackManagerForLLMRun,
+)
 from langchain.llms.base import LLM
 from langchain.llms.utils import enforce_stop_tokens
 from langchain.load.serializable import Serializable
@@ -128,3 +131,75 @@ class YandexGPT(_BaseYandexGPT, LLM):
         if stop is not None:
             text = enforce_stop_tokens(text, stop)
         return text
+
+    async def _acall(
+        self,
+        prompt: str,
+        stop: Optional[List[str]] = None,
+        run_manager: Optional[AsyncCallbackManagerForLLMRun] = None,
+        **kwargs: Any,
+    ) -> str:
+        """Async call the Yandex GPT model and return the output.
+
+        Args:
+            prompt: The prompt to pass into the model.
+            stop: Optional list of stop words to use when generating.
+
+        Returns:
+            The string generated by the model.
+        """
+        try:
+            import asyncio
+
+            import grpc
+            from google.protobuf.wrappers_pb2 import DoubleValue, Int64Value
+            from yandex.cloud.ai.llm.v1alpha.llm_pb2 import GenerationOptions
+            from yandex.cloud.ai.llm.v1alpha.llm_service_pb2 import (
+                InstructRequest,
+                InstructResponse,
+            )
+            from yandex.cloud.ai.llm.v1alpha.llm_service_pb2_grpc import (
+                TextGenerationAsyncServiceStub,
+            )
+            from yandex.cloud.operation.operation_service_pb2 import GetOperationRequest
+            from yandex.cloud.operation.operation_service_pb2_grpc import (
+                OperationServiceStub,
+            )
+        except ImportError as e:
+            raise ImportError(
+                "Please install YandexCloud SDK" " with `pip install yandexcloud`."
+            ) from e
+        operation_api_url = "operation.api.cloud.yandex.net:443"
+        channel_credentials = grpc.ssl_channel_credentials()
+        async with grpc.aio.secure_channel(self.url, channel_credentials) as channel:
+            request = InstructRequest(
+                model=self.model_name,
+                request_text=prompt,
+                generation_options=GenerationOptions(
+                    temperature=DoubleValue(value=self.temperature),
+                    max_tokens=Int64Value(value=self.max_tokens),
+                ),
+            )
+            stub = TextGenerationAsyncServiceStub(channel)
+            if self.iam_token:
+                metadata = (("authorization", f"Bearer {self.iam_token}"),)
+            else:
+                metadata = (("authorization", f"Api-Key {self.api_key}"),)
+            operation = await stub.Instruct(request, metadata=metadata)
+            async with grpc.aio.secure_channel(
+                operation_api_url, channel_credentials
+            ) as operation_channel:
+                operation_stub = OperationServiceStub(operation_channel)
+                while not operation.done:
+                    await asyncio.sleep(1)
+                    operation_request = GetOperationRequest(operation_id=operation.id)
+                    operation = await operation_stub.Get(
+                        operation_request, metadata=metadata
+                    )
+
+            instruct_response = InstructResponse()
+            operation.response.Unpack(instruct_response)
+            text = instruct_response.alternatives[0].text
+            if stop is not None:
+                text = enforce_stop_tokens(text, stop)
+            return text