Fix issue 696 in async query client

Author: Roman Tretiak

tests/aio/query/conftest.py

@@ -1,4 +1,9 @@
+from unittest import mock
+
+import grpc
 import pytest
+from grpc._cython import cygrpc
+
 from ydb.aio.query.session import QuerySession
 from ydb.aio.query.pool import QuerySessionPool
 
@@ -32,3 +37,22 @@ async def tx(session):
 async def pool(driver):
     async with QuerySessionPool(driver) as pool:
         yield pool
+
+
+@pytest.fixture
+async def ydb_terminates_streams_with_unavailable():
+    async def _patch(self):
+        message = await self._read()  # Read the first message
+        while message is not cygrpc.EOF:  # While the message is not empty, continue reading the stream
+            yield message
+            message = await self._read()
+
+        # Emulate stream termination
+        raise grpc.aio.AioRpcError(
+            code=grpc.StatusCode.UNAVAILABLE,
+            initial_metadata=await self.initial_metadata(),
+            trailing_metadata=await self.trailing_metadata(),
+        )
+
+    with mock.patch.object(grpc.aio._call._StreamResponseMixin, "_fetch_stream_responses", _patch):
+        yield

tests/aio/query/test_query_session.py

@@ -1,4 +1,6 @@
 import pytest
+
+import ydb
 from ydb.aio.query.session import QuerySession
 
 
@@ -113,3 +115,13 @@ async def test_two_results(self, session: QuerySession):
 
         assert res == [[1], [2]]
         assert counter == 2
+
+    @pytest.mark.asyncio
+    @pytest.mark.usefixtures("ydb_terminates_streams_with_unavailable")
+    async def test_terminated_stream_raises_ydb_error(self, session: QuerySession):
+        await session.create()
+
+        with pytest.raises(ydb.Unavailable):
+            async with await session.execute("select 1") as results:
+                async for _ in results:
+                    pass

tests/aio/query/test_query_transaction.py

@@ -1,5 +1,6 @@
 import pytest
 
+import ydb
 from ydb.aio.query.transaction import QueryTxContext
 from ydb.query.transaction import QueryTxStateEnum
 
@@ -107,3 +108,13 @@ async def test_execute_two_results(self, tx: QueryTxContext):
 
         assert res == [[1], [2]]
         assert counter == 2
+
+    @pytest.mark.asyncio
+    @pytest.mark.usefixtures("ydb_terminates_streams_with_unavailable")
+    async def test_terminated_stream_raises_ydb_error(self, tx: QueryTxContext):
+        await tx.begin()
+
+        with pytest.raises(ydb.Unavailable):
+            async with await tx.execute("select 1") as results:
+                async for _ in results:
+                    pass

ydb/_errors.py

@@ -1,5 +1,7 @@
 from dataclasses import dataclass
-from typing import Optional
+from typing import Optional, Union
+
+import grpc
 
 from . import issues
 
@@ -52,3 +54,26 @@ def check_retriable_error(err, retry_settings, attempt):
 class ErrorRetryInfo:
     is_retriable: bool
     sleep_timeout_seconds: Optional[float]
+
+
+def stream_error_converter(exc: BaseException) -> Union[issues.Error, BaseException]:
+    """Converts gRPC stream errors to appropriate YDB exception types.
+
+    This function takes a base exception and converts specific gRPC aio stream errors
+    to their corresponding YDB exception types for better error handling and semantic
+    clarity.
+
+    Args:
+        exc (BaseException): The original exception to potentially convert.
+
+    Returns:
+        BaseException: Either a converted YDB exception or the original exception
+                      if no specific conversion rule applies.
+    """
+    if isinstance(exc, (grpc.RpcError, grpc.aio.AioRpcError)):
+        if exc.code() == grpc.StatusCode.UNAVAILABLE:
+            return issues.Unavailable(exc.details() or "")
+        if exc.code() == grpc.StatusCode.DEADLINE_EXCEEDED:
+            return issues.DeadlineExceed("Deadline exceeded on request")
+        return issues.Error("Stream has been terminated. Original exception: {}".format(str(exc.details())))
+    return exc

ydb/aio/_utilities.py

@@ -2,9 +2,10 @@
 
 
 class AsyncResponseIterator(object):
-    def __init__(self, it, wrapper):
+    def __init__(self, it, wrapper, error_converter=None):
         self.it = it.__aiter__()
         self.wrapper = wrapper
+        self.error_converter = error_converter
 
     def cancel(self):
         self.it.cancel()
@@ -17,7 +18,13 @@ def __aiter__(self):
         return self
 
     async def _next(self):
-        res = self.wrapper(await self.it.__anext__())
+        try:
+            res = self.wrapper(await self.it.__anext__())
+        except BaseException as e:
+            if self.error_converter:
+                raise self.error_converter(e) from e
+            raise e
+
         if res is not None:
             return res
         return await self._next()

ydb/aio/query/session.py

@@ -19,6 +19,7 @@
 )
 
 from ..._constants import DEFAULT_INITIAL_RESPONSE_TIMEOUT
+from ..._errors import stream_error_converter
 
 
 class QuerySession(BaseQuerySession):
@@ -151,12 +152,13 @@ async def execute(
         )
 
         return AsyncResponseContextIterator(
-            stream_it,
-            lambda resp: base.wrap_execute_query_response(
+            it=stream_it,
+            wrapper=lambda resp: base.wrap_execute_query_response(
                 rpc_state=None,
                 response_pb=resp,
                 session_state=self._state,
                 session=self,
                 settings=self._settings,
             ),
+            error_converter=stream_error_converter,
         )

ydb/aio/query/transaction.py

@@ -11,6 +11,7 @@
     BaseQueryTxContext,
     QueryTxStateEnum,
 )
+from ..._errors import stream_error_converter
 
 logger = logging.getLogger(__name__)
 
@@ -181,14 +182,15 @@ async def execute(
         )
 
         self._prev_stream = AsyncResponseContextIterator(
-            stream_it,
-            lambda resp: base.wrap_execute_query_response(
+            it=stream_it,
+            wrapper=lambda resp: base.wrap_execute_query_response(
                 rpc_state=None,
                 response_pb=resp,
                 session_state=self._session_state,
                 tx=self,
                 commit_tx=commit_tx,
                 settings=self.session._settings,
             ),
+            error_converter=stream_error_converter,
         )
         return self._prev_stream