refactor: Optimize the use of stellar_sdk.client.AiohttpClient. (#317)

* refactor: Optimize the use of `stellar_sdk.client.AiohttpClient`.
When `stellar_sdk.client.AiohttpClient` cannot establish a Stream connection, `stellar_sdk.exceptions.StreamClientError` will be thrown.

stellar_sdk/call_builder/base_call_builder.py

@@ -90,6 +90,8 @@ def stream(
 
         :return: If it is called synchronous, it will return ``Generator``, If
             it is called asynchronously, it will return ``AsyncGenerator``.
+
+        :raise: :exc:`StreamClientError <stellar_sdk.exceptions.StreamClientError>` - Failed to fetch stream resource.
         """
         if self.__async:
             return self.__stream_async()

stellar_sdk/client/aiohttp_client.py

@@ -2,14 +2,14 @@
 import json
 import logging
 from typing import Optional, AsyncGenerator, Any, Dict
-
 import aiohttp
 from aiohttp_sse_client.client import EventSource
 
 from . import defines
 from .base_async_client import BaseAsyncClient
 from .response import Response
 from ..__version__ import __version__
+from ..exceptions import StreamClientError
 
 logger = logging.getLogger(__name__)
 
@@ -42,7 +42,7 @@ def __init__(
         post_timeout: float = defines.DEFAULT_POST_TIMEOUT_SECONDS,
         backoff_factor: Optional[float] = DEFAULT_BACKOFF_FACTOR,
         user_agent: Optional[str] = None,
-        **kwargs
+        **kwargs,
     ) -> None:
         self.backoff_factor: Optional[float] = backoff_factor
         self.request_timeout: float = request_timeout
@@ -67,7 +67,7 @@ def __init__(
             headers=self.headers.copy(),
             connector=connector,
             timeout=aiohttp.ClientTimeout(total=request_timeout),
-            **kwargs
+            **kwargs,
         )
 
         self._session: aiohttp.ClientSession = session
@@ -77,7 +77,7 @@ async def get(self, url: str, params: Dict[str, str] = None) -> Response:
         """Perform HTTP GET request.
 
         :param url: the request url
-        :param params: the requested params
+        :param params: the request params
         :return: the response from server
         :raise: :exc:`ConnectionError <stellar_sdk.exceptions.ConnectionError>`
         """
@@ -114,11 +114,20 @@ async def post(self, url: str, data: Dict[str, str] = None) -> Response:
     async def stream(
         self, url: str, params: Dict[str, str] = None
     ) -> AsyncGenerator[Dict[str, Any], None]:
-        """Init the sse session """
+        """Perform Stream request.
+
+        :param url: the request url
+        :param params: the request params
+        :return: the stream response from server
+        :raise: :exc:`StreamClientError <stellar_sdk.exceptions.StreamClientError>` - Failed to fetch stream resource.
+        """
+
+        # Init the sse session
         if self._sse_session is None:
-            # No timeout, no special connector
+            # No special connector
             # Other headers such as "Accept: text/event-stream" are added by thr SSEClient
-            self._sse_session = aiohttp.ClientSession()
+            timeout = aiohttp.ClientTimeout(total=60 * 5)
+            self._sse_session = aiohttp.ClientSession(timeout=timeout)
 
         query_params = {**params} if params else dict()
 
@@ -160,10 +169,13 @@ async def stream(
                         except json.JSONDecodeError:
                             # Content was not json-decodable
                             pass
-            except aiohttp.ClientConnectionError:
-                # Retry if the connection dropped after we got the initial response
+            except aiohttp.ClientError as e:
+                raise StreamClientError(
+                    query_params["cursor"], "Failed to get stream message."
+                ) from e
+            except asyncio.exceptions.TimeoutError:
                 logger.warning(
-                    "We have encountered an error and we will try to reconnect, cursor = {}".format(
+                    "We have encountered an timeout error and we will try to reconnect, cursor = {}".format(
                         query_params.get("cursor")
                     )
                 )

stellar_sdk/exceptions.py

@@ -29,6 +29,7 @@
     "BadResponseError",
     "UnknownRequestError",
     "NotPageableError",
+    "StreamClientError"
 ]
 
 
@@ -192,6 +193,18 @@ class NotPageableError(BaseRequestError):
     """
 
 
+class StreamClientError(BaseRequestError):
+    """Failed to fetch stream resource.
+
+    :param current_cursor: The cursor of the last message obtained can be used for reconnect.
+    :param message: error message
+    """
+
+    def __init__(self, current_cursor: str, message: str) -> None:
+        super().__init__(message)
+        self.current_cursor = current_cursor
+
+
 def raise_request_exception(response: Response) -> None:
     status_code = response.status_code
     if status_code == 200: