removed unused functions and tasks from utils.py; added reference lin…

…ks (#64)

* removed unused functions and tasks from utils.py; added reference links

* reformated the code

* flaked8

iso15118/evcc/comm_session_handler.py

@@ -57,7 +57,7 @@
     StopNotification,
     UDPPacketNotification,
 )
-from iso15118.shared.utils import cancel_task, wait_till_finished
+from iso15118.shared.utils import cancel_task, wait_for_tasks
 
 logger = logging.getLogger(__name__)
 
@@ -290,7 +290,7 @@ async def __init__. Therefore, we need to create a separate async
 
         logger.info("Communication session handler started")
 
-        await wait_till_finished(self.list_of_tasks)
+        await wait_for_tasks(self.list_of_tasks)
 
     async def send_sdp(self):
         """

iso15118/secc/comm_session_handler.py

@@ -52,7 +52,7 @@
     TCPClientNotification,
     UDPPacketNotification,
 )
-from iso15118.shared.utils import cancel_task, wait_till_finished
+from iso15118.shared.utils import cancel_task, wait_for_tasks
 
 logger = logging.getLogger(__name__)
 
@@ -195,7 +195,7 @@ async def __init__.
 
         logger.info("Communication session handler started")
 
-        await wait_till_finished(self.list_of_tasks)
+        await wait_for_tasks(self.list_of_tasks)
 
     async def get_from_rcv_queue(self, queue: asyncio.Queue):
         """

iso15118/secc/transport/udp_server.py

@@ -11,7 +11,7 @@
     ReceiveTimeoutNotification,
     UDPPacketNotification,
 )
-from iso15118.shared.utils import wait_till_finished
+from iso15118.shared.utils import wait_for_tasks
 
 logger = logging.getLogger(__name__)
 
@@ -100,7 +100,7 @@ async def start(self):
             f"and port {SDP_SERVER_PORT}"
         )
         tasks = [self.rcv_task()]
-        await wait_till_finished(tasks)
+        await wait_for_tasks(tasks)
 
     def connection_made(self, transport):
         """

iso15118/shared/comm_session.py

@@ -50,7 +50,7 @@
 from iso15118.shared.messages.v2gtp import V2GTPMessage
 from iso15118.shared.notifications import StopNotification
 from iso15118.shared.states import Pause, State, Terminate
-from iso15118.shared.utils import wait_till_finished
+from iso15118.shared.utils import wait_for_tasks
 
 logger = logging.getLogger(__name__)
 
@@ -338,7 +338,7 @@ async def start(self, timeout: float):
 
         try:
             self._started = True
-            await wait_till_finished(tasks)
+            await wait_for_tasks(tasks)
         finally:
             self._started = False
 

iso15118/shared/utils.py

@@ -1,27 +1,10 @@
-"""
-This module contains methods for managing multiple asnycio tasks that are
-supposed to run concurrently.
-"""
-
 import asyncio
-import json
 import logging
-import os
-from contextlib import suppress
-from typing import Any, Awaitable, List
+from typing import Coroutine, List
 
 logger = logging.getLogger(__name__)
 
 
-def load_from_env(variable, default=None):
-    """Read values from the environment and try to convert values from json"""
-    value = os.environ.get(variable, default)
-    if value is not None:
-        with suppress(json.decoder.JSONDecodeError, TypeError):
-            value = json.loads(value)
-    return value
-
-
 async def cancel_task(task):
     """Cancel the task safely"""
     task.cancel()
@@ -31,76 +14,38 @@ async def cancel_task(task):
         pass
 
 
-async def wait_till_finished(
-    awaitables: List[Awaitable[Any]], finished_when=asyncio.FIRST_EXCEPTION
+async def wait_for_tasks(
+    await_tasks: List[Coroutine], return_when=asyncio.FIRST_EXCEPTION
 ):
-    """Run the tasks until one task is finished. The condition to finish
-    depends on the argument 'finished_when', which directly translates
-    to the asyncio.wait argument 'return_when' that can assume the following
-    values: FIRST_COMPLETED, FIRST_EXCEPTION, ALL_COMPLETED
-    (For more information regarding this, please check:
+    """
+    Method to run multiple tasks concurrently.
+    return_when is used directly in the asyncio.wait call and sets the
+    condition to cancel all running tasks and return.
+    The arguments for it can be:
+    asyncio.FIRST_COMPLETED, asyncio.FIRST_EXCEPTION or
+    asyncio.ALL_COMPLETED
+    check:
     https://docs.python.org/3/library/asyncio-task.html#waiting-primitives)
 
-    All unfinished tasks will be cancelled.
-
-    It can happen that multiple tasks finished at the same time.
-    A MultiError is raised if at least one task finished with an exception.
-    This exception wraps the exception of all tasks that finished with an
-    exception.
-
-    Return values of finished tasks are ignored. Use `asyncio.wait()` directly
-    if you need access to the return values of tasks.
-
-    If this function turns out to be useful it might be a good fit for
-    `common/util` or `cc_utils`.
+    Similar solutions for awaiting for several tasks can be found in:
+    * https://python.plainenglish.io/how-to-manage-exceptions-when-waiting-on-multiple-asyncio-tasks-a5530ac10f02  # noqa: E501
+    * https://stackoverflow.com/questions/63583822/asyncio-wait-on-multiple-tasks-with-timeout-and-cancellation  # noqa: E501
 
     """
     tasks = []
 
-    # As of Python 3.8 `asyncio.wait()` should be called only with
-    # `asyncio.Task`s.
-    # See: https://docs.python.org/3/library/asyncio-task.html#asyncio-example-wait-coroutine # noqa: E501
-    for awaitable in awaitables:
-        if not isinstance(awaitable, asyncio.Task):
-            awaitable = asyncio.create_task(awaitable)
-        tasks.append(awaitable)
+    for task in await_tasks:
+        if not isinstance(task, asyncio.Task):
+            task = asyncio.create_task(task)
+        tasks.append(task)
 
-    done, pending = await asyncio.wait(tasks, return_when=finished_when)
+    done, pending = await asyncio.wait(tasks, return_when=return_when)
 
     for task in pending:
         await cancel_task(task)
 
-    errors = []
     for task in done:
         try:
             task.result()
-        except Exception as ex:
-            logger.exception(ex)
-            errors.append(ex)
-
-    if len(errors) == 1:
-        raise errors[0]
-
-    if errors:
-        raise MultiError(errors)
-
-
-class MultiError(Exception):
-    """Exception used to raise multiple exceptions.
-
-    The attribute `errors` gives access to the wrapper errors.
-
-        try:
-            something()
-        except MultiError as e:
-            for error in e.errors:
-                if isinstance(e, ZeroDivisionError):
-                    ...
-                elif isinstance(e, AttributeError):
-                    ...
-
-    """
-
-    def __init__(self, errors: List[Exception]):
-        Exception.__init__(self)
-        self.errors = errors
+        except Exception as e:
+            logger.exception(e)