Backport 3.12 and Below

aiolibs_executor/_executor.py

@@ -1,13 +1,13 @@
+from __future__ import annotations
+
 import contextvars
-import dataclasses
 import itertools
+import sys
 import threading
 from asyncio import (
     AbstractEventLoop,
     CancelledError,
     Future,
-    Queue,
-    QueueShutDown,
     Task,
     gather,
     get_running_loop,
@@ -20,10 +20,50 @@
     Iterable,
 )
 from types import TracebackType
-from typing import Any, Self, final, overload
+from typing import Any, Generic, TypeVar, final, overload
 from warnings import catch_warnings
 
 
+if sys.version_info < (3, 13):
+    from backports.asyncio.queues import (  # type: ignore[import-untyped]
+        Queue,
+        QueueShutDown,
+    )
+else:
+    from asyncio.queues import Queue, QueueShutDown
+
+if sys.version_info < (3, 10):
+    from collections.abc import Awaitable, Sequence
+    from typing import Protocol
+
+    _T = TypeVar("_T")
+
+    class _SupportsAnext(Protocol[_T]):
+        async def __anext__(self) -> _T:
+            pass
+
+    def anext(it: _SupportsAnext[_T]) -> Awaitable:
+        return it.__anext__()
+
+    def aiter(it: Sequence[_T]) -> AsyncIterable[_T]:
+        return it.__aiter__()
+
+
+if sys.version_info < (3, 11):
+    from exceptiongroup import BaseExceptionGroup
+    from typing_extensions import Self
+else:
+    from typing import Self
+
+
+R = TypeVar("R")
+T1 = TypeVar("T1")
+T2 = TypeVar("T2")
+T3 = TypeVar("T3")
+T4 = TypeVar("T4")
+T5 = TypeVar("T5")
+
+
 @final
 class Executor:
     _counter = itertools.count().__next__
@@ -65,7 +105,7 @@ async def __aexit__(
     ) -> None:
         await self.shutdown()
 
-    def submit_nowait[R](
+    def submit_nowait(
         self,
         coro: Coroutine[Any, Any, R],
         /,
@@ -77,7 +117,7 @@ def submit_nowait[R](
         self._work_items.put_nowait(work_item)
         return work_item.future
 
-    async def submit[R](
+    async def submit(
         self,
         coro: Coroutine[Any, Any, R],
         /,
@@ -90,16 +130,17 @@ async def submit[R](
         return work_item.future
 
     @overload
-    def map[R, T1](
+    def map(
         self,
         fn: Callable[[T1], Coroutine[Any, Any, R]],
         it1: Iterable[T1],
         /,
         *,
         context: contextvars.Context | None = None,
     ) -> AsyncIterator[R]: ...
+
     @overload
-    def map[R, T1, T2](
+    def map(
         self,
         fn: Callable[[T1, T2], Coroutine[Any, Any, R]],
         it1: Iterable[T1],
@@ -108,8 +149,9 @@ def map[R, T1, T2](
         *,
         context: contextvars.Context | None = None,
     ) -> AsyncIterator[R]: ...
+
     @overload
-    def map[R, T1, T2, T3](
+    def map(
         self,
         fn: Callable[[T1, T2, T3], Coroutine[Any, Any, R]],
         it1: Iterable[T1],
@@ -120,7 +162,7 @@ def map[R, T1, T2, T3](
         context: contextvars.Context | None = None,
     ) -> AsyncIterator[R]: ...
     @overload
-    def map[R, T1, T2, T3, T4](
+    def map(
         self,
         fn: Callable[[T1, T2, T3, T4], Coroutine[Any, Any, R]],
         it1: Iterable[T1],
@@ -132,7 +174,7 @@ def map[R, T1, T2, T3, T4](
         context: contextvars.Context | None = None,
     ) -> AsyncIterator[R]: ...
     @overload
-    def map[R, T1, T2, T3, T4, T5](
+    def map(
         self,
         fn: Callable[[T1, T2, T3, T4, T5], Coroutine[Any, Any, R]],
         it1: Iterable[T1],
@@ -145,7 +187,7 @@ def map[R, T1, T2, T3, T4, T5](
         context: contextvars.Context | None = None,
     ) -> AsyncIterator[R]: ...
 
-    async def map[R](
+    async def map(
         self,
         fn: Callable[..., Coroutine[Any, Any, R]],
         iterable: Iterable[Any],
@@ -163,7 +205,7 @@ async def map[R](
             yield ret
 
     @overload
-    def amap[R, T1](
+    def amap(
         self,
         fn: Callable[[T1], Coroutine[Any, Any, R]],
         it1: AsyncIterable[T1],
@@ -172,7 +214,7 @@ def amap[R, T1](
         context: contextvars.Context | None = None,
     ) -> AsyncIterator[R]: ...
     @overload
-    def amap[R, T1, T2](
+    def amap(
         self,
         fn: Callable[[T1, T2], Coroutine[Any, Any, R]],
         it1: AsyncIterable[T1],
@@ -182,7 +224,7 @@ def amap[R, T1, T2](
         context: contextvars.Context | None = None,
     ) -> AsyncIterator[R]: ...
     @overload
-    def amap[R, T1, T2, T3](
+    def amap(
         self,
         fn: Callable[[T1, T2, T3], Coroutine[Any, Any, R]],
         it1: AsyncIterable[T1],
@@ -193,7 +235,7 @@ def amap[R, T1, T2, T3](
         context: contextvars.Context | None = None,
     ) -> AsyncIterator[R]: ...
     @overload
-    def amap[R, T1, T2, T3, T4](
+    def amap(
         self,
         fn: Callable[[T1, T2, T3, T4], Coroutine[Any, Any, R]],
         it1: AsyncIterable[T1],
@@ -205,7 +247,7 @@ def amap[R, T1, T2, T3, T4](
         context: contextvars.Context | None = None,
     ) -> AsyncIterator[R]: ...
     @overload
-    def amap[R, T1, T2, T3, T4, T5](
+    def amap(
         self,
         fn: Callable[[T1, T2, T3, T4, T5], Coroutine[Any, Any, R]],
         it1: AsyncIterable[T1],
@@ -217,7 +259,7 @@ def amap[R, T1, T2, T3, T4, T5](
         *,
         context: contextvars.Context | None = None,
     ) -> AsyncIterator[R]: ...
-    async def amap[R](
+    async def amap(
         self,
         fn: Callable[..., Coroutine[Any, Any, R]],
         iterable: AsyncIterable[Any],
@@ -250,13 +292,15 @@ async def shutdown(
         self._shutdown = True
         if self._loop is None:
             return
+
         if cancel_futures:
             # Drain all work items from the queue, and then cancel their
             # associated futures.
             while not self._work_items.empty():
                 self._work_items.get_nowait().cancel()
 
         self._work_items.shutdown()
+
         if not wait:
             for task in self._tasks:
                 task.cancel()
@@ -310,15 +354,34 @@ def _lazy_init(self) -> AbstractEventLoop:
                 )
             return loop
 
-    async def _process_items[R](
-        self, work_items: list["_WorkItem[R]"]
+    async def _process_items(
+        self, work_items: list[_WorkItem[R]]
     ) -> AsyncIterator[R]:
         try:
-            # reverse to keep finishing order
-            work_items.reverse()
-            while work_items:
-                # Careful not to keep a reference to the popped future
-                yield await work_items.pop().future
+            # NOTE: Polling future objects can be a bad apporch
+            # callbacks need to be used in order to return items
+            # in finishing order
+
+            remaining = len(work_items)
+            queue: Queue[Future[R]] = Queue()
+
+            def on_done(fut: Future[R]) -> None:
+                nonlocal queue, remaining
+                queue.put_nowait(fut)
+                remaining -= 1
+
+            # No need to call for a copy,
+            # loop will call it later
+            for w in work_items:
+                w.future.add_done_callback(on_done)
+
+            while remaining or not queue.empty():
+                fut = await queue.get()
+                yield await fut
+
+            # cleanup
+            work_items.clear()
+
         except CancelledError:
             # The current task was cancelled, e.g. by timeout
             for work_item in work_items:
@@ -328,22 +391,35 @@ async def _process_items[R](
     async def _work(self, prefix: str) -> None:
         try:
             while True:
-                await (await self._work_items.get()).execute(prefix)
+                worker = await self._work_items.get()
+                await worker.execute(prefix)
         except QueueShutDown:
             pass
 
 
 _global_lock = threading.Lock()
 
 
-@dataclasses.dataclass
-class _WorkItem[R]:
-    coro: Coroutine[Any, Any, R]
-    loop: AbstractEventLoop
-    context: contextvars.Context | None
-    task: Task[R] | None = None
+class _WorkItem(Generic[R]):
+    __slots__ = (
+        "coro",
+        "loop",
+        "context",
+        "task",
+        "future",
+    )
 
-    def __post_init__(self) -> None:
+    def __init__(
+        self,
+        coro: Coroutine[Any, Any, R],
+        loop: AbstractEventLoop,
+        context: contextvars.Context | None,
+        task: Task[R] | None = None,
+    ) -> None:
+        self.coro = coro
+        self.loop = loop
+        self.context = context
+        self.task = task
         self.future: Future[R] = self.loop.create_future()
 
     async def execute(self, prefix: str) -> None:
@@ -358,9 +434,16 @@ async def execute(self, prefix: str) -> None:
             # Some custom coroutines and mocks could not have __qualname__,
             # don't add a suffix in this case.
             pass
-        self.task = task = self.loop.create_task(
-            self.coro, context=self.context, name=name
-        )
+        if sys.version_info >= (3, 11):
+            self.task = task = self.loop.create_task(  # type: ignore[call-arg]
+                self.coro, context=self.context, name=name
+            )
+        # XXX: older versions of Python can't leverage context variables
+        # Not handling it and letting the bad arguments run results in
+        # a deadlock!
+        else:
+            self.task = task = self.loop.create_task(self.coro, name=name)
+
         fut.add_done_callback(self.done_callback)
         try:
             ret = await task
@@ -374,12 +457,11 @@ async def execute(self, prefix: str) -> None:
                 fut.set_result(ret)
 
     def cancel(self) -> None:
-        fut = self.future
-        fut.cancel()
+        self.future.cancel()
         self.cleanup()
 
     def cleanup(self) -> None:
-        with catch_warnings(action="ignore", category=RuntimeWarning):
+        with catch_warnings(action="ignore", category=RuntimeWarning):  # type: ignore[call-overload]
             # Suppress RuntimeWarning: coroutine 'coro' was never awaited.
             # The warning is possible if .shutdown() was called
             # with cancel_futures=True and there are non-started coroutines

pyproject.toml

@@ -5,8 +5,10 @@ authors = [
     {name = "Andrew Svetlov",email = "[email protected]"}
 ]
 readme = "README.md"
-requires-python = ">=3.13"
+requires-python = ">=3.9"
 dependencies = [
+    'exceptiongroup==1.3.0; python_version<"3.11"',
+    'backports-asyncio-queues==0.1.2; python_version<"3.13"'
 ]
 dynamic = ["version"]
 
@@ -20,12 +22,12 @@ enable = true
 
 [tool.poetry]
 version = "0.0.0"
+
 [tool.poetry.group.dev.dependencies]
 mypy = "^1.15.0"
 coverage = "^7.6.11"
 
 [tool.ruff]
-target-version = "py313"
 line-length = 79
 
 [tool.ruff.lint]