commit: cecd2f8a259cf2991f2324c9a14e26170ba0ddcf Author: Zac Medico <zmedico <AT> gentoo <DOT> org> AuthorDate: Sun Dec 6 09:25:17 2020 +0000 Commit: Zac Medico <zmedico <AT> gentoo <DOT> org> CommitDate: Mon Dec 7 02:32:27 2020 +0000 URL: https://gitweb.gentoo.org/proj/portage.git/commit/?id=cecd2f8a
Use default asyncio event loop implementation in API consumer threads Make the _safe_loop function return an AsyncioEventLoop instance, so that the default asyncio event loop implementation will be used in API consumer threads. This is possible because the underlying asyncio.get_event_loop() function returns a separate event loop for each thread. The AsyncioEventLoop _run_until_complete method will now appropriately handle a ValueError from signal.set_wakeup_fd(-1) if it is not called in the main thread. For external API consumers calling from a non-main thread, an asyncio loop must be registered for the current thread, or else an error will be raised like this: RuntimeError: There is no current event loop in thread 'Thread-1'. In order to avoid this RuntimeError, the external API consumer is responsible for setting an event loop and managing its lifecycle. For example, this code will set an event loop for the current thread: asyncio.set_event_loop(asyncio.new_event_loop()) In order to avoid a ResourceWarning, the caller should also close the corresponding loop before the current thread terminates. Bug: https://bugs.gentoo.org/758755 Signed-off-by: Zac Medico <zmedico <AT> gentoo.org> lib/portage/util/_eventloop/asyncio_event_loop.py | 6 +++++- lib/portage/util/futures/_asyncio/__init__.py | 26 +++++++++++++++++------ 2 files changed, 24 insertions(+), 8 deletions(-) diff --git a/lib/portage/util/_eventloop/asyncio_event_loop.py b/lib/portage/util/_eventloop/asyncio_event_loop.py index 836f1c30a..4d7047ae8 100644 --- a/lib/portage/util/_eventloop/asyncio_event_loop.py +++ b/lib/portage/util/_eventloop/asyncio_event_loop.py @@ -121,4 +121,8 @@ class AsyncioEventLoop(_AbstractEventLoop): try: return self._loop.run_until_complete(future) finally: - self._wakeup_fd = signal.set_wakeup_fd(-1) + try: + self._wakeup_fd = signal.set_wakeup_fd(-1) + except ValueError: + # This is intended to fail when not called in the main thread. + pass diff --git a/lib/portage/util/futures/_asyncio/__init__.py b/lib/portage/util/futures/_asyncio/__init__.py index a902ad895..6f3395a91 100644 --- a/lib/portage/util/futures/_asyncio/__init__.py +++ b/lib/portage/util/futures/_asyncio/__init__.py @@ -34,7 +34,6 @@ import portage portage.proxy.lazyimport.lazyimport(globals(), 'portage.util.futures.unix_events:_PortageEventLoopPolicy', 'portage.util.futures:compat_coroutine@_compat_coroutine', - 'portage.util._eventloop.EventLoop:EventLoop@_EventLoop', ) from portage.util._eventloop.asyncio_event_loop import AsyncioEventLoop as _AsyncioEventLoop from portage.util._eventloop.global_event_loop import ( @@ -246,14 +245,27 @@ def _wrap_loop(loop=None): def _safe_loop(): """ Return an event loop that's safe to use within the current context. - For portage internal callers, this returns a globally shared event - loop instance. For external API consumers, this constructs a - temporary event loop instance that's safe to use in a non-main - thread (it does not override the global SIGCHLD handler). + For portage internal callers or external API consumers calling from + the main thread, this returns a globally shared event loop instance. + + For external API consumers calling from a non-main thread, an + asyncio loop must be registered for the current thread, or else an + error will be raised like this: + + RuntimeError: There is no current event loop in thread 'Thread-1'. + + In order to avoid this RuntimeError, the external API consumer + is responsible for setting an event loop and managing its lifecycle. + For example, this code will set an event loop for the current thread: + + asyncio.set_event_loop(asyncio.new_event_loop()) + + In order to avoid a ResourceWarning, the caller should also close the + corresponding loop before the current thread terminates. @rtype: asyncio.AbstractEventLoop (or compatible) @return: event loop instance """ - if portage._internal_caller: + if portage._internal_caller or threading.current_thread() is threading.main_thread(): return _global_event_loop() - return _EventLoop(main=False) + return _AsyncioEventLoop()
