`strand.running_in_this_thread()` relies on thread-local storage
internally, and may return false positives if the coroutine is resumed
in a different thread than it was suspended in. In debug builds, this is
not problem, since there's no TLS optimization done by the compiler, but
in release builds, the compiler might cache the address of the
thread-local variable read before the coroutine suspension, and thus
potentially reuse the same address in a different thread after
resumption, which would cause `running_in_this_thread()` to return false
or even crash (but we didn't see any crashes related to this). So,
perform the assertion only in debug builds to prevent potential wrong
usages of the `Timeout` class. For more details, see [^1][^2][^3].
[^1]: https://github.com/chriskohlhoff/asio/issues/1366
[^2]: https://bugs.llvm.org/show_bug.cgi?id=19177
[^3]: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=26461
This is inefficient and involves possible bad surprises regarding
waiting durations on busy nodes. Instead, use `AsioConditionVariable#Wait()`
if there are no free slots. It's notified by others'
`CpuBoundWork#~CpuBoundWork()` once finished.
f isn't used otherwise in the function, so if possible, it can just be moved into the lambda, avoiding a copy.
Co-authored-by: Alexander Aleksandrovič Klimov <alexander.klimov@icinga.com>
not just boost::coroutines::detail::forced_unwind.
This is needed because as of Boost 1.87, boost::asio::spawn() uses Fiber, not Coroutine v1.
https://github.com/boostorg/asio/commit/df973a85ed69f021
This is safe because every actual exception shall inherit from std::exception. Except forced_unwind and its Fiber equivalent, so that `catch(const std::exception&)` doesn't catch them and only them.
It's not used. Also, the callback shall run completely at once. This ensures that it won't (continue to) run once another coroutine on the strand calls Timeout#Cancel().
While analyzing a possible memory leak, we encountered several coroutine
exception messages, which unfortunately do not provide any information
about what exactly went wrong, as exception diagnostics were previously
only logged at the notice level.
This is required to
- catch all exceptions and wrap them into Boost exceptions. They
are the only ones allowed with Boost.Coroutine.
- set a dedicated coroutine stack size for Windows.
refs #7431
