Fix coreCount on Linux when using cgroup v2 with CFS throttling disabled
### Motivation:
When using `swift-nio` on Linux with cgroup v2 enabled, but with CFS
throttling disabled, it falls back to attempting to read the cpuset file
at the cgroup v1 path. This does not exist, which in turns falls back to
returning `_SC_NPROCESSORS_ONLN`, which will return the total number of
cores available (ignoring cgroup assignments).
This has unexpected effects, including the default behaviour of starting
the `MultiThreadedEventLoopGroup.singleton` with significantly more
event loops than cores available to the workload.
### Modifications:
- Adds `SystemCalls.statfs`, and associated constants, to determine the
cgroup version.
- Adds `Linux.cgroupVersion()` API to expose cgroup version.
- Adds `Linux.cgroupV2MountPoint` variable to determine the cgroup v2
mount point.
- Adds `Linux.cpuSetPathV1` & `Linux.cpuSetPathV2` (and
`Linux.cpuSetPath` convenience) variables to determine the correct cpu
set path.
- Alters `System.coreCount` to use the appropriate logic from above to
ensure that `cpuset.cpus` is parsed from the correct location.
### Result:
`Linux.coreCount` should correctly parse and return the core count on
Linux cgroup v2 enabled systems (when CFS throttling is disabled), while
maintaining correctness for other configurations.
---------
Co-authored-by: Johannes Weiss <johannesweiss@apple.com>
Co-authored-by: Cory Benfield <lukasa@apple.com>
Motivation:
`IOData` is a legacy but alas also core type that needs to be
`Sendable`. Before this PR however it can't be `Sendable` because it
holds a `FileRegion` which holds a `NIOFileDescriptor`. So let's make
all of these `Sendable` but let's also start the deprecation journey for
the following types:
- `IOData`, now soft-deprecated (no warnings) because on its reliance on
`FileRegion`
- `FileRegion`, now soft-deprecated (no warnings) because on its
reliance on `NIOFileHandle`
- `NIOFileHandle`, now soft-deprecated (warnings on the
`NIOFileHandle(descriptor:)` constructor but with a
`NIOFileHandle(_deprecatedTakingOwnershipOfDescriptor:)` alternative
- `NonBlockingFileIO`, now soft-deprecated (warnings on the `openFile`
functions (but with `_deprecated` alternatives) because of their
reliance on `NIOFileHandle)
Modification:
- Make `NIOFileDescriptor`, `FileRegion` and `IOData` `Sendable` by
tracking the fd number and the usage state in an atomic
- Enforce singular access by making the `withFileDescriptor { fd ... }`
function atomically exchange the fd number for a "I'm busy" sentinel
value
- Start deprecating `IOData`, `NIOFileHandle`, `NonBlockingFileIO`,
`FileRegion`
Result:
- `NIOFileDescriptor`, `FileRegion` and `IOData` can be `Sendable`
* Apply formatting
* Apply no block comments rule
* Apply OmitExplicitReturns
* Apple OnlyOneTrailingClosureArgument
* Apply NoAssignmentInExpressions
* Fix up DontRepeatTypeInStaticProperties lint errors
* Apply `OrderedImports`
* Apply `ReplaceForEachWithForLoop`
* format file
* Enable the formatting pipeline
* Adopt `AmbiguousTrailingClosureOverload`
* Fix license header
* Fix format check
* Fix `EndOfLineComment`
* Fix CI
* Adapt CI script to check if changes when running formatting
* Separate lint and format into to steps
* Fix format
* Adopt `UseEarlyExits`
* Revert "Adopt `UseEarlyExits`"
This reverts commit d1ac5bbe12.
Motivation:
MultcastChannel is a general abstraction for expressing multicast
capabilities on a given Channel. This abstraction doesn't have any
particularly tight tie to the POSIX layer, so it belongs in NIOCore.
This is also expressed in terms of NIONetworkDevice, so we need to move
that over. That also encourages us to bring over
System.enumerateDevices, and given that System.coreCount is also fairly
general-purpose we may as well bring it along too.
Modifications:
- Move MulticastChannel to NIOCore
- Move NIONetworkDevice to NIOCore
- Move System to NIOCore
Result:
More general-purpose abstractions in NIOCore.
Franz Busch
