Eagerly receive messages with MSG_DONTWAIT before polling. This makes
the DNS resolution use case end up doing:
recvmsg (EAGAIN)
poll
recvmsg (success)
recvmsg (success)
rather than:
poll
recvmsg (success)
poll
recvmsg (success)
The logic used to allow providing a path for setting the CWD of a child process in https://codeberg.org/ziglang/zig/pulls/31090 applies here as well:
- Windows must provide a path when setting the CWD, so the path of an `Io.Dir` must be resolved before actually calling RtlSetCurrentDirectory_U
- A directory handle may have multiple paths associated with it, so providing the CWD as a string retains a legitimate use case in cases where the precise path matters
While the general guidance remains useful, it is not the case that
error.Canceled will always pass across the Group task function boundary.
Remove the too-aggressive assertions and add unit test coverage.
Closes#30096Closes#31340Closes#31358
This function works with a slice of futures and returns the index of a
completed one. This doesn't work very well in practice because it's
either too high level or too low level.
At the lower level we have Io.Batch for doing this kind of thing at the
Operation API layer.
At the higher level we have Io.Select which is a convenience wrapper
around an Io.Group and an Io.Queue.
Replaced by the lockStderr functions of std.Io. Trying to make
`std.process.stderr_thread_mutex` be a bridge across different Io
implementations didn't work in practice.
We can't use Io.Mutex in parking_futex; instead, we need a simple
parking-based mutex implementation. That's fairly simple to do.
Also deal with spurious unparks on NetBSD, where they *can* happen (as
opposed to Windows, where they cannot).
It turns out that at least on Windows, spurious unparks are *not*
possible, and in fact triggering them breaks some RTL synchronization
primitives. For instance, if you have a pending unpark going into a
contended `RtlEnterCriticalSection` call, it will never unblock. In
other words, the Windows API worked exactly how I thought it did, and
it's only the NetBSD/Illumos one which is dumb. This is actually exactly
why Windows 8 introduced the parking API despite alertable sleeps being
a thing!
This commit doesn't yet deal with making NetBSD work, nor does it even
compile I imagine. The next commit will fix everything back up.
This reverts commit c518593e97.
Importantly, adds ability to get Clock resolution, which may be zero.
This allows error.Unexpected and error.ClockUnsupported to be removed
from timeout and clock reading error sets.
- delete std.Thread.Futex
- delete std.Thread.Mutex
- delete std.Thread.Semaphore
- delete std.Thread.Condition
- delete std.Thread.RwLock
- delete std.once
std.Thread.Mutex.Recursive remains... for now. it will be replaced with
a special purpose mechanism used only by panic logic.
std.Io.Threaded exposes mutexLock and mutexUnlock for the advanced case
when you need to call them directly.
This commit should be reverted - it's testing a hypothesis that Windows
is deadlocking due to bug in the implementation of
std.Io.Threaded.parking_futex
This implementation is a bit of a hacky workaround, as we use a ntdll
API to grab the full path of the directory handle. As far as I can tell
this might be the only solution to the problem, as
kernel32.CreateProcessW takes a directory path as a string only.
I might be wrong though as haven't researched the problem thoroughly.
Andrew Kelley