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.
- batchAwaitAsync does blocking reads with NtReadFile (no APC, no event)
when the nonblocking flag is unset, but still takes advantage of
APCs when nonblocking flag is set.
- batchAwaitConcurrent returns error.ConcurrencyUnavailable when it
encounters a file_read_streaming operation on a file in blocking mode.
- fileReadStreaming avoids pointlessly checking sync cancelation status
when nonblocking flag is set, uses an APC with a done flag, and waits
on that value to change in NtDelayExecution before returning.
- fix incorrect use of NtCancelIoFile (ntdll function prototype was
wrong, leading to misuse)
On Windows, we need to know ahead of time whether a file was opened in
synchronous mode or asynchronous mode. There may be advantages to
tracking this state for POSIX operating systems as well.
It is legal to call batchWait with already completed operations in the
ring. In such case, we need to avoid waiting in the syscall. The
any_done flag was a poor way of tracking state we already have: whether
the completion queue is empty.
This problem affects the posix poll implementation as well.
Thanks again to jacobly for finding the problem.
Andrew Kelley