reasoning is that polling with large amount of operations will be rarely
done with std.Io.Threaded. However this still provides the opportunity
to provide concurrency for any real world use cases that need it.
This commit shows a proof-of-concept direction for std.Io.VTable to go,
which is to have general support for batching, timeouts, and
non-blocking.
I'm not sure if this is a good idea or not so I'm putting it up for
scrutiny.
This commit introduces `std.Io.operate`, `std.Io.Operation`, and
implements it experimentally for `FileReadStreaming`.
In `std.Io.Threaded`, the implementation is based on poll().
This commit shows how it can be used in `std.process.run` to collect
both stdout and stderr in a single-threaded program using
`std.Threaded.Io`.
It also demonstrates how to upgrade code that was previously using
`std.Io.poll` (*not* integrated with the interface!) using concurrency.
This may not be ideal since it makes the build runner no longer support
single-threaded mode. There is still a needed abstraction for
conveniently reading multiple File streams concurrently without
io.concurrent, but this commit demonstrates that such an API can be
built on top of the new `std.Io.operate` functionality.
When `NtReadFile` returns `SUCCESS`, the APC routine still runs when
next alertable, which was previously clobbering an out of scope `done`.
Instead of adding an extra syscall to the success path, avoid all APC
side effects, allowing instant completions to return immediately.
As mlugg pointed out those race when a thread finishes an operation just
after it is canceled and then that thread to picks up another task,
resulting in these fields being potentially overwritten.
This updates fileReadStreaming on Windows to handle being alerted, and
then manage its own cancelation of the file I/O.
For now, let us refrain from putting the sync mode into the Io.File
struct, and document that to do concurrent batch operations, any Windows
file handles must be in asynchronous mode. The consequences for
violating this requirement is neither illegal behavior, nor an error,
but that concurrency is lost. In other words, deadlock might occur. This
prevents the addition of flags field.
partial revert of 2faf14200f58ee72ec3a13e894d765f59e6483a9
This tracks whether it is a file opened in synchronous mode, or
something that supports APC.
This will be needed in order to know whether concurrent batch operations
on the file should return error.ConcurrencyUnavailable, or use APC to
complete the batch.
This patch also switches to using NtCreateFile directly in
std.Io.Threaded for dirCreateFile, as well as NtReadFile for
fileReadStreaming, making it handle files opened in synchronous mode as
well as files opened in asynchronous mode.
Confusingly, the POSIX spec for clock_nanosleep() says it returns
*positive* error values directly and does not touch `errno`. Not
detecting EINTR properly here was breaking the cancellation of
threads blocked in this call when linking libc.
In Zig standard library, Dir means an open directory handle. path
represents a file system identifier string. This function is better
named after "current path" than "current dir". "get" and "working" are
superfluous.
- remove error.SharingViolation from all error sets since it has the
same meaning as FileBusy
- add error.FileBusy to CreateFileAtomicError and ReadLinkError
- update dirReadLinkWindows to use NtCreateFile and NtFsControlFile and
integrate with cancelation properly.
- move windows CTL_CODE constants to the proper namespace
- delete os.windows.ReadLink
The stated reason for this commit was cancelation didn't work. On
further review, we know why cancelation didn't work, and recent
enhancements on master branch make it easy to make it work.
Meanwhile, not using overlapped means that multiple threads cannot use
the same open socket handle. I also added line comments to explain the
choice in this revert commit.
This reverts commit fd3657bf8c.
closes#31011reopens#30865
It can fail arbitrarily with ENOENT if the kernel happens to not have the FD in
its name cache. That makes it useless for our purposes.
closes https://codeberg.org/ziglang/zig/issues/30843
Andrew Kelley