`std.process.spawn`: remove the TODO for nonblocking file stdio and document the behavior.
Fix a bug in Io.Uring.dup2 where the function does not return on success
Reviewed-on: https://codeberg.org/ziglang/zig/pulls/31379
Reviewed-by: Andrew Kelley <andrew@ziglang.org>
Co-authored-by: breakmit <breakmit@noreply.codeberg.org>
Co-committed-by: breakmit <breakmit@noreply.codeberg.org>
Modifies the `Allocator` implementation provided by `ArenaAllocator` to be
threadsafe using only atomics and no synchronization primitives locked
behind an `Io` implementation.
At its core this is a lock-free singly linked list which uses CAS loops to
exchange the head node. A nice property of `ArenaAllocator` is that the
only functions that can ever remove nodes from its linked list are `reset`
and `deinit`, both of which are not part of the `Allocator` interface and
thus aren't threadsafe, so node-related ABA problems are impossible.
There *are* some trade-offs: end index tracking is now per node instead of
per allocator instance. It's not possible to publish a head node and its
end index at the same time if the latter isn't part of the former.
Another compromise had to be made in regards to resizing existing nodes.
Annoyingly, `rawResize` of an arbitrary thread-safe child allocator can
of course never be guaranteed to be an atomic operation, so only one
`alloc` call can ever resize at the same time, other threads have to
consider any resizes they attempt during that time failed. This causes
slightly less optimal behavior than what could be achieved with a mutex.
The LSB of `Node.size` is used to signal that a node is being resized.
This means that all nodes have to have an even size.
Calls to `alloc` have to allocate new nodes optimistically as they can
only know whether any CAS on a head node will succeed after attempting it,
and to attempt the CAS they of course already need to know the address of
the freshly allocated node they are trying to make the new head.
The simplest solution to this would be to just free the new node again if
a CAS fails, however this can be expensive and would mean that in practice
arenas could only really be used with a GPA as their child allocator. To
work around this, this implementation keeps its own free list of nodes
which didn't make their CAS to be reused by a later `alloc` invocation.
To keep things simple and avoid ABA problems the free list is only ever
be accessed beyond its head by 'stealing' the head node (and thus the
entire list) with an atomic swap. This makes iteration and removal trivial
since there's only ever one thread doing it at a time which also owns all
nodes it's holding. When the thread is done it can just push its list onto
the free list again.
This implementation offers comparable performance to the previous one when
only being accessed by a single thread and a slight speedup compared to
the previous implementation wrapped into a `ThreadSafeAllocator` up to ~7
threads performing operations on it concurrently.
(measured on a base model MacBook Pro M1)
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.
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.
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.
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
This error is actually only ever directly returned from `std.posix.getcwd` (and only on POSIX systems, so never on Windows). Its inclusion in almost all of the error sets its currently found in is a leftover from when `std.fs.path.resolve` called `std.process.getCwdAlloc` (https://github.com/ziglang/zig/issues/13613).
by defining the pointer contents to only be synchronized after explicit
sync points, makes it legal to have a fallback implementation based on
file operations while still supporting a handful of use cases for memory
mapping.
furthermore, it makes it legal for evented I/O implementations to use
evented file I/O for the sync points rather than memory mapping.
not yet done:
- implement checking the length when options.len is null
- some windows impl work
- some wasi impl work
- unit tests
- integration with compiler
this gets the build runner compiling again on linux
this work is incomplete; it only moves code around so that environment
variables can be wrangled properly. a future commit will need to audit
the cancelation and error handling of this moved logic.
There's a good argument to not have this in the std lib but it's more
work to remove it than to leave it in, and this branch is already
20,000+ lines changed.
use the application's Io implementation where possible. This correctly
makes writing to stderr cancelable, fallible, and participate in the
application's event loop. It also removes one more hard-coded
dependency on a secondary Io implementation.
This commit sketches an idea for how to deal with detection of file
streams as being terminals.
When a File stream is a terminal, writes through the stream should have
their escapes stripped unless the programmer explicitly enables terminal
escapes. Furthermore, the programmer needs a convenient API for
intentionally outputting escapes into the stream. In particular it
should be possible to set colors that are silently discarded when the
stream is not a terminal.
This commit makes `Io.File.Writer` track the terminal mode in the
already-existing `mode` field, making it the appropriate place to
implement escape stripping.
`Io.lockStderrWriter` returns a `*Io.File.Writer` with terminal
detection already done by default. This is a higher-level application
layer stream for writing to stderr.
Meanwhile, `std.debug.lockStderrWriter` also returns a `*Io.File.Writer`
but a lower-level one that is hard-coded to use a static single-threaded
`std.Io.Threaded` instance. This is the same instance that is used for
collecting debug information and iterating the unwind info.
