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.
This commit includes some API changes which I agreed with Andrew as a
follow-up to the recent `Io.Group` changes:
* `Io.Group.await` *does* propagate cancelation to group tasks; it then
waits for them to complete, and *also* returns `error.Canceled`. The
assertion that group tasks handle `error.Canceled` "correctly" means
this behavior is loosely analagous to how awaiting a future works. The
important thing is that the semantics of `Group.await` and
`Future.await` are similar, and `error.Canceled` will always be
visible to the caller (assuming correct API usage).
* `Io.Group.awaitUncancelable` is removed.
* `Future.await` calls `recancel` only if the "child" task (the future
being awaited) did not acknowledge cancelation. If it did, then it is
assumed that the future will propagate `error.Canceled` through
`await` as needed.
Now, the return type of functions spawned with `Group.async` and
`Group.concurrent` may be anything that coerces to `Io.Cancelable!void`.
Before this commit, group tasks were the only exception to the rule
"error.Canceled should never be swallowed". Now, there is no exception,
and it is enforced with an assertion upon closure completion.
Finally, fixes a case of swallowing error.Canceled in the compiler,
solving a TODO.
There are three ways to handle `error.Canceled`. In order of most
common:
1. Propagate it
2. After receiving it, io.recancel() and then don't propagate it
3. Make it unreachable with io.swapCancelProtection()
Rename `wait` to `await` to be consistent with Future API. The
convention here is that this set of functionality goes together:
* async/concurrent
* await/cancel
Also rename Select `wait` to `await` for the same reason.
`Group.await` now can return `error.Canceled`. Furthermore,
`Group.await` does not auto-propagate cancelation. Instead, users should
follow the pattern of `defer group.cancel(io);` after initialization,
and doing `try group.await(io);` at the end of the success path.
Advanced logic can choose to do something other than this pattern in the
event of cancelation.
Additionally, fixes a bug in `std.Io.Threaded` future await, in which it
swallowed an `error.Canceled`. Now if a task is canceled while awaiting
a future, after propagating the cancel request, it also recancels,
meaning that the awaiting task will properly detect its own cancelation
at the next cancelation point.
Furthermore, fixes a bug in the compiler where `error.Canceled` was
being swallowed in `dispatchPrelinkWork`.
Finally, fixes std.crypto code that inappropriately used
`catch unreachable` in response to cancelation without even so much as a
comment explaining why it was believed to be unreachable. Now, those
functions have `error.Canceled` in the error set and propagate
cancelation properly.
With this way of doing things, `Group.await` has a nice property: even if
all tasks in the group are CPU bound and without cancelation points, the
`Group.await` can still be canceled. In such case, the task that was
waiting for `await` wakes up with a chance to do some more resource
cleanup tasks, such as canceling more things, before entering the
deferred `Group.cancel` call at which point it has to suspend until the
canceled but uninterruptible CPU bound tasks complete.
closes#30601
move some of the clearing logic from std.Io.Threaded to the Io interface
layer, thus allowing it to be skipped by advanced usage code via calling
the vtable functions directly.
then take advantage of this in std.Progress to avoid clearing the
terminal twice.
closes#30611
Some filesystems, such as ZFS, do not report atime. It's pretty useless
in general, so make it an optional field in File.Stat.
Also take the opportunity to make setting timestamps API more flexible
and match the APIs widely available, which have UTIME_OMIT and UTIME_NOW
constants that can be independently set for both fields.
This is needed to handle smoothly the case when atime is null.
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.
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.
Queues can now be "closed". A closed queue cannot have more elements
appended with `put`, and blocked calls to `put` will immediately unblock
having failed to append some elements. Calls to `get` will continue to
succeed as long as the queue buffer is non-empty, but will then never
block; already-blocked calls to `get` will unblock.
All queue get/put operations can now return `error.Closed` to indicate
that the queue has been closed. For bulk get/put operations, they may
add/receive fewer elements than the minimum requested *if* the queue was
closed or the calling task was canceled. In that case, if any elements
were already added/received, they are returned first, and successive
calls will return `error.Closed` or `error.Canceled`.
Also, fix a bug where `Queue.get` could deadlock because it incorrectly
blocked until the given buffer was *filled*.
Resolves: #30141
This work was partially cherry-picked from Andrew's WIP std.fs branch.
However, I also analyzed and simplified the Mutex and Condition
implementations, and brought them in line with modern Zig style.
Co-authored-by: Andrew Kelley <andrew@ziglang.org>
Now, before a syscall is entered, beginSyscall is called, which may
return error.Canceled. After syscall returns, whether error or success,
endSyscall is called. If the syscall returns EINTR then checkCancel is
called.
`cancelRequested` is removed from the std.Io VTable for now, with plans
to replace it with a more powerful API that allows protection against
cancellation requests.
closes#25751
