For now, this moves the following modules to std::sync
* UnsafeArc (also removed unwrap method)
* mpsc_queue
* spsc_queue
* atomics
* mpmc_bounded_queue
* deque
We may want to remove some of the queues, but for now this moves things out of
std::rt into std::sync
This moves the locking/waiting methods to returning an RAII struct instead of
relying on closures. Additionally, this changes the methods to all take
'&mut self' to discourage recursive locking. The new method to block is to call
`wait` on the returned RAII structure instead of calling it on the lock itself
(this enforces that the lock is held).
At the same time, this improves the Mutex interface a bit by allowing
destruction of non-initialized members and by allowing construction of an empty
mutex (nothing initialized inside).
The reasons for doing this are:
* The model on which linked failure is based is inherently complex
* The implementation is also very complex, and there are few remaining who
fully understand the implementation
* There are existing race conditions in the core context switching function of
the scheduler, and possibly others.
* It's unclear whether this model of linked failure maps well to a 1:1 threading
model
Linked failure is often a desired aspect of tasks, but we would like to take a
much more conservative approach in re-implementing linked failure if at all.
Closes#8674Closes#8318Closes#8863
These two attributes are no longer useful now that Rust has decided to leave
segmented stacks behind. It is assumed that the rust task's stack is always
large enough to make an FFI call (due to the stack being very large).
There's always the case of stack overflow, however, to consider. This does not
change the behavior of stack overflow in Rust. This is still normally triggered
by the __morestack function and aborts the whole process.
C stack overflow will continue to corrupt the stack, however (as it did before
this commit as well). The future improvement of a guard page at the end of every
rust stack is still unimplemented and is intended to be the mechanism through
which we attempt to detect C stack overflow.
Closes#8822Closes#10155
Some code cleanup, sorting of import blocks
Removed std::unstable::UnsafeArc's use of Either
Added run-fail tests for the new FailWithCause impls
Changed future_result and try to return Result<(), ~Any>.
- Internally, there is an enum of possible fail messages passend around.
- In case of linked failure or a string message, the ~Any gets
lazyly allocated in future_results recv method.
- For that, future result now returns a wrapper around a Port.
- Moved and renamed task::TaskResult into rt::task::UnwindResult
and made it an internal enum.
- Introduced a replacement typedef `type TaskResult = Result<(), ~Any>`.
It's not guaranteed that there will always be an event loop to run, and this
implementation will serve as an incredibly basic one which does not provide any
I/O, but allows the scheduler to still run.
cc #9128
This removes the stacking of type parameters that occurs when invoking
trait methods, and fixes all places in the standard library that were
relying on it. It is somewhat awkward in places; I think we'll probably
want something like the `Foo::<for T>::new()` syntax.
This means that fewer `transmute`s are required, so there is less
chance of a `transmute` not having the corresponding `forget`
(possibly leading to use-after-free, etc).
Mostly optimizing TLS accesses to bring local heap allocation performance
closer to that of oldsched. It's not completely at parity but removing the
branches involved in supporting oldsched and optimizing pthread_get/setspecific
to instead use our dedicated TCB slot will probably make up for it.
In the first commit it is obvious why some of the barriers can be changed to ```Relaxed```, but it is not as obvious for the once I changed in ```kill.rs```. The rationale for those is documented as part of the documenting commit.
Also the last commit is a temporary hack to prevent kill signals from being received in taskgroup cleanup code, which could be fixed in a more principled way once the old runtime is gone.
Change the former repetition::
for 5.times { }
to::
do 5.times { }
.times() cannot be broken with `break` or `return` anymore; for those
cases, use a numerical range loop instead.
