This pull request converts the scheduler from a naive shared queue scheduler to a naive workstealing scheduler. The deque is still a queue inside a lock, but there is still a substantial performance gain. Fiddling with the messaging benchmark I got a ~10x speedup and observed massively reduced memory usage.
There are still *many* locations for optimization, but based on my experience so far it is a clear performance win as it is now.
This is a fairly large rollup, but I've tested everything locally, and none of
it should be platform-specific.
r=alexcrichton (bdfdbdd)
r=brson (d803c18)
r=alexcrichton (a5041d0)
r=bstrie (317412a)
r=alexcrichton (135c85e)
r=thestinger (8805baa)
r=pcwalton (0661178)
r=cmr (9397fe0)
r=cmr (caa4135)
r=cmr (6a21d93)
r=cmr (4dc3379)
r=cmr (0aa5154)
r=cmr (18be261)
r=thestinger (f10be03)
This is a reopening of #8182, although this removes any abuse of the compiler internals. Now it's just a pure syntax extension (hard coded what the attribute names are).
Write external iterators for Difference, Sym. Difference, Intersection
and Union set operations.
These iterators are generic insofar that they could work on any ordered
sequence iterators, even though they are type specialized to the
TreeSetIterator in this case.
Looking at the `check` function in the treeset tests, rustc seems
unwilling to compile a function resembling::
fn check<'a, T: Iterator<&'a int>>(... )
so the tests for these iterators are still running the legacy loop
protocol.
According to #7887, we've decided to use the syntax of `fn map<U>(f: &fn(&T) -> U) -> U`, which passes a reference to the closure, and to `fn map_move<U>(f: &fn(T) -> U) -> U` which moves the value into the closure. This PR adds these `.map_move()` functions to `Option` and `Result`.
In addition, it has these other minor features:
* Replaces a couple uses of `option.get()`, `result.get()`, and `result.get_err()` with `option.unwrap()`, `result.unwrap()`, and `result.unwrap_err()`. (See #8268 and #8288 for a more thorough adaptation of this functionality.
* Removes `option.take_map()` and `option.take_map_default()`. These two functions can be easily written as `.take().map_move(...)`.
* Adds a better error message to `result.unwrap()` and `result.unwrap_err()`.
