libuv handles are tied to the event loop that created them. In order to perform IO, the handle must be on the thread with its home event loop. Thus, when as task wants to do IO it must first go to the IO handle's home event loop and pin itself to the corresponding scheduler while the IO action is in flight. Once the IO action completes, the task is unpinned and either returns to its home scheduler if it is a pinned task, or otherwise stays on the current scheduler.
Making new blocking IO implementations (i.e. files) thread safe is rather simple. Add a home field to the IO handle's struct in uvio and implement the HomingIO trait. Wrap every IO call in the HomingIO.home_for_io method, which will take care of the scheduling.
I'm not sure if this remains thread safe in the presence of asynchronous IO at the libuv level. If we decide to do that, then this set up should be revisited.
The first commit message is pretty good, but whomever reviews this should probably also at least glance at the changes I made in LLVM. I basically reorganized our pending patch queue to be a bit more organized and clearer in what needs to go where. After this, our queue would be:
* Add the `no-split-stack` attribute
* Add the `fixedstacksegment` attribute
* Add split-stacks for arm android
* Add split-stacks for arm linux
* Add split stacks for mips
Then there's a patch which I added to get rust to build at all on LLVM-head, and I'm not quite sure why it's there, but nothing seems to be crashing for now! (famous last words).
Otherwise, I just updated code to reflect the changes I made in LLVM with the only major change being the advent of the new `no_split_stack` attribute. This is work towards #1226, but someone more familiar with the code should probably actually assign the attribute to the appropriate functions.
Also as a bonus, I've verified that this closes#5774
Instead of a furious storm of idle callbacks we just have one. This is a major performance gain - around 40% on my machine for the ping pong bench.
Also in this PR is a cleanup commit for the scheduler code. Was previously up as a separate PR, but bors load + imminent merge hell led me to roll them together. Was #8549.
"non-mechanical" : there was lots more hacking than the other more-mechanical ports Felix did.
r? @huonw. (Or @nikomatsakis ; I just want someone to sanity-check this. Its not a thing of beauty.)
Followup to #8623. (See #8527, which was step 1 of 5, for the full outline. Part of #7081.)
Notes on the change follow.
There's also a strange pattern that I hacked in to accommodate the
Outer/Inner traversal structure of the existing code (which was
previously encoding this by untying the Y-combinator style knot of the
vtable, and then retying it but superimposing new methods that "stop
at items"). I hope either I or someone else can come back in the
future and replace this ugliness with something more natural.
Added boilerplate macro; all the OuterLint definitions are the same
(but must be abstracted over implementing struct, thus the macro).
Revised lint.rs use declarations to make ast references explicit.
Also removed unused imports.
That is, there was lots more hacking than the other more-mechanical
ports Felix did.
There's also a strange pattern that I hacked in to accommodate the
Outer/Inner traversal structure of the existing code (which was
previously encoding this by untying the Y-combinator style knot of the
vtable, and then retying it but superimposing new methods that "stop
at items"). I hope either I or someone else can come back in the
future and replace this ugliness with something more natural.
Added boilerplate macro; all the OuterLint definitions are the same
(but must be abstracted over implementing struct, thus the macro).
Revised lint.rs use declarations to make ast references explicit.
Also removed unused imports.
* This has one workaround patch (everything's testing just fine...)
* I reworked the fixedstacksegment attribute to be specified with a string
rather than using a keyword and an integer and modifying the parser
* I added a "no-split-stack" attribute along the same lines as the
"fixedstacksegment" attribute for #1226
r? @brson This necessitated some cleanup to how we parse library filenames
when searching for libraries, since rustpkg may now create filenames
that contain '-' characters. Also cleaned up how rustpkg passes the
sysroot to a custom build script.
Each IO handle has a home event loop, which created it.
When a task wants to use an IO handle, it must first make sure it is on that home event loop.
It uses the scheduler handle in the IO handle to send itself there before starting the IO action.
Once the IO action completes, the task restores its previous home state.
If it is an AnySched task, then it will be executed on the new scheduler.
If it has a normal home, then it will return there before executing any more code after the IO action.
This necessitated some cleanup to how we parse library filenames
when searching for libraries, since rustpkg may now create filenames
that contain '-' characters. Also cleaned up how rustpkg passes the
sysroot to a custom build script.
This requires changes to method search and to codegen. We now emit a
vtable for objects that includes methods from all supertraits.
Closes#4100.
Also, actually populate the cache for vtables, and also key it by type
so that it actually works.
Long-standing branch to remove foreign function wrappers altogether. Calls to C functions are done "in place" with no stack manipulation; the scheme relies entirely on the correct use of `#[fixed_stack_segment]` to guarantee adequate stack space. A linter is added to detect when `#[fixed_stack_segment]` annotations are missing. An `externfn!` macro is added to make it easier to declare foreign fns and wrappers in one go: this macro may need some refinement, though, for example it might be good to be able to declare a group of foreign fns. I leave that for future work (hopefully somebody else's work :) ).
Fixes#3678.
See discussion in #8489, but this selects option 3 by adding a `Default` trait to be implemented by various basic types.
Once this makes it into a snapshot I think it's about time to start overhauling all current use-cases of `fmt!` to move towards `ifmt!`. The goal is to replace `%X` with `{}` in 90% of situations, and this commit should enable that.
@brson grilled me about how this bugfix worked the first time around, and it occurred to me that it didn't in the case where the task is unwinding. Now it will.
When using a `do` block to call an internal iterator, if you forgot to
return a value from the body, it would tell you
error: Do-block body must return bool, but returns () here. Perhaps
you meant to write a `for`-loop?
This advice no longer applies as `for` loops are now for external
iterators. Delete this message outright and let it use the default error
message
error: mismatched types: expected `bool` but found `()`
r? @thestinger
Address issue #5257, for example these values all had the same hash value:
("aaa", "bbb", "ccc")
("aaab", "bb", "ccc")
("aaabbb", "", "ccc")
IterBytes for &[A] now includes the length, before calling iter_bytes on
each element.
IterBytes for &str is now terminated by a byte that does not appear in
UTF-8. This way only one more byte is processed when hashing strings.
