1 // Copyright 2013 The Rust Project Developers. See the COPYRIGHT
2 // file at the top-level directory of this distribution and at
3 // http://rust-lang.org/COPYRIGHT.
5 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
6 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
7 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
8 // option. This file may not be copied, modified, or distributed
9 // except according to those terms.
11 //! Language-level runtime services that should reasonably expected
12 //! to be available 'everywhere'. Local heaps, GC, unwinding,
13 //! local storage, and logging. Even a 'freestanding' Rust would likely want
14 //! to implement this.
16 use super::local_heap::LocalHeap;
23 use libc::{c_void, uintptr_t, c_char, size_t};
25 use option::{Option, Some, None};
26 use rt::borrowck::BorrowRecord;
28 use rt::context::Context;
34 use rt::logging::StdErrLogger;
35 use rt::sched::{Scheduler, SchedHandle};
36 use rt::stack::{StackSegment, StackPool};
37 use send_str::SendStr;
38 use unstable::finally::Finally;
39 use unstable::mutex::Mutex;
41 // The Task struct represents all state associated with a rust
42 // task. There are at this point two primary "subtypes" of task,
43 // however instead of using a subtype we just have a "task_type" field
44 // in the struct. This contains a pointer to another struct that holds
45 // the type-specific state.
49 priv gc: GarbageCollector,
50 storage: LocalStorage,
51 logger: Option<StdErrLogger>,
55 name: Option<SendStr>,
56 coroutine: Option<Coroutine>,
57 sched: Option<~Scheduler>,
59 // Dynamic borrowck debugging info
60 borrow_list: Option<~[BorrowRecord]>,
61 stdout_handle: Option<~Writer>,
63 // See the comments in the scheduler about why this is necessary
64 nasty_deschedule_lock: Mutex,
68 GreenTask(Option<SchedHome>),
72 /// A coroutine is nothing more than a (register context, stack) pair.
73 pub struct Coroutine {
74 /// The segment of stack on which the task is currently running or
75 /// if the task is blocked, on which the task will resume
78 /// Servo needs this to be public in order to tell SpiderMonkey
79 /// about the stack bounds.
80 current_stack_segment: StackSegment,
81 /// Always valid if the task is alive and not running.
82 saved_context: Context
85 /// Some tasks have a dedicated home scheduler that they must run on.
91 pub struct GarbageCollector;
92 pub struct LocalStorage(Option<local_data::Map>);
94 /// Represents the reason for the current unwinding process
95 pub enum UnwindResult {
96 /// The task is ending successfully
99 /// The Task is failing with reason `~Any`
104 /// Returns `true` if this `UnwindResult` is a failure
106 pub fn is_failure(&self) -> bool {
113 /// Returns `true` if this `UnwindResult` is a success
115 pub fn is_success(&self) -> bool {
123 pub struct Unwinder {
129 fn to_unwind_result(&mut self) -> UnwindResult {
131 Failure(self.cause.take().unwrap())
140 // A helper to build a new task using the dynamically found
141 // scheduler and task. Only works in GreenTask context.
142 pub fn build_homed_child(stack_size: Option<uint>,
146 let mut running_task = Local::borrow(None::<Task>);
147 let mut sched = running_task.get().sched.take_unwrap();
148 let new_task = ~running_task.get()
149 .new_child_homed(&mut sched.stack_pool,
153 running_task.get().sched = Some(sched);
157 pub fn build_child(stack_size: Option<uint>, f: proc()) -> ~Task {
158 Task::build_homed_child(stack_size, f, AnySched)
161 pub fn build_homed_root(stack_size: Option<uint>,
165 let mut running_task = Local::borrow(None::<Task>);
166 let mut sched = running_task.get().sched.take_unwrap();
167 let new_task = ~Task::new_root_homed(&mut sched.stack_pool,
171 running_task.get().sched = Some(sched);
175 pub fn build_root(stack_size: Option<uint>, f: proc()) -> ~Task {
176 Task::build_homed_root(stack_size, f, AnySched)
179 pub fn new_sched_task() -> Task {
181 heap: LocalHeap::new(),
182 gc: GarbageCollector,
183 storage: LocalStorage(None),
185 unwinder: Unwinder { unwinding: false, cause: None },
188 coroutine: Some(Coroutine::empty()),
191 task_type: SchedTask,
194 nasty_deschedule_lock: unsafe { Mutex::new() },
198 pub fn new_root(stack_pool: &mut StackPool,
199 stack_size: Option<uint>,
200 start: proc()) -> Task {
201 Task::new_root_homed(stack_pool, stack_size, AnySched, start)
204 pub fn new_child(&mut self,
205 stack_pool: &mut StackPool,
206 stack_size: Option<uint>,
207 start: proc()) -> Task {
208 self.new_child_homed(stack_pool, stack_size, AnySched, start)
211 pub fn new_root_homed(stack_pool: &mut StackPool,
212 stack_size: Option<uint>,
214 start: proc()) -> Task {
216 heap: LocalHeap::new(),
217 gc: GarbageCollector,
218 storage: LocalStorage(None),
220 unwinder: Unwinder { unwinding: false, cause: None },
224 coroutine: Some(Coroutine::new(stack_pool, stack_size, start)),
226 task_type: GreenTask(Some(home)),
229 nasty_deschedule_lock: unsafe { Mutex::new() },
233 pub fn new_child_homed(&mut self,
234 stack_pool: &mut StackPool,
235 stack_size: Option<uint>,
237 start: proc()) -> Task {
239 heap: LocalHeap::new(),
240 gc: GarbageCollector,
241 storage: LocalStorage(None),
243 unwinder: Unwinder { unwinding: false, cause: None },
247 coroutine: Some(Coroutine::new(stack_pool, stack_size, start)),
249 task_type: GreenTask(Some(home)),
252 nasty_deschedule_lock: unsafe { Mutex::new() },
256 pub fn give_home(&mut self, new_home: SchedHome) {
257 match self.task_type {
258 GreenTask(ref mut home) => {
259 *home = Some(new_home);
262 rtabort!("type error: used SchedTask as GreenTask");
267 pub fn take_unwrap_home(&mut self) -> SchedHome {
268 match self.task_type {
269 GreenTask(ref mut home) => {
270 let out = home.take_unwrap();
274 rtabort!("type error: used SchedTask as GreenTask");
279 pub fn run(&mut self, f: ||) {
280 rtdebug!("run called on task: {}", borrow::to_uint(self));
282 // The only try/catch block in the world. Attempt to run the task's
283 // client-specified code and catch any failures.
284 self.unwinder.try(|| {
286 // Run the task main function, then do some cleanup.
289 // First, destroy task-local storage. This may run user dtors.
291 // FIXME #8302: Dear diary. I'm so tired and confused.
292 // There's some interaction in rustc between the box
293 // annihilator and the TLS dtor by which TLS is
294 // accessed from annihilated box dtors *after* TLS is
295 // destroyed. Somehow setting TLS back to null, as the
296 // old runtime did, makes this work, but I don't currently
297 // understand how. I would expect that, if the annihilator
298 // reinvokes TLS while TLS is uninitialized, that
299 // TLS would be reinitialized but never destroyed,
300 // but somehow this works. I have no idea what's going
301 // on but this seems to make things magically work. FML.
303 // (added after initial comment) A possible interaction here is
304 // that the destructors for the objects in TLS themselves invoke
305 // TLS, or possibly some destructors for those objects being
306 // annihilated invoke TLS. Sadly these two operations seemed to
307 // be intertwined, and miraculously work for now...
310 // Destroy remaining boxes. Also may run user dtors.
311 unsafe { cleanup::annihilate(); }
313 // Finally flush and destroy any output handles which the task
314 // owns. There are no boxes here, and no user destructors should
315 // run after this any more.
316 match self.stdout_handle.take() {
318 let mut handle = handle;
327 // Cleanup the dynamic borrowck debugging info
328 borrowck::clear_task_borrow_list();
330 self.death.collect_failure(self.unwinder.to_unwind_result());
331 self.destroyed = true;
334 // New utility functions for homes.
336 pub fn is_home_no_tls(&self, sched: &~Scheduler) -> bool {
337 match self.task_type {
338 GreenTask(Some(AnySched)) => { false }
339 GreenTask(Some(Sched(SchedHandle { sched_id: ref id, .. }))) => {
340 *id == sched.sched_id()
343 rtabort!("task without home");
347 rtabort!("type error: expected: GreenTask, found: SchedTask");
352 pub fn homed(&self) -> bool {
353 match self.task_type {
354 GreenTask(Some(AnySched)) => { false }
355 GreenTask(Some(Sched(SchedHandle { .. }))) => { true }
357 rtabort!("task without home");
360 rtabort!("type error: expected: GreenTask, found: SchedTask");
365 // Grab both the scheduler and the task from TLS and check if the
366 // task is executing on an appropriate scheduler.
367 pub fn on_appropriate_sched() -> bool {
368 let mut task = Local::borrow(None::<Task>);
369 let sched_id = task.get().sched.get_ref().sched_id();
370 let sched_run_anything = task.get().sched.get_ref().run_anything;
371 match task.get().task_type {
372 GreenTask(Some(AnySched)) => {
373 rtdebug!("anysched task in sched check ****");
376 GreenTask(Some(Sched(SchedHandle { sched_id: ref id, ..}))) => {
377 rtdebug!("homed task in sched check ****");
381 rtabort!("task without home");
384 rtabort!("type error: expected: GreenTask, found: SchedTask");
392 rtdebug!("called drop for a task: {}", borrow::to_uint(self));
393 rtassert!(self.destroyed);
395 unsafe { self.nasty_deschedule_lock.destroy(); }
399 // Coroutines represent nothing more than a context and a stack
404 pub fn new(stack_pool: &mut StackPool,
405 stack_size: Option<uint>,
408 let stack_size = match stack_size {
410 None => env::min_stack()
412 let start = Coroutine::build_start_wrapper(start);
413 let mut stack = stack_pool.take_segment(stack_size);
414 let initial_context = Context::new(start, &mut stack);
416 current_stack_segment: stack,
417 saved_context: initial_context
421 pub fn empty() -> Coroutine {
423 current_stack_segment: StackSegment::new(0),
424 saved_context: Context::empty()
428 fn build_start_wrapper(start: proc()) -> proc() {
429 let wrapper: proc() = proc() {
430 // First code after swap to this new context. Run our
434 // Again - might work while safe, or it might not.
436 let mut sched = Local::borrow(None::<Scheduler>);
437 sched.get().run_cleanup_job();
440 // To call the run method on a task we need a direct
441 // reference to it. The task is in TLS, so we can
442 // simply unsafe_borrow it to get this reference. We
443 // need to still have the task in TLS though, so we
444 // need to unsafe_borrow.
445 let task: *mut Task = Local::unsafe_borrow();
447 let mut start_cell = Some(start);
449 // N.B. Removing `start` from the start wrapper
450 // closure by emptying a cell is critical for
451 // correctness. The ~Task pointer, and in turn the
452 // closure used to initialize the first call
453 // frame, is destroyed in the scheduler context,
454 // not task context. So any captured closures must
455 // not contain user-definable dtors that expect to
456 // be in task context. By moving `start` out of
457 // the closure, all the user code goes our of
458 // scope while the task is still running.
459 let start = start_cell.take_unwrap();
464 // We remove the sched from the Task in TLS right now.
465 let sched: ~Scheduler = Local::take();
466 // ... allowing us to give it away when performing a
467 // scheduling operation.
468 sched.terminate_current_task()
473 /// Destroy coroutine and try to reuse stack segment.
474 pub fn recycle(self, stack_pool: &mut StackPool) {
476 Coroutine { current_stack_segment, .. } => {
477 stack_pool.give_segment(current_stack_segment);
485 // Just a sanity check to make sure we are catching a Rust-thrown exception
486 static UNWIND_TOKEN: uintptr_t = 839147;
489 pub fn try(&mut self, f: ||) {
490 use unstable::raw::Closure;
493 let closure: Closure = transmute(f);
494 let code = transmute(closure.code);
495 let env = transmute(closure.env);
497 let token = rust_try(try_fn, code, env);
498 assert!(token == 0 || token == UNWIND_TOKEN);
501 extern fn try_fn(code: *c_void, env: *c_void) {
503 let closure: Closure = Closure {
504 code: transmute(code),
507 let closure: || = transmute(closure);
513 fn rust_try(f: extern "C" fn(*c_void, *c_void),
515 data: *c_void) -> uintptr_t;
519 pub fn begin_unwind(&mut self, cause: ~Any) -> ! {
520 self.unwinding = true;
521 self.cause = Some(cause);
523 rust_begin_unwind(UNWIND_TOKEN);
524 return transmute(());
527 fn rust_begin_unwind(token: uintptr_t);
532 /// This function is invoked from rust's current __morestack function. Segmented
533 /// stacks are currently not enabled as segmented stacks, but rather one giant
534 /// stack segment. This means that whenever we run out of stack, we want to
535 /// truly consider it to be stack overflow rather than allocating a new stack.
536 #[no_mangle] // - this is called from C code
537 #[no_split_stack] // - it would be sad for this function to trigger __morestack
538 #[doc(hidden)] // - Function must be `pub` to get exported, but it's
539 // irrelevant for documentation purposes.
540 #[cfg(not(test))] // in testing, use the original libstd's version
541 pub extern "C" fn rust_stack_exhausted() {
542 use rt::in_green_task_context;
544 use rt::local::Local;
545 use unstable::intrinsics;
548 // We're calling this function because the stack just ran out. We need
549 // to call some other rust functions, but if we invoke the functions
550 // right now it'll just trigger this handler being called again. In
551 // order to alleviate this, we move the stack limit to be inside of the
552 // red zone that was allocated for exactly this reason.
553 let limit = context::get_sp_limit();
554 context::record_sp_limit(limit - context::RED_ZONE / 2);
556 // This probably isn't the best course of action. Ideally one would want
557 // to unwind the stack here instead of just aborting the entire process.
558 // This is a tricky problem, however. There's a few things which need to
561 // 1. We're here because of a stack overflow, yet unwinding will run
562 // destructors and hence arbitrary code. What if that code overflows
563 // the stack? One possibility is to use the above allocation of an
564 // extra 10k to hope that we don't hit the limit, and if we do then
565 // abort the whole program. Not the best, but kind of hard to deal
566 // with unless we want to switch stacks.
568 // 2. LLVM will optimize functions based on whether they can unwind or
569 // not. It will flag functions with 'nounwind' if it believes that
570 // the function cannot trigger unwinding, but if we do unwind on
571 // stack overflow then it means that we could unwind in any function
572 // anywhere. We would have to make sure that LLVM only places the
573 // nounwind flag on functions which don't call any other functions.
575 // 3. The function that overflowed may have owned arguments. These
576 // arguments need to have their destructors run, but we haven't even
577 // begun executing the function yet, so unwinding will not run the
578 // any landing pads for these functions. If this is ignored, then
579 // the arguments will just be leaked.
581 // Exactly what to do here is a very delicate topic, and is possibly
582 // still up in the air for what exactly to do. Some relevant issues:
584 // #3555 - out-of-stack failure leaks arguments
585 // #3695 - should there be a stack limit?
586 // #9855 - possible strategies which could be taken
587 // #9854 - unwinding on windows through __morestack has never worked
588 // #2361 - possible implementation of not using landing pads
590 if in_green_task_context() {
591 let mut task = Local::borrow(None::<Task>);
595 .map(|n| n.as_slice())
596 .unwrap_or("<unnamed>");
598 // See the message below for why this is not emitted to the
599 // task's logger. This has the additional conundrum of the
600 // logger may not be initialized just yet, meaning that an FFI
601 // call would happen to initialized it (calling out to libuv),
602 // and the FFI call needs 2MB of stack when we just ran out.
603 rterrln!("task '{}' has overflowed its stack", n);
605 rterrln!("stack overflow in non-task context");
612 /// This is the entry point of unwinding for things like lang items and such.
613 /// The arguments are normally generated by the compiler, and need to
614 /// have static lifetimes.
615 pub fn begin_unwind_raw(msg: *c_char, file: *c_char, line: size_t) -> ! {
620 fn static_char_ptr(p: *c_char) -> &'static str {
621 let s = unsafe { CString::new(p, false) };
623 Some(s) => unsafe { transmute::<&str, &'static str>(s) },
624 None => rtabort!("message wasn't utf8?")
628 let msg = static_char_ptr(msg);
629 let file = static_char_ptr(file);
631 begin_unwind(msg, file, line as uint)
634 /// This is the entry point of unwinding for fail!() and assert!().
635 pub fn begin_unwind<M: Any + Send>(msg: M, file: &'static str, line: uint) -> ! {
637 use rt::in_green_task_context;
638 use rt::local::Local;
641 use unstable::intrinsics;
645 // Note that this should be the only allocation performed in this block.
646 // Currently this means that fail!() on OOM will invoke this code path,
647 // but then again we're not really ready for failing on OOM anyway. If
648 // we do start doing this, then we should propagate this allocation to
649 // be performed in the parent of this task instead of the task that's
651 let msg = ~msg as ~Any;
654 //let msg: &Any = msg;
655 let msg_s = match msg.as_ref::<&'static str>() {
657 None => match msg.as_ref::<~str>() {
658 Some(s) => s.as_slice(),
663 if !in_green_task_context() {
664 rterrln!("failed in non-task context at '{}', {}:{}",
669 task = Local::unsafe_borrow();
670 let n = (*task).name.as_ref().map(|n| n.as_slice()).unwrap_or("<unnamed>");
672 // XXX: this should no get forcibly printed to the console, this should
673 // either be sent to the parent task (ideally), or get printed to
674 // the task's logger. Right now the logger is actually a uvio
675 // instance, which uses unkillable blocks internally for various
676 // reasons. This will cause serious trouble if the task is failing
677 // due to mismanagment of its own kill flag, so calling our own
678 // logger in its current state is a bit of a problem.
680 rterrln!("task '{}' failed at '{}', {}:{}", n, msg_s, file, line);
682 if (*task).unwinder.unwinding {
683 rtabort!("unwinding again");
687 (*task).unwinder.begin_unwind(msg);
698 do run_in_newsched_task() {
709 do run_in_newsched_task() {
710 local_data_key!(key: @~str)
711 local_data::set(key, @~"data");
712 assert!(*local_data::get(key, |k| k.map(|k| *k)).unwrap() == ~"data");
713 local_data_key!(key2: @~str)
714 local_data::set(key2, @~"data");
715 assert!(*local_data::get(key2, |k| k.map(|k| *k)).unwrap() == ~"data");
721 do run_in_newsched_task() {
722 let result = spawntask_try(proc()());
723 rtdebug!("trying first assert");
724 assert!(result.is_ok());
725 let result = spawntask_try(proc() fail!());
726 rtdebug!("trying second assert");
727 assert!(result.is_err());
733 do run_in_uv_task() {
734 use rand::{rng, Rng};
736 let _ = r.next_u32();
742 do run_in_uv_task() {
743 info!("here i am. logging in a newsched task");
751 do run_in_newsched_task {
752 let (port, chan) = oneshot();
754 assert!(port.recv() == 10);
762 do run_in_newsched_task() {
763 let (port, chan) = stream();
765 assert!(port.recv() == 10);
770 fn comm_shared_chan() {
773 do run_in_newsched_task() {
774 let (port, chan) = stream();
775 let chan = SharedChan::new(chan);
777 assert!(port.recv() == 10);
783 use option::{Option, Some, None};
785 do run_in_newsched_task {
787 next: Option<@mut List>,
790 let a = @mut List { next: None };
791 let b = @mut List { next: Some(a) };
799 fn test_begin_unwind() { begin_unwind("cause", file!(), line!()) }