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;
33 use rt::logging::StdErrLogger;
34 use rt::sched::{Scheduler, SchedHandle};
35 use rt::stack::{StackSegment, StackPool};
36 use send_str::SendStr;
37 use unstable::finally::Finally;
38 use unstable::mutex::Mutex;
40 // The Task struct represents all state associated with a rust
41 // task. There are at this point two primary "subtypes" of task,
42 // however instead of using a subtype we just have a "task_type" field
43 // in the struct. This contains a pointer to another struct that holds
44 // the type-specific state.
48 priv gc: GarbageCollector,
49 storage: LocalStorage,
50 logger: Option<StdErrLogger>,
54 name: Option<SendStr>,
55 coroutine: Option<Coroutine>,
56 sched: Option<~Scheduler>,
58 // Dynamic borrowck debugging info
59 borrow_list: Option<~[BorrowRecord]>,
60 stdout_handle: Option<~Writer>,
62 // See the comments in the scheduler about why this is necessary
63 nasty_deschedule_lock: Mutex,
67 GreenTask(Option<SchedHome>),
71 /// A coroutine is nothing more than a (register context, stack) pair.
72 pub struct Coroutine {
73 /// The segment of stack on which the task is currently running or
74 /// if the task is blocked, on which the task will resume
77 /// Servo needs this to be public in order to tell SpiderMonkey
78 /// about the stack bounds.
79 current_stack_segment: StackSegment,
80 /// Always valid if the task is alive and not running.
81 saved_context: Context
84 /// Some tasks have a dedicated home scheduler that they must run on.
90 pub struct GarbageCollector;
91 pub struct LocalStorage(Option<local_data::Map>);
93 /// Represents the reason for the current unwinding process
94 pub enum UnwindResult {
95 /// The task is ending successfully
98 /// The Task is failing with reason `~Any`
103 /// Returns `true` if this `UnwindResult` is a failure
105 pub fn is_failure(&self) -> bool {
112 /// Returns `true` if this `UnwindResult` is a success
114 pub fn is_success(&self) -> bool {
122 pub struct Unwinder {
128 fn to_unwind_result(&mut self) -> UnwindResult {
130 Failure(self.cause.take().unwrap())
139 // A helper to build a new task using the dynamically found
140 // scheduler and task. Only works in GreenTask context.
141 pub fn build_homed_child(stack_size: Option<uint>,
145 let mut running_task = Local::borrow(None::<Task>);
146 let mut sched = running_task.get().sched.take_unwrap();
147 let new_task = ~running_task.get()
148 .new_child_homed(&mut sched.stack_pool,
152 running_task.get().sched = Some(sched);
156 pub fn build_child(stack_size: Option<uint>, f: proc()) -> ~Task {
157 Task::build_homed_child(stack_size, f, AnySched)
160 pub fn build_homed_root(stack_size: Option<uint>,
164 let mut running_task = Local::borrow(None::<Task>);
165 let mut sched = running_task.get().sched.take_unwrap();
166 let new_task = ~Task::new_root_homed(&mut sched.stack_pool,
170 running_task.get().sched = Some(sched);
174 pub fn build_root(stack_size: Option<uint>, f: proc()) -> ~Task {
175 Task::build_homed_root(stack_size, f, AnySched)
178 pub fn new_sched_task() -> Task {
180 heap: LocalHeap::new(),
181 gc: GarbageCollector,
182 storage: LocalStorage(None),
184 unwinder: Unwinder { unwinding: false, cause: None },
187 coroutine: Some(Coroutine::empty()),
190 task_type: SchedTask,
193 nasty_deschedule_lock: unsafe { Mutex::new() },
197 pub fn new_root(stack_pool: &mut StackPool,
198 stack_size: Option<uint>,
199 start: proc()) -> Task {
200 Task::new_root_homed(stack_pool, stack_size, AnySched, start)
203 pub fn new_child(&mut self,
204 stack_pool: &mut StackPool,
205 stack_size: Option<uint>,
206 start: proc()) -> Task {
207 self.new_child_homed(stack_pool, stack_size, AnySched, start)
210 pub fn new_root_homed(stack_pool: &mut StackPool,
211 stack_size: Option<uint>,
213 start: proc()) -> Task {
215 heap: LocalHeap::new(),
216 gc: GarbageCollector,
217 storage: LocalStorage(None),
219 unwinder: Unwinder { unwinding: false, cause: None },
223 coroutine: Some(Coroutine::new(stack_pool, stack_size, start)),
225 task_type: GreenTask(Some(home)),
228 nasty_deschedule_lock: unsafe { Mutex::new() },
232 pub fn new_child_homed(&mut self,
233 stack_pool: &mut StackPool,
234 stack_size: Option<uint>,
236 start: proc()) -> Task {
238 heap: LocalHeap::new(),
239 gc: GarbageCollector,
240 storage: LocalStorage(None),
242 unwinder: Unwinder { unwinding: false, cause: None },
246 coroutine: Some(Coroutine::new(stack_pool, stack_size, start)),
248 task_type: GreenTask(Some(home)),
251 nasty_deschedule_lock: unsafe { Mutex::new() },
255 pub fn give_home(&mut self, new_home: SchedHome) {
256 match self.task_type {
257 GreenTask(ref mut home) => {
258 *home = Some(new_home);
261 rtabort!("type error: used SchedTask as GreenTask");
266 pub fn take_unwrap_home(&mut self) -> SchedHome {
267 match self.task_type {
268 GreenTask(ref mut home) => {
269 let out = home.take_unwrap();
273 rtabort!("type error: used SchedTask as GreenTask");
278 pub fn run(&mut self, f: ||) {
279 rtdebug!("run called on task: {}", borrow::to_uint(self));
281 // The only try/catch block in the world. Attempt to run the task's
282 // client-specified code and catch any failures.
283 self.unwinder.try(|| {
285 // Run the task main function, then do some cleanup.
288 // First, destroy task-local storage. This may run user dtors.
290 // FIXME #8302: Dear diary. I'm so tired and confused.
291 // There's some interaction in rustc between the box
292 // annihilator and the TLS dtor by which TLS is
293 // accessed from annihilated box dtors *after* TLS is
294 // destroyed. Somehow setting TLS back to null, as the
295 // old runtime did, makes this work, but I don't currently
296 // understand how. I would expect that, if the annihilator
297 // reinvokes TLS while TLS is uninitialized, that
298 // TLS would be reinitialized but never destroyed,
299 // but somehow this works. I have no idea what's going
300 // on but this seems to make things magically work. FML.
302 // (added after initial comment) A possible interaction here is
303 // that the destructors for the objects in TLS themselves invoke
304 // TLS, or possibly some destructors for those objects being
305 // annihilated invoke TLS. Sadly these two operations seemed to
306 // be intertwined, and miraculously work for now...
309 // Destroy remaining boxes. Also may run user dtors.
310 unsafe { cleanup::annihilate(); }
312 // Finally flush and destroy any output handles which the task
313 // owns. There are no boxes here, and no user destructors should
314 // run after this any more.
315 match self.stdout_handle.take() {
317 let mut handle = handle;
326 // Cleanup the dynamic borrowck debugging info
327 borrowck::clear_task_borrow_list();
329 self.death.collect_failure(self.unwinder.to_unwind_result());
330 self.destroyed = true;
333 // New utility functions for homes.
335 pub fn is_home_no_tls(&self, sched: &~Scheduler) -> bool {
336 match self.task_type {
337 GreenTask(Some(AnySched)) => { false }
338 GreenTask(Some(Sched(SchedHandle { sched_id: ref id, .. }))) => {
339 *id == sched.sched_id()
342 rtabort!("task without home");
346 rtabort!("type error: expected: GreenTask, found: SchedTask");
351 pub fn homed(&self) -> bool {
352 match self.task_type {
353 GreenTask(Some(AnySched)) => { false }
354 GreenTask(Some(Sched(SchedHandle { .. }))) => { true }
356 rtabort!("task without home");
359 rtabort!("type error: expected: GreenTask, found: SchedTask");
364 // Grab both the scheduler and the task from TLS and check if the
365 // task is executing on an appropriate scheduler.
366 pub fn on_appropriate_sched() -> bool {
367 let mut task = Local::borrow(None::<Task>);
368 let sched_id = task.get().sched.get_ref().sched_id();
369 let sched_run_anything = task.get().sched.get_ref().run_anything;
370 match task.get().task_type {
371 GreenTask(Some(AnySched)) => {
372 rtdebug!("anysched task in sched check ****");
375 GreenTask(Some(Sched(SchedHandle { sched_id: ref id, ..}))) => {
376 rtdebug!("homed task in sched check ****");
380 rtabort!("task without home");
383 rtabort!("type error: expected: GreenTask, found: SchedTask");
391 rtdebug!("called drop for a task: {}", borrow::to_uint(self));
392 rtassert!(self.destroyed);
394 unsafe { self.nasty_deschedule_lock.destroy(); }
398 // Coroutines represent nothing more than a context and a stack
403 pub fn new(stack_pool: &mut StackPool,
404 stack_size: Option<uint>,
407 let stack_size = match stack_size {
409 None => env::min_stack()
411 let start = Coroutine::build_start_wrapper(start);
412 let mut stack = stack_pool.take_segment(stack_size);
413 let initial_context = Context::new(start, &mut stack);
415 current_stack_segment: stack,
416 saved_context: initial_context
420 pub fn empty() -> Coroutine {
422 current_stack_segment: StackSegment::new(0),
423 saved_context: Context::empty()
427 fn build_start_wrapper(start: proc()) -> proc() {
428 let wrapper: proc() = proc() {
429 // First code after swap to this new context. Run our
433 // Again - might work while safe, or it might not.
435 let mut sched = Local::borrow(None::<Scheduler>);
436 sched.get().run_cleanup_job();
439 // To call the run method on a task we need a direct
440 // reference to it. The task is in TLS, so we can
441 // simply unsafe_borrow it to get this reference. We
442 // need to still have the task in TLS though, so we
443 // need to unsafe_borrow.
444 let task: *mut Task = Local::unsafe_borrow();
446 let mut start_cell = Some(start);
448 // N.B. Removing `start` from the start wrapper
449 // closure by emptying a cell is critical for
450 // correctness. The ~Task pointer, and in turn the
451 // closure used to initialize the first call
452 // frame, is destroyed in the scheduler context,
453 // not task context. So any captured closures must
454 // not contain user-definable dtors that expect to
455 // be in task context. By moving `start` out of
456 // the closure, all the user code goes our of
457 // scope while the task is still running.
458 let start = start_cell.take_unwrap();
463 // We remove the sched from the Task in TLS right now.
464 let sched: ~Scheduler = Local::take();
465 // ... allowing us to give it away when performing a
466 // scheduling operation.
467 sched.terminate_current_task()
472 /// Destroy coroutine and try to reuse stack segment.
473 pub fn recycle(self, stack_pool: &mut StackPool) {
475 Coroutine { current_stack_segment, .. } => {
476 stack_pool.give_segment(current_stack_segment);
484 // Just a sanity check to make sure we are catching a Rust-thrown exception
485 static UNWIND_TOKEN: uintptr_t = 839147;
488 pub fn try(&mut self, f: ||) {
489 use unstable::raw::Closure;
492 let closure: Closure = transmute(f);
493 let code = transmute(closure.code);
494 let env = transmute(closure.env);
496 let token = rust_try(try_fn, code, env);
497 assert!(token == 0 || token == UNWIND_TOKEN);
500 extern fn try_fn(code: *c_void, env: *c_void) {
502 let closure: Closure = Closure {
503 code: transmute(code),
506 let closure: || = transmute(closure);
512 fn rust_try(f: extern "C" fn(*c_void, *c_void),
514 data: *c_void) -> uintptr_t;
518 pub fn begin_unwind(&mut self, cause: ~Any) -> ! {
519 self.unwinding = true;
520 self.cause = Some(cause);
522 rust_begin_unwind(UNWIND_TOKEN);
523 return transmute(());
526 fn rust_begin_unwind(token: uintptr_t);
531 /// This function is invoked from rust's current __morestack function. Segmented
532 /// stacks are currently not enabled as segmented stacks, but rather one giant
533 /// stack segment. This means that whenever we run out of stack, we want to
534 /// truly consider it to be stack overflow rather than allocating a new stack.
535 #[no_mangle] // - this is called from C code
536 #[no_split_stack] // - it would be sad for this function to trigger __morestack
537 #[doc(hidden)] // - Function must be `pub` to get exported, but it's
538 // irrelevant for documentation purposes.
539 #[cfg(not(test))] // in testing, use the original libstd's version
540 pub extern "C" fn rust_stack_exhausted() {
541 use rt::in_green_task_context;
543 use rt::local::Local;
544 use unstable::intrinsics;
547 // We're calling this function because the stack just ran out. We need
548 // to call some other rust functions, but if we invoke the functions
549 // right now it'll just trigger this handler being called again. In
550 // order to alleviate this, we move the stack limit to be inside of the
551 // red zone that was allocated for exactly this reason.
552 let limit = context::get_sp_limit();
553 context::record_sp_limit(limit - context::RED_ZONE / 2);
555 // This probably isn't the best course of action. Ideally one would want
556 // to unwind the stack here instead of just aborting the entire process.
557 // This is a tricky problem, however. There's a few things which need to
560 // 1. We're here because of a stack overflow, yet unwinding will run
561 // destructors and hence arbitrary code. What if that code overflows
562 // the stack? One possibility is to use the above allocation of an
563 // extra 10k to hope that we don't hit the limit, and if we do then
564 // abort the whole program. Not the best, but kind of hard to deal
565 // with unless we want to switch stacks.
567 // 2. LLVM will optimize functions based on whether they can unwind or
568 // not. It will flag functions with 'nounwind' if it believes that
569 // the function cannot trigger unwinding, but if we do unwind on
570 // stack overflow then it means that we could unwind in any function
571 // anywhere. We would have to make sure that LLVM only places the
572 // nounwind flag on functions which don't call any other functions.
574 // 3. The function that overflowed may have owned arguments. These
575 // arguments need to have their destructors run, but we haven't even
576 // begun executing the function yet, so unwinding will not run the
577 // any landing pads for these functions. If this is ignored, then
578 // the arguments will just be leaked.
580 // Exactly what to do here is a very delicate topic, and is possibly
581 // still up in the air for what exactly to do. Some relevant issues:
583 // #3555 - out-of-stack failure leaks arguments
584 // #3695 - should there be a stack limit?
585 // #9855 - possible strategies which could be taken
586 // #9854 - unwinding on windows through __morestack has never worked
587 // #2361 - possible implementation of not using landing pads
589 if in_green_task_context() {
590 let mut task = Local::borrow(None::<Task>);
594 .map(|n| n.as_slice())
595 .unwrap_or("<unnamed>");
597 // See the message below for why this is not emitted to the
598 // task's logger. This has the additional conundrum of the
599 // logger may not be initialized just yet, meaning that an FFI
600 // call would happen to initialized it (calling out to libuv),
601 // and the FFI call needs 2MB of stack when we just ran out.
602 rterrln!("task '{}' has overflowed its stack", n);
604 rterrln!("stack overflow in non-task context");
611 /// This is the entry point of unwinding for things like lang items and such.
612 /// The arguments are normally generated by the compiler, and need to
613 /// have static lifetimes.
614 pub fn begin_unwind_raw(msg: *c_char, file: *c_char, line: size_t) -> ! {
619 fn static_char_ptr(p: *c_char) -> &'static str {
620 let s = unsafe { CString::new(p, false) };
622 Some(s) => unsafe { transmute::<&str, &'static str>(s) },
623 None => rtabort!("message wasn't utf8?")
627 let msg = static_char_ptr(msg);
628 let file = static_char_ptr(file);
630 begin_unwind(msg, file, line as uint)
633 /// This is the entry point of unwinding for fail!() and assert!().
634 pub fn begin_unwind<M: Any + Send>(msg: M, file: &'static str, line: uint) -> ! {
636 use rt::in_green_task_context;
637 use rt::local::Local;
640 use unstable::intrinsics;
644 // Note that this should be the only allocation performed in this block.
645 // Currently this means that fail!() on OOM will invoke this code path,
646 // but then again we're not really ready for failing on OOM anyway. If
647 // we do start doing this, then we should propagate this allocation to
648 // be performed in the parent of this task instead of the task that's
650 let msg = ~msg as ~Any;
653 //let msg: &Any = msg;
654 let msg_s = match msg.as_ref::<&'static str>() {
656 None => match msg.as_ref::<~str>() {
657 Some(s) => s.as_slice(),
662 if !in_green_task_context() {
663 rterrln!("failed in non-task context at '{}', {}:{}",
668 task = Local::unsafe_borrow();
669 let n = (*task).name.as_ref().map(|n| n.as_slice()).unwrap_or("<unnamed>");
671 // XXX: this should no get forcibly printed to the console, this should
672 // either be sent to the parent task (ideally), or get printed to
673 // the task's logger. Right now the logger is actually a uvio
674 // instance, which uses unkillable blocks internally for various
675 // reasons. This will cause serious trouble if the task is failing
676 // due to mismanagment of its own kill flag, so calling our own
677 // logger in its current state is a bit of a problem.
679 rterrln!("task '{}' failed at '{}', {}:{}", n, msg_s, file, line);
681 if (*task).unwinder.unwinding {
682 rtabort!("unwinding again");
686 (*task).unwinder.begin_unwind(msg);
697 do run_in_newsched_task() {
708 do run_in_newsched_task() {
709 local_data_key!(key: @~str)
710 local_data::set(key, @~"data");
711 assert!(*local_data::get(key, |k| k.map(|k| *k)).unwrap() == ~"data");
712 local_data_key!(key2: @~str)
713 local_data::set(key2, @~"data");
714 assert!(*local_data::get(key2, |k| k.map(|k| *k)).unwrap() == ~"data");
720 do run_in_newsched_task() {
721 let result = spawntask_try(proc()());
722 rtdebug!("trying first assert");
723 assert!(result.is_ok());
724 let result = spawntask_try(proc() fail!());
725 rtdebug!("trying second assert");
726 assert!(result.is_err());
732 do run_in_uv_task() {
733 use rand::{rng, Rng};
735 let _ = r.next_u32();
741 do run_in_uv_task() {
742 info!("here i am. logging in a newsched task");
750 do run_in_newsched_task {
751 let (port, chan) = oneshot();
753 assert!(port.recv() == 10);
761 do run_in_newsched_task() {
762 let (port, chan) = stream();
764 assert!(port.recv() == 10);
769 fn comm_shared_chan() {
772 do run_in_newsched_task() {
773 let (port, chan) = stream();
774 let chan = SharedChan::new(chan);
776 assert!(port.recv() == 10);
782 use option::{Option, Some, None};
784 do run_in_newsched_task {
786 next: Option<@mut List>,
789 let a = @mut List { next: None };
790 let b = @mut List { next: Some(a) };
798 fn test_begin_unwind() { begin_unwind("cause", file!(), line!()) }