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.
22 use iter::{Iterator, Take};
26 use option::{Option, Some, None};
28 use result::{Result, Ok, Err};
30 use rt::borrowck::BorrowRecord;
33 use rt::local_heap::LocalHeap;
34 use rt::rtio::LocalIo;
35 use rt::unwind::Unwinder;
36 use send_str::SendStr;
37 use sync::arc::UnsafeArc;
38 use sync::atomics::{AtomicUint, SeqCst};
39 use task::{TaskResult, TaskOpts};
40 use unstable::finally::Finally;
42 // The Task struct represents all state associated with a rust
43 // task. There are at this point two primary "subtypes" of task,
44 // however instead of using a subtype we just have a "task_type" field
45 // in the struct. This contains a pointer to another struct that holds
46 // the type-specific state.
51 storage: LocalStorage,
55 name: Option<SendStr>,
56 // Dynamic borrowck debugging info
57 borrow_list: Option<~[BorrowRecord]>,
59 logger: Option<~Logger>,
60 stdout: Option<~Writer>,
61 stderr: Option<~Writer>,
63 priv imp: Option<~Runtime>,
66 pub struct GarbageCollector;
67 pub struct LocalStorage(Option<local_data::Map>);
69 /// A handle to a blocked task. Usually this means having the ~Task pointer by
70 /// ownership, but if the task is killable, a killer can steal it at any time.
71 pub enum BlockedTask {
73 Shared(UnsafeArc<AtomicUint>),
76 /// Per-task state related to task death, killing, failure, etc.
78 // Action to be done with the exit code. If set, also makes the task wait
79 // until all its watched children exit before collecting the status.
80 on_exit: Option<proc(TaskResult)>,
83 pub struct BlockedTaskIterator {
84 priv inner: UnsafeArc<AtomicUint>,
88 pub fn new() -> Task {
90 heap: LocalHeap::new(),
92 storage: LocalStorage(None),
93 unwinder: Unwinder::new(),
105 /// Executes the given closure as if it's running inside this task. The task
106 /// is consumed upon entry, and the destroyed task is returned from this
107 /// function in order for the caller to free. This function is guaranteed to
108 /// not unwind because the closure specified is run inside of a `rust_try`
109 /// block. (this is the only try/catch block in the world).
111 /// This function is *not* meant to be abused as a "try/catch" block. This
112 /// is meant to be used at the absolute boundaries of a task's lifetime, and
113 /// only for that purpose.
114 pub fn run(~self, f: ||) -> ~Task {
115 // Need to put ourselves into TLS, but also need access to the unwinder.
116 // Unsafely get a handle to the task so we can continue to use it after
117 // putting it in tls (so we can invoke the unwinder).
118 let handle: *mut Task = unsafe {
119 *cast::transmute::<&~Task, &*mut Task>(&self)
123 // The only try/catch block in the world. Attempt to run the task's
124 // client-specified code and catch any failures.
127 // Run the task main function, then do some cleanup.
130 let mut task = Local::borrow(None::<Task>);
131 let logger = task.get().logger.take();
132 let stderr = task.get().stderr.take();
133 let stdout = task.get().stdout.take();
135 drop(logger); // loggers are responsible for flushing
136 match stdout { Some(mut w) => w.flush(), None => {} }
137 match stderr { Some(mut w) => w.flush(), None => {} }
140 // First, flush/destroy the user stdout/logger because these
141 // destructors can run arbitrary code.
144 // First, destroy task-local storage. This may run user dtors.
146 // FIXME #8302: Dear diary. I'm so tired and confused.
147 // There's some interaction in rustc between the box
148 // annihilator and the TLS dtor by which TLS is
149 // accessed from annihilated box dtors *after* TLS is
150 // destroyed. Somehow setting TLS back to null, as the
151 // old runtime did, makes this work, but I don't currently
152 // understand how. I would expect that, if the annihilator
153 // reinvokes TLS while TLS is uninitialized, that
154 // TLS would be reinitialized but never destroyed,
155 // but somehow this works. I have no idea what's going
156 // on but this seems to make things magically work. FML.
158 // (added after initial comment) A possible interaction here is
159 // that the destructors for the objects in TLS themselves invoke
160 // TLS, or possibly some destructors for those objects being
161 // annihilated invoke TLS. Sadly these two operations seemed to
162 // be intertwined, and miraculously work for now...
163 let mut task = Local::borrow(None::<Task>);
165 let task = task.get();
166 let LocalStorage(ref mut optmap) = task.storage;
172 // Destroy remaining boxes. Also may run user dtors.
173 unsafe { cleanup::annihilate(); }
175 // Finally, just in case user dtors printed/logged during TLS
176 // cleanup and annihilation, re-destroy stdout and the logger.
177 // Note that these will have been initialized with a
178 // runtime-provided type which we have control over what the
184 unsafe { (*handle).unwinder.try(try_block); }
186 // Cleanup the dynamic borrowck debugging info
187 borrowck::clear_task_borrow_list();
189 // Here we must unsafely borrow the task in order to not remove it from
190 // TLS. When collecting failure, we may attempt to send on a channel (or
191 // just run aribitrary code), so we must be sure to still have a local
194 let me: *mut Task = Local::unsafe_borrow();
195 (*me).death.collect_failure((*me).unwinder.result());
197 let mut me: ~Task = Local::take();
202 /// Inserts a runtime object into this task, transferring ownership to the
203 /// task. It is illegal to replace a previous runtime object in this task
204 /// with this argument.
205 pub fn put_runtime(&mut self, ops: ~Runtime) {
206 assert!(self.imp.is_none());
207 self.imp = Some(ops);
210 /// Attempts to extract the runtime as a specific type. If the runtime does
211 /// not have the provided type, then the runtime is not removed. If the
212 /// runtime does have the specified type, then it is removed and returned
213 /// (transfer of ownership).
215 /// It is recommended to only use this method when *absolutely necessary*.
216 /// This function may not be available in the future.
217 pub fn maybe_take_runtime<T: 'static>(&mut self) -> Option<~T> {
218 // This is a terrible, terrible function. The general idea here is to
219 // take the runtime, cast it to ~Any, check if it has the right type,
220 // and then re-cast it back if necessary. The method of doing this is
221 // pretty sketchy and involves shuffling vtables of trait objects
222 // around, but it gets the job done.
224 // XXX: This function is a serious code smell and should be avoided at
225 // all costs. I have yet to think of a method to avoid this
226 // function, and I would be saddened if more usage of the function
229 let imp = self.imp.take_unwrap();
230 let &(vtable, _): &(uint, uint) = cast::transmute(&imp);
231 match imp.wrap().move::<T>() {
234 let (_, obj): (uint, uint) = cast::transmute(t);
235 let obj: ~Runtime = cast::transmute((vtable, obj));
236 self.put_runtime(obj);
243 /// Spawns a sibling to this task. The newly spawned task is configured with
244 /// the `opts` structure and will run `f` as the body of its code.
245 pub fn spawn_sibling(mut ~self, opts: TaskOpts, f: proc()) {
246 let ops = self.imp.take_unwrap();
247 ops.spawn_sibling(self, opts, f)
250 /// Deschedules the current task, invoking `f` `amt` times. It is not
251 /// recommended to use this function directly, but rather communication
252 /// primitives in `std::comm` should be used.
253 pub fn deschedule(mut ~self, amt: uint,
254 f: |BlockedTask| -> Result<(), BlockedTask>) {
255 let ops = self.imp.take_unwrap();
256 ops.deschedule(amt, self, f)
259 /// Wakes up a previously blocked task, optionally specifiying whether the
260 /// current task can accept a change in scheduling. This function can only
261 /// be called on tasks that were previously blocked in `deschedule`.
262 pub fn reawaken(mut ~self, can_resched: bool) {
263 let ops = self.imp.take_unwrap();
264 ops.reawaken(self, can_resched);
267 /// Yields control of this task to another task. This function will
268 /// eventually return, but possibly not immediately. This is used as an
269 /// opportunity to allow other tasks a chance to run.
270 pub fn yield_now(mut ~self) {
271 let ops = self.imp.take_unwrap();
275 /// Similar to `yield_now`, except that this function may immediately return
276 /// without yielding (depending on what the runtime decides to do).
277 pub fn maybe_yield(mut ~self) {
278 let ops = self.imp.take_unwrap();
279 ops.maybe_yield(self);
282 /// Acquires a handle to the I/O factory that this task contains, normally
283 /// stored in the task's runtime. This factory may not always be available,
284 /// which is why the return type is `Option`
285 pub fn local_io<'a>(&'a mut self) -> Option<LocalIo<'a>> {
286 self.imp.get_mut_ref().local_io()
289 /// Returns the stack bounds for this task in (lo, hi) format. The stack
290 /// bounds may not be known for all tasks, so the return value may be
292 pub fn stack_bounds(&self) -> Option<(uint, uint)> {
293 self.imp.get_ref().stack_bounds()
299 rtdebug!("called drop for a task: {}", borrow::to_uint(self));
300 rtassert!(self.destroyed);
304 impl Iterator<BlockedTask> for BlockedTaskIterator {
305 fn next(&mut self) -> Option<BlockedTask> {
306 Some(Shared(self.inner.clone()))
311 /// Returns Some if the task was successfully woken; None if already killed.
312 pub fn wake(self) -> Option<~Task> {
314 Owned(task) => Some(task),
315 Shared(arc) => unsafe {
316 match (*arc.get()).swap(0, SeqCst) {
318 n => Some(cast::transmute(n)),
324 // This assertion has two flavours because the wake involves an atomic op.
325 // In the faster version, destructors will fail dramatically instead.
326 #[cfg(not(test))] pub fn trash(self) { }
327 #[cfg(test)] pub fn trash(self) { assert!(self.wake().is_none()); }
329 /// Create a blocked task, unless the task was already killed.
330 pub fn block(task: ~Task) -> BlockedTask {
334 /// Converts one blocked task handle to a list of many handles to the same.
335 pub fn make_selectable(self, num_handles: uint) -> Take<BlockedTaskIterator>
337 let arc = match self {
339 let flag = unsafe { AtomicUint::new(cast::transmute(task)) };
342 Shared(arc) => arc.clone(),
344 BlockedTaskIterator{ inner: arc }.take(num_handles)
347 /// Convert to an unsafe uint value. Useful for storing in a pipe's state
350 pub unsafe fn cast_to_uint(self) -> uint {
353 let blocked_task_ptr: uint = cast::transmute(task);
354 rtassert!(blocked_task_ptr & 0x1 == 0);
358 let blocked_task_ptr: uint = cast::transmute(~arc);
359 rtassert!(blocked_task_ptr & 0x1 == 0);
360 blocked_task_ptr | 0x1
365 /// Convert from an unsafe uint value. Useful for retrieving a pipe's state
368 pub unsafe fn cast_from_uint(blocked_task_ptr: uint) -> BlockedTask {
369 if blocked_task_ptr & 0x1 == 0 {
370 Owned(cast::transmute(blocked_task_ptr))
372 let ptr: ~UnsafeArc<AtomicUint> =
373 cast::transmute(blocked_task_ptr & !1);
380 pub fn new() -> Death {
381 Death { on_exit: None, }
384 /// Collect failure exit codes from children and propagate them to a parent.
385 pub fn collect_failure(&mut self, result: TaskResult) {
386 match self.on_exit.take() {
387 Some(f) => f(result),
393 impl Drop for Death {
395 // make this type noncopyable
416 local_data_key!(key: @~str)
417 local_data::set(key, @~"data");
418 assert!(*local_data::get(key, |k| k.map(|k| *k)).unwrap() == ~"data");
419 local_data_key!(key2: @~str)
420 local_data::set(key2, @~"data");
421 assert!(*local_data::get(key2, |k| k.map(|k| *k)).unwrap() == ~"data");
426 let result = task::try(proc()());
427 rtdebug!("trying first assert");
428 assert!(result.is_ok());
429 let result = task::try::<()>(proc() fail!());
430 rtdebug!("trying second assert");
431 assert!(result.is_err());
436 use rand::{rng, Rng};
438 let _ = r.next_u32();
443 info!("here i am. logging in a newsched task");
448 let (port, chan) = Chan::new();
450 assert!(port.recv() == 10);
454 fn comm_shared_chan() {
455 let (port, chan) = SharedChan::new();
457 assert!(port.recv() == 10);
463 use option::{Option, Some, None};
466 next: Option<@RefCell<List>>,
469 let a = @RefCell::new(List { next: None });
470 let b = @RefCell::new(List { next: Some(a) });
473 let mut a = a.borrow_mut();
474 a.get().next = Some(b);
480 fn test_begin_unwind() {
481 use rt::unwind::begin_unwind;
482 begin_unwind("cause", file!(), line!())
485 // Task blocking tests
488 fn block_and_wake() {
489 let task = ~Task::new();
490 let mut task = BlockedTask::block(task).wake().unwrap();
491 task.destroyed = true;