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.
21 use iter::{Iterator, Take};
24 use option::{Option, Some, None};
26 use result::{Result, Ok, Err};
28 use rt::borrowck::BorrowRecord;
31 use rt::local_heap::LocalHeap;
32 use rt::logging::StdErrLogger;
33 use rt::rtio::LocalIo;
34 use rt::unwind::Unwinder;
35 use send_str::SendStr;
36 use sync::arc::UnsafeArc;
37 use sync::atomics::{AtomicUint, SeqCst};
38 use task::{TaskResult, TaskOpts};
39 use unstable::finally::Finally;
42 pub use rt::unwind::begin_unwind;
44 // The Task struct represents all state associated with a rust
45 // task. There are at this point two primary "subtypes" of task,
46 // however instead of using a subtype we just have a "task_type" field
47 // in the struct. This contains a pointer to another struct that holds
48 // the type-specific state.
53 storage: LocalStorage,
57 name: Option<SendStr>,
58 // Dynamic borrowck debugging info
59 borrow_list: Option<~[BorrowRecord]>,
61 logger: Option<StdErrLogger>,
62 stdout_handle: Option<~Writer>,
64 priv imp: Option<~Runtime>,
67 pub struct GarbageCollector;
68 pub struct LocalStorage(Option<local_data::Map>);
70 /// A handle to a blocked task. Usually this means having the ~Task pointer by
71 /// ownership, but if the task is killable, a killer can steal it at any time.
72 pub enum BlockedTask {
74 Shared(UnsafeArc<AtomicUint>),
77 /// Per-task state related to task death, killing, failure, etc.
79 // Action to be done with the exit code. If set, also makes the task wait
80 // until all its watched children exit before collecting the status.
81 on_exit: Option<proc(TaskResult)>,
84 pub struct BlockedTaskIterator {
85 priv inner: UnsafeArc<AtomicUint>,
89 pub fn new() -> Task {
91 heap: LocalHeap::new(),
93 storage: LocalStorage(None),
94 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.
129 fn flush(w: Option<~Writer>) {
131 Some(mut w) => { w.flush(); }
136 // First, destroy task-local storage. This may run user dtors.
138 // FIXME #8302: Dear diary. I'm so tired and confused.
139 // There's some interaction in rustc between the box
140 // annihilator and the TLS dtor by which TLS is
141 // accessed from annihilated box dtors *after* TLS is
142 // destroyed. Somehow setting TLS back to null, as the
143 // old runtime did, makes this work, but I don't currently
144 // understand how. I would expect that, if the annihilator
145 // reinvokes TLS while TLS is uninitialized, that
146 // TLS would be reinitialized but never destroyed,
147 // but somehow this works. I have no idea what's going
148 // on but this seems to make things magically work. FML.
150 // (added after initial comment) A possible interaction here is
151 // that the destructors for the objects in TLS themselves invoke
152 // TLS, or possibly some destructors for those objects being
153 // annihilated invoke TLS. Sadly these two operations seemed to
154 // be intertwined, and miraculously work for now...
155 let mut task = Local::borrow(None::<Task>);
157 let task = task.get();
158 let LocalStorage(ref mut optmap) = task.storage;
164 // Destroy remaining boxes. Also may run user dtors.
165 unsafe { cleanup::annihilate(); }
167 // Finally flush and destroy any output handles which the task
168 // owns. There are no boxes here, and no user destructors should
169 // run after this any more.
170 let mut task = Local::borrow(None::<Task>);
171 let stdout = task.get().stdout_handle.take();
172 let logger = task.get().logger.take();
180 unsafe { (*handle).unwinder.try(try_block); }
182 // Cleanup the dynamic borrowck debugging info
183 borrowck::clear_task_borrow_list();
185 // Here we must unsafely borrow the task in order to not remove it from
186 // TLS. When collecting failure, we may attempt to send on a channel (or
187 // just run aribitrary code), so we must be sure to still have a local
190 let me: *mut Task = Local::unsafe_borrow();
191 (*me).death.collect_failure((*me).unwinder.result());
193 let mut me: ~Task = Local::take();
198 /// Inserts a runtime object into this task, transferring ownership to the
199 /// task. It is illegal to replace a previous runtime object in this task
200 /// with this argument.
201 pub fn put_runtime(&mut self, ops: ~Runtime) {
202 assert!(self.imp.is_none());
203 self.imp = Some(ops);
206 /// Attempts to extract the runtime as a specific type. If the runtime does
207 /// not have the provided type, then the runtime is not removed. If the
208 /// runtime does have the specified type, then it is removed and returned
209 /// (transfer of ownership).
211 /// It is recommended to only use this method when *absolutely necessary*.
212 /// This function may not be available in the future.
213 pub fn maybe_take_runtime<T: 'static>(&mut self) -> Option<~T> {
214 // This is a terrible, terrible function. The general idea here is to
215 // take the runtime, cast it to ~Any, check if it has the right type,
216 // and then re-cast it back if necessary. The method of doing this is
217 // pretty sketchy and involves shuffling vtables of trait objects
218 // around, but it gets the job done.
220 // XXX: This function is a serious code smell and should be avoided at
221 // all costs. I have yet to think of a method to avoid this
222 // function, and I would be saddened if more usage of the function
225 let imp = self.imp.take_unwrap();
226 let &(vtable, _): &(uint, uint) = cast::transmute(&imp);
227 match imp.wrap().move::<T>() {
230 let (_, obj): (uint, uint) = cast::transmute(t);
231 let obj: ~Runtime = cast::transmute((vtable, obj));
232 self.put_runtime(obj);
239 /// Spawns a sibling to this task. The newly spawned task is configured with
240 /// the `opts` structure and will run `f` as the body of its code.
241 pub fn spawn_sibling(mut ~self, opts: TaskOpts, f: proc()) {
242 let ops = self.imp.take_unwrap();
243 ops.spawn_sibling(self, opts, f)
246 /// Deschedules the current task, invoking `f` `amt` times. It is not
247 /// recommended to use this function directly, but rather communication
248 /// primitives in `std::comm` should be used.
249 pub fn deschedule(mut ~self, amt: uint,
250 f: |BlockedTask| -> Result<(), BlockedTask>) {
251 let ops = self.imp.take_unwrap();
252 ops.deschedule(amt, self, f)
255 /// Wakes up a previously blocked task, optionally specifiying whether the
256 /// current task can accept a change in scheduling. This function can only
257 /// be called on tasks that were previously blocked in `deschedule`.
258 pub fn reawaken(mut ~self, can_resched: bool) {
259 let ops = self.imp.take_unwrap();
260 ops.reawaken(self, can_resched);
263 /// Yields control of this task to another task. This function will
264 /// eventually return, but possibly not immediately. This is used as an
265 /// opportunity to allow other tasks a chance to run.
266 pub fn yield_now(mut ~self) {
267 let ops = self.imp.take_unwrap();
271 /// Similar to `yield_now`, except that this function may immediately return
272 /// without yielding (depending on what the runtime decides to do).
273 pub fn maybe_yield(mut ~self) {
274 let ops = self.imp.take_unwrap();
275 ops.maybe_yield(self);
278 /// Acquires a handle to the I/O factory that this task contains, normally
279 /// stored in the task's runtime. This factory may not always be available,
280 /// which is why the return type is `Option`
281 pub fn local_io<'a>(&'a mut self) -> Option<LocalIo<'a>> {
282 self.imp.get_mut_ref().local_io()
285 /// Returns the stack bounds for this task in (lo, hi) format. The stack
286 /// bounds may not be known for all tasks, so the return value may be
288 pub fn stack_bounds(&self) -> Option<(uint, uint)> {
289 self.imp.get_ref().stack_bounds()
295 rtdebug!("called drop for a task: {}", borrow::to_uint(self));
296 rtassert!(self.destroyed);
300 impl Iterator<BlockedTask> for BlockedTaskIterator {
301 fn next(&mut self) -> Option<BlockedTask> {
302 Some(Shared(self.inner.clone()))
307 /// Returns Some if the task was successfully woken; None if already killed.
308 pub fn wake(self) -> Option<~Task> {
310 Owned(task) => Some(task),
311 Shared(arc) => unsafe {
312 match (*arc.get()).swap(0, SeqCst) {
314 n => Some(cast::transmute(n)),
320 // This assertion has two flavours because the wake involves an atomic op.
321 // In the faster version, destructors will fail dramatically instead.
322 #[cfg(not(test))] pub fn trash(self) { }
323 #[cfg(test)] pub fn trash(self) { assert!(self.wake().is_none()); }
325 /// Create a blocked task, unless the task was already killed.
326 pub fn block(task: ~Task) -> BlockedTask {
330 /// Converts one blocked task handle to a list of many handles to the same.
331 pub fn make_selectable(self, num_handles: uint) -> Take<BlockedTaskIterator>
333 let arc = match self {
335 let flag = unsafe { AtomicUint::new(cast::transmute(task)) };
338 Shared(arc) => arc.clone(),
340 BlockedTaskIterator{ inner: arc }.take(num_handles)
343 /// Convert to an unsafe uint value. Useful for storing in a pipe's state
346 pub unsafe fn cast_to_uint(self) -> uint {
349 let blocked_task_ptr: uint = cast::transmute(task);
350 rtassert!(blocked_task_ptr & 0x1 == 0);
354 let blocked_task_ptr: uint = cast::transmute(~arc);
355 rtassert!(blocked_task_ptr & 0x1 == 0);
356 blocked_task_ptr | 0x1
361 /// Convert from an unsafe uint value. Useful for retrieving a pipe's state
364 pub unsafe fn cast_from_uint(blocked_task_ptr: uint) -> BlockedTask {
365 if blocked_task_ptr & 0x1 == 0 {
366 Owned(cast::transmute(blocked_task_ptr))
368 let ptr: ~UnsafeArc<AtomicUint> =
369 cast::transmute(blocked_task_ptr & !1);
376 pub fn new() -> Death {
377 Death { on_exit: None, }
380 /// Collect failure exit codes from children and propagate them to a parent.
381 pub fn collect_failure(&mut self, result: TaskResult) {
382 match self.on_exit.take() {
383 Some(f) => f(result),
389 impl Drop for Death {
391 // make this type noncopyable
412 local_data_key!(key: @~str)
413 local_data::set(key, @~"data");
414 assert!(*local_data::get(key, |k| k.map(|k| *k)).unwrap() == ~"data");
415 local_data_key!(key2: @~str)
416 local_data::set(key2, @~"data");
417 assert!(*local_data::get(key2, |k| k.map(|k| *k)).unwrap() == ~"data");
422 let result = task::try(proc()());
423 rtdebug!("trying first assert");
424 assert!(result.is_ok());
425 let result = task::try::<()>(proc() fail!());
426 rtdebug!("trying second assert");
427 assert!(result.is_err());
432 use rand::{rng, Rng};
434 let _ = r.next_u32();
439 info!("here i am. logging in a newsched task");
444 let (port, chan) = Chan::new();
446 assert!(port.recv() == 10);
450 fn comm_shared_chan() {
451 let (port, chan) = SharedChan::new();
453 assert!(port.recv() == 10);
459 use option::{Option, Some, None};
462 next: Option<@RefCell<List>>,
465 let a = @RefCell::new(List { next: None });
466 let b = @RefCell::new(List { next: Some(a) });
469 let mut a = a.borrow_mut();
470 a.get().next = Some(b);
476 fn test_begin_unwind() {
477 use rt::unwind::begin_unwind;
478 begin_unwind("cause", file!(), line!())
481 // Task blocking tests
484 fn block_and_wake() {
485 let task = ~Task::new();
486 let mut task = BlockedTask::block(task).wake().unwrap();
487 task.destroyed = true;