/
thread.rs
969 lines (868 loc) · 31.2 KB
/
thread.rs
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
// Copyright 2014 The Rust Project Developers. See the COPYRIGHT
// file at the top-level directory of this distribution and at
// http://rust-lang.org/COPYRIGHT.
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.
//! Native threads
//!
//! ## The threading model
//!
//! An executing Rust program consists of a collection of native OS threads,
//! each with their own stack and local state.
//!
//! Communication between threads can be done through
//! [channels](../../std/sync/mpsc/index.html), Rust's message-passing
//! types, along with [other forms of thread
//! synchronization](../../std/sync/index.html) and shared-memory data
//! structures. In particular, types that are guaranteed to be
//! threadsafe are easily shared between threads using the
//! atomically-reference-counted container,
//! [`Arc`](../../std/sync/struct.Arc.html).
//!
//! Fatal logic errors in Rust cause *thread panic*, during which
//! a thread will unwind the stack, running destructors and freeing
//! owned resources. Thread panic is unrecoverable from within
//! the panicking thread (i.e. there is no 'try/catch' in Rust), but
//! the panic may optionally be detected from a different thread. If
//! the main thread panics, the application will exit with a non-zero
//! exit code.
//!
//! When the main thread of a Rust program terminates, the entire program shuts
//! down, even if other threads are still running. However, this module provides
//! convenient facilities for automatically waiting for the termination of a
//! child thread (i.e., join).
//!
//! ## The `Thread` type
//!
//! Threads are represented via the `Thread` type, which you can
//! get in one of two ways:
//!
//! * By spawning a new thread, e.g. using the `thread::spawn` function.
//! * By requesting the current thread, using the `thread::current` function.
//!
//! Threads can be named, and provide some built-in support for low-level
//! synchronization (described below).
//!
//! The `thread::current()` function is available even for threads not spawned
//! by the APIs of this module.
//!
//! ## Spawning a thread
//!
//! A new thread can be spawned using the `thread::spawn` function:
//!
//! ```rust
//! use std::thread;
//!
//! thread::spawn(move || {
//! // some work here
//! });
//! ```
//!
//! In this example, the spawned thread is "detached" from the current
//! thread. This means that it can outlive its parent (the thread that spawned
//! it), unless this parent is the main thread.
//!
//! ## Scoped threads
//!
//! Often a parent thread uses a child thread to perform some particular task,
//! and at some point must wait for the child to complete before continuing.
//! For this scenario, use the `thread::scoped` function:
//!
//! ```rust
//! use std::thread;
//!
//! let guard = thread::scoped(move || {
//! // some work here
//! });
//!
//! // do some other work in the meantime
//! let output = guard.join();
//! ```
//!
//! The `scoped` function doesn't return a `Thread` directly; instead,
//! it returns a *join guard*. The join guard is an RAII-style guard
//! that will automatically join the child thread (block until it
//! terminates) when it is dropped. You can join the child thread in
//! advance by calling the `join` method on the guard, which will also
//! return the result produced by the thread. A handle to the thread
//! itself is available via the `thread` method of the join guard.
//!
//! ## Configuring threads
//!
//! A new thread can be configured before it is spawned via the `Builder` type,
//! which currently allows you to set the name, stack size, and writers for
//! `println!` and `panic!` for the child thread:
//!
//! ```rust
//! use std::thread;
//!
//! thread::Builder::new().name("child1".to_string()).spawn(move || {
//! println!("Hello, world!");
//! });
//! ```
//!
//! ## Blocking support: park and unpark
//!
//! Every thread is equipped with some basic low-level blocking support, via the
//! `park` and `unpark` functions.
//!
//! Conceptually, each `Thread` handle has an associated token, which is
//! initially not present:
//!
//! * The `thread::park()` function blocks the current thread unless or until
//! the token is available for its thread handle, at which point it atomically
//! consumes the token. It may also return *spuriously*, without consuming the
//! token. `thread::park_timeout()` does the same, but allows specifying a
//! maximum time to block the thread for.
//!
//! * The `unpark()` method on a `Thread` atomically makes the token available
//! if it wasn't already.
//!
//! In other words, each `Thread` acts a bit like a semaphore with initial count
//! 0, except that the semaphore is *saturating* (the count cannot go above 1),
//! and can return spuriously.
//!
//! The API is typically used by acquiring a handle to the current thread,
//! placing that handle in a shared data structure so that other threads can
//! find it, and then `park`ing. When some desired condition is met, another
//! thread calls `unpark` on the handle.
//!
//! The motivation for this design is twofold:
//!
//! * It avoids the need to allocate mutexes and condvars when building new
//! synchronization primitives; the threads already provide basic blocking/signaling.
//!
//! * It can be implemented very efficiently on many platforms.
#![stable(feature = "rust1", since = "1.0.0")]
use prelude::v1::*;
use any::Any;
use cell::UnsafeCell;
use fmt;
use io;
use marker::PhantomData;
use old_io::stdio;
use rt::{self, unwind};
use sync::{Mutex, Condvar, Arc};
use thunk::Thunk;
use time::Duration;
use sys::thread as imp;
use sys_common::{stack, thread_info};
/// Thread configuration. Provides detailed control over the properties
/// and behavior of new threads.
#[stable(feature = "rust1", since = "1.0.0")]
pub struct Builder {
// A name for the thread-to-be, for identification in panic messages
name: Option<String>,
// The size of the stack for the spawned thread
stack_size: Option<usize>,
// Thread-local stdout
stdout: Option<Box<Writer + Send + 'static>>,
// Thread-local stderr
stderr: Option<Box<Writer + Send + 'static>>,
}
impl Builder {
/// Generate the base configuration for spawning a thread, from which
/// configuration methods can be chained.
#[stable(feature = "rust1", since = "1.0.0")]
pub fn new() -> Builder {
Builder {
name: None,
stack_size: None,
stdout: None,
stderr: None,
}
}
/// Name the thread-to-be. Currently the name is used for identification
/// only in panic messages.
#[stable(feature = "rust1", since = "1.0.0")]
pub fn name(mut self, name: String) -> Builder {
self.name = Some(name);
self
}
/// Set the size of the stack for the new thread.
#[stable(feature = "rust1", since = "1.0.0")]
pub fn stack_size(mut self, size: usize) -> Builder {
self.stack_size = Some(size);
self
}
/// Redirect thread-local stdout.
#[unstable(feature = "std_misc",
reason = "Will likely go away after proc removal")]
pub fn stdout(mut self, stdout: Box<Writer + Send + 'static>) -> Builder {
self.stdout = Some(stdout);
self
}
/// Redirect thread-local stderr.
#[unstable(feature = "std_misc",
reason = "Will likely go away after proc removal")]
pub fn stderr(mut self, stderr: Box<Writer + Send + 'static>) -> Builder {
self.stderr = Some(stderr);
self
}
/// Spawn a new thread, and return a join handle for it.
///
/// The child thread may outlive the parent (unless the parent thread
/// is the main thread; the whole process is terminated when the main
/// thread finishes.) The join handle can be used to block on
/// termination of the child thread, including recovering its panics.
///
/// # Errors
///
/// Unlike the `spawn` free function, this method yields an
/// `io::Result` to capture any failure to create the thread at
/// the OS level.
#[stable(feature = "rust1", since = "1.0.0")]
pub fn spawn<F>(self, f: F) -> io::Result<JoinHandle> where
F: FnOnce(), F: Send + 'static
{
self.spawn_inner(Thunk::new(f)).map(|i| JoinHandle(i))
}
/// Spawn a new child thread that must be joined within a given
/// scope, and return a `JoinGuard`.
///
/// The join guard can be used to explicitly join the child thread (via
/// `join`), returning `Result<T>`, or it will implicitly join the child
/// upon being dropped. Because the child thread may refer to data on the
/// current thread's stack (hence the "scoped" name), it cannot be detached;
/// it *must* be joined before the relevant stack frame is popped. See the
/// module documentation for additional details.
///
/// # Errors
///
/// Unlike the `scoped` free function, this method yields an
/// `io::Result` to capture any failure to create the thread at
/// the OS level.
#[stable(feature = "rust1", since = "1.0.0")]
pub fn scoped<'a, T, F>(self, f: F) -> io::Result<JoinGuard<'a, T>> where
T: Send + 'a, F: FnOnce() -> T, F: Send + 'a
{
self.spawn_inner(Thunk::new(f)).map(|inner| {
JoinGuard { inner: inner, _marker: PhantomData }
})
}
fn spawn_inner<T: Send>(self, f: Thunk<(), T>) -> io::Result<JoinInner<T>> {
let Builder { name, stack_size, stdout, stderr } = self;
let stack_size = stack_size.unwrap_or(rt::min_stack());
let my_thread = Thread::new(name);
let their_thread = my_thread.clone();
let my_packet = Packet(Arc::new(UnsafeCell::new(None)));
let their_packet = Packet(my_packet.0.clone());
// Spawning a new OS thread guarantees that __morestack will never get
// triggered, but we must manually set up the actual stack bounds once
// this function starts executing. This raises the lower limit by a bit
// because by the time that this function is executing we've already
// consumed at least a little bit of stack (we don't know the exact byte
// address at which our stack started).
let main = move || {
let something_around_the_top_of_the_stack = 1;
let addr = &something_around_the_top_of_the_stack as *const i32;
let my_stack_top = addr as usize;
let my_stack_bottom = my_stack_top - stack_size + 1024;
unsafe {
stack::record_os_managed_stack_bounds(my_stack_bottom, my_stack_top);
}
match their_thread.name() {
Some(name) => unsafe { imp::set_name(name.as_slice()); },
None => {}
}
thread_info::set(
(my_stack_bottom, my_stack_top),
unsafe { imp::guard::current() },
their_thread
);
let mut output = None;
let f: Thunk<(), T> = if stdout.is_some() || stderr.is_some() {
Thunk::new(move || {
let _ = stdout.map(stdio::set_stdout);
let _ = stderr.map(stdio::set_stderr);
f.invoke(())
})
} else {
f
};
let try_result = {
let ptr = &mut output;
// There are two primary reasons that general try/catch is
// unsafe. The first is that we do not support nested
// try/catch. The fact that this is happening in a newly-spawned
// thread suffices. The second is that unwinding while unwinding
// is not defined. We take care of that by having an
// 'unwinding' flag in the thread itself. For these reasons,
// this unsafety should be ok.
unsafe {
unwind::try(move || *ptr = Some(f.invoke(())))
}
};
unsafe {
*their_packet.0.get() = Some(match (output, try_result) {
(Some(data), Ok(_)) => Ok(data),
(None, Err(cause)) => Err(cause),
_ => unreachable!()
});
}
};
Ok(JoinInner {
native: try!(unsafe { imp::create(stack_size, Thunk::new(main)) }),
thread: my_thread,
packet: my_packet,
joined: false,
})
}
}
/// Spawn a new thread, returning a `JoinHandle` for it.
///
/// The join handle will implicitly *detach* the child thread upon being
/// dropped. In this case, the child thread may outlive the parent (unless
/// the parent thread is the main thread; the whole process is terminated when
/// the main thread finishes.) Additionally, the join handle provides a `join`
/// method that can be used to join the child thread. If the child thread
/// panics, `join` will return an `Err` containing the argument given to
/// `panic`.
///
/// # Panics
///
/// Panicks if the OS fails to create a thread; use `Builder::spawn`
/// to recover from such errors.
#[stable(feature = "rust1", since = "1.0.0")]
pub fn spawn<F>(f: F) -> JoinHandle where F: FnOnce(), F: Send + 'static {
Builder::new().spawn(f).unwrap()
}
/// Spawn a new *scoped* thread, returning a `JoinGuard` for it.
///
/// The join guard can be used to explicitly join the child thread (via
/// `join`), returning `Result<T>`, or it will implicitly join the child
/// upon being dropped. Because the child thread may refer to data on the
/// current thread's stack (hence the "scoped" name), it cannot be detached;
/// it *must* be joined before the relevant stack frame is popped. See the
/// module documentation for additional details.
///
/// # Panics
///
/// Panicks if the OS fails to create a thread; use `Builder::scoped`
/// to recover from such errors.
#[stable(feature = "rust1", since = "1.0.0")]
pub fn scoped<'a, T, F>(f: F) -> JoinGuard<'a, T> where
T: Send + 'a, F: FnOnce() -> T, F: Send + 'a
{
Builder::new().scoped(f).unwrap()
}
/// Gets a handle to the thread that invokes it.
#[stable(feature = "rust1", since = "1.0.0")]
pub fn current() -> Thread {
thread_info::current_thread()
}
/// Cooperatively give up a timeslice to the OS scheduler.
#[stable(feature = "rust1", since = "1.0.0")]
pub fn yield_now() {
unsafe { imp::yield_now() }
}
/// Determines whether the current thread is unwinding because of panic.
#[inline]
#[stable(feature = "rust1", since = "1.0.0")]
pub fn panicking() -> bool {
unwind::panicking()
}
/// Block unless or until the current thread's token is made available (may wake spuriously).
///
/// See the module doc for more detail.
//
// The implementation currently uses the trivial strategy of a Mutex+Condvar
// with wakeup flag, which does not actually allow spurious wakeups. In the
// future, this will be implemented in a more efficient way, perhaps along the lines of
// http://cr.openjdk.java.net/~stefank/6989984.1/raw_files/new/src/os/linux/vm/os_linux.cpp
// or futuxes, and in either case may allow spurious wakeups.
#[stable(feature = "rust1", since = "1.0.0")]
pub fn park() {
let thread = current();
let mut guard = thread.inner.lock.lock().unwrap();
while !*guard {
guard = thread.inner.cvar.wait(guard).unwrap();
}
*guard = false;
}
/// Block unless or until the current thread's token is made available or
/// the specified duration has been reached (may wake spuriously).
///
/// The semantics of this function are equivalent to `park()` except that the
/// thread will be blocked for roughly no longer than dur. This method
/// should not be used for precise timing due to anomalies such as
/// preemption or platform differences that may not cause the maximum
/// amount of time waited to be precisely dur
///
/// See the module doc for more detail.
#[unstable(feature = "std_misc", reason = "recently introduced, depends on Duration")]
pub fn park_timeout(dur: Duration) {
let thread = current();
let mut guard = thread.inner.lock.lock().unwrap();
if !*guard {
let (g, _) = thread.inner.cvar.wait_timeout(guard, dur).unwrap();
guard = g;
}
*guard = false;
}
/// The internal representation of a `Thread` handle
struct Inner {
name: Option<String>,
lock: Mutex<bool>, // true when there is a buffered unpark
cvar: Condvar,
}
unsafe impl Sync for Inner {}
#[derive(Clone)]
#[stable(feature = "rust1", since = "1.0.0")]
/// A handle to a thread.
pub struct Thread {
inner: Arc<Inner>,
}
impl Thread {
// Used only internally to construct a thread object without spawning
fn new(name: Option<String>) -> Thread {
Thread {
inner: Arc::new(Inner {
name: name,
lock: Mutex::new(false),
cvar: Condvar::new(),
})
}
}
/// Deprecated: use module-level free function.
#[deprecated(since = "1.0.0", reason = "use module-level free function")]
#[unstable(feature = "std_misc",
reason = "may change with specifics of new Send semantics")]
pub fn spawn<F>(f: F) -> Thread where F: FnOnce(), F: Send + 'static {
Builder::new().spawn(f).unwrap().thread().clone()
}
/// Deprecated: use module-level free function.
#[deprecated(since = "1.0.0", reason = "use module-level free function")]
#[unstable(feature = "std_misc",
reason = "may change with specifics of new Send semantics")]
pub fn scoped<'a, T, F>(f: F) -> JoinGuard<'a, T> where
T: Send + 'a, F: FnOnce() -> T, F: Send + 'a
{
Builder::new().scoped(f).unwrap()
}
/// Deprecated: use module-level free function.
#[deprecated(since = "1.0.0", reason = "use module-level free function")]
#[stable(feature = "rust1", since = "1.0.0")]
pub fn current() -> Thread {
thread_info::current_thread()
}
/// Deprecated: use module-level free function.
#[deprecated(since = "1.0.0", reason = "use module-level free function")]
#[unstable(feature = "std_misc", reason = "name may change")]
pub fn yield_now() {
unsafe { imp::yield_now() }
}
/// Deprecated: use module-level free function.
#[deprecated(since = "1.0.0", reason = "use module-level free function")]
#[inline]
#[stable(feature = "rust1", since = "1.0.0")]
pub fn panicking() -> bool {
unwind::panicking()
}
/// Deprecated: use module-level free function.
#[deprecated(since = "1.0.0", reason = "use module-level free function")]
#[unstable(feature = "std_misc", reason = "recently introduced")]
pub fn park() {
let thread = current();
let mut guard = thread.inner.lock.lock().unwrap();
while !*guard {
guard = thread.inner.cvar.wait(guard).unwrap();
}
*guard = false;
}
/// Deprecated: use module-level free function.
#[deprecated(since = "1.0.0", reason = "use module-level free function")]
#[unstable(feature = "std_misc", reason = "recently introduced")]
pub fn park_timeout(dur: Duration) {
let thread = current();
let mut guard = thread.inner.lock.lock().unwrap();
if !*guard {
let (g, _) = thread.inner.cvar.wait_timeout(guard, dur).unwrap();
guard = g;
}
*guard = false;
}
/// Atomically makes the handle's token available if it is not already.
///
/// See the module doc for more detail.
#[stable(feature = "rust1", since = "1.0.0")]
pub fn unpark(&self) {
let mut guard = self.inner.lock.lock().unwrap();
if !*guard {
*guard = true;
self.inner.cvar.notify_one();
}
}
/// Get the thread's name.
#[stable(feature = "rust1", since = "1.0.0")]
pub fn name(&self) -> Option<&str> {
self.inner.name.as_ref().map(|s| &**s)
}
}
#[stable(feature = "rust1", since = "1.0.0")]
impl fmt::Debug for Thread {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
fmt::Debug::fmt(&self.name(), f)
}
}
// a hack to get around privacy restrictions
impl thread_info::NewThread for Thread {
fn new(name: Option<String>) -> Thread { Thread::new(name) }
}
/// Indicates the manner in which a thread exited.
///
/// A thread that completes without panicking is considered to exit successfully.
#[stable(feature = "rust1", since = "1.0.0")]
pub type Result<T> = ::result::Result<T, Box<Any + Send + 'static>>;
struct Packet<T>(Arc<UnsafeCell<Option<Result<T>>>>);
unsafe impl<T:Send> Send for Packet<T> {}
unsafe impl<T> Sync for Packet<T> {}
/// Inner representation for JoinHandle and JoinGuard
struct JoinInner<T> {
native: imp::rust_thread,
thread: Thread,
packet: Packet<T>,
joined: bool,
}
impl<T> JoinInner<T> {
fn join(&mut self) -> Result<T> {
assert!(!self.joined);
unsafe { imp::join(self.native) };
self.joined = true;
unsafe {
(*self.packet.0.get()).take().unwrap()
}
}
}
/// An owned permission to join on a thread (block on its termination).
///
/// Unlike a `JoinGuard`, a `JoinHandle` *detaches* the child thread
/// when it is dropped, rather than automatically joining on drop.
///
/// Due to platform restrictions, it is not possible to `Clone` this
/// handle: the ability to join a child thread is a uniquely-owned
/// permission.
#[stable(feature = "rust1", since = "1.0.0")]
pub struct JoinHandle(JoinInner<()>);
impl JoinHandle {
/// Extract a handle to the underlying thread
#[stable(feature = "rust1", since = "1.0.0")]
pub fn thread(&self) -> &Thread {
&self.0.thread
}
/// Wait for the associated thread to finish.
///
/// If the child thread panics, `Err` is returned with the parameter given
/// to `panic`.
#[stable(feature = "rust1", since = "1.0.0")]
pub fn join(mut self) -> Result<()> {
self.0.join()
}
}
#[stable(feature = "rust1", since = "1.0.0")]
impl Drop for JoinHandle {
fn drop(&mut self) {
if !self.0.joined {
unsafe { imp::detach(self.0.native) }
}
}
}
/// An RAII-style guard that will block until thread termination when dropped.
///
/// The type `T` is the return type for the thread's main function.
///
/// Joining on drop is necessary to ensure memory safety when stack
/// data is shared between a parent and child thread.
///
/// Due to platform restrictions, it is not possible to `Clone` this
/// handle: the ability to join a child thread is a uniquely-owned
/// permission.
#[must_use]
#[stable(feature = "rust1", since = "1.0.0")]
pub struct JoinGuard<'a, T: 'a> {
inner: JoinInner<T>,
_marker: PhantomData<&'a T>,
}
#[stable(feature = "rust1", since = "1.0.0")]
unsafe impl<'a, T: Send + 'a> Sync for JoinGuard<'a, T> {}
impl<'a, T: Send + 'a> JoinGuard<'a, T> {
/// Extract a handle to the thread this guard will join on.
#[stable(feature = "rust1", since = "1.0.0")]
pub fn thread(&self) -> &Thread {
&self.inner.thread
}
/// Wait for the associated thread to finish, returning the result of the thread's
/// calculation.
///
/// # Panics
///
/// Panics on the child thread are propagated by panicking the parent.
#[stable(feature = "rust1", since = "1.0.0")]
pub fn join(mut self) -> T {
match self.inner.join() {
Ok(res) => res,
Err(_) => panic!("child thread {:?} panicked", self.thread()),
}
}
}
#[stable(feature = "rust1", since = "1.0.0")]
impl<T: Send> JoinGuard<'static, T> {
/// Detaches the child thread, allowing it to outlive its parent.
#[deprecated(since = "1.0.0", reason = "use spawn instead")]
#[unstable(feature = "std_misc")]
pub fn detach(mut self) {
unsafe { imp::detach(self.inner.native) };
self.inner.joined = true; // avoid joining in the destructor
}
}
#[unsafe_destructor]
#[stable(feature = "rust1", since = "1.0.0")]
impl<'a, T: Send + 'a> Drop for JoinGuard<'a, T> {
fn drop(&mut self) {
if !self.inner.joined {
if self.inner.join().is_err() {
panic!("child thread {:?} panicked", self.thread());
}
}
}
}
#[cfg(test)]
mod test {
use prelude::v1::*;
use any::Any;
use sync::mpsc::{channel, Sender};
use boxed::BoxAny;
use result;
use std::old_io::{ChanReader, ChanWriter};
use super::{Builder};
use thread;
use thunk::Thunk;
use time::Duration;
// !!! These tests are dangerous. If something is buggy, they will hang, !!!
// !!! instead of exiting cleanly. This might wedge the buildbots. !!!
#[test]
fn test_unnamed_thread() {
thread::spawn(move|| {
assert!(thread::current().name().is_none());
}).join().ok().unwrap();
}
#[test]
fn test_named_thread() {
Builder::new().name("ada lovelace".to_string()).scoped(move|| {
assert!(thread::current().name().unwrap() == "ada lovelace".to_string());
}).unwrap().join();
}
#[test]
fn test_run_basic() {
let (tx, rx) = channel();
thread::spawn(move|| {
tx.send(()).unwrap();
});
rx.recv().unwrap();
}
#[test]
fn test_join_success() {
assert!(thread::scoped(move|| -> String {
"Success!".to_string()
}).join() == "Success!");
}
#[test]
fn test_join_panic() {
match thread::spawn(move|| {
panic!()
}).join() {
result::Result::Err(_) => (),
result::Result::Ok(()) => panic!()
}
}
#[test]
fn test_scoped_success() {
let res = thread::scoped(move|| -> String {
"Success!".to_string()
}).join();
assert!(res == "Success!");
}
#[test]
#[should_fail]
fn test_scoped_panic() {
thread::scoped(|| panic!()).join();
}
#[test]
#[should_fail]
fn test_scoped_implicit_panic() {
let _ = thread::scoped(|| panic!());
}
#[test]
fn test_spawn_sched() {
use clone::Clone;
let (tx, rx) = channel();
fn f(i: i32, tx: Sender<()>) {
let tx = tx.clone();
thread::spawn(move|| {
if i == 0 {
tx.send(()).unwrap();
} else {
f(i - 1, tx);
}
});
}
f(10, tx);
rx.recv().unwrap();
}
#[test]
fn test_spawn_sched_childs_on_default_sched() {
let (tx, rx) = channel();
thread::spawn(move|| {
thread::spawn(move|| {
tx.send(()).unwrap();
});
});
rx.recv().unwrap();
}
fn avoid_copying_the_body<F>(spawnfn: F) where F: FnOnce(Thunk<'static>) {
let (tx, rx) = channel();
let x = box 1;
let x_in_parent = (&*x) as *const i32 as usize;
spawnfn(Thunk::new(move|| {
let x_in_child = (&*x) as *const i32 as usize;
tx.send(x_in_child).unwrap();
}));
let x_in_child = rx.recv().unwrap();
assert_eq!(x_in_parent, x_in_child);
}
#[test]
fn test_avoid_copying_the_body_spawn() {
avoid_copying_the_body(|v| {
thread::spawn(move || v.invoke(()));
});
}
#[test]
fn test_avoid_copying_the_body_thread_spawn() {
avoid_copying_the_body(|f| {
thread::spawn(move|| {
f.invoke(());
});
})
}
#[test]
fn test_avoid_copying_the_body_join() {
avoid_copying_the_body(|f| {
let _ = thread::spawn(move|| {
f.invoke(())
}).join();
})
}
#[test]
fn test_child_doesnt_ref_parent() {
// If the child refcounts the parent task, this will stack overflow when
// climbing the task tree to dereference each ancestor. (See #1789)
// (well, it would if the constant were 8000+ - I lowered it to be more
// valgrind-friendly. try this at home, instead..!)
const GENERATIONS: u32 = 16;
fn child_no(x: u32) -> Thunk<'static> {
return Thunk::new(move|| {
if x < GENERATIONS {
thread::spawn(move|| child_no(x+1).invoke(()));
}
});
}
thread::spawn(|| child_no(0).invoke(()));
}
#[test]
fn test_simple_newsched_spawn() {
thread::spawn(move || {});
}
#[test]
fn test_try_panic_message_static_str() {
match thread::spawn(move|| {
panic!("static string");
}).join() {
Err(e) => {
type T = &'static str;
assert!(e.is::<T>());
assert_eq!(*e.downcast::<T>().ok().unwrap(), "static string");
}
Ok(()) => panic!()
}
}
#[test]
fn test_try_panic_message_owned_str() {
match thread::spawn(move|| {
panic!("owned string".to_string());
}).join() {
Err(e) => {
type T = String;
assert!(e.is::<T>());
assert_eq!(*e.downcast::<T>().ok().unwrap(), "owned string".to_string());
}
Ok(()) => panic!()
}
}
#[test]
fn test_try_panic_message_any() {
match thread::spawn(move|| {
panic!(box 413u16 as Box<Any + Send>);
}).join() {
Err(e) => {
type T = Box<Any + Send>;
assert!(e.is::<T>());
let any = e.downcast::<T>().ok().unwrap();
assert!(any.is::<u16>());
assert_eq!(*any.downcast::<u16>().ok().unwrap(), 413u16);
}
Ok(()) => panic!()
}
}
#[test]
fn test_try_panic_message_unit_struct() {
struct Juju;
match thread::spawn(move|| {
panic!(Juju)
}).join() {
Err(ref e) if e.is::<Juju>() => {}
Err(_) | Ok(()) => panic!()
}
}
#[test]
fn test_stdout() {
let (tx, rx) = channel();
let mut reader = ChanReader::new(rx);
let stdout = ChanWriter::new(tx);
Builder::new().stdout(box stdout as Box<Writer + Send>).scoped(move|| {
print!("Hello, world!");
}).unwrap().join();
let output = reader.read_to_string().unwrap();
assert_eq!(output, "Hello, world!".to_string());
}
#[test]
fn test_park_timeout_unpark_before() {
for _ in 0..10 {
thread::current().unpark();
thread::park_timeout(Duration::seconds(10_000_000));
}
}
#[test]
fn test_park_timeout_unpark_not_called() {
for _ in 0..10 {
thread::park_timeout(Duration::milliseconds(10));
}
}
#[test]
fn test_park_timeout_unpark_called_other_thread() {
use std::old_io;
for _ in 0..10 {
let th = thread::current();
let _guard = thread::spawn(move || {
old_io::timer::sleep(Duration::milliseconds(50));
th.unpark();
});
thread::park_timeout(Duration::seconds(10_000_000));
}
}
// NOTE: the corresponding test for stderr is in run-pass/task-stderr, due
// to the test harness apparently interfering with stderr configuration.
}