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 /*! The Rust Runtime, including the task scheduler and I/O
13 The `rt` module provides the private runtime infrastructure necessary
14 to support core language features like the exchange and local heap,
15 the garbage collector, logging, local data and unwinding. It also
16 implements the default task scheduler and task model. Initialization
17 routines are provided for setting up runtime resources in common
18 configurations, including that used by `rustc` when generating
21 It is intended that the features provided by `rt` can be factored in a
22 way such that the core library can be built with different 'profiles'
23 for different use cases, e.g. excluding the task scheduler. A number
24 of runtime features though are critical to the functioning of the
25 language and an implementation must be provided regardless of the
26 execution environment.
28 Of foremost importance is the global exchange heap, in the module
29 `global_heap`. Very little practical Rust code can be written without
30 access to the global heap. Unlike most of `rt` the global heap is
31 truly a global resource and generally operates independently of the
34 All other runtime features are task-local, including the local heap,
35 the garbage collector, local storage, logging and the stack unwinder.
37 The relationship between `rt` and the rest of the core library is
38 not entirely clear yet and some modules will be moving into or
39 out of `rt` as development proceeds.
41 Several modules in `core` are clients of `rt`:
43 * `std::task` - The user-facing interface to the Rust task model.
44 * `std::task::local_data` - The interface to local data.
45 * `std::gc` - The garbage collector.
46 * `std::unstable::lang` - Miscellaneous lang items, some of which rely on `std::rt`.
47 * `std::condition` - Uses local data.
48 * `std::cleanup` - Local heap destruction.
49 * `std::io` - In the future `std::io` will use an `rt` implementation.
57 // XXX: this should not be here.
58 #[allow(missing_doc)];
61 use container::Container;
63 use option::{Option, None, Some};
66 use rt::sched::{Scheduler, Shutdown};
67 use rt::sleeper_list::SleeperList;
68 use rt::task::UnwindResult;
69 use rt::task::{Task, SchedTask, GreenTask, Sched};
70 use send_str::SendStrStatic;
71 use unstable::atomics::{AtomicInt, AtomicBool, SeqCst};
72 use unstable::sync::UnsafeArc;
73 use vec::{OwnedVector, MutableVector, ImmutableVector};
76 use self::thread::Thread;
78 // the os module needs to reach into this helper, so allow general access
79 // through this reexport.
80 pub use self::util::set_exit_status;
82 // this is somewhat useful when a program wants to spawn a "reasonable" number
83 // of workers based on the constraints of the system that it's running on.
84 // Perhaps this shouldn't be a `pub use` though and there should be another
86 pub use self::util::default_sched_threads;
88 // Re-export of the functionality in the kill module
89 pub use self::kill::BlockedTask;
91 // XXX: these probably shouldn't be public...
93 pub mod shouldnt_be_public {
94 pub use super::select::SelectInner;
95 pub use super::select::{SelectInner, SelectPortInner};
96 pub use super::local_ptr::native::maybe_tls_key;
97 #[cfg(not(windows), not(target_os = "android"))]
98 pub use super::local_ptr::compiled::RT_TLS_PTR;
101 // Internal macros used by the runtime.
104 /// Basic implementation of an EventLoop, provides no I/O interfaces
107 /// The global (exchange) heap.
110 /// Implementations of language-critical runtime features like @.
113 /// Facilities related to task failure, killing, and death.
116 /// The coroutine task scheduler, built on the `io` event loop.
119 /// The EventLoop and internal synchronous I/O interface.
122 /// The Local trait for types that are accessible via thread-local
123 /// or task-local storage.
126 /// A parallel queue.
127 pub mod message_queue;
129 /// A mostly lock-free multi-producer, single consumer queue.
132 /// A lock-free multi-producer, multi-consumer bounded queue.
133 mod mpmc_bounded_queue;
135 /// A parallel work-stealing deque
138 /// A parallel data structure for tracking sleeping schedulers.
139 pub mod sleeper_list;
141 /// Stack segments and caching.
144 /// CPU context swapping.
147 /// Bindings to system threading libraries.
150 /// The runtime configuration, read from environment variables.
153 /// The local, managed heap
156 /// The Logger trait and implementations
162 /// Tools for testing the runtime
165 /// Reference counting
168 /// A simple single-threaded channel type for passing buffered data between
169 /// scheduler and task context
172 /// Simple reimplementation of std::comm
177 /// The runtime needs to be able to put a pointer into thread-local storage.
180 /// Bindings to pthread/windows thread-local storage.
181 mod thread_local_storage;
186 // Global command line argument storage
189 // Support for dynamic borrowck
192 /// Set up a default runtime configuration, given compiler-supplied arguments.
194 /// This is invoked by the `start` _language item_ (unstable::lang) to
195 /// run a Rust executable.
199 /// * `argc` & `argv` - The argument vector. On Unix this information is used
204 /// The return value is used as the process return code. 0 on success, 101 on error.
205 pub fn start(argc: int, argv: **u8, main: proc()) -> int {
208 let exit_code = run(main);
209 // unsafe is ok b/c we're sure that the runtime is gone
210 unsafe { cleanup(); }
215 /// Like `start` but creates an additional scheduler on the current thread,
216 /// which in most cases will be the 'main' thread, and pins the main task to it.
218 /// This is appropriate for running code that must execute on the main thread,
219 /// such as the platform event loop and GUI.
220 pub fn start_on_main_thread(argc: int, argv: **u8, main: proc()) -> int {
222 let exit_code = run_on_main_thread(main);
223 // unsafe is ok b/c we're sure that the runtime is gone
224 unsafe { cleanup(); }
229 /// One-time runtime initialization.
231 /// Initializes global state, including frobbing
232 /// the crate's logging flags, registering GC
233 /// metadata, and storing the process arguments.
234 pub fn init(argc: int, argv: **u8) {
235 // XXX: Derefing these pointers is not safe.
236 // Need to propagate the unsafety to `start`.
238 args::init(argc, argv);
244 /// One-time runtime cleanup.
246 /// This function is unsafe because it performs no checks to ensure that the
247 /// runtime has completely ceased running. It is the responsibility of the
248 /// caller to ensure that the runtime is entirely shut down and nothing will be
249 /// poking around at the internal components.
251 /// Invoking cleanup while portions of the runtime are still in use may cause
252 /// undefined behavior.
253 pub unsafe fn cleanup() {
255 local_ptr::cleanup();
258 /// Execute the main function in a scheduler.
260 /// Configures the runtime according to the environment, by default
261 /// using a task scheduler with the same number of threads as cores.
262 /// Returns a process exit code.
263 pub fn run(main: proc()) -> int {
267 pub fn run_on_main_thread(main: proc()) -> int {
271 fn run_(main: proc(), use_main_sched: bool) -> int {
272 static DEFAULT_ERROR_CODE: int = 101;
274 let nscheds = util::default_sched_threads();
276 let mut main = Some(main);
278 // The shared list of sleeping schedulers.
279 let sleepers = SleeperList::new();
281 // Create a work queue for each scheduler, ntimes. Create an extra
282 // for the main thread if that flag is set. We won't steal from it.
283 let mut pool = deque::BufferPool::new();
284 let arr = vec::from_fn(nscheds, |_| pool.deque());
285 let (workers, stealers) = vec::unzip(arr.move_iter());
288 let mut scheds = ~[];
289 // Handles to the schedulers. When the main task ends these will be
290 // sent the Shutdown message to terminate the schedulers.
291 let mut handles = ~[];
293 for worker in workers.move_iter() {
294 rtdebug!("inserting a regular scheduler");
296 // Every scheduler is driven by an I/O event loop.
297 let loop_ = new_event_loop();
298 let mut sched = ~Scheduler::new(loop_,
302 let handle = sched.make_handle();
305 handles.push(handle);
308 // If we need a main-thread task then create a main thread scheduler
309 // that will reject any task that isn't pinned to it
310 let main_sched = if use_main_sched {
312 // Create a friend handle.
313 let mut friend_sched = scheds.pop();
314 let friend_handle = friend_sched.make_handle();
315 scheds.push(friend_sched);
317 // This scheduler needs a queue that isn't part of the stealee
319 let (worker, _) = pool.deque();
321 let main_loop = new_event_loop();
322 let mut main_sched = ~Scheduler::new_special(main_loop,
327 Some(friend_handle));
328 let mut main_handle = main_sched.make_handle();
329 // Allow the scheduler to exit when the main task exits.
330 // Note: sending the shutdown message also prevents the scheduler
331 // from pushing itself to the sleeper list, which is used for
332 // waking up schedulers for work stealing; since this is a
333 // non-work-stealing scheduler it should not be adding itself
335 main_handle.send(Shutdown);
341 // Create a shared cell for transmitting the process exit
342 // code from the main task to this function.
343 let exit_code = UnsafeArc::new(AtomicInt::new(0));
344 let exit_code_clone = exit_code.clone();
346 // Used to sanity check that the runtime only exits once
347 let exited_already = UnsafeArc::new(AtomicBool::new(false));
349 // When the main task exits, after all the tasks in the main
350 // task tree, shut down the schedulers and set the exit code.
351 let handles = handles;
352 let on_exit: proc(UnwindResult) = proc(exit_success) {
354 assert!(!(*exited_already.get()).swap(true, SeqCst),
355 "the runtime already exited");
358 let mut handles = handles;
359 for handle in handles.mut_iter() {
360 handle.send(Shutdown);
364 let exit_code = if exit_success.is_success() {
367 // If we're exiting successfully, then return the global
368 // exit status, which can be set programmatically.
369 util::get_exit_status()
373 (*exit_code_clone.get()).store(exit_code, SeqCst);
377 let mut threads = ~[];
378 let mut on_exit = Some(on_exit);
382 // In the case where we do not use a main_thread scheduler we
383 // run the main task in one of our threads.
385 let mut main_task = ~Task::new_root(&mut scheds[0].stack_pool,
387 ::util::replace(&mut main,
389 main_task.name = Some(SendStrStatic("<main>"));
390 main_task.death.on_exit = ::util::replace(&mut on_exit, None);
392 let sched = scheds.pop();
393 let main_task = main_task;
394 let thread = do Thread::start {
395 sched.bootstrap(main_task);
397 threads.push(thread);
400 // Run each remaining scheduler in a thread.
401 for sched in scheds.move_rev_iter() {
402 rtdebug!("creating regular schedulers");
403 let thread = do Thread::start {
404 let mut sched = sched;
405 let bootstrap_task = ~do Task::new_root(&mut sched.stack_pool, None) || {
406 rtdebug!("boostraping a non-primary scheduler");
408 sched.bootstrap(bootstrap_task);
410 threads.push(thread);
413 // If we do have a main thread scheduler, run it now.
416 rtdebug!("about to create the main scheduler task");
418 let mut main_sched = main_sched.unwrap();
420 let home = Sched(main_sched.make_handle());
421 let mut main_task = ~Task::new_root_homed(&mut main_sched.stack_pool,
424 ::util::replace(&mut main,
427 main_task.name = Some(SendStrStatic("<main>"));
428 main_task.death.on_exit = ::util::replace(&mut on_exit, None);
429 rtdebug!("bootstrapping main_task");
431 main_sched.bootstrap(main_task);
434 rtdebug!("waiting for threads");
436 // Wait for schedulers
437 for thread in threads.move_iter() {
441 // Return the exit code
443 (*exit_code.get()).load(SeqCst)
447 pub fn in_sched_context() -> bool {
449 let task_ptr: Option<*mut Task> = Local::try_unsafe_borrow();
452 match (*task).task_type {
462 pub fn in_green_task_context() -> bool {
464 let task: Option<*mut Task> = Local::try_unsafe_borrow();
467 match (*task).task_type {
468 GreenTask(_) => true,
477 pub fn new_event_loop() -> ~rtio::EventLoop {
478 match crate_map::get_crate_map() {
481 match map.event_loop_factory {
483 Some(factory) => return factory()
488 // If the crate map didn't specify a factory to create an event loop, then
489 // instead just use a basic event loop missing all I/O services to at least
490 // get the scheduler running.
491 return basic::event_loop();