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)];
62 use container::Container;
64 use option::{Option, None, Some};
67 use rt::sched::{Scheduler, Shutdown};
68 use rt::sleeper_list::SleeperList;
69 use rt::task::UnwindResult;
70 use rt::task::{Task, SchedTask, GreenTask, Sched};
71 use send_str::SendStrStatic;
72 use unstable::atomics::{AtomicInt, AtomicBool, SeqCst};
73 use unstable::sync::UnsafeArc;
74 use vec::{OwnedVector, MutableVector, ImmutableVector};
77 use self::thread::Thread;
78 use self::work_queue::WorkQueue;
80 // the os module needs to reach into this helper, so allow general access
81 // through this reexport.
82 pub use self::util::set_exit_status;
84 // this is somewhat useful when a program wants to spawn a "reasonable" number
85 // of workers based on the constraints of the system that it's running on.
86 // Perhaps this shouldn't be a `pub use` though and there should be another
88 pub use self::util::default_sched_threads;
90 // Re-export of the functionality in the kill module
91 pub use self::kill::BlockedTask;
93 // XXX: these probably shouldn't be public...
95 pub mod shouldnt_be_public {
96 pub use super::select::SelectInner;
97 pub use super::select::{SelectInner, SelectPortInner};
98 pub use super::local_ptr::native::maybe_tls_key;
99 #[cfg(not(stage0), not(windows), not(target_os = "android"))]
100 pub use super::local_ptr::compiled::RT_TLS_PTR;
103 // Internal macros used by the runtime.
106 /// Basic implementation of an EventLoop, provides no I/O interfaces
109 /// The global (exchange) heap.
112 /// Implementations of language-critical runtime features like @.
115 /// Facilities related to task failure, killing, and death.
118 /// The coroutine task scheduler, built on the `io` event loop.
126 /// The EventLoop and internal synchronous I/O interface.
129 /// The Local trait for types that are accessible via thread-local
130 /// or task-local storage.
133 /// A parallel work-stealing deque.
136 /// A parallel queue.
137 pub mod message_queue;
139 /// A mostly lock-free multi-producer, single consumer queue.
142 /// A lock-free multi-producer, multi-consumer bounded queue.
143 mod mpmc_bounded_queue;
145 /// A parallel data structure for tracking sleeping schedulers.
146 pub mod sleeper_list;
148 /// Stack segments and caching.
151 /// CPU context swapping.
154 /// Bindings to system threading libraries.
157 /// The runtime configuration, read from environment variables.
160 /// The local, managed heap
163 /// The Logger trait and implementations
169 /// Tools for testing the runtime
172 /// Reference counting
175 /// A simple single-threaded channel type for passing buffered data between
176 /// scheduler and task context
179 /// Simple reimplementation of std::comm
184 /// The runtime needs to be able to put a pointer into thread-local storage.
187 /// Bindings to pthread/windows thread-local storage.
188 mod thread_local_storage;
193 // Global command line argument storage
196 // Support for dynamic borrowck
199 /// Set up a default runtime configuration, given compiler-supplied arguments.
201 /// This is invoked by the `start` _language item_ (unstable::lang) to
202 /// run a Rust executable.
206 /// * `argc` & `argv` - The argument vector. On Unix this information is used
211 /// The return value is used as the process return code. 0 on success, 101 on error.
212 pub fn start(argc: int, argv: **u8, main: proc()) -> int {
215 let exit_code = run(main);
216 // unsafe is ok b/c we're sure that the runtime is gone
217 unsafe { cleanup(); }
222 /// Like `start` but creates an additional scheduler on the current thread,
223 /// which in most cases will be the 'main' thread, and pins the main task to it.
225 /// This is appropriate for running code that must execute on the main thread,
226 /// such as the platform event loop and GUI.
227 pub fn start_on_main_thread(argc: int, argv: **u8, main: proc()) -> int {
229 let exit_code = run_on_main_thread(main);
230 // unsafe is ok b/c we're sure that the runtime is gone
231 unsafe { cleanup(); }
236 /// One-time runtime initialization.
238 /// Initializes global state, including frobbing
239 /// the crate's logging flags, registering GC
240 /// metadata, and storing the process arguments.
241 pub fn init(argc: int, argv: **u8) {
242 // XXX: Derefing these pointers is not safe.
243 // Need to propagate the unsafety to `start`.
245 args::init(argc, argv);
251 /// One-time runtime cleanup.
253 /// This function is unsafe because it performs no checks to ensure that the
254 /// runtime has completely ceased running. It is the responsibility of the
255 /// caller to ensure that the runtime is entirely shut down and nothing will be
256 /// poking around at the internal components.
258 /// Invoking cleanup while portions of the runtime are still in use may cause
259 /// undefined behavior.
260 pub unsafe fn cleanup() {
262 local_ptr::cleanup();
265 /// Execute the main function in a scheduler.
267 /// Configures the runtime according to the environment, by default
268 /// using a task scheduler with the same number of threads as cores.
269 /// Returns a process exit code.
270 pub fn run(main: proc()) -> int {
274 pub fn run_on_main_thread(main: proc()) -> int {
278 fn run_(main: proc(), use_main_sched: bool) -> int {
279 static DEFAULT_ERROR_CODE: int = 101;
281 let nscheds = util::default_sched_threads();
283 let main = Cell::new(main);
285 // The shared list of sleeping schedulers.
286 let sleepers = SleeperList::new();
288 // Create a work queue for each scheduler, ntimes. Create an extra
289 // for the main thread if that flag is set. We won't steal from it.
290 let work_queues: ~[WorkQueue<~Task>] = vec::from_fn(nscheds, |_| WorkQueue::new());
293 let mut scheds = ~[];
294 // Handles to the schedulers. When the main task ends these will be
295 // sent the Shutdown message to terminate the schedulers.
296 let mut handles = ~[];
298 for work_queue in work_queues.iter() {
299 rtdebug!("inserting a regular scheduler");
301 // Every scheduler is driven by an I/O event loop.
302 let loop_ = new_event_loop();
303 let mut sched = ~Scheduler::new(loop_,
307 let handle = sched.make_handle();
310 handles.push(handle);
313 // If we need a main-thread task then create a main thread scheduler
314 // that will reject any task that isn't pinned to it
315 let main_sched = if use_main_sched {
317 // Create a friend handle.
318 let mut friend_sched = scheds.pop();
319 let friend_handle = friend_sched.make_handle();
320 scheds.push(friend_sched);
322 // This scheduler needs a queue that isn't part of the stealee
324 let work_queue = WorkQueue::new();
326 let main_loop = new_event_loop();
327 let mut main_sched = ~Scheduler::new_special(main_loop,
332 Some(friend_handle));
333 let mut main_handle = main_sched.make_handle();
334 // Allow the scheduler to exit when the main task exits.
335 // Note: sending the shutdown message also prevents the scheduler
336 // from pushing itself to the sleeper list, which is used for
337 // waking up schedulers for work stealing; since this is a
338 // non-work-stealing scheduler it should not be adding itself
340 main_handle.send(Shutdown);
346 // Create a shared cell for transmitting the process exit
347 // code from the main task to this function.
348 let exit_code = UnsafeArc::new(AtomicInt::new(0));
349 let exit_code_clone = exit_code.clone();
351 // Used to sanity check that the runtime only exits once
352 let exited_already = UnsafeArc::new(AtomicBool::new(false));
354 // When the main task exits, after all the tasks in the main
355 // task tree, shut down the schedulers and set the exit code.
356 let handles = handles;
357 let on_exit: proc(UnwindResult) = proc(exit_success) {
359 assert!(!(*exited_already.get()).swap(true, SeqCst),
360 "the runtime already exited");
363 let mut handles = handles;
364 for handle in handles.mut_iter() {
365 handle.send(Shutdown);
369 let exit_code = if exit_success.is_success() {
372 // If we're exiting successfully, then return the global
373 // exit status, which can be set programmatically.
374 util::get_exit_status()
378 (*exit_code_clone.get()).store(exit_code, SeqCst);
382 let mut threads = ~[];
384 let on_exit = Cell::new(on_exit);
388 // In the case where we do not use a main_thread scheduler we
389 // run the main task in one of our threads.
391 let mut main_task = ~Task::new_root(&mut scheds[0].stack_pool, None, main.take());
392 main_task.name = Some(SendStrStatic("<main>"));
393 main_task.death.on_exit = Some(on_exit.take());
394 let main_task_cell = Cell::new(main_task);
396 let sched = scheds.pop();
397 let sched_cell = Cell::new(sched);
398 let thread = do Thread::start {
399 let sched = sched_cell.take();
400 sched.bootstrap(main_task_cell.take());
402 threads.push(thread);
405 // Run each remaining scheduler in a thread.
406 for sched in scheds.move_rev_iter() {
407 rtdebug!("creating regular schedulers");
408 let sched_cell = Cell::new(sched);
409 let thread = do Thread::start {
410 let mut sched = sched_cell.take();
411 let bootstrap_task = ~do Task::new_root(&mut sched.stack_pool, None) || {
412 rtdebug!("boostraping a non-primary scheduler");
414 sched.bootstrap(bootstrap_task);
416 threads.push(thread);
419 // If we do have a main thread scheduler, run it now.
423 rtdebug!("about to create the main scheduler task");
425 let mut main_sched = main_sched.unwrap();
427 let home = Sched(main_sched.make_handle());
428 let mut main_task = ~Task::new_root_homed(&mut main_sched.stack_pool, None,
430 main_task.name = Some(SendStrStatic("<main>"));
431 main_task.death.on_exit = Some(on_exit.take());
432 rtdebug!("bootstrapping main_task");
434 main_sched.bootstrap(main_task);
437 rtdebug!("waiting for threads");
439 // Wait for schedulers
440 for thread in threads.move_iter() {
444 // Return the exit code
446 (*exit_code.get()).load(SeqCst)
450 pub fn in_sched_context() -> bool {
452 let task_ptr: Option<*mut Task> = Local::try_unsafe_borrow();
455 match (*task).task_type {
465 pub fn in_green_task_context() -> bool {
467 let task: Option<*mut Task> = Local::try_unsafe_borrow();
470 match (*task).task_type {
471 GreenTask(_) => true,
480 pub fn new_event_loop() -> ~rtio::EventLoop {
481 match crate_map::get_crate_map() {
484 match map.event_loop_factory {
486 Some(factory) => return factory()
491 // If the crate map didn't specify a factory to create an event loop, then
492 // instead just use a basic event loop missing all I/O services to at least
493 // get the scheduler running.
494 return basic::event_loop();