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 * `core::task` - The user-facing interface to the Rust task model.
44 * `core::task::local_data` - The interface to local data.
45 * `core::gc` - The garbage collector.
46 * `core::unstable::lang` - Miscellaneous lang items, some of which rely on `core::rt`.
47 * `core::condition` - Uses local data.
48 * `core::cleanup` - Local heap destruction.
49 * `core::io` - In the future `core::io` will use an `rt` implementation.
58 #[deny(unused_imports)];
60 #[deny(unused_variable)];
61 #[deny(unused_unsafe)];
65 use container::Container;
66 use iterator::{Iterator, IteratorUtil, range};
67 use option::{Some, None};
70 use rt::sched::{Scheduler, Shutdown};
71 use rt::sleeper_list::SleeperList;
72 use rt::task::{Task, SchedTask, GreenTask, Sched};
73 use rt::thread::Thread;
74 use rt::work_queue::WorkQueue;
75 use rt::uv::uvio::UvEventLoop;
76 use unstable::atomics::{AtomicInt, SeqCst};
77 use unstable::sync::UnsafeAtomicRcBox;
78 use vec::{OwnedVector, MutableVector};
80 /// The global (exchange) heap.
83 /// Implementations of language-critical runtime features like @.
86 /// Facilities related to task failure, killing, and death.
89 /// The coroutine task scheduler, built on the `io` event loop.
95 /// The EventLoop and internal synchronous I/O interface.
98 /// libuv and default rtio implementation.
101 /// The Local trait for types that are accessible via thread-local
102 /// or task-local storage.
105 /// A parallel work-stealing deque.
108 /// A parallel queue.
111 /// A parallel data structure for tracking sleeping schedulers.
114 /// Stack segments and caching.
117 /// CPU context swapping.
120 /// Bindings to system threading libraries.
123 /// The runtime configuration, read from environment variables
126 /// The local, managed heap
129 /// The Logger trait and implementations
132 /// Tools for testing the runtime
135 /// Reference counting
138 /// A simple single-threaded channel type for passing buffered data between
139 /// scheduler and task context
142 /// Simple reimplementation of core::comm
145 /// Routines for select()ing on pipes.
148 // FIXME #5248 shouldn't be pub
149 /// The runtime needs to be able to put a pointer into thread-local storage.
152 // FIXME #5248: The import in `sched` doesn't resolve unless this is pub!
153 /// Bindings to pthread/windows thread-local storage.
154 pub mod thread_local_storage;
158 // FIXME #5248 shouldn't be pub
162 // Global command line argument storage
165 // Support for dynamic borrowck
168 /// Set up a default runtime configuration, given compiler-supplied arguments.
170 /// This is invoked by the `start` _language item_ (unstable::lang) to
171 /// run a Rust executable.
175 /// * `argc` & `argv` - The argument vector. On Unix this information is used
177 /// * `crate_map` - Runtime information about the executing crate, mostly for logging
181 /// The return value is used as the process return code. 0 on success, 101 on error.
182 pub fn start(argc: int, argv: **u8, crate_map: *u8, main: ~fn()) -> int {
184 init(argc, argv, crate_map);
185 let exit_code = run(main);
191 /// Like `start` but creates an additional scheduler on the current thread,
192 /// which in most cases will be the 'main' thread, and pins the main task to it.
194 /// This is appropriate for running code that must execute on the main thread,
195 /// such as the platform event loop and GUI.
196 pub fn start_on_main_thread(argc: int, argv: **u8, crate_map: *u8, main: ~fn()) -> int {
197 init(argc, argv, crate_map);
198 let exit_code = run_on_main_thread(main);
204 /// One-time runtime initialization.
206 /// Initializes global state, including frobbing
207 /// the crate's logging flags, registering GC
208 /// metadata, and storing the process arguments.
209 pub fn init(argc: int, argv: **u8, crate_map: *u8) {
210 // XXX: Derefing these pointers is not safe.
211 // Need to propagate the unsafety to `start`.
213 args::init(argc, argv);
215 logging::init(crate_map);
216 rust_update_gc_metadata(crate_map);
220 fn rust_update_gc_metadata(crate_map: *u8);
224 /// One-time runtime cleanup.
229 /// Execute the main function in a scheduler.
231 /// Configures the runtime according to the environment, by default
232 /// using a task scheduler with the same number of threads as cores.
233 /// Returns a process exit code.
234 pub fn run(main: ~fn()) -> int {
238 pub fn run_on_main_thread(main: ~fn()) -> int {
242 fn run_(main: ~fn(), use_main_sched: bool) -> int {
243 static DEFAULT_ERROR_CODE: int = 101;
245 let nscheds = util::default_sched_threads();
247 let main = Cell::new(main);
249 // The shared list of sleeping schedulers.
250 let sleepers = SleeperList::new();
252 // Create a work queue for each scheduler, ntimes. Create an extra
253 // for the main thread if that flag is set. We won't steal from it.
254 let mut work_queues = ~[];
255 for _ in range(0u, nscheds) {
256 let work_queue: WorkQueue<~Task> = WorkQueue::new();
257 work_queues.push(work_queue);
261 let mut scheds = ~[];
262 // Handles to the schedulers. When the main task ends these will be
263 // sent the Shutdown message to terminate the schedulers.
264 let mut handles = ~[];
266 for i in range(0u, nscheds) {
267 rtdebug!("inserting a regular scheduler");
269 // Every scheduler is driven by an I/O event loop.
270 let loop_ = ~UvEventLoop::new();
271 let mut sched = ~Scheduler::new(loop_,
272 work_queues[i].clone(),
275 let handle = sched.make_handle();
278 handles.push(handle);
281 // If we need a main-thread task then create a main thread scheduler
282 // that will reject any task that isn't pinned to it
283 let main_sched = if use_main_sched {
285 // Create a friend handle.
286 let mut friend_sched = scheds.pop();
287 let friend_handle = friend_sched.make_handle();
288 scheds.push(friend_sched);
290 // This scheduler needs a queue that isn't part of the stealee
292 let work_queue = WorkQueue::new();
294 let main_loop = ~UvEventLoop::new();
295 let mut main_sched = ~Scheduler::new_special(main_loop,
300 Some(friend_handle));
301 let main_handle = main_sched.make_handle();
302 handles.push(main_handle);
308 // Create a shared cell for transmitting the process exit
309 // code from the main task to this function.
310 let exit_code = UnsafeAtomicRcBox::new(AtomicInt::new(0));
311 let exit_code_clone = exit_code.clone();
313 // When the main task exits, after all the tasks in the main
314 // task tree, shut down the schedulers and set the exit code.
315 let handles = Cell::new(handles);
316 let on_exit: ~fn(bool) = |exit_success| {
318 let mut handles = handles.take();
319 for handle in handles.mut_iter() {
320 handle.send(Shutdown);
324 let exit_code = if exit_success {
327 // If we're exiting successfully, then return the global
328 // exit status, which can be set programmatically.
329 util::get_exit_status()
333 (*exit_code_clone.get()).store(exit_code, SeqCst);
337 let mut threads = ~[];
339 let on_exit = Cell::new(on_exit);
343 // In the case where we do not use a main_thread scheduler we
344 // run the main task in one of our threads.
346 let mut main_task = ~Task::new_root(&mut scheds[0].stack_pool, None, main.take());
347 main_task.death.on_exit = Some(on_exit.take());
348 let main_task_cell = Cell::new(main_task);
350 let sched = scheds.pop();
351 let sched_cell = Cell::new(sched);
352 let thread = do Thread::start {
353 let sched = sched_cell.take();
354 sched.bootstrap(main_task_cell.take());
356 threads.push(thread);
359 // Run each remaining scheduler in a thread.
360 while !scheds.is_empty() {
361 rtdebug!("creating regular schedulers");
362 let sched = scheds.pop();
363 let sched_cell = Cell::new(sched);
364 let thread = do Thread::start {
365 let mut sched = sched_cell.take();
366 let bootstrap_task = ~do Task::new_root(&mut sched.stack_pool, None) || {
367 rtdebug!("boostraping a non-primary scheduler");
369 sched.bootstrap(bootstrap_task);
371 threads.push(thread);
374 // If we do have a main thread scheduler, run it now.
378 rtdebug!("about to create the main scheduler task");
380 let mut main_sched = main_sched.unwrap();
382 let home = Sched(main_sched.make_handle());
383 let mut main_task = ~Task::new_root_homed(&mut main_sched.stack_pool, None,
385 main_task.death.on_exit = Some(on_exit.take());
386 rtdebug!("bootstrapping main_task");
388 main_sched.bootstrap(main_task);
391 rtdebug!("waiting for threads");
393 // Wait for schedulers
394 for thread in threads.consume_iter() {
398 // Return the exit code
400 (*exit_code.get()).load(SeqCst)
404 /// Possible contexts in which Rust code may be executing.
405 /// Different runtime services are available depending on context.
406 /// Mostly used for determining if we're using the new scheduler
407 /// or the old scheduler.
409 pub enum RuntimeContext {
410 // Only the exchange heap is available
412 // The scheduler may be accessed
414 // Full task services, e.g. local heap, unwinding
416 // Running in an old-style task
420 /// Determine the current RuntimeContext
421 pub fn context() -> RuntimeContext {
423 use task::rt::rust_task;
425 if unsafe { rust_try_get_task().is_not_null() } {
426 return OldTaskContext;
427 } else if Local::exists::<Task>() {
428 // In this case we know it is a new runtime context, but we
429 // need to check which one. Going to try borrowing task to
430 // check. Task should always be in TLS, so hopefully this
431 // doesn't conflict with other ops that borrow.
432 return do Local::borrow::<Task,RuntimeContext> |task| {
433 match task.task_type {
434 SchedTask => SchedulerContext,
435 GreenTask(_) => TaskContext
439 return GlobalContext;
444 pub fn rust_try_get_task() -> *rust_task;