Remove Runtime trait

This commit removes most of the remaining runtime infrastructure related
to the green/native split. In particular, it removes the `Runtime` trait
and instead inlines the native implementation.

Closes rust-lang#17325

[breaking-change]

Author: aturon

src/libnative/task.rs

@@ -24,252 +24,6 @@ use std::rt::task::{Task, BlockedTask, TaskOpts};
 use std::rt::thread::Thread;
 use std::rt;
 
-use std::task::{TaskBuilder, Spawner};
-
-/// Creates a new Task which is ready to execute as a 1:1 task.
-pub fn new(stack_bounds: (uint, uint), stack_guard: uint) -> Box<Task> {
-    let mut task = box Task::new();
-    let mut ops = ops();
-    ops.stack_bounds = stack_bounds;
-    ops.stack_guard = stack_guard;
-    task.put_runtime(ops);
-    return task;
-}
-
-fn ops() -> Box<Ops> {
-    box Ops {
-        lock: unsafe { NativeMutex::new() },
-        awoken: false,
-        // these *should* get overwritten
-        stack_bounds: (0, 0),
-        stack_guard: 0
-    }
-}
-
-/// A spawner for native tasks
-pub struct NativeSpawner;
-
-impl Spawner for NativeSpawner {
-    fn spawn(self, opts: TaskOpts, f: proc():Send) {
-        let TaskOpts { name, stack_size, on_exit } = opts;
-
-        let mut task = box Task::new();
-        task.name = name;
-        task.death.on_exit = on_exit;
-
-        let stack = stack_size.unwrap_or(rt::min_stack());
-        let task = task;
-        let ops = ops();
-
-        // Note that this increment must happen *before* the spawn in order to
-        // guarantee that if this task exits it will always end up waiting for
-        // the spawned task to exit.
-        let token = bookkeeping::increment();
-
-        // 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).
-        Thread::spawn_stack(stack, proc() {
-            let something_around_the_top_of_the_stack = 1;
-            let addr = &something_around_the_top_of_the_stack as *const int;
-            let my_stack = addr as uint;
-            unsafe {
-                stack::record_os_managed_stack_bounds(my_stack - stack + 1024,
-                                                      my_stack);
-            }
-            let mut ops = ops;
-            ops.stack_guard = rt::thread::current_guard_page();
-            ops.stack_bounds = (my_stack - stack + 1024, my_stack);
-
-            let mut f = Some(f);
-            let mut task = task;
-            task.put_runtime(ops);
-            drop(task.run(|| { f.take().unwrap()() }).destroy());
-            drop(token);
-        })
-    }
-}
-
-/// An extension trait adding a `native` configuration method to `TaskBuilder`.
-pub trait NativeTaskBuilder {
-    fn native(self) -> TaskBuilder<NativeSpawner>;
-}
-
-impl<S: Spawner> NativeTaskBuilder for TaskBuilder<S> {
-    fn native(self) -> TaskBuilder<NativeSpawner> {
-        self.spawner(NativeSpawner)
-    }
-}
-
-// This structure is the glue between channels and the 1:1 scheduling mode. This
-// structure is allocated once per task.
-struct Ops {
-    lock: NativeMutex,       // native synchronization
-    awoken: bool,      // used to prevent spurious wakeups
-
-    // This field holds the known bounds of the stack in (lo, hi) form. Not all
-    // native tasks necessarily know their precise bounds, hence this is
-    // optional.
-    stack_bounds: (uint, uint),
-
-    stack_guard: uint
-}
-
-impl rt::Runtime for Ops {
-    fn yield_now(self: Box<Ops>, mut cur_task: Box<Task>) {
-        // put the task back in TLS and then invoke the OS thread yield
-        cur_task.put_runtime(self);
-        Local::put(cur_task);
-        Thread::yield_now();
-    }
-
-    fn maybe_yield(self: Box<Ops>, mut cur_task: Box<Task>) {
-        // just put the task back in TLS, on OS threads we never need to
-        // opportunistically yield b/c the OS will do that for us (preemption)
-        cur_task.put_runtime(self);
-        Local::put(cur_task);
-    }
-
-    fn wrap(self: Box<Ops>) -> Box<Any+'static> {
-        self as Box<Any+'static>
-    }
-
-    fn stack_bounds(&self) -> (uint, uint) { self.stack_bounds }
-
-    fn stack_guard(&self) -> Option<uint> {
-        if self.stack_guard != 0 {
-            Some(self.stack_guard)
-        } else {
-            None
-        }
-    }
-
-    fn can_block(&self) -> bool { true }
-
-    // This function gets a little interesting. There are a few safety and
-    // ownership violations going on here, but this is all done in the name of
-    // shared state. Additionally, all of the violations are protected with a
-    // mutex, so in theory there are no races.
-    //
-    // The first thing we need to do is to get a pointer to the task's internal
-    // mutex. This address will not be changing (because the task is allocated
-    // on the heap). We must have this handle separately because the task will
-    // have its ownership transferred to the given closure. We're guaranteed,
-    // however, that this memory will remain valid because *this* is the current
-    // task's execution thread.
-    //
-    // The next weird part is where ownership of the task actually goes. We
-    // relinquish it to the `f` blocking function, but upon returning this
-    // function needs to replace the task back in TLS. There is no communication
-    // from the wakeup thread back to this thread about the task pointer, and
-    // there's really no need to. In order to get around this, we cast the task
-    // to a `uint` which is then used at the end of this function to cast back
-    // to a `Box<Task>` object. Naturally, this looks like it violates
-    // ownership semantics in that there may be two `Box<Task>` objects.
-    //
-    // The fun part is that the wakeup half of this implementation knows to
-    // "forget" the task on the other end. This means that the awakening half of
-    // things silently relinquishes ownership back to this thread, but not in a
-    // way that the compiler can understand. The task's memory is always valid
-    // for both tasks because these operations are all done inside of a mutex.
-    //
-    // You'll also find that if blocking fails (the `f` function hands the
-    // BlockedTask back to us), we will `mem::forget` the handles. The
-    // reasoning for this is the same logic as above in that the task silently
-    // transfers ownership via the `uint`, not through normal compiler
-    // semantics.
-    //
-    // On a mildly unrelated note, it should also be pointed out that OS
-    // condition variables are susceptible to spurious wakeups, which we need to
-    // be ready for. In order to accommodate for this fact, we have an extra
-    // `awoken` field which indicates whether we were actually woken up via some
-    // invocation of `reawaken`. This flag is only ever accessed inside the
-    // lock, so there's no need to make it atomic.
-    fn deschedule(mut self: Box<Ops>,
-                  times: uint,
-                  mut cur_task: Box<Task>,
-                  f: |BlockedTask| -> Result<(), BlockedTask>) {
-        let me = &mut *self as *mut Ops;
-        cur_task.put_runtime(self);
-
-        unsafe {
-            let cur_task_dupe = &mut *cur_task as *mut Task;
-            let task = BlockedTask::block(cur_task);
-
-            if times == 1 {
-                let guard = (*me).lock.lock();
-                (*me).awoken = false;
-                match f(task) {
-                    Ok(()) => {
-                        while !(*me).awoken {
-                            guard.wait();
-                        }
-                    }
-                    Err(task) => { mem::forget(task.wake()); }
-                }
-            } else {
-                let iter = task.make_selectable(times);
-                let guard = (*me).lock.lock();
-                (*me).awoken = false;
-
-                // Apply the given closure to all of the "selectable tasks",
-                // bailing on the first one that produces an error. Note that
-                // care must be taken such that when an error is occurred, we
-                // may not own the task, so we may still have to wait for the
-                // task to become available. In other words, if task.wake()
-                // returns `None`, then someone else has ownership and we must
-                // wait for their signal.
-                match iter.map(f).filter_map(|a| a.err()).next() {
-                    None => {}
-                    Some(task) => {
-                        match task.wake() {
-                            Some(task) => {
-                                mem::forget(task);
-                                (*me).awoken = true;
-                            }
-                            None => {}
-                        }
-                    }
-                }
-                while !(*me).awoken {
-                    guard.wait();
-                }
-            }
-            // re-acquire ownership of the task
-            cur_task = mem::transmute(cur_task_dupe);
-        }
-
-        // put the task back in TLS, and everything is as it once was.
-        Local::put(cur_task);
-    }
-
-    // See the comments on `deschedule` for why the task is forgotten here, and
-    // why it's valid to do so.
-    fn reawaken(mut self: Box<Ops>, mut to_wake: Box<Task>) {
-        unsafe {
-            let me = &mut *self as *mut Ops;
-            to_wake.put_runtime(self);
-            mem::forget(to_wake);
-            let guard = (*me).lock.lock();
-            (*me).awoken = true;
-            guard.signal();
-        }
-    }
-
-    fn spawn_sibling(self: Box<Ops>,
-                     mut cur_task: Box<Task>,
-                     opts: TaskOpts,
-                     f: proc():Send) {
-        cur_task.put_runtime(self);
-        Local::put(cur_task);
-
-        NativeSpawner.spawn(opts, f);
-    }
-}
-
 #[cfg(test)]
 mod tests {
     use std::rt::local::Local;

src/librustrt/lib.rs

@@ -39,11 +39,6 @@ pub use self::unwind::{begin_unwind, begin_unwind_fmt};
 
 use core::prelude::*;
 
-use alloc::boxed::Box;
-use core::any::Any;
-
-use task::{Task, BlockedTask, TaskOpts};
-
 mod macros;
 
 mod at_exit_imp;
@@ -60,46 +55,11 @@ pub mod exclusive;
 pub mod local;
 pub mod local_data;
 pub mod mutex;
-pub mod rtio;
 pub mod stack;
 pub mod task;
 pub mod thread;
 pub mod unwind;
 
-/// The interface to the current runtime.
-///
-/// This trait is used as the abstraction between 1:1 and M:N scheduling. The
-/// two independent crates, libnative and libgreen, both have objects which
-/// implement this trait. The goal of this trait is to encompass all the
-/// fundamental differences in functionality between the 1:1 and M:N runtime
-/// modes.
-pub trait Runtime {
-    // Necessary scheduling functions, used for channels and blocking I/O
-    // (sometimes).
-    fn yield_now(self: Box<Self>, cur_task: Box<Task>);
-    fn maybe_yield(self: Box<Self>, cur_task: Box<Task>);
-    fn deschedule(self: Box<Self>,
-                  times: uint,
-                  cur_task: Box<Task>,
-                  f: |BlockedTask| -> Result<(), BlockedTask>);
-    fn reawaken(self: Box<Self>, to_wake: Box<Task>);
-
-    // Miscellaneous calls which are very different depending on what context
-    // you're in.
-    fn spawn_sibling(self: Box<Self>,
-                     cur_task: Box<Task>,
-                     opts: TaskOpts,
-                     f: proc():Send);
-    /// The (low, high) edges of the current stack.
-    fn stack_bounds(&self) -> (uint, uint); // (lo, hi)
-    /// The last writable byte of the stack next to the guard page
-    fn stack_guard(&self) -> Option<uint>;
-    fn can_block(&self) -> bool;
-
-    // FIXME: This is a serious code smell and this should not exist at all.
-    fn wrap(self: Box<Self>) -> Box<Any+'static>;
-}
-
 /// The default error code of the rust runtime if the main task panics instead
 /// of exiting cleanly.
 pub const DEFAULT_ERROR_CODE: int = 101;