Introduce std::thread

Also removes:

* `std::task`
* `std::rt::task`
* `std::rt::thread`

Notes for the new API are in a follow-up commit.

Closes #18000

1 files changed, 655 insertions, 0 deletions

diff --git a/src/libstd/thread.rs b/src/libstd/thread.rs
new file mode 100644
index 00000000000..a6e114bc2c3
--- /dev/null
+++ b/src/libstd/thread.rs
@@ -0,0 +1,655 @@
+// 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.
+//!
+//! Threads generally have their memory *isolated* from each other by virtue of
+//! Rust's owned types (which of course may only be owned by a single thread at
+//! a time). Communication between threads can be done through
+//! [channels](../../std/comm/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
+//! 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), described below.
+//!
+//! ## The `Thread` type
+//!
+//! Already-running 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` constructor;
+//! * 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
+//!
+//! There are a few different ways to spawn a new thread, depending on how it
+//! should relate to the parent thread.
+//!
+//! ### Simple detached threads
+//!
+//! The simplest case just spawns a completely independent (detached) thread,
+//! returning a new `Thread` handle to it:
+//!
+//! ```rust
+//! use std::thread::Thread;
+//!
+//! Thread::spawn(proc() {
+//!     println!("Hello, World!");
+//! })
+//! ```
+//!
+//! The spawned thread may outlive its parent.
+//!
+//! ### Joining
+//!
+//! Alternatively, the `with_join` constructor spawns a new thread and returns a
+//! `JoinGuard` which can be used to wait until the child thread completes,
+//! returning its result (or `Err` if the child thread panicked):
+//!
+//! ```rust
+//! use std::thread::Thread;
+//!
+//! let guard = Thread::with_join(proc() { panic!() };
+//! assert!(guard.join().is_err());
+//! ```
+//!
+//! The guard works in RAII style, meaning that the child thread is
+//! automatically joined when the guard is dropped. A handle to the thread
+//! itself is available via the `thread` method on the guard.
+//!
+//! ### Configured threads
+//!
+//! Finally, a new thread can be configured independently of how it is
+//! spawned. Configuration is available via the `Cfg` builder, 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::cfg().name("child1").spawn(proc() { 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.
+//!
+//! * 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 highly efficiently on many platforms.
+
+use core::prelude::*;
+
+use any::Any;
+use borrow::IntoCow;
+use boxed::Box;
+use mem;
+use sync::{Mutex, Condvar, Arc};
+use string::String;
+use rt::{mod, unwind};
+use io::{Writer, stdio};
+
+use sys::thread as imp;
+use sys_common::{stack, thread_info};
+
+/// Thread configuation. Provides detailed control over the properties
+/// and behavior of new threads.
+pub struct Cfg {
+    // 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<uint>,
+    // Thread-local stdout
+    stdout: Option<Box<Writer + Send>>,
+    // Thread-local stderr
+    stderr: Option<Box<Writer + Send>>,
+}
+
+impl Cfg {
+    /// Generate the base configuration for spawning a thread, from which
+    /// configuration methods can be chained.
+    pub fn new() -> Cfg {
+        Cfg {
+            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.
+    pub fn name(mut self, name: String) -> Cfg {
+        self.name = Some(name);
+        self
+    }
+
+    /// Deprecated: use `name` instead
+    #[deprecated = "use name instead"]
+    pub fn named<T: IntoCow<'static, String, str>>(self, name: T) -> Cfg {
+        self.name(name.into_cow().into_owned())
+    }
+
+    /// Set the size of the stack for the new thread.
+    pub fn stack_size(mut self, size: uint) -> Cfg {
+        self.stack_size = Some(size);
+        self
+    }
+
+    /// Redirect thread-local stdout.
+    #[experimental = "Will likely go away after proc removal"]
+    pub fn stdout(mut self, stdout: Box<Writer + Send>) -> Cfg {
+        self.stdout = Some(stdout);
+        self
+    }
+
+    /// Redirect thread-local stderr.
+    #[experimental = "Will likely go away after proc removal"]
+    pub fn stderr(mut self, stderr: Box<Writer + Send>) -> Cfg {
+        self.stderr = Some(stderr);
+        self
+    }
+
+    fn core_spawn<T: Send>(self, f: proc():Send -> T, after: proc(Result<T>):Send)
+                           -> (imp::rust_thread, Thread)
+    {
+        let Cfg { 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();
+
+        // 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 = 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_top = addr as uint;
+            let my_stack_bottom = my_stack_top - stack_size + 1024;
+            unsafe {
+                stack::record_os_managed_stack_bounds(my_stack_bottom, my_stack_top);
+            }
+            thread_info::set(
+                (my_stack_bottom, my_stack_top),
+                thread::current_guard_page(),
+                their_thread
+            );
+
+            // 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 {
+                let mut output = None;
+                let mut f_opt = Some( // option dance
+                    if stdout.is_some() || stderr.is_some() {
+                        proc() {
+                            let _ = stdout.map(stdio::set_stdout);
+                            let _ = stderr.map(stdio::set_stderr);
+                            f()
+                        }
+                    } else {
+                        f
+                    });
+                let try_result = unwind::try(|| output = Some((f_opt.take().unwrap())()));
+                match (output, try_result) {
+                    (Some(data), Ok(_)) => after(Ok(data)),
+                    (None, Err(cause)) => after(Err(cause)),
+                    _ => unreachable!()
+                }
+            }
+        };
+        (unsafe { imp::create(stack, box main) }, my_thread)
+    }
+
+    /// Spawn a detached thread, and return a handle to it.
+    ///
+    /// The new child thread may outlive its parent.
+    pub fn spawn(self, f: proc():Send) -> Thread {
+        let (native, thread) = self.core_spawn(f, proc(_) {});
+        unsafe { imp::detach(native) };
+        thread
+    }
+
+    /// Spawn a joinable thread, and return an RAII guard for it.
+    pub fn with_join<T: Send>(self, f: proc():Send -> T) -> JoinGuard<T> {
+        // We need the address of the packet to fill in to be stable so when
+        // `main` fills it in it's still valid, so allocate an extra box to do
+        // so.
+        let my_packet = box Err(box 0); // sentinel value
+        let their_packet: *mut Result<T> = unsafe {
+            *mem::transmute::<&Box<Result<T>>, *const *mut Result<T>>(&my_packet)
+        };
+
+        let (native, thread) = self.core_spawn(f, proc(result) {
+            *their_packet = result;
+        });
+
+        JoinGuard {
+            native: native,
+            joined: false,
+            packet: my_packet,
+            thread: thread,
+        }
+    }
+}
+
+/// A convenience function for creating configurations.
+pub fn cfg() -> Cfg { Cfg::new() }
+
+struct Inner {
+    name: Option<String>,
+    lock: Mutex<bool>,          // true when there is a buffered unpark
+    cvar: Condvar,
+}
+
+#[deriving(Clone)]
+/// A handle to a thread.
+pub struct Thread {
+    inner: Arc<Inner>,
+}
+
+impl Thread {
+    fn new(name: Option<String>) -> Thread {
+        Thread {
+            inner: Arc::new(Inner {
+                name: name,
+                lock: Mutex::new(false),
+                cvar: Condvar::new(),
+            })
+        }
+    }
+
+    /// Spawn a detached thread, and return a handle to it.
+    ///
+    /// The new child thread may outlive its parent.
+    pub fn spawn(f: proc():Send) -> Thread {
+        Cfg::new().spawn(f)
+    }
+
+    /// Spawn a joinable thread, and return an RAII guard for it.
+    pub fn with_join<T: Send>(f: proc():Send -> T) -> JoinGuard<T> {
+        Cfg::new().with_join(f)
+    }
+
+    /// Gets a handle to the thread that invokes it.
+    pub fn current() -> Thread {
+        ThreadInfo::current_thread()
+    }
+
+    /// Cooperatively give up a timeslice to the OS scheduler.
+    pub fn yield_now() {
+        unsafe { imp::yield_now() }
+    }
+
+    /// Determines whether the current thread is panicking.
+    pub fn panicking() -> bool {
+        ThreadInfo::panicking()
+    }
+
+    // http://cr.openjdk.java.net/~stefank/6989984.1/raw_files/new/src/os/linux/vm/os_linux.cpp
+    /// Block unless or until the current thread's token is made available (may wake spuriously).
+    ///
+    /// See the module doc for more detail.
+    pub fn park() {
+        let thread = Thread::current();
+        let guard = thread.inner.lock.lock();
+        while !*guard {
+            thread.inner.cvar.wait(guard);
+        }
+        *guard = false;
+    }
+
+    /// Atomically makes the handle's token available if it is not already.
+    ///
+    /// See the module doc for more detail.
+    pub fn unpark(&self) {
+        let guard = self.inner.lock();
+        if !*guard {
+            *guard = true;
+            self.inner.cvar.notify_one();
+        }
+    }
+
+    /// Get the thread's name.
+    pub fn name(&self) -> Option<&str> {
+        self.inner.name.as_ref()
+    }
+}
+
+// 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.
+pub type Result<T> = result::Result<T, Box<Any + Send>>;
+
+#[must_use]
+/// An RAII guard that will block until thread termination when dropped.
+pub struct JoinGuard<T> {
+    native: imp::rust_thread,
+    thread: Thread,
+    joined: bool,
+    packet: Box<Result<T>>,
+}
+
+impl<T: Send> JoinGuard<T> {
+    /// Extract a handle to the thread this guard will join on.
+    pub fn thread(&self) -> Thread {
+        self.thread.clone()
+    }
+
+    /// Wait for the associated thread to finish, returning the result of the thread's
+    /// calculation.
+    pub fn join(mut self) -> Result<T> {
+        assert!(!self.joined);
+        unsafe { imp::join(self.native) };
+        self.joined = true;
+        let box res =  self.packet.take().unwrap();
+        res
+    }
+}
+
+#[unsafe_destructor]
+impl<T: Send> Drop for JoinGuard<T> {
+    fn drop(&mut self) {
+        // This is required for correctness. If this is not done then the thread
+        // would fill in a return box which no longer exists.
+        if !self.joined {
+            unsafe { imp::join(self.native) };
+        }
+    }
+}
+
+// TODO: fix tests
+#[cfg(test)]
+mod test {
+    use any::{Any, AnyRefExt};
+    use boxed::BoxAny;
+    use prelude::*;
+    use result::Result::{Ok, Err};
+    use result;
+    use std::io::{ChanReader, ChanWriter};
+    use string::String;
+    use super::{Thread, cfg};
+
+    // !!! 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::with_join(proc() {
+            assert!(Thread::current().name().is_none());
+        }).join().map_err(|_| ()).unwrap();
+    }
+
+    #[test]
+    fn test_named_thread() {
+        cfg().name("ada lovelace".to_string()).with_join(proc() {
+            assert!(Thread::current().name().unwrap() == "ada lovelace".to_string());
+        }).join().map_err(|_| ()).unwrap();
+    }
+
+    #[test]
+    fn test_run_basic() {
+        let (tx, rx) = channel();
+        Thread::spawn(proc() {
+            tx.send(());
+        });
+        rx.recv();
+    }
+
+    #[test]
+    fn test_join_success() {
+        match Thread::with_join::<String>(proc() {
+            "Success!".to_string()
+        }).join().as_ref().map(|s| s.as_slice()) {
+            result::Result::Ok("Success!") => (),
+            _ => panic!()
+        }
+    }
+
+    #[test]
+    fn test_join_panic() {
+        match Thread::with_join(proc() {
+            panic!()
+        }).join() {
+            result::Result::Err(_) => (),
+            result::Result::Ok(()) => panic!()
+        }
+    }
+
+    #[test]
+    fn test_spawn_sched() {
+        use clone::Clone;
+
+        let (tx, rx) = channel();
+
+        fn f(i: int, tx: Sender<()>) {
+            let tx = tx.clone();
+            Thread::spawn(proc() {
+                if i == 0 {
+                    tx.send(());
+                } else {
+                    f(i - 1, tx);
+                }
+            });
+
+        }
+        f(10, tx);
+        rx.recv();
+    }
+
+    #[test]
+    fn test_spawn_sched_childs_on_default_sched() {
+        let (tx, rx) = channel();
+
+        Thread::spawn(proc() {
+            Thread::spawn(proc() {
+                tx.send(());
+            });
+        });
+
+        rx.recv();
+    }
+
+    fn avoid_copying_the_body(spawnfn: |v: proc():Send|) {
+        let (tx, rx) = channel::<uint>();
+
+        let x = box 1;
+        let x_in_parent = (&*x) as *const int as uint;
+
+        spawnfn(proc() {
+            let x_in_child = (&*x) as *const int as uint;
+            tx.send(x_in_child);
+        });
+
+        let x_in_child = rx.recv();
+        assert_eq!(x_in_parent, x_in_child);
+    }
+
+    #[test]
+    fn test_avoid_copying_the_body_spawn() {
+        avoid_copying_the_body(|v| { Thread::spawn(v); });
+    }
+
+    #[test]
+    fn test_avoid_copying_the_body_thread_spawn() {
+        avoid_copying_the_body(|f| {
+            let builder = cfg();
+            builder.spawn(proc() {
+                f();
+            });
+        })
+    }
+
+    #[test]
+    fn test_avoid_copying_the_body_join() {
+        avoid_copying_the_body(|f| {
+            let _ = Thread::with_join(proc() {
+                f()
+            }).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..!)
+        static GENERATIONS: uint = 16;
+        fn child_no(x: uint) -> proc(): Send {
+            return proc() {
+                if x < GENERATIONS {
+                    Thread::spawn(child_no(x+1));
+                }
+            }
+        }
+        Thread::spawn(child_no(0));
+    }
+
+    #[test]
+    fn test_simple_newsched_spawn() {
+        Thread::spawn(proc()());
+    }
+
+    #[test]
+    fn test_try_panic_message_static_str() {
+        match Thread::with_join(proc() {
+            panic!("static string");
+        }).join() {
+            Err(e) => {
+                type T = &'static str;
+                assert!(e.is::<T>());
+                assert_eq!(*e.downcast::<T>().unwrap(), "static string");
+            }
+            Ok(()) => panic!()
+        }
+    }
+
+    #[test]
+    fn test_try_panic_message_owned_str() {
+        match Thread::with_join(proc() {
+            panic!("owned string".to_string());
+        }).join() {
+            Err(e) => {
+                type T = String;
+                assert!(e.is::<T>());
+                assert_eq!(*e.downcast::<T>().unwrap(), "owned string".to_string());
+            }
+            Ok(()) => panic!()
+        }
+    }
+
+    #[test]
+    fn test_try_panic_message_any() {
+        match Thread::with_join(proc() {
+            panic!(box 413u16 as Box<Any + Send>);
+        }).join() {
+            Err(e) => {
+                type T = Box<Any + Send>;
+                assert!(e.is::<T>());
+                let any = e.downcast::<T>().unwrap();
+                assert!(any.is::<u16>());
+                assert_eq!(*any.downcast::<u16>().unwrap(), 413u16);
+            }
+            Ok(()) => panic!()
+        }
+    }
+
+    #[test]
+    fn test_try_panic_message_unit_struct() {
+        struct Juju;
+
+        match Thread::with_join(proc() {
+            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);
+
+        let r = cfg().stdout(box stdout as Box<Writer + Send>).with_join(proc() {
+                print!("Hello, world!");
+            }).join();
+        assert!(r.is_ok());
+
+        let output = reader.read_to_string().unwrap();
+        assert_eq!(output, "Hello, world!".to_string());
+    }
+
+    // NOTE: the corresponding test for stderr is in run-pass/task-stderr, due
+    // to the test harness apparently interfering with stderr configuration.
+}