Revise std::thread API to join by default

This commit is part of a series that introduces a `std::thread` API to
replace `std::task`.

In the new API, `spawn` returns a `JoinGuard`, which by default will
join the spawned thread when dropped. It can also be used to join
explicitly at any time, returning the thread's result. Alternatively,
the spawned thread can be explicitly detached (so no join takes place).

As part of this change, Rust processes now terminate when the main
thread exits, even if other detached threads are still running, moving
Rust closer to standard threading models. This new behavior may break code
that was relying on the previously implicit join-all.

In addition to the above, the new thread API also offers some built-in
support for building blocking abstractions in user space; see the module
doc for details.

Closes rust-lang#18000

[breaking-change]

Author: aturon

src/compiletest/runtest.rs

@@ -445,7 +445,7 @@ fn run_debuginfo_gdb_test(config: &Config, props: &TestProps, testfile: &Path) {
             loop {
                 //waiting 1 second for gdbserver start
                 timer::sleep(Duration::milliseconds(1000));
-                let result = Thread::with_join(move || {
+                let result = Thread::spawn(move || {
                     tcp::TcpStream::connect("127.0.0.1:5039").unwrap();
                 }).join();
                 if result.is_err() {

src/doc/guide-tasks.md

@@ -1,5 +1,7 @@
 % The Rust Tasks and Communication Guide
 
+**NOTE** This guide is badly out of date an needs to be rewritten.
+
 # Introduction
 
 Rust provides safe concurrent abstractions through a number of core library
@@ -22,7 +24,7 @@ from shared mutable state.
 At its simplest, creating a task is a matter of calling the `spawn` function
 with a closure argument. `spawn` executes the closure in the new task.
 
-```{rust}
+```{rust,ignore}
 # use std::task::spawn;
 
 // Print something profound in a different task using a named function
@@ -49,7 +51,7 @@ closure is limited to capturing `Send`-able data from its environment
 ensures that `spawn` can safely move the entire closure and all its
 associated state into an entirely different task for execution.
 
-```{rust}
+```{rust,ignore}
 # use std::task::spawn;
 # fn generate_task_number() -> int { 0 }
 // Generate some state locally
@@ -75,7 +77,7 @@ The simplest way to create a channel is to use the `channel` function to create
 of a channel, and a **receiver** is the receiving endpoint. Consider the following
 example of calculating two results concurrently:
 
-```{rust}
+```{rust,ignore}
 # use std::task::spawn;
 
 let (tx, rx): (Sender<int>, Receiver<int>) = channel();
@@ -96,15 +98,15 @@ stream for sending and receiving integers (the left-hand side of the `let`,
 `(tx, rx)`, is an example of a destructuring let: the pattern separates a tuple
 into its component parts).
 
-```{rust}
+```{rust,ignore}
 let (tx, rx): (Sender<int>, Receiver<int>) = channel();
 ```
 
 The child task will use the sender to send data to the parent task, which will
 wait to receive the data on the receiver. The next statement spawns the child
 task.
 
-```{rust}
+```{rust,ignore}
 # use std::task::spawn;
 # fn some_expensive_computation() -> int { 42 }
 # let (tx, rx) = channel();
@@ -123,7 +125,7 @@ computation, then sends the result over the captured channel.
 Finally, the parent continues with some other expensive computation, then waits
 for the child's result to arrive on the receiver:
 
-```{rust}
+```{rust,ignore}
 # fn some_other_expensive_computation() {}
 # let (tx, rx) = channel::<int>();
 # tx.send(0);
@@ -154,7 +156,7 @@ spawn(move || {
 
 Instead we can clone the `tx`, which allows for multiple senders.
 
-```{rust}
+```{rust,ignore}
 let (tx, rx) = channel();
 
 for init_val in range(0u, 3) {
@@ -179,7 +181,7 @@ Note that the above cloning example is somewhat contrived since you could also
 simply use three `Sender` pairs, but it serves to illustrate the point. For
 reference, written with multiple streams, it might look like the example below.
 
-```{rust}
+```{rust,ignore}
 # use std::task::spawn;
 
 // Create a vector of ports, one for each child task
@@ -203,7 +205,7 @@ getting the result later.
 
 The basic example below illustrates this.
 
-```{rust}
+```{rust,ignore}
 use std::sync::Future;
 
 # fn main() {
@@ -230,7 +232,7 @@ called.
 Here is another example showing how futures allow you to background
 computations. The workload will be distributed on the available cores.
 
-```{rust}
+```{rust,ignore}
 # use std::num::Float;
 # use std::sync::Future;
 fn partial_sum(start: uint) -> f64 {
@@ -268,7 +270,7 @@ Here is a small example showing how to use Arcs. We wish to run concurrently
 several computations on a single large vector of floats. Each task needs the
 full vector to perform its duty.
 
-```{rust}
+```{rust,ignore}
 use std::num::Float;
 use std::rand;
 use std::sync::Arc;
@@ -295,7 +297,7 @@ The function `pnorm` performs a simple computation on the vector (it computes
 the sum of its items at the power given as argument and takes the inverse power
 of this value). The Arc on the vector is created by the line:
 
-```{rust}
+```{rust,ignore}
 # use std::rand;
 # use std::sync::Arc;
 # fn main() {
@@ -309,7 +311,7 @@ the wrapper and not its contents. Within the task's procedure, the captured
 Arc reference can be used as a shared reference to the underlying vector as
 if it were local.
 
-```{rust}
+```{rust,ignore}
 # use std::rand;
 # use std::sync::Arc;
 # fn pnorm(nums: &[f64], p: uint) -> f64 { 4.0 }
@@ -346,11 +348,11 @@ and `()`, callers can pattern-match on a result to check whether it's an `Ok`
 result with an `int` field (representing a successful result) or an `Err` result
 (representing termination with an error).
 
-```{rust}
+```{rust,ignore}
 # use std::thread::Thread;
 # fn some_condition() -> bool { false }
 # fn calculate_result() -> int { 0 }
-let result: Result<int, Box<std::any::Any + Send>> = Thread::with_join(move || {
+let result: Result<int, Box<std::any::Any + Send>> = Thread::spawn(move || {
     if some_condition() {
         calculate_result()
     } else {

src/doc/guide.md

@@ -5217,6 +5217,8 @@ the same function, so our binary is a little bit larger.
 
 # Tasks
 
+**NOTE**: this section is currently out of date and will be rewritten soon.
+
 Concurrency and parallelism are topics that are of increasing interest to a
 broad subsection of software developers. Modern computers are often multi-core,
 to the point that even embedded devices like cell phones have more than one
@@ -5231,7 +5233,7 @@ library, and not part of the language. This means that in the future, other
 concurrency libraries can be written for Rust to help in specific scenarios.
 Here's an example of creating a task:
 
-```{rust}
+```{rust,ignore}
 spawn(move || {
     println!("Hello from a task!");
 });
@@ -5261,7 +5263,7 @@ If tasks were only able to capture these values, they wouldn't be very useful.
 Luckily, tasks can communicate with each other through **channel**s. Channels
 work like this:
 
-```{rust}
+```{rust,ignore}
 let (tx, rx) = channel();
 
 spawn(move || {
@@ -5280,7 +5282,7 @@ which returns an `Result<T, TryRecvError>` and does not block.
 
 If you want to send messages to the task as well, create two channels!
 
-```{rust}
+```{rust,ignore}
 let (tx1, rx1) = channel();
 let (tx2, rx2) = channel();
 
@@ -5340,7 +5342,7 @@ we'll just get the value immediately.
 Tasks don't always succeed, they can also panic. A task that wishes to panic
 can call the `panic!` macro, passing a message:
 
-```{rust}
+```{rust,ignore}
 spawn(move || {
     panic!("Nope.");
 });
@@ -5349,7 +5351,7 @@ spawn(move || {
 If a task panics, it is not possible for it to recover. However, it can
 notify other tasks that it has panicked. We can do this with `task::try`:
 
-```{rust}
+```{rust,ignore}
 use std::task;
 use std::rand;
 

src/doc/intro.md

@@ -389,11 +389,13 @@ safe concurrent programs.
 Here's an example of a concurrent Rust program:
 
 ```{rust}
+use std::thread::Thread;
+
 fn main() {
     for _ in range(0u, 10u) {
-        spawn(move || {
+        Thread::spawn(move || {
             println!("Hello, world!");
-        });
+        }).detach();
     }
 }
 ```
@@ -403,7 +405,8 @@ This program creates ten threads, who all print `Hello, world!`. The
 double bars `||`. (The `move` keyword indicates that the closure takes
 ownership of any data it uses; we'll have more on the significance of
 this shortly.) This closure is executed in a new thread created by
-`spawn`.
+`spawn`. The `detach` method means that the child thread is allowed to
+outlive its parent.
 
 One common form of problem in concurrent programs is a 'data race.'
 This occurs when two different threads attempt to access the same
@@ -418,13 +421,15 @@ problem.
 Let's see an example. This Rust code will not compile:
 
 ```{rust,ignore}
+use std::thread::Thread;
+
 fn main() {
     let mut numbers = vec![1i, 2i, 3i];
 
     for i in range(0u, 3u) {
-        spawn(move || {
+        Thread::spawn(move || {
             for j in range(0, 3) { numbers[j] += 1 }
-        });
+        }).detach();
     }
 }
 ```
@@ -469,20 +474,21 @@ mutation doesn't cause a data race.
 Here's what using an Arc with a Mutex looks like:
 
 ```{rust}
+use std::thread::Thread;
 use std::sync::{Arc,Mutex};
 
 fn main() {
     let numbers = Arc::new(Mutex::new(vec![1i, 2i, 3i]));
 
     for i in range(0u, 3u) {
         let number = numbers.clone();
-        spawn(move || {
+        Thread::spawn(move || {
             let mut array = number.lock();
 
             (*array)[i] += 1;
 
             println!("numbers[{}] is {}", i, (*array)[i]);
-        });
+        }).detach();
     }
 }
 ```
@@ -532,13 +538,15 @@ As an example, Rust's ownership system is _entirely_ at compile time. The
 safety check that makes this an error about moved values:
 
 ```{rust,ignore}
+use std::thread::Thread;
+
 fn main() {
     let vec = vec![1i, 2, 3];
 
     for i in range(1u, 3) {
-        spawn(move || {
+        Thread::spawn(move || {
             println!("{}", vec[i]);
-        });
+        }).detach();
     }
 }
 ```

src/liballoc/arc.rs

@@ -39,6 +39,7 @@ use heap::deallocate;
 ///
 /// ```rust
 /// use std::sync::Arc;
+/// use std::thread::Thread;
 ///
 /// fn main() {
 ///     let numbers = Vec::from_fn(100, |i| i as f32);
@@ -47,11 +48,11 @@ use heap::deallocate;
 ///     for _ in range(0u, 10) {
 ///         let child_numbers = shared_numbers.clone();
 ///
-///         spawn(move || {
+///         Thread::spawn(move || {
 ///             let local_numbers = child_numbers.as_slice();
 ///
 ///             // Work with the local numbers
-///         });
+///         }).detach();
 ///     }
 /// }
 /// ```

src/libcollections/slice.rs

@@ -1344,6 +1344,7 @@ pub mod raw {
 
 #[cfg(test)]
 mod tests {
+    use std::boxed::Box;
     use std::cell::Cell;
     use std::default::Default;
     use std::mem;
@@ -1627,7 +1628,10 @@ mod tests {
     #[test]
     fn test_swap_remove_noncopyable() {
         // Tests that we don't accidentally run destructors twice.
-        let mut v = vec![Box::new(()), Box::new(()), Box::new(())];
+        let mut v = Vec::new();
+        v.push(box 0u8);
+        v.push(box 0u8);
+        v.push(box 0u8);
         let mut _e = v.swap_remove(0);
         assert_eq!(v.len(), 2);
         _e = v.swap_remove(1);

src/libcore/borrow.rs

@@ -92,7 +92,7 @@ impl<'a, T, Sized? B> BorrowFrom<Cow<'a, T, B>> for B where B: ToOwned<T> {
 
 /// Trait for moving into a `Cow`
 pub trait IntoCow<'a, T, Sized? B> {
-    /// Moves `serlf` into `Cow`
+    /// Moves `self` into `Cow`
     fn into_cow(self) -> Cow<'a, T, B>;
 }
 

src/libcoretest/finally.rs

@@ -9,7 +9,7 @@
 // except according to those terms.
 
 use core::finally::{try_finally, Finally};
-use std::task::failing;
+use std::thread::Thread;
 
 #[test]
 fn test_success() {
@@ -20,7 +20,7 @@ fn test_success() {
             *i = 10;
         },
         |i| {
-            assert!(!failing());
+            assert!(!Thread::panicking());
             assert_eq!(*i, 10);
             *i = 20;
         });
@@ -38,7 +38,7 @@ fn test_fail() {
             panic!();
         },
         |i| {
-            assert!(failing());
+            assert!(Thread::panicking());
             assert_eq!(*i, 10);
         })
 }

src/librustc_driver/lib.rs

@@ -475,22 +475,18 @@ pub fn monitor<F:FnOnce()+Send>(f: F) {
     static STACK_SIZE: uint = 32000000; // 32MB
 
     let (tx, rx) = channel();
-    let mut w = Some(io::ChanWriter::new(tx)); // option dance
+    let w = io::ChanWriter::new(tx);
     let mut r = io::ChanReader::new(rx);
 
-    let mut cfg = thread::cfg().name("rustc".to_string());
+    let mut cfg = thread::Builder::new().name("rustc".to_string());
 
     // FIXME: Hacks on hacks. If the env is trying to override the stack size
     // then *don't* set it explicitly.
     if os::getenv("RUST_MIN_STACK").is_none() {
         cfg = cfg.stack_size(STACK_SIZE);
     }
 
-    let f = proc() {
-        std::io::stdio::set_stderr(box w.take().unwrap());
-        f()
-    };
-    match cfg.with_join(f).join() {
+    match cfg.spawn(move || { std::io::stdio::set_stderr(box w); f() }).join() {
         Ok(()) => { /* fallthrough */ }
         Err(value) => {
             // Task panicked without emitting a fatal diagnostic