diff --git a/src/doc/trpl/rust-inside-other-languages.md b/src/doc/trpl/rust-inside-other-languages.md index 0a1860769d231..6129c98259ba4 100644 --- a/src/doc/trpl/rust-inside-other-languages.md +++ b/src/doc/trpl/rust-inside-other-languages.md @@ -66,10 +66,14 @@ threads = [] 5_000_000.times do count += 1 end + + count end end -threads.each { |t| t.join } +threads.each do |t| + puts "Thread finished with count=#{t.value}" +end puts "done!" ``` @@ -103,50 +107,26 @@ use std::thread; fn process() { let handles: Vec<_> = (0..10).map(|_| { thread::spawn(|| { - let mut _x = 0; + let mut x = 0; for _ in (0..5_000_000) { - _x += 1 + x += 1 } + x }) }).collect(); for h in handles { - h.join().ok().expect("Could not join a thread!"); + println!("Thread finished with count={}", + h.join().map_err(|_| "Could not join a thread!").unwrap()); } + println!("done!"); } ``` Some of this should look familiar from previous examples. We spin up ten threads, collecting them into a `handles` vector. Inside of each thread, we -loop five million times, and add one to `_x` each time. Why the underscore? -Well, if we remove it and compile: - -```bash -$ cargo build - Compiling embed v0.1.0 (file:///home/steve/src/embed) -src/lib.rs:3:1: 16:2 warning: function is never used: `process`, #[warn(dead_code)] on by default -src/lib.rs:3 fn process() { -src/lib.rs:4 let handles: Vec<_> = (0..10).map(|_| { -src/lib.rs:5 thread::spawn(|| { -src/lib.rs:6 let mut x = 0; -src/lib.rs:7 for _ in (0..5_000_000) { -src/lib.rs:8 x += 1 - ... -src/lib.rs:6:17: 6:22 warning: variable `x` is assigned to, but never used, #[warn(unused_variables)] on by default -src/lib.rs:6 let mut x = 0; - ^~~~~ -``` - -That first warning is because we are building a library. If we had a test -for this function, the warning would go away. But for now, it’s never -called. - -The second is related to `x` versus `_x`. Because we never actually _do_ -anything with `x`, we get a warning about it. In our case, that’s perfectly -okay, as we’re just trying to waste CPU cycles. Prefixing `x` with the -underscore removes the warning. - -Finally, we join on each thread. +loop five million times, and add one to `x` each time. Finally, we join on +each thread. Right now, however, this is a Rust library, and it doesn’t expose anything that’s callable from C. If we tried to hook this up to another language right