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sync: Once is no longer unsafe, update docs #14813

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Jun 12, 2014
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sync: Once is no longer unsafe, update docs #14813

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16 changes: 6 additions & 10 deletions src/libsync/one.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -18,22 +18,18 @@ use std::sync::atomics;

use mutex::{StaticMutex, MUTEX_INIT};

/// A type which can be used to run a one-time global initialization. This type
/// is *unsafe* to use because it is built on top of the `Mutex` in this module.
/// It does not know whether the currently running task is in a green or native
/// context, and a blocking mutex should *not* be used under normal
/// circumstances on a green task.
///
/// Despite its unsafety, it is often useful to have a one-time initialization
/// routine run for FFI bindings or related external functionality. This type
/// can only be statically constructed with the `ONCE_INIT` value.
/// A synchronization primitive which can be used to run a one-time global
/// initialization. Useful for one-time initialization for FFI or related
/// functionality. This type can only be constructed with the `ONCE_INIT`
/// value.
///
/// # Example
///
/// ```rust
/// use sync::one::{Once, ONCE_INIT};
///
/// static mut START: Once = ONCE_INIT;
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The mut here should go away.

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Nope. Can't borrow static which contains Unsafe.

///
/// unsafe {
/// START.doit(|| {
/// // run initialization here
Expand All @@ -58,7 +54,7 @@ impl Once {
/// will be executed if this is the first time `doit` has been called, and
/// otherwise the routine will *not* be invoked.
///
/// This method will block the calling *os thread* if another initialization
/// This method will block the calling task if another initialization
/// routine is currently running.
///
/// When this function returns, it is guaranteed that some initialization
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