diff options
Diffstat (limited to 'library/std/src')
| -rw-r--r-- | library/std/src/thread/mod.rs | 12 |
1 files changed, 5 insertions, 7 deletions
diff --git a/library/std/src/thread/mod.rs b/library/std/src/thread/mod.rs index e5e9638aaa8..8f16259b870 100644 --- a/library/std/src/thread/mod.rs +++ b/library/std/src/thread/mod.rs @@ -1270,18 +1270,16 @@ pub type Result<T> = crate::result::Result<T, Box<dyn Any + Send + 'static>>; // (the caller will never read this packet until the thread has exited). // // An Arc to the packet is stored into a `JoinInner` which in turns is placed -// in `JoinHandle`. Due to the usage of `UnsafeCell` we need to manually worry -// about impls like Send and Sync. The type `T` should already always be Send -// (otherwise the thread could not have been created) and this type is -// inherently Sync because no methods take &self. Regardless, however, we add -// inheriting impls for Send/Sync to this type to ensure it's Send/Sync and -// that future modifications will still appropriately classify it. +// in `JoinHandle`. struct Packet<'scope, T> { scope: Option<&'scope scoped::ScopeData>, result: UnsafeCell<Option<Result<T>>>, } -unsafe impl<'scope, T: Send> Send for Packet<'scope, T> {} +// Due to the usage of `UnsafeCell` we need to manually implement Sync. +// The type `T` should already always be Send (otherwise the thread could not +// have been created) and the Packet is Sync because all access to the +// `UnsafeCell` synchronized (by the `join()` boundary), and `ScopeData` is Sync. unsafe impl<'scope, T: Sync> Sync for Packet<'scope, T> {} impl<'scope, T> Drop for Packet<'scope, T> { |