pub struct JoinHandle<T>(_);
Expand description
An owned permission to join on a thread (block on its termination).
A JoinHandle
detaches the associated thread when it is dropped, which
means that there is no longer any handle to the thread and no way to join
on it.
Due to platform restrictions, it is not possible to Clone
this
handle: the ability to join a thread is a uniquely-owned permission.
This struct
is created by the thread::spawn
function and the
thread::Builder::spawn
method.
Examples
Creation from thread::spawn
:
use std::thread;
let join_handle: thread::JoinHandle<_> = thread::spawn(|| {
// some work here
});
Creation from thread::Builder::spawn
:
use std::thread;
let builder = thread::Builder::new();
let join_handle: thread::JoinHandle<_> = builder.spawn(|| {
// some work here
}).unwrap();
A thread being detached and outliving the thread that spawned it:
use std::thread;
use std::time::Duration;
let original_thread = thread::spawn(|| {
let _detached_thread = thread::spawn(|| {
// Here we sleep to make sure that the first thread returns before.
thread::sleep(Duration::from_millis(10));
// This will be called, even though the JoinHandle is dropped.
println!("♫ Still alive ♫");
});
});
original_thread.join().expect("The thread being joined has panicked");
println!("Original thread is joined.");
// We make sure that the new thread has time to run, before the main
// thread returns.
thread::sleep(Duration::from_millis(1000));
Implementations
sourceimpl<T> JoinHandle<T>
impl<T> JoinHandle<T>
sourcepub fn thread(&self) -> &Thread
pub fn thread(&self) -> &Thread
Extracts a handle to the underlying thread.
Examples
use std::thread;
let builder = thread::Builder::new();
let join_handle: thread::JoinHandle<_> = builder.spawn(|| {
// some work here
}).unwrap();
let thread = join_handle.thread();
println!("thread id: {:?}", thread.id());
sourcepub fn join(self) -> Result<T, Box<dyn Any + Send + 'static, Global>>
pub fn join(self) -> Result<T, Box<dyn Any + Send + 'static, Global>>
Waits for the associated thread to finish.
This function will return immediately if the associated thread has already finished.
In terms of atomic memory orderings, the completion of the associated
thread synchronizes with this function returning. In other words, all
operations performed by that thread happen
before all
operations that happen after join
returns.
If the associated thread panics, Err
is returned with the parameter given
to panic!
.
Panics
This function may panic on some platforms if a thread attempts to join itself or otherwise may create a deadlock with joining threads.
Examples
use std::thread;
let builder = thread::Builder::new();
let join_handle: thread::JoinHandle<_> = builder.spawn(|| {
// some work here
}).unwrap();
join_handle.join().expect("Couldn't join on the associated thread");
1.61.0 · sourcepub fn is_finished(&self) -> bool
pub fn is_finished(&self) -> bool
Checks if the associated thread has finished running its main function.
is_finished
supports implementing a non-blocking join operation, by checking
is_finished
, and calling join
if it returns true
. This function does not block. To
block while waiting on the thread to finish, use join
.
This might return true
for a brief moment after the thread’s main
function has returned, but before the thread itself has stopped running.
However, once this returns true
, join
can be expected
to return quickly, without blocking for any significant amount of time.
Trait Implementations
1.16.0 · sourceimpl<T> Debug for JoinHandle<T>
impl<T> Debug for JoinHandle<T>
1.9.0 · sourceimpl<T> JoinHandleExt for JoinHandle<T>
impl<T> JoinHandleExt for JoinHandle<T>
sourcefn as_pthread_t(&self) -> u64
fn as_pthread_t(&self) -> u64
Extracts the raw pthread_t without taking ownership
sourcefn into_pthread_t(self) -> u64
fn into_pthread_t(self) -> u64
Consumes the thread, returning the raw pthread_t Read more
impl<T> Send for JoinHandle<T>
impl<T> Sync for JoinHandle<T>
Auto Trait Implementations
impl<T> !RefUnwindSafe for JoinHandle<T>
impl<T> Unpin for JoinHandle<T>
impl<T> !UnwindSafe for JoinHandle<T>
Blanket Implementations
sourceimpl<T> BorrowMut<T> for T where
T: ?Sized,
impl<T> BorrowMut<T> for T where
T: ?Sized,
const: unstable · sourcefn borrow_mut(&mut self) -> &mut T
fn borrow_mut(&mut self) -> &mut T
Mutably borrows from an owned value. Read more
sourceimpl<T> Downcast for T where
T: Any,
impl<T> Downcast for T where
T: Any,
sourcefn into_any(self: Box<T, Global>) -> Box<dyn Any + 'static, Global>ⓘNotable traits for Box<W, Global>impl<W> Write for Box<W, Global> where
W: Write + ?Sized, impl<R> Read for Box<R, Global> where
R: Read + ?Sized, impl<I, A> Iterator for Box<I, A> where
I: Iterator + ?Sized,
A: Allocator, type Item = <I as Iterator>::Item;
fn into_any(self: Box<T, Global>) -> Box<dyn Any + 'static, Global>ⓘNotable traits for Box<W, Global>impl<W> Write for Box<W, Global> where
W: Write + ?Sized, impl<R> Read for Box<R, Global> where
R: Read + ?Sized, impl<I, A> Iterator for Box<I, A> where
I: Iterator + ?Sized,
A: Allocator, type Item = <I as Iterator>::Item;
W: Write + ?Sized, impl<R> Read for Box<R, Global> where
R: Read + ?Sized, impl<I, A> Iterator for Box<I, A> where
I: Iterator + ?Sized,
A: Allocator, type Item = <I as Iterator>::Item;
Convert Box<dyn Trait>
(where Trait: Downcast
) to Box<dyn Any>
. Box<dyn Any>
can
then be further downcast
into Box<ConcreteType>
where ConcreteType
implements Trait
. Read more
sourcefn into_any_rc(self: Rc<T>) -> Rc<dyn Any + 'static>
fn into_any_rc(self: Rc<T>) -> Rc<dyn Any + 'static>
Convert Rc<Trait>
(where Trait: Downcast
) to Rc<Any>
. Rc<Any>
can then be
further downcast
into Rc<ConcreteType>
where ConcreteType
implements Trait
. Read more
sourcefn as_any(&self) -> &(dyn Any + 'static)
fn as_any(&self) -> &(dyn Any + 'static)
Convert &Trait
(where Trait: Downcast
) to &Any
. This is needed since Rust cannot
generate &Any
’s vtable from &Trait
’s. Read more
sourcefn as_any_mut(&mut self) -> &mut (dyn Any + 'static)
fn as_any_mut(&mut self) -> &mut (dyn Any + 'static)
Convert &mut Trait
(where Trait: Downcast
) to &Any
. This is needed since Rust cannot
generate &mut Any
’s vtable from &mut Trait
’s. Read more
sourceimpl<T> DowncastSync for T where
T: Any + Send + Sync,
impl<T> DowncastSync for T where
T: Any + Send + Sync,
sourceimpl<A> DynCastExt for A
impl<A> DynCastExt for A
sourcefn dyn_cast<T>(
self
) -> Result<<A as DynCastExtHelper<T>>::Target, <A as DynCastExtHelper<T>>::Source> where
A: DynCastExtHelper<T>,
T: ?Sized,
fn dyn_cast<T>(
self
) -> Result<<A as DynCastExtHelper<T>>::Target, <A as DynCastExtHelper<T>>::Source> where
A: DynCastExtHelper<T>,
T: ?Sized,
Use this to cast from one trait object type to another. Read more
sourcefn dyn_upcast<T>(self) -> <A as DynCastExtAdvHelper<T, T>>::Target where
A: DynCastExtAdvHelper<T, T, Source = <A as DynCastExtAdvHelper<T, T>>::Target>,
T: ?Sized,
fn dyn_upcast<T>(self) -> <A as DynCastExtAdvHelper<T, T>>::Target where
A: DynCastExtAdvHelper<T, T, Source = <A as DynCastExtAdvHelper<T, T>>::Target>,
T: ?Sized,
Use this to upcast a trait to one of its supertraits. Read more
sourcefn dyn_cast_adv<F, T>(
self
) -> Result<<A as DynCastExtAdvHelper<F, T>>::Target, <A as DynCastExtAdvHelper<F, T>>::Source> where
A: DynCastExtAdvHelper<F, T>,
F: ?Sized,
T: ?Sized,
fn dyn_cast_adv<F, T>(
self
) -> Result<<A as DynCastExtAdvHelper<F, T>>::Target, <A as DynCastExtAdvHelper<F, T>>::Source> where
A: DynCastExtAdvHelper<F, T>,
F: ?Sized,
T: ?Sized,
sourcefn dyn_cast_with_config<C>(
self
) -> Result<<A as DynCastExtAdvHelper<<C as DynCastConfig>::Source, <C as DynCastConfig>::Target>>::Target, <A as DynCastExtAdvHelper<<C as DynCastConfig>::Source, <C as DynCastConfig>::Target>>::Source> where
C: DynCastConfig,
A: DynCastExtAdvHelper<<C as DynCastConfig>::Source, <C as DynCastConfig>::Target>,
fn dyn_cast_with_config<C>(
self
) -> Result<<A as DynCastExtAdvHelper<<C as DynCastConfig>::Source, <C as DynCastConfig>::Target>>::Target, <A as DynCastExtAdvHelper<<C as DynCastConfig>::Source, <C as DynCastConfig>::Target>>::Source> where
C: DynCastConfig,
A: DynCastExtAdvHelper<<C as DynCastConfig>::Source, <C as DynCastConfig>::Target>,
Use this to cast from one trait object type to another. With this method the type parameter is a config type that uniquely specifies which cast should be preformed. Read more