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#![deny(missing_docs)]
#[cfg(feature = "scope")]
mod scope;
#[cfg(feature = "recv")]
mod recv;
#[cfg(feature = "scope")]
#[cfg_attr(docsrs, doc(cfg(feature = "scope")))]
pub use scope::Scope;
#[cfg(feature = "recv")]
#[cfg_attr(docsrs, doc(cfg(feature = "recv")))]
pub use recv::JobHandle;
use std::{
thread::{self, JoinHandle},
error,
fmt,
io,
};
use crossbeam_channel::{unbounded, Sender};
#[cfg(feature = "num_cpus")]
fn cpu_count() -> usize {
num_cpus::get()
}
#[cfg(not(feature = "num_cpus"))]
fn cpu_count() -> usize {
std::thread::available_concurrency()
.map(|n| n.get())
.unwrap_or(ThreadPool::DEFAULT_THREAD_COUNT)
}
#[derive(Debug)]
pub enum Error {
Io(io::Error),
NoThreads,
Timeout,
}
impl fmt::Display for Error {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
match self {
Self::Io(err) => write!(f, "{}", err),
Self::NoThreads => write!(f, "thread pool has no threads"),
Self::Timeout => write!(f, "a timeout occurred"),
}
}
}
impl error::Error for Error {}
struct Job {
f: Box<dyn FnOnce() + Send>,
}
lazy_static::lazy_static! {
static ref GLOBAL: ThreadPool = ThreadPool::default();
}
pub struct ThreadPool {
tx: Sender<Job>,
handles: Vec<JoinHandle<()>>,
}
impl Default for ThreadPool {
fn default() -> Self { Self::build().finish().unwrap() }
}
impl ThreadPool {
pub const DEFAULT_THREAD_COUNT: usize = 8;
pub fn global() -> &'static Self { &*GLOBAL }
pub fn build() -> ThreadPoolBuilder {
ThreadPoolBuilder::default()
}
pub fn thread_count(&self) -> usize { self.handles.len() }
pub fn queue_len(&self) -> usize { self.tx.len() }
pub fn run<F: FnOnce() + Send + 'static>(&self, f: F) {
self.tx.send(Job { f: Box::new(f) }).unwrap()
}
#[cfg(feature = "recv")]
pub fn run_recv<F: FnOnce() -> R + Send + 'static, R: Send + 'static>(&self, f: F) -> recv::JobHandle<R> {
let (tx, rx) = oneshot::channel();
self.run(move || { let _ = tx.send(f()); });
recv::JobHandle::new(rx)
}
pub fn join_all(self) -> thread::Result<()> {
let Self { tx, handles } = self;
drop(tx);
for handle in handles {
handle.join()?;
}
Ok(())
}
#[cfg(feature = "scope")]
pub fn scoped<'pool, 'scope, F: FnOnce(scope::Scope<'pool, 'scope>) -> R, R>(&'pool self, f: F) -> R {
scope::run(self, f)
}
}
#[derive(Clone, Default)]
pub struct ThreadPoolBuilder {
thread_count: Option<usize>,
thread_name: Option<String>,
thread_stack_size: Option<usize>,
}
impl ThreadPoolBuilder {
pub fn with_thread_count(self, thread_count: usize) -> Self {
Self { thread_count: Some(thread_count), ..self }
}
pub fn with_thread_name(self, name: String) -> Self {
Self { thread_name: Some(name), ..self }
}
pub fn with_thread_stack_size(self, size: usize) -> Self {
Self { thread_stack_size: Some(size), ..self }
}
pub fn finish(self) -> Result<ThreadPool, Error> {
let thread_count = self.thread_count
.unwrap_or(cpu_count());
if thread_count == 0 {
return Err(Error::NoThreads);
}
let (tx, rx) = unbounded();
Ok(ThreadPool {
tx,
handles: (0..thread_count)
.map(|_| {
let rx = rx.clone();
let builder = thread::Builder::new();
let builder = match self.thread_name.clone() {
Some(name) => builder.name(name),
None => builder,
};
let builder = match self.thread_stack_size {
Some(size) => builder.stack_size(size),
None => builder,
};
builder.spawn(move || {
while let Ok(job) = rx.recv() {
let job = std::panic::AssertUnwindSafe(job);
let _ = std::panic::catch_unwind(move || {
(job.0.f)();
});
}
}).map_err(Error::Io)
})
.collect::<Result<_, _>>()?,
})
}
}