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/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
//! Utilities which statically ensure we're on the specified thread.
use moz_task::AsyncTask;
use std::marker::PhantomData;
pub enum ThreadGuard {
Main(MainThreadGuard),
Background(BackgroundThreadGuard),
}
/// Guard that ensures calling context is on the main thread.
#[derive(Copy, Clone)]
pub struct MainThreadGuard {
// For !Send and !Sync.
_not_send_not_sync: PhantomData<*const ()>,
}
/// Guard that ensures calling context is on a background thread.
#[derive(Copy, Clone)]
pub struct BackgroundThreadGuard {
// For !Send and !Sync.
_not_send_not_sync: PhantomData<*const ()>,
}
/// Returns guard for the current thread type.
pub fn get_thread_guard() -> ThreadGuard {
if moz_task::is_main_thread() {
ThreadGuard::Main(MainThreadGuard {
_not_send_not_sync: PhantomData,
})
} else {
ThreadGuard::Background(BackgroundThreadGuard {
_not_send_not_sync: PhantomData,
})
}
}
/// Spawns the provided Future onto a blocking background thread with guard.
pub fn spawn_background_guard<Fn, Fut>(name: &'static str, cb: Fn) -> AsyncTask<Fut::Output>
where
Fn: FnOnce(BackgroundThreadGuard) -> Fut + Send + 'static,
Fut: Future + 'static,
Fut::Output: Send + 'static,
{
moz_task::spawn_blocking(name, async move {
futures::executor::block_on(cb(BackgroundThreadGuard {
_not_send_not_sync: PhantomData,
}))
})
}