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//! Type definitions for putting shared ownership and synchronized mutation behind the `threading` feature toggle.
//!
//! That way, single-threaded applications will not have to use thread-safe primitives, and simply do not specify the 'threading' feature.
#[cfg(feature = "parallel")]
mod _impl {
use std::sync::Arc;
/// A thread-safe cell which can be written to only once.
#[cfg(feature = "once_cell")]
pub type OnceCell<T> = once_cell::sync::OnceCell<T>;
/// A reference counted pointer type for shared ownership.
pub type OwnShared<T> = Arc<T>;
/// A synchronization primitive which can start read-only and transition to support mutation.
pub type MutableOnDemand<T> = parking_lot::RwLock<T>;
/// A synchronization primitive which provides read-write access right away.
pub type Mutable<T> = parking_lot::Mutex<T>;
/// A guarded reference suitable for safekeeping in a struct.
pub type RefGuard<'a, T> = parking_lot::RwLockReadGuard<'a, T>;
/// A mapped reference created from a `RefGuard`
pub type MappedRefGuard<'a, U> = parking_lot::MappedRwLockReadGuard<'a, U>;
/// Get a shared reference through a [`MutableOnDemand`] for read-only access.
pub fn get_ref<T>(v: &MutableOnDemand<T>) -> RefGuard<'_, T> {
v.read()
}
/// Get a mutable reference through a [`MutableOnDemand`] for read-write access.
pub fn get_mut<T>(v: &MutableOnDemand<T>) -> parking_lot::RwLockWriteGuard<'_, T> {
v.write()
}
/// Get a mutable reference through a [`Mutable`] for read-write access.
pub fn lock<T>(v: &Mutable<T>) -> parking_lot::MutexGuard<'_, T> {
v.lock()
}
/// Downgrade a handle previously obtained with [`get_mut()`] to drop mutation support.
pub fn downgrade_mut_to_ref<'a, T>(
v: parking_lot::RwLockWriteGuard<'a, T>,
_orig: &'a MutableOnDemand<T>,
) -> RefGuard<'a, T> {
parking_lot::RwLockWriteGuard::downgrade(v)
}
/// Map a read guard into a sub-type it contains.
pub fn map_ref<T, U: ?Sized>(v: RefGuard<'_, T>, f: impl FnOnce(&T) -> &U) -> MappedRefGuard<'_, U> {
parking_lot::RwLockReadGuard::map(v, f)
}
}
#[cfg(not(feature = "parallel"))]
mod _impl {
use std::{
cell::{Ref, RefCell, RefMut},
rc::Rc,
};
/// A thread-safe cell which can be written to only once.
#[cfg(feature = "once_cell")]
pub type OnceCell<T> = once_cell::unsync::OnceCell<T>;
/// A reference counted pointer type for shared ownership.
pub type OwnShared<T> = Rc<T>;
/// A synchronization primitive which can start read-only and transition to support mutation.
pub type MutableOnDemand<T> = RefCell<T>;
/// A synchronization primitive which provides read-write access right away.
pub type Mutable<T> = RefCell<T>;
/// A guarded reference suitable for safekeeping in a struct.
pub type RefGuard<'a, T> = Ref<'a, T>;
/// A mapped reference created from a RefGuard
pub type MappedRefGuard<'a, U> = Ref<'a, U>;
/// Get a shared reference through a [`MutableOnDemand`] for read-only access.
pub fn get_mut<T>(v: &RefCell<T>) -> RefMut<'_, T> {
v.borrow_mut()
}
/// Get a mutable reference through a [`Mutable`] for read-write access.
pub fn lock<T>(v: &Mutable<T>) -> RefMut<'_, T> {
v.borrow_mut()
}
/// Get a mutable reference through a [`MutableOnDemand`] for read-write access.
pub fn get_ref<T>(v: &RefCell<T>) -> RefGuard<'_, T> {
v.borrow()
}
/// Downgrade a handle previously obtained with [`upgrade_ref_to_mut()`] to drop mutation support.
pub fn downgrade_mut_to_ref<'a, T>(v: RefMut<'a, T>, orig: &'a RefCell<T>) -> RefGuard<'a, T> {
drop(v);
orig.borrow()
}
/// Map a read guard into a sub-type it contains.
pub fn map_ref<T, U: ?Sized>(v: RefGuard<'_, T>, f: impl FnOnce(&T) -> &U) -> MappedRefGuard<'_, U> {
Ref::map(v, f)
}
}
pub use _impl::*;
|
