cfg_if::cfg_if! {
if #[cfg(feature = "locking")] {
use std::sync::{RwLock, RwLockReadGuard, RwLockWriteGuard};
pub enum LockGuard<'a, T> {
Exclusive(RwLockWriteGuard<'a, T>),
Shared(RwLockReadGuard<'a, T>),
}
impl<'a, T> LockGuard<'a, T> {
pub fn acquire(rw_lock: &'a RwLock<T>, exclusive: bool) -> Self {
if cfg!(feature = "full_locking") || exclusive {
Self::Exclusive(rw_lock.write().expect("Failed to acquire exclusive lock!"))
} else {
Self::Shared(rw_lock.read().expect("Failed to acquire shared lock!"))
}
}
#[allow(dead_code)]
pub fn is_exclusive(&self) -> bool {
match self {
Self::Exclusive(_guard) => true,
Self::Shared(_guard) => false,
}
}
}
} else {
use std::sync::RwLock;
pub enum LockGuard {
None,
}
impl LockGuard {
pub fn acquire<T>(_rw_lock: &RwLock<T>, _exclusive: bool) -> Self {
LockGuard::None
}
#[allow(dead_code)]
pub fn is_exclusive(&self) -> bool {
panic!("Error: Locking feature is not enabled!")
}
}
}
}
#[cfg(test)]
#[cfg(feature = "locking")]
mod tests {
use super::LockGuard;
use std::{
collections::VecDeque,
sync::{
Arc, Barrier, RwLock,
atomic::{AtomicUsize, Ordering},
},
thread,
};
#[test]
fn test_lock() {
static TEST_RWLOCK: RwLock<()> = RwLock::new(());
{
let guard = LockGuard::acquire(&TEST_RWLOCK, false);
assert!(!guard.is_exclusive());
assert!(matches!(guard, LockGuard::Shared(_read_guard)));
}
{
let guard = LockGuard::acquire(&TEST_RWLOCK, true);
assert!(guard.is_exclusive());
assert!(matches!(guard, LockGuard::Exclusive(_write_guard)));
}
}
#[test]
fn test_threads() {
static TEST_RWLOCK: RwLock<()> = RwLock::new(());
const THREAD_COUNT: usize = 32usize;
let barrier = Arc::new(Barrier::new(THREAD_COUNT));
let mut thread_list = VecDeque::with_capacity(THREAD_COUNT);
let counter = Arc::new(AtomicUsize::new(0usize));
for _tid in 0..THREAD_COUNT {
let thread_barrier = Arc::clone(&barrier);
let thread_counter = Arc::clone(&counter);
thread_list.push_back(thread::spawn(move || {
let is_leader = thread_barrier.wait().is_leader();
for _iteration in 0..100000 {
let guard = LockGuard::acquire(&TEST_RWLOCK, is_leader);
let value = thread_counter.fetch_add(1usize, Ordering::Relaxed);
if guard.is_exclusive() {
assert_eq!(value, 0usize, "Invalid counter value!");
}
thread::yield_now();
thread_counter.fetch_sub(1usize, Ordering::Relaxed);
}
}));
}
for thread in thread_list.drain(..) {
thread.join().unwrap();
}
}
}