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use once_cell::sync::Lazy;
use parking_lot::{Mutex, MutexGuard};
use std::collections::HashMap;
use std::sync::{Arc, Weak};
mod error;
#[cfg(unix)]
mod unix;
#[cfg(windows)]
mod windows;
pub use crate::error::*;
#[cfg(unix)]
use crate::unix::RawNamedLock;
#[cfg(windows)]
use crate::windows::RawNamedLock;
static OPENED_RAW_LOCKS: Lazy<
Mutex<HashMap<String, Weak<Mutex<RawNamedLock>>>>,
> = Lazy::new(|| Mutex::new(HashMap::new()));
#[derive(Debug)]
pub struct NamedLock {
raw: Arc<Mutex<RawNamedLock>>,
}
impl NamedLock {
pub fn create(name: &str) -> Result<NamedLock> {
let mut opened_locks = OPENED_RAW_LOCKS.lock();
let lock = match opened_locks.get(name).and_then(|x| x.upgrade()) {
Some(lock) => lock,
None => {
let lock = Arc::new(Mutex::new(RawNamedLock::create(name)?));
opened_locks.insert(name.to_owned(), Arc::downgrade(&lock));
lock
}
};
Ok(NamedLock {
raw: lock,
})
}
pub fn try_lock<'r>(&'r self) -> Result<NamedLockGuard<'r>> {
let guard = self.raw.try_lock().ok_or(Error::WouldBlock)?;
guard.try_lock()?;
Ok(NamedLockGuard {
raw: guard,
})
}
pub fn lock<'r>(&'r self) -> Result<NamedLockGuard<'r>> {
let guard = self.raw.lock();
guard.lock()?;
Ok(NamedLockGuard {
raw: guard,
})
}
}
#[derive(Debug)]
pub struct NamedLockGuard<'r> {
raw: MutexGuard<'r, RawNamedLock>,
}
impl<'r> Drop for NamedLockGuard<'r> {
fn drop(&mut self) {
let _ = self.raw.unlock();
}
}
#[cfg(test)]
mod tests {
use super::*;
use matches::assert_matches;
use uuid::Uuid;
#[test]
fn check_lock() -> Result<()> {
let uuid = Uuid::new_v4().to_hyphenated().to_string();
let lock1 = NamedLock::create(&uuid)?;
let lock2 = NamedLock::create(&uuid)?;
{
let _guard1 = lock1.lock()?;
assert_matches!(lock1.try_lock(), Err(Error::WouldBlock));
assert_matches!(lock2.try_lock(), Err(Error::WouldBlock));
}
{
let _guard2 = lock2.lock()?;
assert_matches!(lock1.try_lock(), Err(Error::WouldBlock));
assert_matches!(lock2.try_lock(), Err(Error::WouldBlock));
}
Ok(())
}
#[test]
fn check_try_lock() -> Result<()> {
let uuid = Uuid::new_v4().to_hyphenated().to_string();
let lock1 = NamedLock::create(&uuid)?;
let lock2 = NamedLock::create(&uuid)?;
{
let _guard1 = lock1.try_lock()?;
assert_matches!(lock1.try_lock(), Err(Error::WouldBlock));
assert_matches!(lock2.try_lock(), Err(Error::WouldBlock));
}
{
let _guard2 = lock2.try_lock()?;
assert_matches!(lock1.try_lock(), Err(Error::WouldBlock));
assert_matches!(lock2.try_lock(), Err(Error::WouldBlock));
}
Ok(())
}
}