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Allowing change callbacks to recurse still

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The last fix had a panic where a guard should have been allowed to be
created. Change callbacks detect when they are about to be fired from
themselves, and prevent the deadlock.
This commit is contained in:
Jonathan Johnson 2024-09-25 11:17:23 -07:00
parent e54bbd743d
commit 2045d5fb4a
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GPG key ID: A66D6A34D6620579
1 changed files with 13 additions and 10 deletions
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23
src/value.rs
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@ -1227,7 +1227,7 @@ impl<T> Dynamic<T> {
} }
fn lock_inner<const READONLY: bool>(&self) -> DynamicGuard<'_, T, READONLY> { fn lock_inner<const READONLY: bool>(&self) -> DynamicGuard<'_, T, READONLY> {
let guard = self.0.state().expect("deadlocked"); let mut guard = self.0.state().expect("deadlocked");
// Before allowing a lock, we need to ensure that the current change // Before allowing a lock, we need to ensure that the current change
// callbacks aren't executing. Otherwise, during drop of this guard, if // callbacks aren't executing. Otherwise, during drop of this guard, if
// we notify of changes from a second thread than one set is already // we notify of changes from a second thread than one set is already
@ -1235,16 +1235,19 @@ impl<T> Dynamic<T> {
// other and deadlocking. By ensuring a single guard and change // other and deadlocking. By ensuring a single guard and change
// callbacks cycle can exist at any one time, we prevent this deadlock. // callbacks cycle can exist at any one time, we prevent this deadlock.
if !READONLY && guard.callbacks.currently_executing.lock().thread.is_some() { if !READONLY && guard.callbacks.currently_executing.lock().thread.is_some() {
let current_thread_id = std::thread::current().id();
let callbacks = guard.callbacks.clone(); let callbacks = guard.callbacks.clone();
let mut executing = callbacks.currently_executing.lock(); guard.unlocked(|| {
loop { let current_thread_id = std::thread::current().id();
match &executing.thread { let mut executing = callbacks.currently_executing.lock();
Some(th) if th == &current_thread_id => panic!("deadlocked"),
Some(_) => callbacks.sync.wait(&mut executing), loop {
None => break, match &executing.thread {
}; Some(th) if th == &current_thread_id => break,
} None => break,
Some(_) => callbacks.sync.wait(&mut executing),
};
}
});
} }
DynamicGuard { DynamicGuard {
guard: DynamicOrOwnedGuard::Dynamic(guard), guard: DynamicOrOwnedGuard::Dynamic(guard),