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Fix panic in Promise::try_result #585

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Merged
typester merged 2 commits into from
Mar 3, 2025
Merged

Fix panic in Promise::try_result #585

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7731c8d
fix crash on try_result
typester Mar 3, 2025
e6288b1
there was still the cases where panics occur
typester Mar 3, 2025
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4 changes: 2 additions & 2 deletions Cargo.lock
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22 changes: 16 additions & 6 deletions livekit-protocol/src/promise.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -12,12 +12,12 @@
// See the License for the specific language governing permissions and
// limitations under the License.

use tokio::sync::{oneshot, Mutex};
use tokio::sync::{oneshot, Mutex, RwLock};

pub struct Promise<T> {
tx: Mutex<Option<oneshot::Sender<T>>>,
rx: Mutex<Option<oneshot::Receiver<T>>>,
result: Mutex<Option<T>>,
result: RwLock<Option<T>>,
}

impl<T: Clone> Promise<T> {
Expand All @@ -37,14 +37,24 @@ impl<T: Clone> Promise<T> {
}

pub async fn result(&self) -> T {
{
let result_read = self.result.read().await;
if let Some(result) = result_read.clone() {
return result;
}
}

let mut rx = self.rx.lock().await;
if rx.is_some() {
self.result.lock().await.replace(rx.take().unwrap().await.unwrap());
if let Some(rx) = rx.take() {
let result = rx.await.unwrap();
*self.result.write().await = Some(result.clone());
result
} else {
self.result.read().await.clone().unwrap()
}
self.result.lock().await.clone().unwrap()
}

pub fn try_result(&self) -> Option<T> {
self.result.try_lock().unwrap().clone()
self.result.try_read().unwrap().clone()
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@theomonnom theomonnom Mar 3, 2025

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isn't try_read also panicking? when unwrapping?

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@typester typester Mar 3, 2025

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Oh, good catch! Thank you. I believe a panic would occur if a write lock is held.

So in this case, I'll modify it to return None instead of unwrapping. Since Promise is designed to acquire the write lock only once, this should not be an issue.

}
}
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