Crate timed_locks

timed-locks is a set of smart pointers to tokio::sync locks that can be used as drop-in replacement and will either panic or return an error after a given timeout when the lock cannot be acquired. Default timeout is 30 seconds.

Motivation

In smaller codebases it’s fairly trivial to prevent deadlocks by making sure that you simply don’t introduce any. As the codebase gets more complex however, it gets more complex to cover all branches with automated or manual testing and so the chances to unintentionally introduce deadlocks get higher. In case a potential deadlock is introduced and makes it way into production, it might not happen directly but only after a while when a specific scenario in the codebase happens. In such cases it’s often wanted that a service can recover. While you can monitor services for responsiveness from the outside and restart them if required, doing that is offloading the responsbility to a thirdparty. So in order to have a backup plan inside the service itself, it can be useful to have failsafe mechanism in place that makes it possible to have the service itself recover from a deadlock.

The default behavior of panicking was chosen since just returning an error might not help break the deadlock in a service in case the bug is selfenforcing. So to have higher chances of recovering the process or task should be shutdown completely by just panicking. However, if you are certain that in your specific scenario returning errors can lead to gracefully handling a deadlock there are the read_err / write_err methods that return an error instead of panicking.

Examples

Deadlock that panics after 30 seconds:

let lock = timed_locks::RwLock::new(std::collections::HashSet::<usize>::new());
let _lock = lock.read().await;
lock.write().await;

Deadlock that returns an error after 30 seconds:

let lock = timed_locks::RwLock::new(std::collections::HashSet::<usize>::new());
let _lock = lock.read().await;
lock.write_err().await.unwrap();

Structs

Mutex

Smart pointer to tokio::sync::Mutex.

RwLock

Smart pointer to tokio::sync::RwLock.

Enums

Error

Timed locks errors.

Constants

DEFAULT_TIMEOUT_DURATION

Duration constant of 30 seconds for the default timeout.

Type Aliases

Result

Custom result.