Function extend_redlock 

pub async fn extend_redlock<F, Fut>(
    try_extend_fn: F,
    clients: &[RedisClient],
    acquire_results: &[bool],
    timeouts: &RedLockTimeouts,
    cancel_token: &Receiver<bool>,
) -> Result<Option<bool>, LockError>
where
    F: Fn(&RedisClient) -> Fut + Send + Sync + Clone + 'static,
    Fut: Future<Output = Result<bool, LockError>> + Send,

Extends a lock using the RedLock algorithm across multiple Redis servers.

Similar to acquire, requires majority consensus for successful extension.

Arguments

• try_extend_fn - Function that attempts to extend the lock on a single client
• clients - List of Redis clients where lock was acquired
• acquire_results - Previous acquire results indicating which clients hold the lock
• timeouts - Timeout configuration
• cancel_token - Cancellation token