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Using distributed locks

This section provides information on how to acquire distributed locks in a command.

API reference:

Required scopes:

  • Data/Buildby.Taskurai/locks/create
  • Data/Buildby.Taskurai/locks/read
  • Data/Buildby.Taskurai/locks/delete

Prerequisites​

Acquiring a lock in a command​

In this example, a lock is acquired with id EuSalesLock for the owner SalesCollector.CollectEUSales with a lease time of 2 minutes, the call will wait 30 seconds to acquire a lock. If the call fails, an exception will be thrown.

[Command]
public async Task<double> CollectEUSales(TaskuraiTaskContext context, CancellationToken cancellationToken, string country)
{
  await using (var distributedLock = await context.AcquireLockAsync(
    lockId: "EuSalesLock", 
    owner: "SalesCollector.CollectEUSales", 
    ttl: TimeSpan.FromMinutes(2), 
    timeout: TimeSpan.FromSeconds(30)))
  {
    // Check if task may start after acquiring lock
    context.CheckTaskExpired();

    // Throw if lock is expired.
    distributedLock.ThrowIfLockExpired();
  }
}

Expiration status​

When using the notStartAfter setting in the task execution options in combination with distributed locks, it is recommended to check the expiration status using CheckTaskExpired after acquiring the lock.

// Check if task may start after acquiring lock
context.CheckTaskExpired();

Checking lock lease​

When running long operations is a lock, it is required to check if the lock lease is still active using the IsLocked(), IsLockedAsync() or ThrowIfLockExpired() methods on TaskuraiDistributedLock class.

// Throw if lock is expired.
distributedLock.ThrowIfLockExpired();