/// <summary>
/// Creates a specific subscription to a topic if it doesn't exist yet.
/// </summary>
/// <param name="topic">The <see cref="ITopic"/> that we are subscribing to.</param>
/// <param name="name">The name of the subscription we are doing on the <see cref="ITopic"/>.</param>
/// <param name="deleteOnIdleDurationInMinutes">number of minutes for a subscription to be deleted when idle. If not provided then duration is infinite (TimeSpan.Max)</param>
/// <returns>The <see cref="ISubscription"/> entity object that references the subscription.</returns>
public static async Task <ISubscription> CreateSubscriptionIfNotExists(this ITopic topic, string name, int?deleteOnIdleDurationInMinutes = null)
{
var subscription = await topic.GetSubscriptionByNameAsync(name);
if (subscription != null)
{
return(subscription);
}
var builder = topic.Subscriptions
.Define(name.ToLowerInvariant())
.WithMessageLockDurationInSeconds(60)
.WithExpiredMessageMovedToDeadLetterSubscription()
.WithMessageMovedToDeadLetterSubscriptionOnMaxDeliveryCount(10);
if (deleteOnIdleDurationInMinutes.HasValue)
{
builder.WithDeleteOnIdleDurationInMinutes(deleteOnIdleDurationInMinutes.Value);
}
return(await builder.CreateAsync());
// No error handling is required for race conditions creating topic subscriptions - when the create is called, if
// already exists, the existing subscription is returned with the create call. Different behaviour from the creation
// of topics or queues.
}