// remove a subscription from one member
private async ValueTask <bool> RemoveSubscriptionAsync(MemberSubscription subscription, CancellationToken cancellationToken)
{
// fast: if the connection is down, consider the subscription removed
if (!subscription.Connection.Active)
{
return(true);
}
try
{
// remove the member subscription = trigger the server-side un-subscribe
// this *may* throw if we fail to talk to the member
// this *may* return false for some reason
var unsubscribeRequest = subscription.ClusterSubscription.CreateUnsubscribeRequest(subscription.ServerSubscriptionId);
var responseMessage = await _clusterMessaging.SendToMemberAsync(unsubscribeRequest, subscription.Connection, cancellationToken).CfAwait();
var removed = subscription.ClusterSubscription.ReadUnsubscribeResponse(responseMessage);
return(removed);
}
catch (Exception e)
{
// if the connection is down, consider the subscription removed
if (!subscription.Connection.Active)
{
return(true);
}
// otherwise something went wrong and maybe we want to try again
_logger.LogError(e, "Caught an exception while unsubscribing to events.");
return(false);
}
}
// add a member subscription to be collected, start the collect task if needed
private void CollectSubscription(MemberSubscription subscription)
{
lock (_collectMutex)
{
_collectSubscriptions.Add(subscription);
_collectTask ??= CollectSubscriptionsAsync(_cancel.Token);
}
}
/// <summary>
/// Removes a subscription from one member.
/// </summary>
/// <param name="memberSubscription">The subscription.</param>
/// <param name="cancellationToken">A cancellation token.</param>
/// <returns>Whether the subscription was removed.</returns>
/// <remarks>
/// <para>This methods always remove the event handlers associated with the subscription, regardless
/// of the response from the server. Even when the server returns false, meaning it failed to
/// properly remove the subscription, no events for that subscription will be triggered anymore
/// because the client will ignore these events when the server sends them.</para>
/// </remarks>
private async ValueTask <bool> RemoveMemberSubscriptionAsync(MemberSubscription memberSubscription, CancellationToken cancellationToken = default)
{
// always remove the correlated subscription
_correlatedSubscriptions.TryRemove(memberSubscription.CorrelationId, out _);
// trigger the server-side un-subscribe
var unsubscribeRequest = memberSubscription.ClusterSubscription.CreateUnsubscribeRequest(memberSubscription.ServerSubscriptionId);
var responseMessage = await _clusterMessaging.SendToMemberAsync(unsubscribeRequest, memberSubscription.Connection, cancellationToken).CfAwait();
var removed = memberSubscription.ClusterSubscription.ReadUnsubscribeResponse(responseMessage);
return(removed);
}
/// <summary>
/// Removes a subscription from one member.
/// </summary>
/// <param name="memberSubscription">The subscription.</param>
/// <param name="cancellationToken">A cancellation token.</param>
/// <returns>Whether the subscription was removed.</returns>
/// <remarks>
/// <para>This methods always remove the event handlers associated with the subscription, regardless
/// of the response from the server. Even when the server returns false, meaning it failed to
/// properly remove the subscription, no events for that subscription will be triggered anymore
/// because the client will ignore these events when the server sends them.</para>
/// </remarks>
private async ValueTask <bool> RemoveSubscriptionAsync(MemberSubscription memberSubscription, CancellationToken cancellationToken = default)
{
// whatever happens, remove the event handler
// if the client hasn't properly unsubscribed, it may receive more event messages,
// which will be ignored since their correlation identifier won't match any handler.
_correlatedSubscriptions.TryRemove(memberSubscription.CorrelationId, out _);
// trigger the server-side un-subscribe
var unsubscribeRequest = memberSubscription.ClusterSubscription.CreateUnsubscribeRequest(memberSubscription.ServerSubscriptionId);
var responseMessage = await _clusterMessaging.SendToMemberAsync(unsubscribeRequest, memberSubscription.Connection, cancellationToken).CAF();
return(memberSubscription.ClusterSubscription.ReadUnsubscribeResponse(responseMessage));
}
