// runs once on the whole cluster
private async Task RunAsync(CancellationToken cancellationToken)
{
_logger.LogDebug("Run heartbeat");
var now = DateTime.UtcNow;
var connections = _clusterMembers.SnapshotConnections(true);
// start one task per member
// TODO: throttle?
var tasks = connections
.Select(x => RunAsync(x, now, cancellationToken))
.ToList();
await Task.WhenAll(tasks).CAF(); // may throw in case of cancellation
}
// runs once on the whole cluster
private async Task RunAsync(CancellationToken cancellationToken)
{
_logger.LogDebug("Run heartbeat");
var now = DateTime.Now; // now, or utcNow, but *must* be same as what is used in socket connection base!
var connections = _clusterMembers.SnapshotConnections(true);
// start one task per member
// TODO: throttle?
var tasks = connections
.Select(x => RunAsync(x, now, cancellationToken))
.ToList();
await Task.WhenAll(tasks).CfAwait(); // may throw in case of cancellation
}
/// <summary>
/// Installs a subscription on the cluster, i.e. on each member.
/// </summary>
/// <param name="subscription">The subscription.</param>
/// <param name="cancellationToken">A cancellation token.</param>
/// <returns>A task that will complete when the subscription has been installed.</returns>
public async Task InstallSubscriptionAsync(ClusterSubscription subscription, CancellationToken cancellationToken = default)
{
if (subscription == null)
{
throw new ArgumentNullException(nameof(subscription));
}
// capture active clients, and adds the subscription - atomically.
List <MemberConnection> connections;
lock (_clusterState.Mutex)
{
connections = _clusterMembers.SnapshotConnections(true);
if (!_subscriptions.TryAdd(subscription.Id, subscription))
{
throw new InvalidOperationException("A subscription with the same identifier already exists.");
}
}
// from now on,
// - if new clients are added, we won't deal with them here, but they will
// subscribe on their own since the subscription is now listed.
// - if a captured client goes away while we install subscriptions, we
// will just ignore the associated errors and skip it entirely.
// subscribe each captured client
// TODO: could we install in parallel?
// ReSharper disable once ForeachCanBePartlyConvertedToQueryUsingAnotherGetEnumerator
foreach (var connection in connections)
{
// don't even try clients that became inactive
if (!connection.Active)
{
continue;
}
// this never throws
var attempt = await InstallSubscriptionAsync(subscription, connection, cancellationToken).CfAwait();
switch (attempt.Value)
{
case InstallResult.Success:
case InstallResult.ClientNotActive:
continue;
case InstallResult.SubscriptionNotActive:
case InstallResult.ConfusedServer:
// not active: some other code must have
// - removed the subscriptions from _subscriptions
// - dealt with its existing clients
// nothing left to do here
throw new HazelcastException(attempt.Value == InstallResult.SubscriptionNotActive
? "Failed to install the subscription because it was removed."
: "Failed to install the subscription because it was removed (and the server may be confused).", attempt.Exception);
case InstallResult.Failed:
// failed: client is active but installing the subscription failed
// however, we might have installed it on other clients
await RemoveSubscriptionAsync(subscription, cancellationToken).CfAwait();
throw new HazelcastException("Failed to install subscription (see inner exception).", attempt.Exception);
default:
throw new NotSupportedException();
}
}
}