public ClusterMembershipService(
MembershipTableManager membershipTableManager,
ILogger <ClusterMembershipService> log,
IFatalErrorHandler fatalErrorHandler)
{
this.snapshot = membershipTableManager.MembershipTableSnapshot.CreateClusterMembershipSnapshot();
this.updates = new AsyncEnumerable <ClusterMembershipSnapshot>(
(previous, proposed) => proposed.Version == MembershipVersion.MinValue || proposed.Version > previous.Version,
this.snapshot)
{
OnPublished = update => Interlocked.Exchange(ref this.snapshot, update)
};
this.membershipTableManager = membershipTableManager;
this.log = log;
this.fatalErrorHandler = fatalErrorHandler;
}
/// <summary>
/// Returns a <see cref="ClusterMembershipUpdate"/> which represents the change in cluster membership from the provided snapshot to this instance.
/// </summary>
/// <returns>A <see cref="ClusterMembershipUpdate"/> which represents the change in cluster membership from the provided snapshot to this instance.</returns>
public ClusterMembershipUpdate CreateUpdate(ClusterMembershipSnapshot previous)
{
if (previous is null)
{
throw new ArgumentNullException(nameof(previous));
}
if (this.Version < previous.Version)
{
throw new ArgumentException($"Argument must have a previous version to the current instance. Expected <= {this.Version}, encountered {previous.Version}", nameof(previous));
}
if (this.Version == previous.Version)
{
return(new ClusterMembershipUpdate(this, ImmutableArray <ClusterMember> .Empty));
}
var changes = ImmutableHashSet.CreateBuilder <ClusterMember>();
foreach (var entry in this.Members)
{
// Include any entry which is new or has changed state.
if (!previous.Members.TryGetValue(entry.Key, out var previousEntry) || previousEntry.Status != entry.Value.Status)
{
changes.Add(entry.Value);
}
}
// Handle entries which were removed entirely.
foreach (var entry in previous.Members)
{
if (!this.Members.TryGetValue(entry.Key, out _))
{
changes.Add(new ClusterMember(entry.Key, SiloStatus.Dead, entry.Value.Name));
}
}
return(new ClusterMembershipUpdate(this, changes.ToImmutableArray()));
}
/// <summary>
/// Initializes a new instance of the <see cref="ClusterMembershipUpdate"/> class.
/// </summary>
/// <param name="snapshot">The snapshot.</param>
/// <param name="changes">The changes.</param>
public ClusterMembershipUpdate(ClusterMembershipSnapshot snapshot, ImmutableArray <ClusterMember> changes)
{
this.Snapshot = snapshot;
this.Changes = changes;
}