/// <summary>
/// Notifies of a 'members view' event.
/// </summary>
/// <param name="version">The version.</param>
/// <param name="members">The members.</param>
public async ValueTask <MembersUpdatedEventArgs> NotifyMembersView(int version, ICollection <MemberInfo> members)
{
// FIXME could we process two of these at a time?
// get a new table
var table = new MemberTable(version, members);
// compute changes
// count 1 for old members, 2 for new members, and then the result is
// that 1=removed, 2=added, 3=unchanged
// MemberInfo overrides GetHashCode and can be used as a key here
var diff = new Dictionary <MemberInfo, int>();
if (_memberTable == null)
{
foreach (var m in table.Members.Values)
{
diff[m] = 2;
}
}
else
{
foreach (var m in _memberTable.Members.Values)
{
diff[m] = 1;
}
foreach (var m in table.Members.Values)
{
if (diff.ContainsKey(m))
{
diff[m] += 2;
}
else
{
diff[m] = 2;
}
}
}
// replace the table
_memberTable = table;
// notify the load balancer of the new list of members
_loadBalancer.NotifyMembers(members.Select(x => x.Id));
// signal once
if (Interlocked.CompareExchange(ref _firstMembersViewed, 1, 0) == 0)
{
_firstMembersView.Release();
}
// process changes, gather events
var added = new List <MemberInfo>();
var removed = new List <MemberInfo>();
foreach (var(member, status) in diff)
{
switch (status)
{
case 1: // old but not new = removed
HConsole.WriteLine(this, $"Removed member {member.Id}");
removed.Add(member);
if (_connections.TryGetValue(member.Id, out var client))
{
await client.TerminateAsync().CfAwait(); // TODO: consider dying in the background?
}
break;
case 2: // new but not old = added
HConsole.WriteLine(this, $"Added member {member.Id}");
added.Add(member);
break;
case 3: // old and new = no change
break;
default:
throw new NotSupportedException();
}
}
return(new MembersUpdatedEventArgs(added, removed, table.Members.Values));
}
