/// <summary>
/// nominate itself to be a manager
/// </summary>
protected virtual async Task <IWorkerInfo> SetManager(string activityId, IWorkerInfo worker, IWorkerInfo current)
{
var tableLock = await _table.AcquireLock();
_tracer.TraceInformation(activityId, worker, string.Format("Acquire table lock id: {0}", tableLock.Id));
try
{
var manager = await _table.GetManager();
// other worker already takes up manager position
if (!ScaleUtils.WorkerEquals(manager, current))
{
return(manager);
}
await _table.SetManager(worker);
_tracer.TraceInformation(activityId, worker, "This worker is set to be a manager.");
return(worker);
}
finally
{
await tableLock.Release();
_tracer.TraceInformation(activityId, worker, string.Format("Release table lock id: {0}", tableLock.Id));
}
}
/// <summary>
/// this routine does ..
/// - ping and update worker status
/// - ensure manager
/// - if manager, make scale decision
/// - if manager, stale worker management
/// </summary>
protected virtual async Task ProcessWorkItem(string activityId)
{
// get worker status
var worker = await _provider.GetWorkerInfo(activityId);
_worker = worker;
// update worker status and keep alive
await PingWorker(activityId, worker);
// select manager
var manager = await EnsureManager(activityId, worker);
// if this is manager, perform scale decision and stale worker management
if (ScaleUtils.WorkerEquals(worker, manager))
{
// perform scale decision
await MakeScaleDecision(activityId, worker);
// stale worker management
await CheckStaleWorker(activityId, worker);
}
}
