private async Task WaitFor(TimeSpan delayPeriod, CancellationToken token, CoordinatorToken coordinatorToken)
{
var sw = new Stopwatch();
sw.Start();
while (!token.IsCancellationRequested && !coordinatorToken.FencingTokenViolation)
{
if (sw.Elapsed < delayPeriod)
{
await Task.Delay(100);
}
else
{
break;
}
}
}
private void PostLeaderEvent(int fencingToken,
TimeSpan keepAliveExpiryPeriod,
CoordinatorToken coordinatorToken,
BlockingCollection <ClientEvent> clientEvents)
{
this.logger.Debug($"{clientId} is leader");
this.isCoordinator = true;
var clientEvent = new ClientEvent()
{
ResourceGroup = this.resourceGroup,
EventType = EventType.Coordinator,
FencingToken = fencingToken,
CoordinatorToken = coordinatorToken,
KeepAliveExpiryPeriod = keepAliveExpiryPeriod
};
clientEvents.Add(clientEvent);
}
private async Task ExecuteLeaseRenewals(CancellationToken token,
BlockingCollection <ClientEvent> clientEvents,
Lease lease)
{
var coordinatorToken = new CoordinatorToken();
PostLeaderEvent(lease.FencingToken, lease.ExpiryPeriod, coordinatorToken, clientEvents);
await WaitFor(GetInterval(lease.HeartbeatPeriod), token, coordinatorToken);
// lease renewal loop
while (!token.IsCancellationRequested && !coordinatorToken.FencingTokenViolation)
{
var response = await TryRenewLeaseAsync(new RenewLeaseRequest()
{
ClientId = this.clientId, ResourceGroup = this.resourceGroup, FencingToken = lease.FencingToken
}, token);
if (response.Result == LeaseResult.Granted)
{
PostLeaderEvent(lease.FencingToken, lease.ExpiryPeriod, coordinatorToken, clientEvents);
await WaitFor(GetInterval(lease.HeartbeatPeriod), token, coordinatorToken);
}
else if (response.Result == LeaseResult.Denied)
{
PostFollowerEvent(lease.ExpiryPeriod, clientEvents);
await WaitFor(GetInterval(lease.HeartbeatPeriod), token);
break;
}
else if (response.Result == LeaseResult.NoLease)
{
throw new RebalanserException($"The resource group {this.resourceGroup} does not exist.");
}
else if (response.IsErrorResponse())
{
throw new RebalanserException("An non-recoverable error occurred.", response.Exception);
}
else
{
throw new RebalanserException("A non-supported lease result was received"); // should never happen, just in case I screw up in the future
}
}
}