public Lease GetLease(Instance instance, GetLeaseRequest leaseRequest)
{
ValidateLeaseTimeSpan(leaseRequest.LeaseTimeSpan);
DelayedInstanceWrap delayedWrap;
if (!leaseProviders.TryGetValue(instance, out delayedWrap))
{
RequestInstanceDiscovery();
throw new InstanceNotRegisteredException(instance.Identity.GetAnyString());
}
if (delayedWrap.InstanceLeaseProvider == null)
{
throw new Exception($"LeaseProvider for Instance {instance.Identity.GetAnyString()} will be available " +
$"in at most {leaseConfiguration.ClockDrift.TotalMilliseconds} ms.");
}
return(delayedWrap.InstanceLeaseProvider.GetLease(new GetLeaseRequest
{
LeaseTimeSpan = leaseRequest.LeaseTimeSpan,
RequestorIdentity = leaseRequest.RequestorIdentity,
MinValidityTimeFraction = leaseRequest.MinValidityTimeFraction
}));
}
private void ReadOrRenewLease(GetLeaseRequest request)
{
var lease = AсquireOrLearnLease(ballotGenerator.New(instance.Identity),
request.RequestorIdentity,
request.LeaseTimeSpan);
lastKnownLease = lease;
}
public Lease GetLease(GetLeaseRequest request)
{
if (LeaseNullOrExpired(lastKnownLease) ||
IsLeaseOwner(request.RequestorIdentity, lastKnownLease) && LeaseShouldBeProlonged(request, lastKnownLease))
{
ReadOrRenewLease(request);
}
return(lastKnownLease);
}
private bool LeaseShouldBeProlonged(GetLeaseRequest request, Lease lastKnownLease) => lastKnownLease.ExpiresAt - DateTime.UtcNow <= Max(minLeaseValidityPeriod, request.LeaseTimeSpan.DivideBy(Math.Max(request.MinValidityTimeFraction, 1)));
