/// <summary>
/// Finds the silo that owns the directory information for the given grain ID.
/// This method will only be null when I'm the only silo in the cluster and I'm shutting down
/// </summary>
/// <param name="grainId"></param>
/// <returns></returns>
public SiloAddress CalculateGrainDirectoryPartition(GrainId grainId)
{
// give a special treatment for special grains
if (grainId.IsSystemTarget())
{
if (Constants.SystemMembershipTableType.Equals(grainId))
{
if (Seed == null)
{
var errorMsg =
$"Development clustering cannot run without a primary silo. " +
$"Please configure {nameof(DevelopmentClusterMembershipOptions)}.{nameof(DevelopmentClusterMembershipOptions.PrimarySiloEndpoint)} " +
"or provide a primary silo address to the UseDevelopmentClustering extension. " +
"Alternatively, you may want to use reliable membership, such as Azure Table.";
throw new ArgumentException(errorMsg, "grainId = " + grainId);
}
}
if (log.IsEnabled(LogLevel.Trace))
{
log.Trace("Silo {0} looked for a system target {1}, returned {2}", MyAddress, grainId, MyAddress);
}
// every silo owns its system targets
return(MyAddress);
}
SiloAddress siloAddress = null;
int hash = unchecked ((int)grainId.GetUniformHashCode());
// excludeMySelf from being a TargetSilo if we're not running and the excludeThisSIloIfStopping flag is true. see the comment in the Stop method.
// excludeThisSIloIfStopping flag was removed because we believe that flag complicates things unnecessarily. We can add it back if it turns out that flag
// is doing something valuable.
bool excludeMySelf = !Running;
var existing = this.directoryMembership;
if (existing.MembershipRingList.Count == 0)
{
// If the membership ring is empty, then we're the owner by default unless we're stopping.
return(!Running ? null : MyAddress);
}
// need to implement a binary search, but for now simply traverse the list of silos sorted by their hashes
for (var index = existing.MembershipRingList.Count - 1; index >= 0; --index)
{
var item = existing.MembershipRingList[index];
if (IsSiloNextInTheRing(item, hash, excludeMySelf))
{
siloAddress = item;
break;
}
}
if (siloAddress == null)
{
// If not found in the traversal, last silo will do (we are on a ring).
// We checked above to make sure that the list isn't empty, so this should always be safe.
siloAddress = existing.MembershipRingList[existing.MembershipRingList.Count - 1];
// Make sure it's not us...
if (siloAddress.Equals(MyAddress) && excludeMySelf)
{
siloAddress = existing.MembershipRingList.Count > 1 ? existing.MembershipRingList[existing.MembershipRingList.Count - 2] : null;
}
}
if (log.IsEnabled(LogLevel.Trace))
{
log.Trace("Silo {0} calculated directory partition owner silo {1} for grain {2}: {3} --> {4}", MyAddress, siloAddress, grainId, hash, siloAddress?.GetConsistentHashCode());
}
return(siloAddress);
}