private FindKeySuccessorResult FindPredecessorForId(FindKeySuccessorArg id)
{
var result = FindClosestPrecedingFinger(id.Id);
Log.Write(LogEvent.Debug,
"FindSuccessorForId(from: {1}, for {2}): FindClosestPrecedingFinger returned node {0} and ...",
result.Id,
LocalNode.Id,
id
);
// stop recursion
if (result.Equals(LocalNode)) {
Log.Write(LogEvent.Debug,
"FindSuccessorForId(from: {0}, for {1}): ... actually it is the same as local node {0}, so return it",
LocalNode.Id,
id
);
return new FindKeySuccessorResult(LocalNode, false).CopyStatistics(id);
}
if (ChordOverlayHelper.IsInCircularInterval(id.Id, LocalNode.Id, LocalNode.Successor.Id, includeRight: true)) {
Log.Write(LogEvent.Debug,
"FindSuccessorForId(from: {0}, for {1}): ... OverlayHelper.IsInCircularInterval({1}, {0}, {2}, includeRight: true) is true, so return it",
LocalNode.Id,
id,
LocalNode.Successor.Id
);
return new FindKeySuccessorResult(result, true).CopyStatistics(id);
} else {
var resultNodeSrv = CommunicationMgr.GetChannel(result);
try {
Log.Write(LogEvent.Debug,
"FindSuccessorForId(from: {0}, for {1}): ... OverlayHelper.IsInCircularInterval({1}, {0}, {2}, includeRight: true) is false, so call FindSuccessorForId(from: {3}, for {1})",
LocalNode.Id,
id,
LocalNode.Successor.Id,
result.Id
);
// +1 hop, since we are calling the same method on the remote successor
id.StatsCollector.IncreaseHopsCount(1);
// if we call this recursively, we do not need to get the successor of the result inside
return resultNodeSrv.Service.FindKeySuccessor(new FindKeySuccessorArg(id.Id, false).CopyStatistics(id));
} catch (Exception ex) {
if (resultNodeSrv.IsUnavailable) {
Log.Write(
LogEvent.Warn,
"Node {0} cannot propagate FindSuccessorForId for node {1} because the service is unaccessible, returning local node instead. Error details: \r\n {2}",
LocalNode,
result,
ex.ToString()
);
// TODO: correct?
return new FindKeySuccessorResult(LocalNode, false).CopyStatistics(id);
} else {
throw;
}
}
}
}
public FindKeySuccessorResult FindKeySuccessor(FindKeySuccessorArg key)
{
Log.Write(LogEvent.Debug, "FindSuccessorForId(from: {0}, for {1})", LocalNode.Id, key);
// check if my successor is actually the successor of this id
if (ChordOverlayHelper.IsInCircularInterval(key.Id, LocalNode.Id, LocalNode.Successor.Id, includeRight: true)) {
Log.Write(LogEvent.Debug,
"FindSuccessorForId(from: {1}, for {0}): OverlayHelper.IsInCircularInterval({0}, {1}, {2}, includeRight: true) is true, returning LocalNode.Successor: {2}",
key, LocalNode.Id, LocalNode.Successor.Id
);
return new FindKeySuccessorResult(LocalNode.Successor, false).CopyStatistics(key);
}
// check if me is actually the successor of this id
if (LocalNode.Predecessor != null && ChordOverlayHelper.IsInCircularInterval(key.Id, LocalNode.Predecessor.Id, LocalNode.Id, includeRight: true)) {
Log.Write(LogEvent.Debug,
"FindSuccessorForId(from: {2}, for {0}): OverlayHelper.IsInCircularInterval({0}, {1}, {2}, includeRight: true) is true, returning LocalNode: {2}",
key, LocalNode.Predecessor.Id, LocalNode.Id
);
return new FindKeySuccessorResult(LocalNode, false).CopyStatistics(key);
}
var pred = FindPredecessorForId(key);
var predSrv = CommunicationMgr.GetChannel(pred.Node);
try {
var returnSuccessorAsResult = pred.ReturnSuccessorAsResult && key.ReturnSuccessorAsResult;
var res = returnSuccessorAsResult ? predSrv.Service.GetSuccessor() : pred.Node;
if (returnSuccessorAsResult) {
key.StatsCollector.IncreaseHopsCount(1); // for GetSuccessor
}
Log.Write(LogEvent.Debug,
returnSuccessorAsResult
? "FindSuccessorForId(from: {2}, for {3}): FindPredecessorForId returned node {0}, thus the result of FindSuccessorForId is {0}'s successor: {1}"
: "FindSuccessorForId(from: {2}, for {3}): FindPredecessorForId returned node {0}, thus the result of FindSuccessorForId is {0}",
pred.Node.Id,
res.Id,
LocalNode.Id,
key
);
return new FindKeySuccessorResult(res, false).CopyStatistics(key);
} catch (Exception ex) {
if (predSrv.IsUnavailable) {
Log.Write(
LogEvent.Warn,
"Node {0} cannot call GetNodeSuccessor for node {1} because the service is unaccessible, returning local node instead. Error details: \r\n {2}",
LocalNode,
pred,
ex.ToString()
);
// TODO: correct?
return new FindKeySuccessorResult(LocalNode, false).CopyStatistics(key);
} else {
throw;
}
}
throw new NotImplementedException();
}