public static bool HappensAfter(VectorClock first, VectorClock second)
{
// Create immutable other to protect from concurrent accesses
ImmutableVectorClock immutableFirst = first.ToImmutable();
ImmutableVectorClock immutableSecond = second.ToImmutable();
// Get all possible ids
ImmutableHashSet <string> firstIds = immutableFirst.Ids;
ImmutableHashSet <string> secondIds = immutableSecond.Ids;
HashSet <string> allIds = new HashSet <string>(firstIds);
allIds.UnionWith(secondIds);
// For all ids, at least one has to be greater than
// other and none can be less
bool oneGreater = false;
foreach (string id in allIds)
{
int firstClock = immutableFirst[id];
int secondClock = immutableSecond[id];
if (firstClock > secondClock)
{
oneGreater = true;
}
else if (firstClock < secondClock)
{
return(false);
}
}
return(oneGreater);
}
public void Merge(VectorClock other)
{
// Create immutable other to protect from concurrent accesses
ImmutableVectorClock immutableOther = other.ToImmutable();
ImmutableHashSet <string> secondIds = immutableOther.Ids;
// Dont let concurrent updates while merging
lock (this) {
// Get all possible ids
HashSet <string> allIds = new HashSet <string>(vc.Keys);
allIds.UnionWith(secondIds);
foreach (string id in allIds)
{
int otherClock = immutableOther[id];
// Add other value if not there or
// update with max between both values
vc.AddOrUpdate(id, otherClock, (key, prev) => Math.Max(prev, otherClock));
}
// Invalidate immutable this
immutableThis = null;
}
}
public static bool Equal(VectorClock first, VectorClock second)
{
// Create immutable other to protect from concurrent accesses
ImmutableVectorClock immutableFirst = first.ToImmutable();
ImmutableVectorClock immutableSecond = second.ToImmutable();
// Get all possible ids
ImmutableHashSet <string> firstIds = immutableFirst.Ids;
ImmutableHashSet <string> secondIds = immutableSecond.Ids;
if (firstIds.Count != secondIds.Count)
{
return(false);
}
foreach (string id in firstIds)
{
if (immutableFirst[id] != immutableSecond[id])
{
return(false);
}
}
return(true);
}
