public override void FindShortestSeparator(ref string start, Slice limit)
{
// Attempt to shorten the user portion of the key
Slice user_start = new Slice(start).ExtractUserKey();
Slice user_limit = limit.ExtractUserKey();
string tmp = user_start.Data.GetString(user_start.Size);
UserComparator.FindShortestSeparator(ref tmp, user_limit);
if (tmp.Length < user_start.Size &&
UserComparator.Compare(user_start, new Slice(tmp)) < 0)
{
// User key has become shorter physically, but larger logically.
// Tack on the earliest possible number to the shortened user key.
Coding.PutFixed64(ref tmp,
Global.PackSequenceAndType(Global.kMaxSequenceNumber, Global.kValueTypeForSeek));
Debug.Assert(this.Compare(new Slice(start), new Slice(tmp)) < 0);
Debug.Assert(this.Compare(new Slice(tmp), limit) < 0);
start = start.Swap(ref tmp);
}
}
public override int Compare(Slice akey, Slice bkey)
{
// Order by:
// increasing user key (according to user-supplied comparator)
// decreasing sequence number
// decreasing type (though sequence# should be enough to disambiguate)
int r = UserComparator.Compare(akey.ExtractUserKey(), bkey.ExtractUserKey());
if (r == 0)
{
UInt64 anum = Coding.DecodeFixed64(akey.Data + (akey.Size - 8));
UInt64 bnum = Coding.DecodeFixed64(bkey.Data + (bkey.Size - 8));
if (anum > bnum)
{
r = -1;
}
else if (anum < bnum)
{
r = +1;
}
}
return r;
}