private bool TryUseExistingPrefix(MemorySlice key, out PrefixedSlice prefixedSlice)
{
if (_prefixSection->NextPrefixId < 1)
{
prefixedSlice = null;
return(false);
}
var prefix = new PrefixNode();
BestPrefixMatch bestMatch = null;
for (byte prefixId = 0; prefixId < _prefixSection->NextPrefixId; prefixId++)
{
AssertPrefixNode(prefixId);
prefix.Set(_base + _prefixSection->PrefixOffsets[prefixId], PageNumber);
var length = key.FindPrefixSize(new Slice(prefix.ValuePtr, prefix.PrefixLength));
if (length == 0)
{
continue;
}
if (length == prefix.PrefixLength) // full prefix usage
{
prefixedSlice = new PrefixedSlice(prefixId, length, key.Skip(length));
return(true);
}
// keep on looking for a better prefix
if (bestMatch == null)
{
bestMatch = new BestPrefixMatch
{
PrefixId = prefixId,
PrefixUsage = length
};
}
else if (length > bestMatch.PrefixUsage)
{
bestMatch.PrefixId = prefixId;
bestMatch.PrefixUsage = length;
}
}
if (bestMatch != null && bestMatch.PrefixUsage > MinPrefixLength(key))
{
prefixedSlice = new PrefixedSlice(bestMatch.PrefixId, bestMatch.PrefixUsage, key.Skip(bestMatch.PrefixUsage));
return(true);
}
prefixedSlice = null;
return(false);
}
private bool TryUseExistingPrefix(MemorySlice key, out PrefixedSlice prefixedSlice)
{
if (_prefixSection->NextPrefixId < 1)
{
prefixedSlice = null;
return false;
}
BestPrefixMatch bestMatch = null;
for (byte prefixId = 0; prefixId < _prefixSection->NextPrefixId; prefixId++)
{
AssertPrefixNode(prefixId);
var prefix = new PrefixNode();
prefix.Set(_base + _prefixSection->PrefixOffsets[prefixId], PageNumber);
var length = key.FindPrefixSize(new Slice(prefix.ValuePtr, prefix.PrefixLength));
if (length == 0)
continue;
if (length == prefix.PrefixLength) // full prefix usage
{
prefixedSlice = new PrefixedSlice(prefixId, length, key.Skip(length))
{
Prefix = prefix
};
return true;
}
// keep on looking for a better prefix
if (bestMatch == null)
{
bestMatch = new BestPrefixMatch
{
PrefixId = prefixId,
PrefixUsage = length,
PrefixNode = prefix
};
}
else if (length > bestMatch.PrefixUsage)
{
bestMatch.PrefixId = prefixId;
bestMatch.PrefixUsage = length;
bestMatch.PrefixNode = prefix;
}
}
if (bestMatch != null && bestMatch.PrefixUsage > MinPrefixLength(key))
{
prefixedSlice = new PrefixedSlice(bestMatch.PrefixId, bestMatch.PrefixUsage, key.Skip(bestMatch.PrefixUsage))
{
Prefix = bestMatch.PrefixNode
};
return true;
}
prefixedSlice = null;
return false;
}
