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);
}
public PrefixNode[] GetPrefixes()
{
var prefixes = new PrefixNode[_prefixSection->NextPrefixId];
for (byte prefixId = 0; prefixId < _prefixSection->NextPrefixId; prefixId++)
{
var prefix = new PrefixNode();
prefix.Set(_base + _prefixSection->PrefixOffsets[prefixId], PageNumber);
prefixes[prefixId] = prefix;
}
return(prefixes);
}
private void Defrag(Transaction tx)
{
TemporaryPage tmp;
using (tx.Environment.GetTemporaryPage(tx, out tmp))
{
var tempPage = tmp.GetTempPage(KeysPrefixed);
MemoryUtils.Copy(tempPage.Base, Base, _pageSize);
var numberOfEntries = NumberOfEntries;
Upper = KeysPrefixed ? (ushort)(_pageSize - Constants.PrefixInfoSectionSize) : _pageSize;
for (int i = 0; i < numberOfEntries; i++)
{
var node = tempPage.GetNode(i);
var size = node->GetNodeSize() - Constants.NodeOffsetSize;
size += size & 1;
MemoryUtils.Copy(Base + Upper - size, (byte *)node, size);
Upper -= (ushort)size;
KeysOffsets[i] = Upper;
}
if (KeysPrefixed == false)
{
return;
}
var prefixNode = new PrefixNode();
for (byte i = 0; i < _prefixSection->NextPrefixId; i++)
{
tempPage.AssertPrefixNode(i);
prefixNode.Set(tempPage._base + tempPage._prefixSection->PrefixOffsets[i], tempPage.PageNumber);
var prefixNodeSize = Constants.PrefixNodeHeaderSize + prefixNode.PrefixLength;
prefixNodeSize += prefixNodeSize & 1;
MemoryUtils.Copy(Base + Upper - prefixNodeSize, prefixNode.Base, prefixNodeSize);
Upper -= (ushort)prefixNodeSize;
_prefixSection->PrefixOffsets[i] = Upper;
}
}
}
private void Defrag(Transaction tx)
{
TemporaryPage tmp;
using (tx.Environment.GetTemporaryPage(tx, out tmp))
{
var tempPage = tmp.GetTempPage(KeysPrefixed);
Memory.Copy(tempPage.Base, Base, _pageSize);
var numberOfEntries = NumberOfEntries;
Upper = KeysPrefixed ? (ushort) (_pageSize - Constants.PrefixInfoSectionSize) : _pageSize;
for (int i = 0; i < numberOfEntries; i++)
{
var node = tempPage.GetNode(i);
var size = node->GetNodeSize() - Constants.NodeOffsetSize;
size += size & 1;
Memory.Copy(Base + Upper - size, (byte*)node, size);
Upper -= (ushort) size;
KeysOffsets[i] = Upper;
}
if (KeysPrefixed == false)
return;
var prefixNode = new PrefixNode();
for (byte i = 0; i < _prefixSection->NextPrefixId; i++)
{
tempPage.AssertPrefixNode(i);
prefixNode.Set(tempPage._base + tempPage._prefixSection->PrefixOffsets[i], tempPage.PageNumber);
var prefixNodeSize = Constants.PrefixNodeHeaderSize + prefixNode.PrefixLength;
prefixNodeSize += prefixNodeSize & 1;
Memory.Copy(Base + Upper - prefixNodeSize, prefixNode.Base, prefixNodeSize);
Upper -= (ushort) prefixNodeSize;
_prefixSection->PrefixOffsets[i] = Upper;
}
}
}
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;
}
public PrefixNode[] GetPrefixes()
{
var prefixes = new PrefixNode[_prefixSection->NextPrefixId];
for (byte prefixId = 0; prefixId < _prefixSection->NextPrefixId; prefixId++)
{
var prefix = new PrefixNode();
prefix.Set(_base + _prefixSection->PrefixOffsets[prefixId], PageNumber);
prefixes[prefixId] = prefix;
}
return prefixes;
}