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;
}
}
}
public int CalcSizeUsed()
{
var size = 0;
for (int i = 0; i < NumberOfEntries; i++)
{
var node = GetNode(i);
var nodeSize = node->GetNodeSize();
size += nodeSize + (nodeSize & 1);
}
if (KeysPrefixed)
{
PrefixNode prefixNode = null;
for (byte i = 0; i < _prefixSection->NextPrefixId; i++)
{
if (prefixNode == null)
{
prefixNode = new PrefixNode();
}
AssertPrefixNode(i);
prefixNode.Set(_base + _prefixSection->PrefixOffsets[i], PageNumber);
var prefixNodeSize = Constants.PrefixNodeHeaderSize + prefixNode.PrefixLength;
size += prefixNodeSize + (prefixNodeSize & 1);
}
size += Constants.PrefixInfoSectionSize;
}
Debug.Assert(size <= _pageSize);
Debug.Assert(SizeUsed >= size);
return(size);
}
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;
}
public int CalcSizeUsed()
{
var size = 0;
for (int i = 0; i < NumberOfEntries; i++)
{
var node = GetNode(i);
var nodeSize = node->GetNodeSize();
size += nodeSize + (nodeSize & 1);
}
if (KeysPrefixed)
{
PrefixNode prefixNode = null;
for (byte i = 0; i < _prefixSection->NextPrefixId; i++)
{
if (prefixNode == null)
prefixNode = new PrefixNode();
AssertPrefixNode(i);
prefixNode.Set(_base + _prefixSection->PrefixOffsets[i], PageNumber);
var prefixNodeSize = Constants.PrefixNodeHeaderSize + prefixNode.PrefixLength;
size += prefixNodeSize + (prefixNodeSize & 1);
}
size += Constants.PrefixInfoSectionSize;
}
Debug.Assert(size <= _pageSize);
Debug.Assert(SizeUsed >= size);
return size;
}
private int AdjustSplitPosition(int currentIndex, int splitIndex, PrefixNode[] prefixes, ref bool newPosition)
{
MemorySlice keyToInsert;
if (_tree.KeysPrefixing)
keyToInsert = new PrefixedSlice(_newKey); // let's assume that _newkey won't be prefixed to ensure the destination page will have enough space
else
keyToInsert = _newKey;
var pageSize = SizeOf.NodeEntry(AbstractPager.PageMaxSpace, keyToInsert , _len) + Constants.NodeOffsetSize;
if (prefixes != null)
{
// we are going to copy all existing prefixes so we need to take into account their sizes
for (var i = 0; i < prefixes.Length; i++)
{
pageSize += (Constants.PrefixNodeHeaderSize + prefixes[i].Header.PrefixLength) & 1; // & 1 because we need 2-byte alignment
}
}
if (currentIndex <= splitIndex)
{
newPosition = false;
for (int i = 0; i < splitIndex; i++)
{
NodeHeader* node = _page.GetNode(i);
pageSize += node->GetNodeSize();
pageSize += pageSize & 1;
if (pageSize > AbstractPager.PageMaxSpace)
{
if (i <= currentIndex)
{
if (i < currentIndex)
newPosition = true;
return currentIndex;
}
return (ushort) i;
}
}
}
else
{
for (int i = _page.NumberOfEntries - 1; i >= splitIndex; i--)
{
NodeHeader* node = _page.GetNode(i);
pageSize += node->GetNodeSize();
pageSize += pageSize & 1;
if (pageSize > AbstractPager.PageMaxSpace)
{
if (i >= currentIndex)
{
newPosition = false;
return currentIndex;
}
return (ushort) (i + 1);
}
}
}
return splitIndex;
}
private int AdjustSplitPosition(int currentIndex, int splitIndex, PrefixNode[] prefixes, ref bool toRight)
{
MemorySlice keyToInsert;
int pageSize = 0;
if (_tree.KeysPrefixing)
{
keyToInsert = new PrefixedSlice(_newKey); // let's assume that _newkey won't match any of the existing prefixes
pageSize += Constants.PrefixInfoSectionSize;
pageSize += Constants.PrefixNodeHeaderSize + 1; // possible new prefix, + 1 because of possible 2-byte alignment
}
else
keyToInsert = _newKey;
pageSize += SizeOf.NodeEntry(AbstractPager.PageMaxSpace, keyToInsert , _len) + Constants.NodeOffsetSize;
if (prefixes != null)
{
// we are going to copy all existing prefixes so we need to take into account their sizes
for (var i = 0; i < prefixes.Length; i++)
{
var prefixNodeSize = Constants.PrefixNodeHeaderSize + prefixes[i].Header.PrefixLength;
pageSize += prefixNodeSize + (prefixNodeSize & 1); // & 1 because we need 2-byte alignment
}
}
if (toRight == false)
{
for (int i = 0; i < splitIndex; i++)
{
NodeHeader* node = _page.GetNode(i);
pageSize += node->GetNodeSize();
pageSize += pageSize & 1;
if (pageSize > AbstractPager.PageMaxSpace)
{
if (i <= currentIndex)
{
if (i < currentIndex)
toRight = true;
return currentIndex;
}
return i;
}
}
}
else
{
for (int i = _page.NumberOfEntries - 1; i >= splitIndex; i--)
{
NodeHeader* node = _page.GetNode(i);
pageSize += node->GetNodeSize();
pageSize += pageSize & 1;
if (pageSize > AbstractPager.PageMaxSpace)
{
if (i >= currentIndex)
{
toRight = false;
return currentIndex;
}
return i + 1;
}
}
}
return splitIndex;
}
public override void PrepareForSearching()
{
if (Prefix == null && NewPrefix != null)
{
Prefix = new PrefixNode(new PrefixNodeHeader
{
PrefixLength = NewPrefix.KeyLength
}, NewPrefix.Array, -1);
}
}
