public bool ReadKey(BTreeValue *pEntry, ushort keyType, out TangleKey key)
{
if (keyType == 0)
{
key = default(TangleKey);
return(false);
}
var buffer = ImmutableArrayPool <byte> .Allocate(pEntry->KeyLength);
if (pEntry->KeyLength <= BTreeValue.KeyPrefixSize)
{
fixed(byte *pBuffer = buffer.Array)
Native.memmove(pBuffer + buffer.Offset, pEntry->KeyPrefix, new UIntPtr(pEntry->KeyLength));
}
else
{
using (var keyRange = KeyStream.AccessRange(
pEntry->KeyOffset, pEntry->KeyLength, MemoryMappedFileAccess.Read
))
Unsafe.ReadBytes(keyRange.Pointer, 0, buffer.Array, buffer.Offset, pEntry->KeyLength);
}
key = new TangleKey(buffer, keyType);
return(true);
}
/// <summary>
/// Serializes a given value so that it can be written to the provided IndexEntry.
/// The IndexEntry's KeyLength and KeyOffset values must be filled in and the key must have been written to KeyOffset.
/// </summary>
public ArraySegment <byte> Serialize <T> (BTreeValue *pEntry, Serializer <T> serializer, ushort keyType, ref T value)
{
if (_SerializationBuffer == null)
{
_SerializationBuffer = new MemoryStream();
}
var context = new SerializationContext(_GetKeyOfEntry, pEntry, keyType, _SerializationBuffer);
serializer(ref context, ref value);
var result = context.Bytes;
if (_SerializationBuffer.Capacity > MaxSerializationBufferSize)
{
_SerializationBuffer.Dispose();
_SerializationBuffer = null;
}
else
{
_SerializationBuffer.Seek(0, SeekOrigin.Begin);
_SerializationBuffer.SetLength(0);
}
return(result);
}
internal DeserializationContext(GetKeyOfEntryFunc getKeyOfEntry, BTreeValue *pEntry, ushort keyType, byte *source, uint sourceLength)
{
GetKeyOfEntry = getKeyOfEntry;
_Key = default(TangleKey);
_KeyCached = false;
KeyType = keyType;
ValuePointer = pEntry;
Source = source;
SourceLength = sourceLength;
_Stream = null;
}
public unsafe void ReadData <T> (BTreeValue *pEntry, ushort keyType, Deserializer <T> deserializer, out T value)
{
using (var range = DataStream.AccessRange(pEntry->DataOffset, pEntry->DataLength)) {
var context = new DeserializationContext(_GetKeyOfEntry, pEntry, keyType, range.Pointer, pEntry->DataLength);
try {
deserializer(ref context, out value);
} finally {
context.Dispose();
}
}
}
public void ReadData <T> (BTreeValue *pEntry, Deserializer <T> deserializer, out T value)
{
var keyType = pEntry->KeyType;
if (keyType == 0)
{
throw new InvalidDataException();
}
ReadData(pEntry, keyType, deserializer, out value);
}
public void UnlockValue(BTreeValue *pEntry, ushort keyType)
{
unchecked {
if (pEntry->KeyType != 0)
{
throw new InvalidDataException();
}
pEntry->KeyType = keyType;
}
}
internal SerializationContext(GetKeyOfEntryFunc getKeyOfEntry, BTreeValue *pEntry, ushort keyType, MemoryStream stream)
{
GetKeyOfEntry = getKeyOfEntry;
ValuePointer = pEntry;
KeyType = keyType;
_Key = default(TangleKey);
_KeyCached = false;
_Stream = stream;
BytesProvided = false;
StreamInUse = false;
_Bytes = default(ArraySegment <byte>);
}
public void WriteData(BTreeValue *pEntry, ArraySegment <byte> data)
{
bool append = (data.Count > pEntry->DataLength + pEntry->ExtraDataBytes);
long?dataOffset;
uint size = (uint)data.Count;
if (append)
{
dataOffset = AllocateDataSpace(ref size);
}
else
{
dataOffset = pEntry->DataOffset;
}
WriteData(ref *pEntry, data, append, dataOffset, size);
}
public void WriteNewKey(BTreeValue *pEntry, TangleKey key)
{
if (key.Data.Count > BTreeValue.KeyPrefixSize)
{
pEntry->KeyOffset = (uint)KeyStream.AllocateSpace((uint)key.Data.Count).Value;
}
else
{
pEntry->KeyOffset = 0;
}
pEntry->KeyLength = (ushort)key.Data.Count;
// It's important that we zero out these fields so that when we write the data,
// it's done in append mode instead of replace mode
pEntry->DataOffset = 0;
pEntry->DataLength = 0;
pEntry->ExtraDataBytes = 0;
WriteKey(ref *pEntry, key);
}
public bool ReadKey(BTreeValue *pEntry, out TangleKey key)
{
ushort keyType = pEntry->KeyType;
return(ReadKey(pEntry, keyType, out key));
}
/// <summary>
/// Performs a binary search of the values stored within a BTree node.
/// </summary>
/// <param name="entries">Pointer to the first value within the node.</param>
/// <param name="entryCount">The number of values within the node.</param>
/// <param name="pSearchKey">Pointer to the first byte of the key to search for.</param>
/// <param name="searchKeyLength">The number of bytes in the key to search for.</param>
/// <param name="resultIndex">The index of the value within the node that matches the provided key, if any, otherwise the index of the leaf that should contain the provided key.</param>
/// <returns>True if one of the node's values matches the provided key. False if the provided key was not found.</returns>
private bool SearchValues(BTreeValue *entries, ushort entryCount, byte *pSearchKey, uint searchKeyLength, out uint resultIndex)
{
int min = 0, max = entryCount - 1;
int delta = 0, pivot;
uint compareLength;
while (min <= max)
{
unchecked {
pivot = min + ((max - min) >> 1);
}
var pEntry = &entries[pivot];
if (pEntry->KeyType == 0)
{
throw new InvalidDataException();
}
compareLength = Math.Min(Math.Min(pEntry->KeyLength, searchKeyLength), BTreeValue.KeyPrefixSize);
// Calling out to a function here introduces unnecessary overhead since the prefix is so small
for (uint i = 0; i < compareLength; i++)
{
delta = pEntry->KeyPrefix[i] - pSearchKey[i];
if (delta != 0)
{
break;
}
}
if ((delta == 0) && (pEntry->KeyLength > BTreeValue.KeyPrefixSize))
{
using (var keyRange = KeyStream.AccessRange(
pEntry->KeyOffset, pEntry->KeyLength, MemoryMappedFileAccess.Read
)) {
var pLhs = keyRange.Pointer;
compareLength = Math.Min(pEntry->KeyLength, searchKeyLength);
delta = Native.memcmp(pLhs, pSearchKey, new UIntPtr(compareLength));
}
}
if (delta == 0)
{
if (pEntry->KeyLength > searchKeyLength)
{
delta = 1;
}
else if (searchKeyLength > pEntry->KeyLength)
{
delta = -1;
}
}
if (delta == 0)
{
resultIndex = (uint)pivot;
return(true);
}
else if (delta < 0)
{
min = pivot + 1;
}
else
{
max = pivot - 1;
}
}
resultIndex = (uint)min;
return(false);
}
public StreamRange LockValue(long nodeIndex, uint valueIndex, long?minimumSize, out BTreeValue *pValue, out ushort keyType)
{
var result = AccessNode(nodeIndex, true);
unchecked {
pValue = (BTreeValue *)(result.Pointer + BTreeNode.OffsetOfValues + (valueIndex * BTreeValue.Size));
keyType = pValue->KeyType;
pValue->KeyType = 0;
}
var lockLength = pValue->DataLength;
if ((minimumSize.HasValue) && (minimumSize.Value > lockLength))
{
lockLength = (uint)minimumSize.Value;
var oldPosition = pValue->DataOffset;
var oldLength = pValue->DataLength + pValue->ExtraDataBytes;
pValue->DataOffset = (uint)AllocateDataSpace(ref lockLength).Value;
pValue->ExtraDataBytes = (uint)(lockLength - oldLength);
using (var oldDataRange = DataStream.AccessRange(oldPosition, oldLength))
using (var dataRange = DataStream.AccessRange(pValue->DataOffset, pValue->DataLength)) {
Native.memmove(dataRange.Pointer, oldDataRange.Pointer, new UIntPtr(pValue->DataLength));
Native.memset(oldDataRange.Pointer, 0, new UIntPtr(pValue->DataLength));
}
FreelistPut(oldPosition, oldLength);
}
return(result);
}
