public void BuildIndex(Guid dataIdentifier, Int64 dataOffset, BuildIndexBehaviour buildIndexBehaviour, StreamStateBehaviour indexStreamStateBehaviour)
{
int indexInGuid = 0;
long currentOffsetInIndexFile = OffsetFirstIndexBlock;
BuildIndex(dataIdentifier, indexInGuid, currentOffsetInIndexFile, dataOffset, buildIndexBehaviour, indexStreamStateBehaviour);
}
private void BuildIndex(Guid dataIdentifier, int currentIndexInGuid, Int64 currentOffset, Int64 dataOffset, BuildIndexBehaviour buildIndexBehaviour, StreamStateBehaviour indexStreamStateBehaviour)
{
byte[] bytes = dataIdentifier.ToByteArray();
int indexerInGuid = bytes[currentIndexInGuid];
Int64 endOfFileOffset = IndexStream.Length;
AllocationTableStruct currentIndexStruct = GetIndexStruct(currentOffset, indexStreamStateBehaviour);
if (currentIndexInGuid < 15)
{
long nextOffset = currentIndexStruct.Pointers[indexerInGuid];
if (nextOffset == 0)
{
//
// does not point to anywhere; this means we have to;
// * append a new block at the end of the file, with 0-pointers for each guid indexer over there
// * update the reference for the specific index in the guid to the end of the filestream
//
// update the struct
currentIndexStruct.Pointers[indexerInGuid] = endOfFileOffset;
// write the struct
StoreStruct(currentOffset, currentIndexStruct);
// create a new struct with offsets 0 for each index in guid
var newIndexStruct = new AllocationTableStruct
{
Pointers = new Int64[256]
};
StoreStruct(endOfFileOffset, newIndexStruct);
nextOffset = endOfFileOffset;
//
// recursively call BuildIndex for the next index in the guid
//
BuildIndex(dataIdentifier, currentIndexInGuid + 1, nextOffset, dataOffset, buildIndexBehaviour, indexStreamStateBehaviour);
}
else
{
//
// recursively call BuildIndex for the next index in the guid
//
BuildIndex(dataIdentifier, currentIndexInGuid + 1, nextOffset, dataOffset, buildIndexBehaviour, indexStreamStateBehaviour);
}
}
else if (currentIndexInGuid == 15)
{
//
// we reached the last index struct
//
switch (buildIndexBehaviour)
{
case BuildIndexBehaviour.OverrideWhenAlreadyExists:
//
// no matter if it already existed or not, we will override it
//
break;
case BuildIndexBehaviour.ThrowExceptionWhenIndexAlreadyExists:
if (currentIndexStruct.Pointers[indexerInGuid] == 0)
{
//
// its still free, continue
//
break;
}
//
// if we reach this point, it means the pointer was already allocated
//
throw new NotSupportedException(string.Format("Index {0} is already allocated", dataIdentifier));
default:
throw new NotSupportedException(string.Format("{0} is an unsupported BuildIndexBehaviour", buildIndexBehaviour));
}
currentIndexStruct.Pointers[indexerInGuid] = dataOffset;
// store the index block
StoreStruct(currentOffset, currentIndexStruct);
}
else
{
throw new IndexOutOfRangeException(currentIndexInGuid.ToString());
}
}