// Copies a section of data from master stream to the log stream
void BackupData(long location, int size)
{
logStream.Seek(0, SeekOrigin.End);
// Write segment header
SegmentMetadata sh = new SegmentMetadata
{
TransactionId = logStreamHeader.TransactionId,
Position = location,
Size = size
};
long metadataPos = logStream.Position;
sh.Save(logStream);
// Copy data
masterStream.Position = location;
int bytesCopied = CopyData(masterStream, size, logStream);
// If bytes copied differ from size in header, update the header
if (bytesCopied != size)
{
logStream.Position = metadataPos;
sh.Size = bytesCopied;
sh.Save(logStream);
}
logStream.Flush();
// Update log stream header
logStreamHeader.SegmentCount++;
logStreamHeader.Save(logStream);
logStream.Flush();
}