private void reloadStartRecordPointer(Int64 sectionStartPointer)
{
Int64 position = 0;
for (int i = 0; i < this.maxJumpTableLevel; i++)
{
position = sectionStartPointer + i * sectionlen + 46; //46 is the start 46 bytes for counter, etc.
byte[] nextpointer = new byte[8];
lock (_object)
{
IndexStream.Position = position + 11; //warning, 11 is the next pointer position, it might change.
IndexStream.Read(nextpointer, 0, 8);
}
if (BitConverter.ToInt64(nextpointer, 0) > 0)
{
break;
}
}
lock (_object)
{
IndexStream.Position = sectionStartPointer + this.startRecordPointerPositionIndex;
IndexStream.Write(BitConverter.GetBytes(position), 0, 8);
}
}
private void updateNavigator(Int64 recorddiskposition, Int64 PointerDiskPosition, enumPosition position)
{
int relativeposition = 0;
switch (position)
{
case enumPosition.next:
relativeposition = 11;
break;
case enumPosition.previous:
relativeposition = 3;
break;
case enumPosition.top:
relativeposition = 19;
break;
case enumPosition.bottom:
relativeposition = 27;
break;
default:
relativeposition = 11;
break;
}
lock (_object)
{
IndexStream.Position = recorddiskposition + relativeposition;
IndexStream.Write(BitConverter.GetBytes(PointerDiskPosition), 0, 8);
}
}
private JumpRecord insertNewRecord(Int64 blockposition)
{
JumpRecord record = new JumpRecord();
record.BlockPosition = blockposition;
record.Indicator = enumSectionType.Record;
Int64 insertposition = getInsertPosition();
IndexStream.Position = insertposition;
IndexStream.Write(record.ToBytes(), 0, sectionlen);
record.diskLocation = insertposition;
return(record);
}
private Int64 createNewStartSection()
{
/// in the format of
/// [8] start search pointer. Pointer to the highest jump table.
/// [2] * = number of counter of each level. start pointer =
// header section + number levels.
int totallen = sectionlen + this.maxJumpTableLevel * sectionlen;
byte[] totalbytes = new byte[totallen];
byte[] header = new byte[sectionlen];
header[0] = startbyteone;
header[1] = startbytetwo;
header[44] = startbyteone;
header[45] = startbytetwo;
header[2] = (byte)enumSectionType.StartSection;
List <JumpRecord> tablelist = new List <JumpRecord>();
for (int i = 0; i < this.maxJumpTableLevel; i++)
{
JumpRecord newrecord = new JumpRecord();
newrecord.BlockPosition = Int64.MinValue;
newrecord.Indicator = enumSectionType.Record;
newrecord.level = (byte)i;
tablelist.Add(newrecord);
}
for (int i = 0; i < tablelist.Count; i++)
{
if (i == 0)
{
updateNavigator(tablelist[i].diskLocation, tablelist[i + 1].diskLocation, enumPosition.next);
}
else if (i == tablelist.Count - 1)
{
updateNavigator(tablelist[i].diskLocation, tablelist[i - 1].diskLocation, enumPosition.previous);
}
else
{
// in the middle.
updateNavigator(tablelist[i].diskLocation, tablelist[i - 1].diskLocation, enumPosition.previous);
updateNavigator(tablelist[i].diskLocation, tablelist[i + 1].diskLocation, enumPosition.next);
}
}
Int64 writeposition = getInsertPosition();
//write position for each start of level table.
for (int i = 0; i < tablelist.Count; i++)
{
tablelist[i].diskLocation = writeposition + 46 + i * 46;
}
Int64 lastitemindex = tablelist[tablelist.Count - 1].diskLocation;
System.Buffer.BlockCopy(BitConverter.GetBytes(lastitemindex), 0, header, 3, 8);
lock (_object)
{
IndexStream.Position = writeposition;
IndexStream.Write(header, 0, sectionlen);
foreach (var item in tablelist)
{
IndexStream.Position = item.diskLocation;
IndexStream.Write(item.ToBytes(), 0, sectionlen);
}
}
return(writeposition);
}
