/// <summary>
/// Navigates to a block that will be only read and not modified.
/// </summary>
/// <param name="blockIndex"></param>
/// <param name="blockType">the type of this block.</param>
/// <param name="indexValue">a value put in the footer of the block designating the index of this block</param>
/// <returns></returns>
public void ReadOld(uint blockIndex, BlockType blockType, uint indexValue)
{
BlockIndex = blockIndex;
BlockType = (byte)blockType;
IndexValue = indexValue;
ReadCount++;
if (IsDisposed)
{
throw new ObjectDisposedException(GetType().FullName);
}
if (m_diskIo.IsDisposed)
{
throw new ObjectDisposedException(typeof(DiskIo).FullName);
}
IsValid = true;
ReadBlock(false);
IoReadState readState = IsFooterValidFromOldBlock();
if (readState != IoReadState.Valid)
{
IsValid = false;
throw new Exception("Read Error: " + readState.ToString());
}
}
/// <summary>
/// Navigates to a block that will be written to.
/// This block must currently exist and have the correct parameters passed to this function
/// In order to allow this block to be modified.
/// </summary>
/// <param name="blockIndex">the index value of this block</param>
/// <param name="blockType">the type of this block.</param>
/// <param name="indexValue">a value put in the footer of the block designating the index of this block</param>
/// <returns></returns>
public void WriteToExistingBlock(uint blockIndex, BlockType blockType, uint indexValue)
{
BlockIndex = blockIndex;
BlockType = (byte)blockType;
IndexValue = indexValue;
WriteCount++;
ReadCount++;
if (IsDisposed)
{
throw new ObjectDisposedException(GetType().FullName);
}
if (m_diskIo.IsDisposed)
{
throw new ObjectDisposedException(typeof(DiskIo).FullName);
}
if (m_isReadOnly)
{
throw new ReadOnlyException("The subfile used for this io session is read only.");
}
if ((blockIndex > 10 && blockIndex <= m_lastReadonlyBlock))
{
throw new ArgumentOutOfRangeException("blockIndex", "Cannot write to committed blocks");
}
IsValid = true;
ReadBlock(true);
IoReadState readState = IsFooterCurrentSnapshotAndValid();
if (readState != IoReadState.Valid)
{
IsValid = false;
throw new Exception("Read Error: " + readState.ToString());
}
}
