/// <summary>
/// Extends the <see cref="ArchiveFile"/> by the specified number of <see cref="ArchiveDataBlock"/>s.
/// </summary>
/// <param name="dataBlocksToAdd">Number of <see cref="ArchiveDataBlock"/>s to add to the <see cref="ArchiveFile"/>.</param>
public void Extend(int dataBlocksToAdd)
{
// Extend the FAT.
lock (m_dataBlockPointers)
{
for (int i = 1; i <= dataBlocksToAdd; i++)
{
m_dataBlockPointers.Add(new ArchiveDataBlockPointer(m_parent, m_dataBlockPointers.Count));
}
m_dataBlockCount = m_dataBlockPointers.Count;
}
Save();
// Initialize newly added data blocks.
ArchiveDataBlock dataBlock;
for (int i = m_dataBlockCount - dataBlocksToAdd; i < m_dataBlockCount; i++)
{
dataBlock = new ArchiveDataBlock(m_parent, i, -1);
dataBlock.Reset();
}
}
/// <summary>
/// Returns an <see cref="ArchiveDataBlock"/> for writing <see cref="ArchiveDataPoint"/>s for the specified <paramref name="historianID"/>.
/// </summary>
/// <param name="historianID">Historian identifier for which the <see cref="ArchiveDataBlock"/> is being requested.</param>
/// <param name="dataTime"><see cref="TimeTag"/> of the <see cref="ArchiveDataPoint"/> to be written to the <see cref="ArchiveDataBlock"/>.</param>
/// <param name="blockIndex"><see cref="ArchiveDataBlock.Index"/> of the <see cref="ArchiveDataBlock"/> last used for writing <see cref="ArchiveDataPoint"/>s for the <paramref name="historianID"/>.</param>
/// <returns><see cref="ArchiveDataBlock"/> object if available; otherwise null if all <see cref="ArchiveDataBlock"/>s have been allocated.</returns>
internal ArchiveDataBlock RequestDataBlock(int historianID, TimeTag dataTime, int blockIndex)
{
ArchiveDataBlock dataBlock = null;
ArchiveDataBlockPointer dataBlockPointer = null;
if (blockIndex >= 0 && blockIndex < m_dataBlockCount)
{
// Valid data block index is specified, so retrieve the corresponding data block.
lock (m_dataBlockPointers)
{
dataBlockPointer = m_dataBlockPointers[blockIndex];
}
dataBlock = dataBlockPointer.DataBlock;
if (!dataBlockPointer.IsAllocated && dataBlock.SlotsUsed > 0)
{
// Clear existing data from the data block since it is unallocated.
dataBlock.Reset();
}
else if (dataBlockPointer.IsAllocated && (dataBlockPointer.HistorianID != historianID || (dataBlockPointer.HistorianID == historianID && dataBlock.SlotsAvailable == 0)))
{
// Search for a new data block since the suggested data block cannot be used.
blockIndex = -1;
}
}
if (blockIndex < 0)
{
// Negative data block index is specified indicating a search must be performed for a data block.
dataBlock = FindLastDataBlock(historianID);
if ((object)dataBlock != null && dataBlock.SlotsAvailable == 0)
{
// Previously used data block is full.
dataBlock = null;
}
if ((object)dataBlock == null)
{
// Look for the first unallocated data block.
dataBlock = FindDataBlock(-1);
if ((object)dataBlock == null)
{
// Extend the file for historic writes only.
if (m_parent.FileType == ArchiveFileType.Historic)
{
Extend();
dataBlock = m_dataBlockPointers[m_dataBlockPointers.Count - 1].DataBlock;
}
}
else
{
// Reset the unallocated data block if there is data in it.
if (dataBlock.SlotsUsed > 0)
{
dataBlock.Reset();
}
}
}
// Get the pointer to the data block so that its information can be updated if necessary.
if ((object)dataBlock == null)
{
dataBlockPointer = null;
}
else
{
lock (m_dataBlockPointers)
{
dataBlockPointer = m_dataBlockPointers[dataBlock.Index];
}
}
}
if ((object)dataBlockPointer != null && !dataBlockPointer.IsAllocated)
{
// Mark the data block as allocated.
dataBlockPointer.HistorianID = historianID;
dataBlockPointer.StartTime = dataTime;
// Set the file start time if not set.
if (m_fileStartTime == TimeTag.MinValue)
{
m_fileStartTime = dataTime;
}
// Persist data block information to disk.
lock (m_parent.FileData)
{
// We'll write information about the just allocated data block to the file.
m_parent.FileData.Seek(DataLength + ArrayDescriptorLength + (dataBlockPointer.Index * ArchiveDataBlockPointer.FixedLength), SeekOrigin.Begin);
dataBlockPointer.CopyBinaryImageToStream(m_parent.FileData);
// We'll also write the fixed part of the FAT data that resides at the end.
m_parent.FileData.Seek(-m_fixedTableRegion.BinaryLength, SeekOrigin.End);
// Copy generated binary image to stream
m_fixedTableRegion.CopyBinaryImageToStream(m_parent.FileData);
if (!m_parent.CacheWrites)
{
m_parent.FileData.Flush();
}
}
// Re-fetch the data block with updated information after allocation.
dataBlock = dataBlockPointer.DataBlock;
}
return(dataBlock);
}
/// <summary>
/// Extends the <see cref="ArchiveFile"/> by the specified number of <see cref="ArchiveDataBlock"/>s.
/// </summary>
/// <param name="dataBlocksToAdd">Number of <see cref="ArchiveDataBlock"/>s to add to the <see cref="ArchiveFile"/>.</param>
public void Extend(int dataBlocksToAdd)
{
// Extend the FAT.
lock (m_dataBlockPointers)
{
for (int i = 1; i <= dataBlocksToAdd; i++)
{
m_dataBlockPointers.Add(new ArchiveDataBlockPointer(m_parent, m_dataBlockPointers.Count));
}
m_dataBlockCount = m_dataBlockPointers.Count;
}
Save();
// Initialize newly added data blocks.
ArchiveDataBlock dataBlock;
for (int i = m_dataBlockCount - dataBlocksToAdd; i < m_dataBlockCount; i++)
{
dataBlock = new ArchiveDataBlock(m_parent, i, -1);
dataBlock.Reset();
}
}
