/// <summary>
/// Tests if the <paramref name="dataBlockPointer"/> matches the specified search criteria.
/// </summary>
/// <param name="dataBlockPointer"><see cref="ArchiveDataBlockPointer"/> to test.</param>
/// <param name="historianID">Desired historian ID.</param>
/// <param name="startTime">Desired start time.</param>
/// <param name="endTime">Desired end time.</param>
/// <returns><c>true</c> if the specified <paramref name="dataBlockPointer"/> is for <paramref name="historianID"/> and falls within the <paramref name="startTime"/> and <paramref name="endTime"/>; otherwise <c>false</c>.</returns>
public static bool Matches(this ArchiveDataBlockPointer dataBlockPointer, int historianID, TimeTag startTime, TimeTag endTime)
{
// Note: The StartTime value of the pointer is ignored if m_searchStartTime = TimeTag.MinValue and
// m_searchEndTime = TimeTag.MaxValue. In this case only the PointID value is compared. This
// comes in handy when the first or last pointer is to be found from the list of pointers for
// a point ID in addition to all the pointers for a point ID.
if ((object)dataBlockPointer != null)
{
return(dataBlockPointer.HistorianID == historianID &&
(startTime.CompareTo(TimeTag.MinValue) == 0 || dataBlockPointer.StartTime.CompareTo(startTime) >= 0) &&
(endTime.CompareTo(TimeTag.MaxValue) == 0 || dataBlockPointer.StartTime.CompareTo(endTime) <= 0));
}
return(false);
}
/// <summary>
/// Returns all <see cref="ArchiveDataBlock"/>s in the <see cref="ArchiveFile"/> for the specified <paramref name="historianID"/> with <see cref="ArchiveDataPoint"/>s between the specified <paramref name="startTime"/> and <paramref name="endTime"/>.
/// </summary>
/// <param name="historianID">Historian identifier.</param>
/// <param name="startTime">Start <see cref="TimeTag"/>.</param>
/// <param name="endTime">End <see cref="TimeTag"/>.</param>
/// <param name="preRead">true to pre-read data to locate write cursor.</param>
/// <returns>A collection of <see cref="ArchiveDataBlock"/>s.</returns>
public List <ArchiveDataBlock> FindDataBlocks(int historianID, TimeTag startTime, TimeTag endTime, bool preRead = true)
{
if ((object)startTime == null)
{
startTime = TimeTag.MaxValue;
}
if ((object)endTime == null)
{
endTime = TimeTag.MaxValue;
}
List <ArchiveDataBlockPointer> blockPointers;
lock (m_dataBlockPointers)
{
// Get all block pointers for given point ID over specified time range
blockPointers = m_dataBlockPointers.FindAll(dataBlockPointer => dataBlockPointer.Matches(historianID, startTime, endTime));
// Look for pointer to data block on the borders of the specified range which may contain data
if (!(startTime == TimeTag.MinValue || endTime == TimeTag.MaxValue))
{
// There are 2 different search criteria for this:
// 1) If matching data block pointers have been found, then find data block pointer before the first matching data block pointer.
// or
// 2) Find the last data block pointer in the time range of TimeTag.MinValue to m_searchEndTime.
TimeTag searchEndTime = endTime;
if (blockPointers.Count > 0)
{
searchEndTime = new TimeTag(blockPointers.First().StartTime.Value - 1.0D);
}
ArchiveDataBlockPointer borderMatch = m_dataBlockPointers.LastOrDefault(dataBlockPointer => dataBlockPointer.Matches(historianID, TimeTag.MinValue, searchEndTime));
if ((object)borderMatch != null)
{
blockPointers.Insert(0, borderMatch);
}
}
}
// Return list of data blocks for given block pointers
return(blockPointers.Select(pointer => pointer.GetDataBlock(preRead)).ToList());
}
/// <summary>
/// Initializes <see cref="VariableTableRegion"/> by parsing the specified <paramref name="buffer"/> containing a binary image.
/// </summary>
/// <param name="buffer">Buffer containing binary image to parse.</param>
/// <param name="startIndex">0-based starting index in the <paramref name="buffer"/> to start parsing.</param>
/// <param name="length">Valid number of bytes within <paramref name="buffer"/> from <paramref name="startIndex"/>.</param>
/// <returns>The number of bytes used for initialization in the <paramref name="buffer"/> (i.e., the number of bytes parsed).</returns>
/// <exception cref="ArgumentNullException"><paramref name="buffer"/> is null.</exception>
/// <exception cref="ArgumentOutOfRangeException">
/// <paramref name="startIndex"/> or <paramref name="length"/> is less than 0 -or-
/// <paramref name="startIndex"/> and <paramref name="length"/> will exceed <paramref name="buffer"/> length.
/// </exception>
public int ParseBinaryImage(byte[] buffer, int startIndex, int length)
{
buffer.ValidateParameters(startIndex, length);
ArchiveDataBlockPointer blockPointer;
// Set parsing cursor beyond old-style visual basic array descriptor
int index = startIndex + ArrayDescriptorLength;
for (int i = 0; i < m_parent.m_dataBlockCount; i++)
{
blockPointer = new ArchiveDataBlockPointer(m_parent.m_parent, i);
index += blockPointer.ParseBinaryImage(buffer, index, length - (index - startIndex));
m_parent.m_dataBlockPointers.Add(blockPointer);
}
return(index - startIndex);
}
/// <summary>
/// Compares the current <see cref="ArchiveDataBlockPointer"/> object to <paramref name="obj"/>.
/// </summary>
/// <param name="obj">Object against which the current <see cref="ArchiveDataBlockPointer"/> object is to be compared.</param>
/// <returns>
/// Negative value if the current <see cref="ArchiveDataBlockPointer"/> object is less than <paramref name="obj"/>,
/// Zero if the current <see cref="ArchiveDataBlockPointer"/> object is equal to <paramref name="obj"/>,
/// Positive value if the current <see cref="ArchiveDataBlockPointer"/> object is greater than <paramref name="obj"/>.
/// </returns>
public virtual int CompareTo(object obj)
{
ArchiveDataBlockPointer other = obj as ArchiveDataBlockPointer;
if ((object)other == null)
{
return(1);
}
int result = m_historianID.CompareTo(other.HistorianID);
if (result != 0)
{
return(result);
}
return(m_startTime.CompareTo(other.StartTime));
}
/// <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>
/// Initializes <see cref="VariableTableRegion"/> by parsing the specified <paramref name="buffer"/> containing a binary image.
/// </summary>
/// <param name="buffer">Buffer containing binary image to parse.</param>
/// <param name="startIndex">0-based starting index in the <paramref name="buffer"/> to start parsing.</param>
/// <param name="length">Valid number of bytes within <paramref name="buffer"/> from <paramref name="startIndex"/>.</param>
/// <returns>The number of bytes used for initialization in the <paramref name="buffer"/> (i.e., the number of bytes parsed).</returns>
/// <exception cref="ArgumentNullException"><paramref name="buffer"/> is null.</exception>
/// <exception cref="ArgumentOutOfRangeException">
/// <paramref name="startIndex"/> or <paramref name="length"/> is less than 0 -or-
/// <paramref name="startIndex"/> and <paramref name="length"/> will exceed <paramref name="buffer"/> length.
/// </exception>
public int ParseBinaryImage(byte[] buffer, int startIndex, int length)
{
buffer.ValidateParameters(startIndex, length);
ArchiveDataBlockPointer blockPointer;
// Set parsing cursor beyond old-style visual basic array descriptor
int index = startIndex + ArrayDescriptorLength;
for (int i = 0; i < m_parent.m_dataBlockCount; i++)
{
blockPointer = new ArchiveDataBlockPointer(m_parent.m_parent, i);
index += blockPointer.ParseBinaryImage(buffer, index, length - (index - startIndex));
m_parent.m_dataBlockPointers.Add(blockPointer);
}
return (index - startIndex);
}
