private static ArchiveFile OpenArchiveFile(string fileName)
{
Console.WriteLine("Inside OpenArchiveFile function..");
string m_archiveLocation = FilePath.GetDirectoryName(fileName);
//string m_archiveLocation = "C:\\Program Files\\openPDC\\Archive\\";
Console.WriteLine("This is the m_archiveLocation: {0}", m_archiveLocation);
string instance = fileName.Substring(0, fileName.LastIndexOf('_'));
ArchiveFile file = new ArchiveFile();
file.FileName = fileName;
file.FileAccessMode = FileAccess.Read;
file.StateFile = new StateFile();
file.StateFile.FileAccessMode = FileAccess.Read;
file.StateFile.FileName = string.Format("{0}_startup.dat", instance);
file.IntercomFile = new IntercomFile();
file.IntercomFile.FileAccessMode = FileAccess.Read;
file.IntercomFile.FileName = string.Format("{0}scratch.dat", m_archiveLocation);
file.MetadataFile = new MetadataFile();
file.MetadataFile.FileAccessMode = FileAccess.Read;
file.MetadataFile.FileName = string.Format("{0}_dbase.dat", instance);
file.MetadataFile.LoadOnOpen = true;
Console.WriteLine("OpenArchiveFile has finished");
file.Open();
return file;
}
/// <summary>
/// Initializes a new instance of the <see cref="ArchiveDataBlock"/> class.
/// </summary>
/// <param name="parent">An <see cref="ArchiveFile"/> object.</param>
/// <param name="index">0-based index of the <see cref="ArchiveDataBlock"/>.</param>
/// <param name="historianID">Historian identifier whose <see cref="ArchiveData"/> is stored in the <see cref="ArchiveDataBlock"/>.</param>
/// <param name="reset">true if the <see cref="ArchiveDataBlock"/> is to be <see cref="Reset()"/>; otherwise false.</param>
internal ArchiveDataBlock(ArchiveFile parent, int index, int historianID, bool reset)
{
m_parent = parent;
m_index = index;
m_historianID = historianID;
m_writeCursor = Location;
m_lastActivityTime = DateTime.Now;
if (reset)
Reset(); // Clear existing data.
else
foreach (ArchiveData dataPoint in Read()) { } // Read existing data.
}
private TimeTag m_searchEndTime; // <=|
#endregion
#region [ Constructors ]
/// <summary>
/// Initializes a new instance of the <see cref="ArchiveFileAllocationTable"/> class.
/// </summary>
/// <param name="parent">An <see cref="ArchiveFile"/> object.</param>
internal ArchiveFileAllocationTable(ArchiveFile parent)
{
m_parent = parent;
m_dataBlockPointers = new List<ArchiveDataBlockPointer>();
if (m_parent.FileData.Length == 0)
{
// File is brand new.
m_fileStartTime = TimeTag.MinValue;
m_fileEndTime = TimeTag.MinValue;
m_dataBlockSize = m_parent.DataBlockSize;
m_dataBlockCount = ArchiveFile.MaximumDataBlocks(m_parent.FileSize, m_parent.DataBlockSize);
for (int i = 0; i < m_dataBlockCount; i++)
{
m_dataBlockPointers.Add(new ArchiveDataBlockPointer(m_parent, i));
}
}
else
{
// File was created previously.
byte[] fixedFatData = new byte[FixedBinaryLength];
m_parent.FileData.Seek(-fixedFatData.Length, SeekOrigin.End);
m_parent.FileData.Read(fixedFatData, 0, fixedFatData.Length);
FileStartTime = new TimeTag(EndianOrder.LittleEndian.ToDouble(fixedFatData, 0));
FileEndTime = new TimeTag(EndianOrder.LittleEndian.ToDouble(fixedFatData, 8));
DataPointsReceived = EndianOrder.LittleEndian.ToInt32(fixedFatData, 16);
DataPointsArchived = EndianOrder.LittleEndian.ToInt32(fixedFatData, 20);
DataBlockSize = EndianOrder.LittleEndian.ToInt32(fixedFatData, 24);
DataBlockCount = EndianOrder.LittleEndian.ToInt32(fixedFatData, 28);
byte[] variableFatData = new byte[m_dataBlockCount * ArchiveDataBlockPointer.ByteCount];
m_parent.FileData.Seek(-(variableFatData.Length + FixedBinaryLength), SeekOrigin.End);
m_parent.FileData.Read(variableFatData, 0, variableFatData.Length);
for (int i = 0; i < m_dataBlockCount; i++)
{
m_dataBlockPointers.Add(new ArchiveDataBlockPointer(m_parent, i, variableFatData, i * ArchiveDataBlockPointer.ByteCount, variableFatData.Length));
}
}
}
private void WriteToHistoricArchiveFile(ArchiveData[] items)
{
if (m_buildHistoricFileListThread.IsAlive)
// Wait until the historic file list has been built.
m_buildHistoricFileListThread.Join();
OnHistoricDataWriteStart();
Dictionary<int, List<ArchiveData>> sortedPointData = new Dictionary<int, List<ArchiveData>>();
// First we'll seperate all point data by ID.
for (int i = 0; i < items.Length; i++)
{
if (!sortedPointData.ContainsKey(items[i].HistorianID))
{
sortedPointData.Add(items[i].HistorianID, new List<ArchiveData>());
}
sortedPointData[items[i].HistorianID].Add(items[i]);
}
ProcessProgress<int> historicWriteProgress = new ProcessProgress<int>("HistoricWrite");
historicWriteProgress.Total = items.Length;
foreach (int pointID in sortedPointData.Keys)
{
// We'll sort the point data for the current point ID by time.
sortedPointData[pointID].Sort();
ArchiveFile historicFile = null;
ArchiveDataBlock historicFileBlock = null;
try
{
for (int i = 0; i < sortedPointData[pointID].Count; i++)
{
if (historicFile == null)
{
// We'll try to find a historic file when the current point data belongs.
Info historicFileInfo;
m_writeSearchTimeTag = sortedPointData[pointID][i].Time;
lock (m_historicArchiveFiles)
{
historicFileInfo = m_historicArchiveFiles.Find(FindHistoricArchiveFileForWrite);
}
if (historicFileInfo != null)
{
// Found a historic file where the data can be written.
historicFile = new ArchiveFile();
historicFile.FileName = historicFileInfo.FileName;
historicFile.StateFile = m_stateFile;
historicFile.IntercomFile = m_intercomFile;
historicFile.MetadataFile = m_metadataFile;
historicFile.Open();
}
}
if (historicFile != null)
{
if (sortedPointData[pointID][i].Time.CompareTo(historicFile.Fat.FileStartTime) >= 0 && sortedPointData[pointID][i].Time.CompareTo(historicFile.Fat.FileEndTime) <= 0)
{
// The current point data belongs to the current historic archive file.
if (historicFileBlock == null || historicFileBlock.SlotsAvailable == 0)
{
// Request a new or previously used data block for point data.
historicFileBlock = historicFile.Fat.RequestDataBlock(pointID, sortedPointData[pointID][i].Time, -1);
}
historicFileBlock.Write(sortedPointData[pointID][i]);
historicFile.Fat.DataPointsReceived++;
historicFile.Fat.DataPointsArchived++;
if (i == sortedPointData[pointID].Count() - 1)
{
// Last piece of data for the point, so we close the currently open file.
historicFile.Save();
historicFile.Dispose();
historicFile = null;
historicFileBlock = null;
}
historicWriteProgress.Complete++;
}
else
{
// The current point data doesn't belong to the current historic archive file, so we have
// to write all the point data we have so far for the current historic archive file to it.
i--;
historicFile.Dispose();
historicFile = null;
historicFileBlock = null;
}
}
}
// Notify of progress per point.
historicWriteProgress.ProgressMessage = string.Format("Wrote historic data for point id {0} ({1} of {2}).", pointID, "{0}", "{1}");
OnHistoricDataWriteProgress(historicWriteProgress);
}
catch (Exception ex)
{
// Free-up used memory.
if (historicFile != null)
{
try
{
historicFile.Dispose();
historicFile = null;
}
catch
{
}
}
// Notify of the exception.
OnHistoricDataWriteException(ex);
}
}
OnHistoricDataWriteComplete();
}
private Info GetHistoricFileInfo(string fileName)
{
Info fileInfo = null;
try
{
if (File.Exists(fileName))
{
// We'll open the file and get relevant information about it.
ArchiveFile historicArchiveFile = new ArchiveFile();
historicArchiveFile.FileName = fileName;
historicArchiveFile.StateFile = m_stateFile;
historicArchiveFile.IntercomFile = m_intercomFile;
historicArchiveFile.MetadataFile = m_metadataFile;
try
{
historicArchiveFile.Open();
fileInfo = new Info();
fileInfo.FileName = fileName;
fileInfo.StartTimeTag = historicArchiveFile.Fat.FileStartTime;
fileInfo.EndTimeTag = historicArchiveFile.Fat.FileEndTime;
}
catch (Exception)
{
}
finally
{
historicArchiveFile.Dispose();
historicArchiveFile = null;
}
}
else
{
// We'll resolve to getting the file information from its name only if the file no longer exists
// at the location. This will be the case when file is moved to a different location. In this
// case the file information we provide is only as good as the file name.
string datesString = FilePath.GetFileNameWithoutExtension(fileName).Substring((FilePath.GetFileNameWithoutExtension(m_fileName) + "_").Length);
string[] fileStartEndDates = datesString.Split(new string[] { "_to_" }, StringSplitOptions.None);
fileInfo = new Info();
fileInfo.FileName = fileName;
if (fileStartEndDates.Length == 2)
{
fileInfo.StartTimeTag = new TimeTag(Convert.ToDateTime(fileStartEndDates[0].Replace('!', ':')));
fileInfo.EndTimeTag = new TimeTag(Convert.ToDateTime(fileStartEndDates[1].Replace('!', ':')));
}
}
}
catch (Exception)
{
}
return fileInfo;
}
private void PrepareForRollover()
{
try
{
DriveInfo archiveDrive = new DriveInfo(Path.GetPathRoot(m_fileName));
if (archiveDrive.AvailableFreeSpace < archiveDrive.TotalSize * (1 - ((double)m_fileOffloadThreshold / 100)))
{
// We'll start offloading historic files if we've reached the offload threshold.
OffloadHistoricFiles();
}
OnRolloverPreparationStart();
// Opening and closing a new archive file in "standby" mode will create a "standby" archive file.
ArchiveFile standbyArchiveFile = new ArchiveFile();
standbyArchiveFile.FileName = StandbyArchiveFileName;
standbyArchiveFile.FileSize = m_fileSize;
standbyArchiveFile.DataBlockSize = m_dataBlockSize;
standbyArchiveFile.StateFile = m_stateFile;
standbyArchiveFile.IntercomFile = m_intercomFile;
standbyArchiveFile.MetadataFile = m_metadataFile;
try
{
standbyArchiveFile.Open();
}
catch (Exception)
{
string standbyFileName = standbyArchiveFile.FileName;
standbyArchiveFile.Close();
// We didn't succeed in creating a "standby" archive file, so we'll delete it if it was created
// partially (might happen if there isn't enough disk space or thread is aborted). This is to
// ensure that this preparation processes is kicked off again until a valid "standby" archive
// file is successfully created.
if (File.Exists(standbyFileName))
{
File.Delete(standbyFileName);
}
throw; // Rethrow the exception so the appropriate action is taken.
}
finally
{
standbyArchiveFile.Dispose();
}
OnRolloverPreparationComplete();
}
catch (ThreadAbortException)
{
// This thread must die now...
}
catch (Exception ex)
{
OnRolloverPreparationException(ex);
}
}
/// <summary>
/// Reads <see cref="ArchiveData"/> points.
/// </summary>
/// <param name="historianID">Historian identifier for which <see cref="ArchiveData"/> points are to be retrieved.</param>
/// <param name="startTime">Start <see cref="TimeTag"/> (in GMT) for the <see cref="ArchiveData"/> points to be retrieved.</param>
/// <param name="endTime">End <see cref="TimeTag"/> (in GMT) for the <see cref="ArchiveData"/> points to be retrieved.</param>
/// <returns><see cref="IEnumerable{T}"/> object containing zero or more <see cref="ArchiveData"/> points.</returns>
public IEnumerable<IDataPoint> ReadData(int historianID, TimeTag startTime, TimeTag endTime)
{
// Ensure that the current file is open.
if (!IsOpen)
throw new InvalidOperationException(string.Format("\"{0}\" file is not open.", m_fileName));
// Ensure that the current file is active.
if (m_fileType != ArchiveFileType.Active)
throw new InvalidOperationException("Data can only be directly read from files that are Active.");
// Ensure that the start and end time are valid.
if (startTime > endTime)
throw new ArgumentException("End Time preceeds Start Time in the specified timespan.");
// Yeild to the rollover process if it is in progress.
m_rolloverWaitHandle.WaitOne();
List<Info> dataFiles = new List<Info>();
if (startTime < m_fat.FileStartTime)
{
// Data is to be read from historic file(s).
if (m_buildHistoricFileListThread.IsAlive)
m_buildHistoricFileListThread.Join();
m_readSearchStartTimeTag = startTime;
m_readSearchEndTimeTag = endTime;
lock (m_historicArchiveFiles)
{
dataFiles.AddRange(m_historicArchiveFiles.FindAll(FindHistoricArchiveFileForRead));
}
}
if (endTime >= m_fat.FileStartTime)
{
// Data is to be read from the active file.
Info activeFileInfo = new Info();
activeFileInfo.FileName = m_fileName;
activeFileInfo.StartTimeTag = m_fat.FileStartTime;
activeFileInfo.EndTimeTag = m_fat.FileEndTime;
dataFiles.Add(activeFileInfo);
}
// Read data from all qualifying files.
foreach (Info dataFile in dataFiles)
{
ArchiveFile file = new ArchiveFile();
IList<ArchiveDataBlock> dataBlocks;
try
{
file.FileName = dataFile.FileName;
file.StateFile = m_stateFile;
file.IntercomFile = m_intercomFile;
file.MetadataFile = m_metadataFile;
file.Open();
dataBlocks = file.Fat.FindDataBlocks(historianID, startTime, endTime);
if (dataBlocks.Count > 0)
{
// Data block before the first data block matching the search criteria might contain some data
// for the specified search criteria, so look for such a data block and process its data.
lock (file.Fat.DataBlockPointers)
{
for (int i = dataBlocks[0].Index - 1; i >= 0; i--)
{
if (file.Fat.DataBlockPointers[i].HistorianID == historianID)
{
foreach (ArchiveData data in file.Fat.DataBlockPointers[i].DataBlock.Read())
{
if (data.Time >= startTime)
yield return data;
}
break;
}
}
}
// Read data from rest of the data blocks and scan the last data block for data matching the
// the search criteria as it may contain data beyond the timespan specified in the search.
for (int i = 0; i < dataBlocks.Count; i++)
{
if (i < dataBlocks.Count - 1)
{
// Read all the data.
foreach (ArchiveData data in dataBlocks[i].Read())
{
yield return data;
}
}
else
{
// Scan through the data block.
foreach (ArchiveData data in dataBlocks[i].Read())
{
if (data.Time <= endTime)
yield return data;
else
yield break;
}
}
}
}
}
finally
{
if (file.IsOpen)
{
file.Close();
}
}
}
}
/// <summary>
/// Initializes a new instance of the <see cref="ArchiveDataBlockPointer"/> class.
/// </summary>
/// <param name="parent">An <see cref="ArchiveFile"/> object.</param>
/// <param name="index">0-based index of the <see cref="ArchiveDataBlockPointer"/>.</param>
/// <param name="binaryImage">Binary image to be used for initializing <see cref="ArchiveDataBlockPointer"/>.</param>
/// <param name="startIndex">0-based starting index of initialization data in the <paramref name="binaryImage"/>.</param>
/// <param name="length">Valid number of bytes in <paramref name="binaryImage"/> from <paramref name="startIndex"/>.</param>
internal ArchiveDataBlockPointer(ArchiveFile parent, int index, byte[] binaryImage, int startIndex, int length)
: this(parent, index)
{
Initialize(binaryImage, startIndex, length);
}
/// <summary>
/// Initializes a new instance of the <see cref="ArchiveDataBlockPointer"/> class.
/// </summary>
/// <param name="parent">An <see cref="ArchiveFile"/> object.</param>
/// <param name="index">0-based index of the <see cref="ArchiveDataBlockPointer"/>.</param>
internal ArchiveDataBlockPointer(ArchiveFile parent, int index)
{
m_parent = parent;
m_index = index;
Reset();
}
/// <summary>
/// Initializes a new instance of the <see cref="ArchiveDataBlock"/> class.
/// </summary>
/// <param name="parent">An <see cref="ArchiveFile"/> object.</param>
/// <param name="index">0-based index of the <see cref="ArchiveDataBlock"/>.</param>
/// <param name="historianID">Historian identifier whose <see cref="ArchiveDataPoint"/> is stored in the <see cref="ArchiveDataBlock"/>.</param>
/// <param name="reset">true if the <see cref="ArchiveDataBlock"/> is to be <see cref="Reset()"/>; otherwise false.</param>
/// <param name="preRead">true to pre-read data to locate write cursor.</param>
internal ArchiveDataBlock(ArchiveFile parent, int index, int historianID, bool reset, bool preRead = true)
{
m_parent = parent;
m_index = index;
m_historianID = historianID;
m_readBuffer = new byte[ArchiveDataPoint.FixedLength];
m_writeCursor = Location;
m_lastActivityTime = DateTime.Now;
if (reset)
{
// Clear existing data.
Reset();
}
else if (preRead)
{
// Scan through existing data to locate write cursor
foreach (ArchiveDataPoint dataPoint in Read())
{
}
}
}
private void CloseArchiveFile()
{
if ((object)m_archiveFile != null)
{
m_archiveFile.DataReadException -= file_DataReadException;
m_archiveFile.HistoricFileListBuildComplete -= file_HistoricFileListBuildComplete;
m_archiveFile.HistoricFileListBuildException -= file_HistoricFileListBuildException;
m_archiveFile.HistoricFileListBuildStart -= file_HistoricFileListBuildStart;
m_archiveFile.HistoricFileListUpdated -= file_HistoricFileListUpdated;
m_archiveFile.RolloverComplete -= file_RolloverComplete;
m_archiveFile.RolloverStart -= file_RolloverStart;
m_archiveFile.Dispose();
}
m_archiveFile = null;
}
// Opens an archive file as read-only and returns the ArchiveFile object.
private ArchiveFile OpenArchiveFile(string fileName)
{
const string metadataFileName = "{0}{1}_dbase.dat";
const string stateFileName = "{0}{1}_startup.dat";
const string intercomFileName = "{0}scratch.dat";
string archiveLocation = FilePath.GetDirectoryName(fileName);
string archiveName = FilePath.GetFileName(fileName);
string instance = archiveName.Substring(0, archiveName.LastIndexOf('_'));
ArchiveFile file = new ArchiveFile
{
FileName = fileName,
FileAccessMode = FileAccess.Read,
MonitorNewArchiveFiles = true,
PersistSettings = false,
StateFile = new StateFile
{
FileAccessMode = FileAccess.Read,
FileName = string.Format(stateFileName, archiveLocation, instance)
},
IntercomFile = new IntercomFile
{
FileAccessMode = FileAccess.Read,
FileName = string.Format(intercomFileName, archiveLocation)
},
MetadataFile = new MetadataFile
{
FileAccessMode = FileAccess.Read,
FileName = string.Format(metadataFileName, archiveLocation, instance),
LoadOnOpen = true
}
};
file.DataReadException += file_DataReadException;
file.HistoricFileListBuildComplete += file_HistoricFileListBuildComplete;
file.HistoricFileListBuildException += file_HistoricFileListBuildException;
file.HistoricFileListBuildStart += file_HistoricFileListBuildStart;
file.HistoricFileListUpdated += file_HistoricFileListUpdated;
file.RolloverComplete += file_RolloverComplete;
file.RolloverStart += file_RolloverStart;
// Initialize the archive file (starts file watchers)
file.Initialize();
// Open the active archive file
file.Open();
// Start the roll-over watch timer
m_rolloverWatcher.Start();
return file;
}
/// <summary>
/// Opens the <see cref="ArchiveFile"/> for use.
/// </summary>
/// <param name="fileName">Archive .D archive file name.</param>
public void Open(string fileName)
{
CloseArchiveFile();
m_archiveFile = OpenArchiveFile(fileName);
}
private Info GetHistoricFileInfo(string fileName)
{
Info fileInfo = null;
try
{
if (File.Exists(fileName))
{
// We'll open the file and get relevant information about it.
ArchiveFile historicArchiveFile = new ArchiveFile();
historicArchiveFile.FileName = fileName;
historicArchiveFile.StateFile = m_stateFile;
historicArchiveFile.IntercomFile = m_intercomFile;
historicArchiveFile.MetadataFile = m_metadataFile;
historicArchiveFile.FileAccessMode = FileAccess.Read;
try
{
historicArchiveFile.Open();
fileInfo = new Info();
fileInfo.FileName = fileName;
fileInfo.StartTimeTag = historicArchiveFile.Fat.FileStartTime;
fileInfo.EndTimeTag = historicArchiveFile.Fat.FileEndTime;
}
catch (Exception ex)
{
OnHistoricFileListBuildException(new InvalidOperationException(string.Format("Failed to access historic data file \"{0}\" due to exception: {1}", FilePath.GetFileName(fileName), ex.Message), ex));
}
finally
{
historicArchiveFile.Dispose();
}
}
//else
//{
// // We'll resolve to getting the file information from its name only if the file no longer exists
// // at the location. This will be the case when file is moved to a different location. In this
// // case the file information we provide is only as good as the file name.
// string datesString = FilePath.GetFileNameWithoutExtension(fileName).Substring((FilePath.GetFileNameWithoutExtension(m_fileName) + "_").Length);
// string[] fileStartEndDates = datesString.Split(new string[] { "_to_" }, StringSplitOptions.None);
// fileInfo = new Info();
// fileInfo.FileName = fileName;
// if (fileStartEndDates.Length == 2)
// {
// fileInfo.StartTimeTag = new TimeTag(Convert.ToDateTime(fileStartEndDates[0].Replace('!', ':')));
// fileInfo.EndTimeTag = new TimeTag(Convert.ToDateTime(fileStartEndDates[1].Replace('!', ':')));
// }
//}
}
catch
{
}
return fileInfo;
}
// Read data implementation
private IEnumerable<IDataPoint> ReadData(IEnumerable<int> historianIDs, TimeTag startTime, TimeTag endTime, int lastHistorianID)
{
// Yield to archive rollover process.
m_rolloverWaitHandle.WaitOne();
// Ensure that the current file is open.
if (!IsOpen)
throw new InvalidOperationException(string.Format("\"{0}\" file is not open", m_fileName));
// Ensure that the current file is active.
if (m_fileType != ArchiveFileType.Active)
throw new InvalidOperationException("Data can only be directly read from files that are Active");
// Ensure that the start and end time are valid.
if (startTime.CompareTo(endTime) > 0)
throw new ArgumentException("End Time preceeds Start Time in the specified timespan");
List<Info> dataFiles = new List<Info>();
bool pendingRollover = false;
bool usingActiveFile = false;
if (startTime.CompareTo(m_fat.FileStartTime) < 0)
{
// Data is to be read from historic file(s) - make sure that the list has been built
if (m_buildHistoricFileListThread.IsAlive)
m_buildHistoricFileListThread.Join();
lock (m_historicArchiveFiles)
{
dataFiles.AddRange(m_historicArchiveFiles.FindAll(info => FindHistoricArchiveFileForRead(info, startTime, endTime)));
}
}
if (endTime.CompareTo(m_fat.FileStartTime) >= 0)
{
// Data is to be read from the active file.
Info activeFileInfo = new Info();
activeFileInfo.FileName = m_fileName;
activeFileInfo.StartTimeTag = m_fat.FileStartTime;
activeFileInfo.EndTimeTag = m_fat.FileEndTime;
dataFiles.Add(activeFileInfo);
}
// Read data from all qualifying files.
foreach (Info dataFile in dataFiles)
{
ArchiveFile file = null;
try
{
if (string.Compare(dataFile.FileName, m_fileName, true) == 0)
{
// Read data from current file.
usingActiveFile = true;
file = this;
// Atomically increment total number of readers for active file
Interlocked.Increment(ref m_activeFileReaders);
}
else
{
// Read data from historic file.
usingActiveFile = false;
file = new ArchiveFile();
file.FileName = dataFile.FileName;
file.StateFile = m_stateFile;
file.IntercomFile = m_intercomFile;
file.MetadataFile = m_metadataFile;
file.FileAccessMode = FileAccess.Read;
file.Open();
}
// Create new time sorted data point scanner for the desired points in this file and given time range
TimeSortedDataPointScanner scanner = new TimeSortedDataPointScanner(file.Fat, historianIDs, startTime, endTime, lastHistorianID, (sender, e) => OnDataReadException(e.Argument));
// Reset last historian ID to scan from beginning after picking up where left off from roll over
lastHistorianID = -1;
// Return data points
foreach (IDataPoint dataPoint in scanner.Read())
{
yield return dataPoint;
// If a rollover needs to happen, we need to relinquish read lock and close file
if (m_rolloverInProgress)
{
startTime = dataPoint.Time;
lastHistorianID = dataPoint.HistorianID;
pendingRollover = true;
break;
}
}
}
finally
{
if (usingActiveFile)
{
// Atomically decrement active file reader count to signal in-process code that read is complete or yielded
Interlocked.Decrement(ref m_activeFileReaders);
}
else if ((object)file != null && file.IsOpen)
{
file.Close();
}
}
if (pendingRollover)
break;
}
if (pendingRollover)
{
// Recurse into this function with an updated start time and last read point ID so that read can
// resume right where it left off - recursed function call will wait until rollover is complete
foreach (IDataPoint dataPoint in ReadData(historianIDs, startTime, endTime, lastHistorianID))
{
yield return dataPoint;
}
}
}
/// <summary>
/// Initializes a new instance of the <see cref="ArchiveFileAllocationTable"/> class.
/// </summary>
/// <param name="parent">An <see cref="ArchiveFile"/> object.</param>
internal ArchiveFileAllocationTable(ArchiveFile parent)
{
m_parent = parent;
m_dataBlockPointers = new List<ArchiveDataBlockPointer>();
m_fixedTableRegion = new FixedTableRegion(this);
m_variableTableRegion = new VariableTableRegion(this);
if (m_parent.FileData.Length == 0)
{
// File is brand new.
m_fileStartTime = TimeTag.MinValue;
m_fileEndTime = TimeTag.MinValue;
m_dataBlockSize = m_parent.DataBlockSize;
m_dataBlockCount = ArchiveFile.MaximumDataBlocks(m_parent.FileSize, m_parent.DataBlockSize);
for (int i = 0; i < m_dataBlockCount; i++)
{
m_dataBlockPointers.Add(new ArchiveDataBlockPointer(m_parent, i));
}
}
else
{
// Existing file, read table regions:
// Seek to beginning of fixed table region
m_parent.FileData.Seek(-m_fixedTableRegion.BinaryLength, SeekOrigin.End);
// Parse fixed table region
m_fixedTableRegion.ParseBinaryImageFromStream(m_parent.FileData);
// Seek to beginning of variable table region (above fixed from bottom of file)
m_parent.FileData.Seek(-(m_fixedTableRegion.BinaryLength + m_variableTableRegion.BinaryLength), SeekOrigin.End);
// Parse variable table region
m_variableTableRegion.ParseBinaryImageFromStream(m_parent.FileData);
}
}
