FileRegion.Offset Property
Definition
Important
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Gets the offset into the file where the data begins.
public:
property long Offset { long get(); };
public long Offset { get; }
member this.Offset : int64
Public ReadOnly Property Offset As Long
Property Value
The offset into the file where the data begins.
Examples
The following example demonstrates how to archive a log store to XML using the LogStore and FileRegion classes.
class LogBackup
{
static void ArchiveToXML(LogStore logStore, string fileName)
{
LogArchiveSnapshot snapshot = logStore.CreateLogArchiveSnapshot();
{
XmlTextWriter writer = new XmlTextWriter(fileName, System.Text.Encoding.ASCII);
writer.WriteStartElement("logArchive");
foreach (FileRegion region in snapshot.ArchiveRegions)
{
writer.WriteStartElement("fileRegion");
writer.WriteElementString("path",
region.Path);
writer.WriteElementString("length",
region.FileLength.ToString());
writer.WriteElementString("offset",
region.Offset.ToString());
using (Stream dataStream = region.GetStream())
{
byte[] data = new byte[dataStream.Length];
dataStream.Read(data, 0, data.Length);
writer.WriteElementString("data", System.Convert.ToBase64String(data));
}
writer.WriteEndElement();
}
writer.Close();
logStore.SetArchiveTail(snapshot.LastSequenceNumber);
}
}
static void RestoreFromXML(string fileName)
{
using (XmlTextReader reader = new XmlTextReader(fileName))
{
reader.ReadStartElement("logArchive");
while (reader.IsStartElement())
{
string path;
long length;
long offset;
path = reader.ReadElementString("path");
length = System.Int64.Parse(reader.ReadElementString("length"));
offset = System.Int64.Parse(reader.ReadElementString("offset"));
string dataString = reader.ReadElementString("data");
byte[] data = System.Convert.FromBase64String(dataString);
FileStream fileStream;
using (fileStream = new FileStream(path,
FileMode.OpenOrCreate,
FileAccess.Write))
{
fileStream.SetLength(length);
fileStream.Position = offset;
fileStream.Write(data, 0, data.Length);
}
}
reader.ReadEndElement();
}
}
}
Friend Class LogBackup
Private Shared Sub ArchiveToXML(ByVal logStore As LogStore, ByVal fileName As String)
Dim snapshot As LogArchiveSnapshot = logStore.CreateLogArchiveSnapshot()
Dim writer As New XmlTextWriter(fileName, System.Text.Encoding.ASCII)
writer.WriteStartElement("logArchive")
For Each region As FileRegion In snapshot.ArchiveRegions
With writer
.WriteStartElement("fileRegion")
.WriteElementString("path", region.Path)
.WriteElementString("length", region.FileLength.ToString())
.WriteElementString("offset", region.Offset.ToString())
End With
Using dataStream As Stream = region.GetStream()
Dim data(dataStream.Length - 1) As Byte
dataStream.Read(data, 0, data.Length)
writer.WriteElementString("data", System.Convert.ToBase64String(data))
End Using
writer.WriteEndElement()
Next region
writer.Close()
logStore.SetArchiveTail(snapshot.LastSequenceNumber)
End Sub
Private Shared Sub RestoreFromXML(ByVal fileName As String)
Using reader As New XmlTextReader(fileName)
reader.ReadStartElement("logArchive")
Do While reader.IsStartElement()
Dim path As String
Dim length As Long
Dim offset As Long
path = reader.ReadElementString("path")
length = System.Int64.Parse(reader.ReadElementString("length"))
offset = System.Int64.Parse(reader.ReadElementString("offset"))
Dim dataString = reader.ReadElementString("data")
Dim data() = System.Convert.FromBase64String(dataString)
Dim fileStream As FileStream
fileStream = New FileStream(path, FileMode.OpenOrCreate, FileAccess.Write)
Using fileStream
fileStream.SetLength(length)
fileStream.Position = offset
fileStream.Write(data, 0, data.Length)
End Using
Loop
reader.ReadEndElement()
End Using
End Sub
End Class
Applies to
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