public long TryAppend(byte[] buffer, TapeAppendCondition condition)
{
if (buffer == null)
{
throw new ArgumentNullException("buffer");
}
if (buffer.Length == 0)
{
throw new ArgumentException("Buffer must contain at least one byte.");
}
using (var file = OpenForWrite())
{
// we need to know version first.
file.Seek(0, SeekOrigin.End);
var version = TapeStreamSerializer.ReadVersionFromTheEnd(file);
if (!condition.Satisfy(version))
{
return(0);
}
var versionToWrite = version + 1;
TapeStreamSerializer.WriteRecord(file, buffer, versionToWrite);
return(versionToWrite);
}
}
public long GetCurrentVersion()
{
try
{
using (var s = OpenForRead())
{
// seek end
s.Seek(0, SeekOrigin.End);
return(TapeStreamSerializer.ReadVersionFromTheEnd(s));
}
}
catch (FileNotFoundException)
{
return(0);
}
catch (DirectoryNotFoundException)
{
return(0);
}
}