/// <summary>
/// Writes the buffer to SQL and empties it.
/// </summary>
private void WriteData()
{
lock (this)
{
// This and the lock are to circumvent a small multithreading dillema
if (this.Available)
{
Trace.WriteLine(String.Format(CultureInfo.InvariantCulture,
"BufferRecorder::WriteData called when Available at time {0}. Returning.",
DateTime.Now.Ticks));
return;
}
// Going to try a spin-wait just to see if we can resolve this multithreading problem
while (this.writing)
{
Thread.Sleep(10);
}
writing = true;
bool overflowed;
do
{
overflowed = false;
try
{
// Don't try to write an empty buffer
if (currentIndex > 0)
{
#if TIMING
long startTimer = DateTime.Now.Ticks;
#endif
// Try to detect and fix overflow before it happens to avoid the exception and hopefully improve performance.
if (DBHelper.WouldOverflowStream(this.streamID, this.indices[this.currentIndex - 1].end))
{
this.Overflowed(this, EventArgs.Empty);
}
// TODO: Find out why this gets called twice on one data set OR find a workaround.
Trace.WriteLine(String.Format(CultureInfo.InvariantCulture,
"BufferRecorder::WriteData doing SBAI on buffer {0}, stream {1} at {2}",
number, streamID, DateTime.Now.Ticks));
DBHelper.SaveBufferAndIndices(
this.streamID,
this.indices,
this.currentIndex,
buffer);
#if TIMING
long takenTime = DateTime.Now.Ticks - startTimer;
Trace.WriteLine(string.Format(CultureInfo.InvariantCulture, "TIMING: SBAI took {0} ms",
(takenTime / Constants.TicksPerMs)));
#endif
}
}
catch (SqlException ex)
{
// Catch the overflow case, where we have more data than the 'int' type holds
if (ex.Message.ToLower(CultureInfo.InvariantCulture).IndexOf("overflow") >= 0)
{
overflowed = true; // by setting this, we directly try to write the data again
this.Overflowed(this, EventArgs.Empty);
}
// Two exceptions are seen here:
// Timeouts in SQL due to taking a *really* bad performance beating
// OR Constraint violation in Frame table due to unusual multithreading problem not yet solved (mentioned above)
// Dont do anything, b/c failed DB ops are already event-logged. Just move on & hope that the stream is playable.
}
catch (InvalidOperationException ex)
{
// In the worst of performance cases, we run out of pooled connections and get this exception
eventLog.WriteEntry(string.Format(CultureInfo.CurrentCulture, Strings.DatabaseOperationFailedError,
ex.ToString()), EventLogEntryType.Error, ArchiveServiceEventLog.ID.DBOpFailed);
// Again, ignore & move on, dropping the frames.
}
} // In the specific case where we've overflowed, try again immediately (to hopefully preempt other buffers from going out-of-order)
while (overflowed);
writing = false;
isAvailable = true;
bufferIndex = 0;
currentIndex = 0;
Trace.WriteLine("BufferRecorder::WriteData completed.");
}
}
