public virtual void Flush()

in src/log4net/Appender/BufferingAppenderSkeleton.cs [250:298]
39 lines of code
9 McCabe index (conditional complexity)

  public virtual void Flush(bool flushLossyBuffer)
  {
    // This method will be called outside the AppenderSkeleton DoAppend() method
    // therefore it needs to be protected by its own lock. This will block any
    // Appends while the buffer is flushed.
    lock (LockObj)
    {
      if (_cyclicBuffer is not null && _cyclicBuffer.Length > 0)
      {
        if (Lossy)
        {
          // If we are allowed to eagerly flush from the lossy buffer
          if (flushLossyBuffer)
          {
            if (LossyEvaluator is not null)
            {
              // Test the contents of the buffer against the lossy evaluator
              LoggingEvent[] bufferedEvents = _cyclicBuffer.PopAll();
              var filteredEvents = new List<LoggingEvent>(bufferedEvents.Length);

              foreach (LoggingEvent loggingEvent in bufferedEvents)
              {
                if (LossyEvaluator.IsTriggeringEvent(loggingEvent))
                {
                  filteredEvents.Add(loggingEvent);
                }
              }

              // Send the events that meet the lossy evaluator criteria
              if (filteredEvents.Count > 0)
              {
                SendBuffer(filteredEvents.ToArray());
              }
            }
            else
            {
              // No lossy evaluator, all buffered events are discarded
              _cyclicBuffer.Clear();
            }
          }
        }
        else
        {
          // Not lossy, send whole buffer
          SendFromBuffer(null, _cyclicBuffer);
        }
      }
    }
  }