in core/src/main/scala/org/apache/pekko/persistence/cassandra/journal/TagWriter.scala [298:308]
private def flushIfRequired(buffer: Buffer, tagSequenceNrs: Map[String, Long]): Unit = {
if (buffer.isEmpty) {
context.become(idle(buffer, tagSequenceNrs))
} else if (buffer.shouldWrite() || settings.flushInterval == Duration.Zero) {
write(buffer, tagSequenceNrs, None)
} else {
if (!timers.isTimerActive(FlushKey))
timers.startSingleTimer(FlushKey, InternalFlush, settings.flushInterval)
context.become(idle(buffer, tagSequenceNrs))
}
}