ss-single-thread-loop.txt

    def getServer(criteria):

        startTime = loopEndTime = gettime()
        maxTime = startTime + serverSelectionTimeoutMS/1000

        if topology.lastUpdateTime - startTime > heartbeatFrequencyMS/1000:
            topology.stale = true

        while true:

            if topology.stale:
                scanReadyTime = topology.lastUpdateTime + minHeartbeatFrequencyMS/1000

                if ((not serverSelectionTryOnce) && (scanReadyTime > maxTime)):
                    throw server selection error with details

                sleepTime = scanReadyTime - loopEndTime

                if sleepTime > 0:
                    sleep sleepTime

                # rescan must update topology.lastUpdateTime
                rescan all servers

            if not topology.compatible:
                topology.stale = true
                throw invalid wire protocol range error with details

            servers = all servers in topology matching criteria

            if servers is not empty:
                in_window = servers within the latency window
                return random entry from in_window
            else:
                topology.stale = true

            loopEndTime = gettime();

            if serverSelectionTryOnce:
                if topology.lastUpdateTime > startTime:
                    throw server selection error with details
            else if loopEndTime > maxTime:
                throw server selection error with details