<<>>
    <<RoundTripServer.mesa>>
        <<Copyright Ó 1992 by Xerox Corporation.  All rights reserved.>>
        <<Spreitze, March 25, 1992 12:47 pm PST>>

    DIRECTORY BasicTime, Commander, IO, NetworkStream, Process, SimpleFeedback;

    RoundTripServer: CEDAR PROGRAM
        IMPORTS BasicTime, Commander, IO, NetworkStream, Process, SimpleFeedback
        =

    BEGIN

    Time: TYPE ~ RECORD [s, us: INT];

    unixOrg: BasicTime.GMT ~ BasicTime.Pack[[year: 1970, month: January, day: 1, hour: 0, minute: 0, second: 0, zone: 0, dst: no]];

    soon: CARD ¬ 0;

    l: NetworkStream.Listener ¬ NIL;

    SetSoon: Commander.CommandProc ~ {
        in: IO.STREAM ~ IO.RIS[cmd.commandLine];
        soon ¬ in.GetCard[];
        RETURN [$Success, IO.PutFR1["soon = %g", [cardinal[soon]] ]]};

    Stopit: Commander.CommandProc ~ {
        IF l#NIL THEN {
            NetworkStream.DestroyListener[l !NetworkStream.Error => CONTINUE];
            l ¬ NIL;
            Process.PauseMsec[5000]};
        RETURN};

    Restart: Commander.CommandProc ~ {
        IF l#NIL THEN {
            NetworkStream.DestroyListener[l !NetworkStream.Error => CONTINUE];
            l ¬ NIL;
            Process.PauseMsec[5000]};
        IF MakeListener[]
            THEN RETURN [$Success, "Server re-made"]
            ELSE RETURN [$Failure, "Something went wrong"]};

    MakeListener: PROC RETURNS [success: BOOL ¬ TRUE] ~ {
        l ¬ NetworkStream.CreateListener[
            protocolFamily: $ARPA,
            local: ":58801",
            transportClass: $basicStream,
            listenerWorkerProc: Work
            !NetworkStream.Error => {
                SimpleFeedback.PutFL[$RoundTripServer, oneLiner, $Error, "NetworkStream.Error[LIST[%g, ..], %g] creating RoundTripServer 
                listener.", LIST[[atom[codes.first]], [rope[msg]] ]];
                success ¬ FALSE;
                CONTINUE}
            ];
        RETURN};

    Work: PROC [listener: NetworkStream.Listener, in, out: IO.STREAM] ~ {
        start, mid: Time;
        GetNow: PROC RETURNS [Time] ~ {
            egmt: BasicTime.ExtendedGMT ~ BasicTime.ExtendedNow[];
            RETURN [[BasicTime.Period[from: unixOrg, to: egmt.gmt], egmt.usecs]]};
        GetTime: PROC RETURNS [Time] ~ {
            s: CARD ~ GetCard[];
            us: CARD ~ GetCard[];
            RETURN [[s, us]]};
        GetCard: PROC RETURNS [CARD] ~ {
            hi: CARDINAL ~ GetShort[]; RETURN [hi*10000H + GetShort[]]};
        GetShort: PROC RETURNS [CARDINAL] ~ {
            hi: BYTE ~ in.GetChar[].ORD;
            RETURN [hi*100H + in.GetChar[].ORD]};
        PutCard: PROC [c: CARD] ~ {PutShort[c/10000H]; PutShort[c MOD 10000H]};
        PutShort: PROC [c: CARDINAL] ~ {
            out.PutChar[VAL[c/100H]];
            out.PutChar[VAL[c MOD 100H]]};
        DO ENABLE IO.Error, IO.EndOfStream => EXIT;
            start ¬ GetTime[];
            mid ¬ GetNow[];
            PutCard[start.s];
            PutCard[start.us];
            PutCard[mid.s];
            PutCard[mid.us];
            NetworkStream.SendSoon[out, soon];
            ENDLOOP;
        in.Close[!IO.Error => CONTINUE];
        out.Close[!IO.Error => CONTINUE];
        RETURN};

    Start: PROC ~ {
        [] ¬ MakeListener[];
        Commander.Register["RoundTripSetSoon", SetSoon, "<milliseconds>"];
        Commander.Register["RoundTripStop", Stopit, "kills server"];
        Commander.Register["RoundTripRestart", Restart, "(re-)creates server"];
        };

    Start[];

    END.