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%TITLE 'DIU Request Scheduler'

MODULE DIUSCH (         IDENT = '252',
                        LANGUAGE(BLISS36),
                        ENTRY(Sched)
      		       ) =
BEGIN
!	COPYRIGHT (C) DIGITAL EQUIPMENT CORPORATION 1986.
!	ALL RIGHTS RESERVED.
!
!	THIS SOFTWARE IS FURNISHED UNDER A LICENSE AND MAY  BE  USED  AND
!	COPIED ONLY IN ACCORDANCE WITH THE TERMS OF SUCH LICENSE AND WITH
!	THE INCLUSION OF THE ABOVE COPYRIGHT NOTICE.   THIS  SOFTWARE  OR
!	ANY  OTHER  COPIES  THEREOF MAY NOT BE PROVIDED OR OTHERWISE MADE
!	AVAILABLE TO ANY OTHER PERSON.  NO TITLE TO AND OWNERSHIP OF  THE
!	SOFTWARE IS HEREBY TRANSFERRED.
!
!	THE INFORMATION IN THIS SOFTWARE IS  SUBJECT  TO  CHANGE  WITHOUT
!	NOTICE  AND  SHOULD  NOT  BE CONSTRUED AS A COMMITMENT BY DIGITAL
!	EQUIPMENT CORPORATION.
!
!	DIGITAL ASSUMES NO RESPONSIBILITY FOR THE USE OR  RELIABILITY  OF
!	ITS SOFTWARE ON EQUIPMENT THAT IS NOT SUPPLIED BY DIGITAL.
!
!++
! ABSTRACT:
!   This module contains the job scheduler for DIU-20.  It selects
!   jobs from the DIU queue for processing, and calls the create job
!   service to create a job to handle each request.  It can be called
!   at interrupt level, in response to timer requests, IPCF messages,
!   or network topology changes.
!
! ENVIRONMENT:
!   User mode, XPORT.
!
! VARIANTS:
!    /VARIANT (on TOPS-10) will compile code to support TOPS-10 V7.02
!
! CREATION DATE: 17-Jun-85
!
! AUTHOR: Andrew Nourse
!         Adapted from FTSSCH, which was written by Larry Campbell
! HISTORY:
!
!  252	Remove library of CONDIT.
!	Sandy Clemens  1-Jul-86
!
!  234  Change library of RMSUSR to RMSINT.
!       Gregory A. Scott 17-Jul-86
!
!  174  Remove library TOPS20.
!       Gregory A. Scott 20-May-86
!
!  167  Remove external for s$node_check since it is not used here.
!       Gregory A. Scott 19-May-86
!
!  154  Rename start_job to j$start and kill_job to j$kill.   We  were  calling
!       lj$event and lj$uevent when we meant l$event and l$uevent.  
!       Gregory A. Scott 12-May-86
!
!  152  The routine that tried to expire requests whose  deadlines  had  passed
!       did a rather incomplete job.  Same way with the  timeout routine.   So,
!       now we do it the same way that ipc_delete does.
!       Gregory A. Scott 11-May-86
!
!  126  Change module name to DIUSCH for  DDT and GLOB.  DO_SCHED is a  NOVALUE
!       routine, so why should  it return a value.   S$TIMINT always takes  the
!       channel from t_channel on  the -20, so now  it only takes one  argument
!       which is the time to wake up.
!       Gregory A. Scott 26-Apr-86
!
!      40 Put the REQUIRE/LIBRARY of 'TOPS20' into a TOPS-20 only
!         conditional.
!         Sandy Clemens  7-Oct-85
!
! 02 -    Change the interrupt code for TOPS-10 [Doug Rayner, 25-Jul-85]
! 01 -    Initial version of DIUSCH, extracted from FTSSCH
!--
!************************************************************************
!                        L I B R A R I E S                      
!************************************************************************

LIBRARY 'BLI:XPORT';                    ! XPORT of course
LIBRARY 'FAO';                          ! FAO services
LIBRARY 'RMSINT';                       ! RMS services
LIBRARY 'DIU';                          ! DIU Data Structures
!
! TABLE OF CONTENTS:
!
FORWARD ROUTINE
    sched : NOVALUE,                    ! Schedule a request
    do_sched : NOVALUE,                 ! The actual work routine
    expire : NOVALUE,                   ! Stomp on an expired request
    timeout : NOVALUE,                  ! Requeue a timed-out request
    abort_sched;                        ! Condition handler for scheduler

!
! EQUATED SYMBOLS:
!
LITERAL
    bignum =
        %BLISS16 (%O'177777')
        %BLISS32 (%X'FFFFFFFF')
        %BLISS36 (%O'377777777777');    ! Largest positive integer

LITERAL
    timeout_interval =
     %IF %SWITCHES (TOPS20)
     %THEN
        (5 * 60 / 3);                   ! 5 minute timeout
     %ELSE
	(%O'1000000' / (24 * 60)) * 5;	! Five minute timeout checks
     %FI

LITERAL
    short_sleep =
        (%O'1000000' / (24 * 60)) * 10; ![10] Ten minute sleep if PMR

LITERAL
    long_sleep = (%O'1000000' / (24 * 60)) * 20; ! Twenty minute sleep

!
! OWN STORAGE:
!

OWN
    ssleep : INITIAL (short_sleep),     ! [5] Make sleep intervals
    lsleep : INITIAL (long_sleep);      !   patchable

OWN TIMOUT : INITIAL(timeout_interval); ![7] 5 minute timeout **PATCHABLE**

OWN SCHTIM: INITIAL(0);                 ![7] Time of last scheduler pass

GLOBAL
    mjob : INITIAL (4),                 ! Max jobs running concurrently
    njob;                               ! Number of current jobs

OWN
    next_event_time;                    ! Earliest /AFTER to expire next

%IF %SWITCHES (TOPS10) %THEN
%IF %VARIANT ! TOPS-10 V7.02 support
%THEN
OWN
    query_pid : INITIAL(0);		! Pid to use to query SYSTEM[INFO]
%FI
%FI

!
! EXTERNAL REFERENCES:
!
EXTERNAL
    jobstatus : BLOCKVECTOR [DIU$K_MAX_MJOB, DIUJ$K_LEN]
                FIELD (DIUJ$$JOBSTAT_FIELDS),
    shutdown,                           ! Spooler shut down
    mst_flag : VOLATILE;                ! We are the master job

EXTERNAL ROUTINE
    s$strchk,                           ! Check to see if structure online
    q$find,                             ! Find a request in the queue
    q$delete,                           ! Delete a request
    q$reque,                            ! Requeue a request
    q$modify,                           ! Modify a request
    j$start : NOVALUE,                  ! Start a request
    j$kill,                             ! Kill an active job
    l$event : NOVALUE,                  ! Log an event to system log file
    l$uevent : NOVALUE,                 ! Log an event to user log file
    abort : NOVALUE,                    ! Abort dependents of dying request
    notify : NOVALUE,                   ! Notify owner of request disposition
    q$req_block_init : NOVALUE,         ! Init a request block
    q$release_chain : NOVALUE,          ! Release chain of request blocks
    diu$abort : NOVALUE,                ! Condition handler
    s$noint : NOVALUE,                  ! Disable interrupts
    s$okint : NOVALUE,                  ! Reenable interrupts
    s$time,                             ! Return current time of day
    s$jobtime,                          ! get runtime for job
    s$timint;                           ! Post timer interrupt

%IF %SWITCHES (TOPS10) %THEN
%IF %VARIANT ! TOPS-10 V7.02 support
%THEN
EXTERNAL ROUTINE
    ip$check_pid;			! Check to see if a PID is still valid
%FI
%FI
GLOBAL ROUTINE sched : NOVALUE =
!++
! FUNCTIONAL DESCRIPTION:
!   The job scheduler for DIU.  This routine can be called at command
!   level (START, for example) or at interrupt level (on receipt of a new
!   request).  Because we can be called at interrupt level we ENABLE
!   the default condition handler here to catch errors so we DEBRK properly.
!
! FORMAL PARAMETERS:
!   NONE
!
! IMPLICIT INPUTS:
!   NONE
!
! IMPLICIT OUTPUTS:
!   NONE
!
! ROUTINE VALUE and
! COMPLETION CODES:
!   NONE
!
! SIDE EFFECTS:
!   NONE
!
!--
    BEGIN

    ENABLE
        diu$abort;

    IF NOT .mst_flag
    THEN
        RETURN (DIU$_NO_SPOOLER);
    IF .shutdown
    THEN
        RETURN (DIU$_SHUTDOWN);
    IF .njob GEQ .mjob
    THEN
        RETURN (DIU$_MJOB_EXCEEDED);
    do_sched ();                        ! Call the work routine
    END;                                ! End of sched
ROUTINE do_sched : NOVALUE =
!++
! FUNCTIONAL DESCRIPTION:
!   Schedule a request.  If MJOB is not full yet (slots are available),
!   the queue is searched for eligible requests.  For each one found,
!   a job is created and logged in and the request initiated.  We establish
!   a condition handler here in order to free up any memory we may have
!   allocated in the event of errors.
!--
    BEGIN
    LOCAL
        retcode,
        req_id,
        chain_head : VOLATILE,
        chain_copy,                     ! Hold copy of chain head
        current_block,
        req_block : $DIU_BLOCK,
        now,                         ! current time
        check_for_hung_requests;     ! nonzero if time to look for hung jobs

    ENABLE
        abort_sched (chain_head);
    !
    ! Disable interrupts to prevent confusion
    !
    s$noint ();



    now=S$TIME();                       ! what time is it? 
    IF .SCHTIM EQL 0                    ! If first time here, 
    THEN SCHTIM = .now;                 ! do not check timeout

    IF (check_for_hung_requests=(.now-.SCHTIM) GTR .TIMOUT) ! time to look?
    THEN SCHTIM=.now;                   ! yes remember this time

    ! Must do pass even if MJOB exceeded,
    ! to expire deadlined & timed-out jobs
    ! Just return immediately if we're full.
    !

    !
    ! Get a list of all requests in the queue.
    !
    q$req_block_init (req_block);
    q$find (req_block, chain_head);
    current_block = chain_head;
    chain_copy = .chain_head;           ! Make copy of chain head
                                        ! so we can remember if queue empty
    ! 
    ! Set artificial value (largest positive number) for earliest /AFTER
    ! 
    next_event_time = bignum;

    !
    ! Now chase the chain of request blocks, picking and starting eligible ones
    !
    WHILE ((current_block = ..current_block) NEQ 0)
    DO
        BEGIN
        BIND
            req_block = .current_block + 1 : $DIU_BLOCK;
        !
        ! If deadline expired, kill the request and don't make any other tests
        !
        IF .req_block[DIU$G_DEADLINE] NEQ 0
            AND .req_block[DIU$G_DEADLINE] LEQ s$time ()
        THEN
            expire (req_block)
        ELSE
            BEGIN
            !
            ! Deadline is not expired...  keep checking...
            !
            IF (.check_for_hung_requests neq 0)     ! If time to check
            AND .req_block[DIU$V_ACTIVE]            ! If request is active
            THEN                                    ! see if it timed out
                BEGIN                               ! 
                LOCAL jobtime;                      ! runtime now
                LOCAL oldjobtime: INITIAL(0);       ! runtime on last pass
                LOCAL jobnum;                       ! job number 
                LOCAL reqid;                        ! job number 
                LOCAL index: INITIAL(0);            ! index in JOBSTATUS
                                                    !
                reqid=.req_block[DIU$H_REQUEST_ID]; !

                DO  BEGIN                                                  !
                    IF (.JOBSTATUS[.index,DIUJ$H_REQUEST_ID] EQL .reqid)   !
                    AND .JOBSTATUS[.index,DIUJ$V_INUSE]                    !
                    THEN EXITLOOP                                          !
                    ELSE index=.index+1;                                   !
                    END WHILE .index LSS DIU$K_MAX_MJOB;                   !

                IF .index EQL DIU$K_MAX_MJOB   ! Can't find request! OOPS  !
                THEN SIGNAL(DIU$_BUG,DIU$_REQ_NOT_FOUND);                  !

                jobnum=.JOBSTATUS[.index,DIUJ$H_JOB_NUMBER];

%IF %SWITCHES (TOPS20)
%THEN                                   ! TOPS-20 ONLY
                jobtime=s$jobtime(.jobnum);     ! get current runtime
                oldjobtime=.JOBSTATUS[.index,DIUJ$G_JOB_RUNTIME];
                JOBSTATUS[.index,DIUJ$G_JOB_RUNTIME]=.jobtime;
                IF (.jobtime EQL .oldjobtime)   ! If it used NO time,
                THEN timeout(req_block)         !   time it out

%ELSE                                   ! TOPS-10 ONLY
		IF .jobnum LSS 0
		THEN
		    IF .jobnum EQL -1
		    THEN
			JOBSTATUS[.index,DIUJ$H_JOB_NUMBER] = -2
			! Remember seen this pass.  Timeout next pass if
			!  still not started.
		    ELSE
		    timeout(req_block)		! Long overdue to start

		ELSE

		    BEGIN
%IF %VARIANT ! TOPS-10 V7.02 support
%THEN
		    IF .JOBSTATUS[.index,DIUJ$V_PID_INVALID]
		    THEN
			timeout(req_block)	! Second time around so timeout
		    ELSE
			IF NOT ip$check_pid(query_pid,
					.JOBSTATUS[.index, DIUJ$G_SLAVE_PID])
			THEN
			    JOBSTATUS[.index,DIUJ$V_PID_INVALID] = 1
			    ! If the PID is not valid anymore,
			    ! mark to timeout next pass
			ELSE
%FI
			BEGIN
                        jobtime=s$jobtime(.jobnum);     ! get current runtime
                        oldjobtime=.JOBSTATUS[.index,DIUJ$G_JOB_RUNTIME];
                        JOBSTATUS[.index,DIUJ$G_JOB_RUNTIME]=.jobtime;
                        IF (.jobtime EQL .oldjobtime)   ! If it used NO time,
                        THEN timeout(req_block)         !   time it out
			END;
		    END;
%FI                                     ! END OF TOPS-10 / TOPS-20 CONDITIONAL
                END;

            ! Check /AFTER switch, holding bit,
            !  active bit, and dependency

            IF  (.req_block[DIU$G_AFTER] LEQ .now)  ! use remembered time
                AND (NOT .req_block[DIU$V_HOLDING])
                AND (NOT .req_block[DIU$V_ACTIVE])
                AND (.req_block[DIU$H_PREREQUISITE_ID] EQL 0)
                AND (.njob lss .mjob)               ! check mjob here
            THEN
                !
                ! Request passes all tests, start it up
                !
                j$start (req_block)
            ELSE
                !
                ! Keep track of earliest unexpired /AFTER time
                !
                IF .req_block[DIU$G_AFTER] NEQ 0
                    AND .req_block[DIU$G_AFTER] GTR .now    ! use remembered
                THEN
                    next_event_time = MIN (.next_event_time,
                                           .req_block[DIU$G_AFTER]);
            !
            ! If this request has a deadline, consider it for next event...
            !
            IF .req_block[DIU$G_DEADLINE] NEQ 0
            THEN
                next_event_time = MIN (.next_event_time,
                                       .req_block[DIU$G_DEADLINE]);
            END;
        END;                            ! Loop

    q$release_chain (.chain_head); 
    chain_head = 0;

    !+
    ! Post a timer interrupt for now plus a couple of minutes.
    !-

    IF .next_event_time NEQ 0
    THEN
        next_event_time = MIN (.now + .ssleep, ! use remembered time
                               .next_event_time)
    ELSE
        next_event_time = .now + .ssleep;       ! use remembered time


    !+
    ! If we have an event to wake up on, post a timer interrupt for it
    !-

    IF .chain_copy neq 0                ! If Q empty, sleep forever
    THEN
        BEGIN
        IF .next_event_time NEQ 0
            AND .next_event_time NEQ bignum
        THEN s$timint (.next_event_time)        ! Wake for next request
        ELSE s$timint (.now+.lsleep);   ! wake occasionally
        END;

    s$okint();                          ! Reenable interrupts
    END;                                ! End of do_sched
ROUTINE expire (p_req_block) : NOVALUE =
!++
! FUNCTIONAL DESCRIPTION:
!
!       Stomp on an expired request (/DEADLINE passed)
!
! FORMAL PARAMETERS:
!
!       p_req_block: pointer to request block
!
! SIDE EFFECTS:
!
!       The request is deleted from the queue and the user notified if desired.
!       Any requests dependent on the expired request are killed if queued with
!       /SEQUENCE:ABORT.  Requests depending on this one have their dependencys
!       removed.  A line is written to the user and system log files.
!
!--
BEGIN

LOCAL job_handle,
      log_descr : $STR_DESCRIPTOR(CLASS=DYNAMIC);

BIND req_block = .p_req_block : $DIU_BLOCK;

! Make a supplementary message up for passing along

$STR_DESC_INIT(DESC = log_descr, CLASS = DYNAMIC);

$STR_COPY(TARGET = log_descr,
          STRING = $STR_CONCAT ('Request ',
                                $STR_ASCII (.req_block[DIU$H_REQUEST_ID]),
                                ' (',
                                (.req_block[DIU$H_JOBNAME],
                                 CH$PTR(req_block[DIU$T_JOBNAME])),
                                ') killed, deadline expired'));

! If request is active, stomp on the corresponding slave job (dependent jobs
! will be killed by slave job cleanup code).  If not active, must kill
! dependents now.

job_handle = -1;                        ! Set job_handle to "not found"
IF .req_block[DIU$V_ACTIVE]             ! If the job was active, kill it
THEN job_handle = j$kill (.req_block[DIU$H_REQUEST_ID],
                          DIU$_DEADLINE_EXPIRED);

IF .job_handle NEQ -1
THEN BEGIN                              ! If the job was active and we found it
     jobstatus[.job_handle, DIUJ$V_ALREADY_DELETED] = 1;
     $STR_COPY (TARGET = jobstatus[.job_handle, DIUJ$T_EXTRA_TEXT],
                STRING = log_descr);
     END
ELSE BEGIN                              ! The job wasn't active
     l$event(DIU$_DEADLINE_EXPIRED, 0, log_descr);
     l$uevent(DIU$_DEADLINE_EXPIRED, 0, log_descr, .req_block);
     notify (DIU$_DEADLINE_EXPIRED, 0, log_descr, .req_block);
     IF .req_block[DIU$H_DEPENDENT_ID] NEQ 0
     THEN abort (.req_block[DIU$H_DEPENDENT_ID]);
     END;

! Clear any prerequisiste request's dependency on this request, I know this is
! rather obscure but it should work

IF .req_block[DIU$H_PREREQUISITE_ID] NEQ 0      ! If request has prerequisite
THEN Q$MODIFY (.req_block[DIU$H_PREREQUISITE_ID],       ! Zap it
               DIUQ$K_DEPENDENT_ID,
               0);

! Delete the request block from the queue.

q$delete (.req_block[DIU$H_REQUEST_ID]);

END;                                    ! end of expire
ROUTINE timeout (p_req_block) : NOVALUE =
!++
! FUNCTIONAL DESCRIPTION:
!
!       Requeue on a timed-out request
!
! FORMAL PARAMETERS:
!
!       p_req_block: pointer to request block
!
!
! SIDE EFFECTS:
!
!       The request is requeued, events written to user and system log file
!--
BEGIN

LOCAL job_handle,
      log_descr : $STR_DESCRIPTOR(CLASS=DYNAMIC);

BIND req_block = .p_req_block : $DIU_BLOCK;

$STR_DESC_INIT(DESC = log_descr, CLASS = DYNAMIC);

$STR_COPY(TARGET = log_descr,
          STRING = $STR_CONCAT ('Request ',
                                $STR_ASCII (.req_block[DIU$H_REQUEST_ID]),
                                ' (',
                                (.req_block[DIU$H_JOBNAME],
                                 CH$PTR(req_block[DIU$T_JOBNAME])),
                                ') requeued due to time out'));

! If request is active, stomp on the corresponding slave job.

job_handle = -1;                        ! Set job_handle to "not found"
IF .req_block[DIU$V_ACTIVE]             ! If the job was active, kill it
THEN job_handle = j$kill (.req_block[DIU$H_REQUEST_ID],
                          DIU$_REQ_TIME_OUT);

IF .job_handle NEQ -1
THEN BEGIN                              ! If the job was active and we found it
     $STR_COPY (TARGET = jobstatus[.job_handle, DIUJ$T_EXTRA_TEXT],
                STRING = log_descr);
     END
ELSE BEGIN                              ! The job wasn't active
     l$event(DIU$_REQ_TIME_OUT, 0, log_descr);
     l$uevent(DIU$_REQ_TIME_OUT, 0, log_descr, .req_block);
     END;

! Requeue the request

q$reque (.req_block[DIU$H_REQUEST_ID]);

END;                                ! End of timeout
ROUTINE abort_sched (sig, mech, enbl) =
!++
! FUNCTIONAL DESCRIPTION:
!   Condition handler for scheduler.  This routine releases
!   the chain of (one) request blocks and then resignals.
!   We also try to reenable interrupts (all since all signals
!   in DO_SCHED occur NOINT, we always OKINT here).
!
! FORMAL PARAMETERS:
!   sig         - signal vector
!   mech        - mechanism vector
!   enbl        - enable vector (element 1 is head of chain)
!
! IMPLICIT INPUTS:
!   NONE
!
! IMPLICIT OUTPUTS:
!   NONE
!
! ROUTINE VALUE and
! COMPLETION CODES:
!   0           - to force resignalling
!
! SIDE EFFECTS:
!   NONE
!
!--
    BEGIN

    MAP
        sig : REF VECTOR,
        mech : REF VECTOR,
        enbl : REF VECTOR;

    ENABLE                              ! Prevent nested signals here
        diu$abort;

    IF .sig[1] EQL STS$K_UNWIND
    THEN
        RETURN (0);
    IF ..enbl[1] NEQ 0
        AND NOT .sig[1]                 ! Only release memory on errors
    THEN
        BEGIN
        q$release_chain (..enbl[1]);
        .enbl[1] = 0;                   ! Empty chain
        s$okint ();                     ! Reenable interrupts
        END;
    RETURN (0)                          ! Resignal
    END;                                ! End of abort_sched
END                                     ! End of module
ELUDOM