Process.mesa_Sep78 Process.mesa Sep78

Process.mesa_Sep78 Process.mesa_Sep78

User Manual: Process.mesa_Sep78

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Process.mesa

-- Process.Mesa

2-Sep-78 13:58:17

Edited by Redell on July 31, 1978

Page

3:39 PM

DIRECTORY
ControlDefs: FROM "controldefs" USING [
Frame, FrameHandle, Free, Lreg, NullFrame, SetReturnFrame, StateVector],
InlineDefs: FROM "inlinedefs" USING [BITOR, BITSHIFT],
NucleusDefs: FROM "nucleusdefs",
ProcessDefs: FROM "processdefs" USING [
ActiveWord, Broadcast, Clean, Condition, CurrentPSB, CurrentState,
DefaultPriority, DefaultTimeout, DisableInterrupts, DIW, Empty,
EnableAndRequeue, EnableInterrupts, Enter, Exit, MonitorLock, Notify,
NullQueueHandle, Priority, ProcessHandle, PSB, ReadyList, ReEnter, SOC,
Ticks, TimeoutLevel, TimerGrain, UnlockedEmpty, Wait],
SDDefs: FROM "sddefs· USING [
SO, sFirstProcess, sFirstStateVector, sFork, sJoin, sLastProcess,
sProcessTrap]:
Process: MONITOR LOCKS Processes
EXPORTS NucleusDefs, ProcessDefs SHARES ProcessDefs •
BEGIN OPEN ProcessDefs:
PSBBase: CARDINAL· 0:
Aborted: PUBLIC SIGNAL c CODE:
TimedOut: PUBLIC SIGNAL = CODE:
TooManyProcesses: PUBLIC ERROR = CODE:
Processes: MONITORLOCK:
frameReady, frameTaken, dead, rebirth: CONDITION:
DyingFrameHandle: TYPE = POINTER TO dying ControlOefs.Frame:
Fork: PUBLIC PROCEDURE [root: UNSPECIFIED] RETURNS [ProcessHandle] a
BEGIN
sv: ControlDefs.StateVector:
self: ControlDefs.FrameHandle:
Forker: PROCEDURE [ProcessHandle]:
newPSB: ProcessHandle:
sv .. STATE:
WHILE ~Enter[@Processes] DO NULL ENDLOOP:
self" REGISTER[ControlDefs.Lreg]:
Forker .. LOOPHOLE[self.returnlink]:
IF LOOPHOLE[rebirth, Condition].queue = Empty THEN
BEGIN
Exit[@Processes]:
ERROR TooManyProcesses:
END:
newPSB" (PSBBase+LOOPHOLE[rebirth, Condition].queue). link:
newPSBt .. PSB[
link: newPSB.link,
cleanup: Clean,
timeout: 0,
priority: CurrentPSB.priority,
enterFailed: FALSE,
detached: FALSE,
fill:O,
state: dead,
in case of timeout before Notify (below)
timeoutAllowed: TRUE,
abortPending: FALSE,
timeoutPending: FALSE,
waitingOnCV: TRUE,
frame: self];
Notify[@rebirth]:
-- wake up newPSB, and set alive: DEPENDS
newPSB.state .. alive:
-- on new process not preempting parent ...
ControlDefs.Set.ReturnFrame[ControlDefs.NullFrame]:
Forker[newPSB]:
"returns" handle to site of FORK
-- Note that the lines above are executed by the forking process, while
-- the lines below are executed by the forked process. Note also that the
-- monitor remains LOCKED during this fancy footwork ... 1
sv.dest .. root;
sv.source .. End;
Exit[@Processes]:
RETURN WInl sv
END:
deadFrame: DyingFrameHandle .. NIL:

-- only for detached processes

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Process.mesa

2-Sep-7B 13:58:17

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2

End: PROCEDURE·
BEGIN OPEN p: CurrentPSBt;
sv: ControlDefs.StateVector;
frame: DyingFrameHandle;
sv ~ STATE;
WHILE -Enter[@Processes] DO NULL ENDLOOP;
frame ~ REGISTER[ControlDefs.Lreg];
frame. state ~ alive;
p.state ~ frameReady;
p.abortPending ~ FALSE; -- too late for Aborts: they no-op
Broadcast[@frameReady];
UNTIL p.state • frameTaken OR p.detached DO
Wait[@Processes. @frameTaken. LOOPHOLE[frameTaken. Condition].timeout];
WHILE ~ReEnter[@Processes. @frameTaken] DO NULL ENDLOOP;
ENDLOOP;
IF deadFrame # NIL THEN
BEGIN ControlDefs.Free[deadFrame]; deadFrame ~ NIL END;
IF p.detached THEN deadFrame ~ frame; -- Leave our frame for freeing
frame.state ~ dead;
p.state ~ dead;
Broadcast[@dead];
Wait[@Processes. @rebirth. LOOPHOLE[rebirth. Condition].timeout];
WHILE -ReEnter[@Processes. @rebirth] DO NULL ENDLOOP; -- dying process exits here; JOINing process
**does below.
sv.dest ~ frame.returnlink; -- set to site of JOIN by Join
sv.source ~ 0;
Exit[@Processes];
RETURN WITH sv;
END;
Join: PUBLIC ENTRY PROCEDURE [process: UNSPECIFIED]
RETURNS [ControlDefs.FrameHandle] •
BEGIN
p: ProcessHandle • process;
frame: DyingFrameHandle;
self: ControlDefs.FrameHandle = REGISTER[ControlDefs.Lreg];
ValidateProcess[p];
WHILE p.state # frameReady DO WAIT frameReady ENDLOOP;
-- guaranteed to be a dying frame by the time we get here
frame ~ LOOPHOLE[p.frame];
p.state ~ frameTaken;
BROADCAST frameTaken;
WHILE frame. state # dead DO WAIT dead ENDLOOP;
frame.returnlink ~ self.returnlink; -- site of JOIN
RETURN[frame]
END;
Detach: PUBLIC ENTRY PROCEDURE [process: UNSPECIFIED]
BEGIN
p: ProcessHandle = process;
ValidateProcess[p];
p.detached ~ TRUE;
BROADCAST frameTaken;
END;
Abort: PUBLIC PROCEDURE [process: UNSPECIFIED] a
BEGIN
p: ProcessHandle • process;
ValidateProcess[p];
DisableInterrupts[];
IF p.state • alive THEN
BEGIN
p.abortPending ~ TRUE;
IF p.waitingOnCV THEN
BEGIN
p.waitingOnCV ~ FALSE;
EnableAndRequeue[NullQueueHandle. ReadyList. p];
RETURN;
END;
END;
EnableInterrupts[];
END;
Processfrap: PROCEDURE RETURNS [BOOLEAN] •
BEGIN
abort. timeout: BOOLEAN;

~

Process.mesa

Page

2-Sep-78 13:58:17

CurrentPSB.wait'ingOnCV +- FALSE;
abort +- CUI'rentPSB.abortPen.cling;
CurrentPSB.abortPending ... fAlSE;
IF abort THEN ERROR Aborted;
timeout +- CurrentPSB.timeout¥ending;
CurrentPSB.timeoutPending +- fALSE;
IF timeout THEN SIGNAL TimedOut;
RETURN[FALSE]
END;
DisableScheduling: PUBLIC PROCEDURE·
BEGIN
DisableInterrupts[]:
SDCt ... SDCt + 1;
EnableInterrupts[];
RETURN
END;
EnableScheduling: PUBLIC PROCEDURE •
BEGIN
DisableInterrupts[]:
SDCt +- SDCt - 1;
EnableAndRequeue[ReadyList, ReadyList, CurrentPSBt]:
RETURN
END:
Yield: PUBLIC PROCEDURE·
BEGIN
DisableInterrupts[]:
EnableAndRequeue[ReadyList, ReadyList, CurrentPSBt]:
RETURN
.
END;
GetPriority: PUBLIC PROCEDURE RETURNS [p: Priority]
BEGIN
DisableInterrupts[]:
p +- CurrentPSB.priority;
EnableInterrupts[];
RETURN
END;

a

SetPriority: PUBLIC PROCEDURE [p: Priority] •
BEGIN
DisableInterrupts[];
CurrentPSB.priority ... p;
EnableAndRequeue[ReadyList, ReadyList, CurrentPSBt];
END;
SetTimeout: PUBLIC PROCEDURE [
condition: POINTER TO CONDITION, ticks: CARDINAL] •
BEGIN
LOOPHOLE[condition, POINTER TO Condition].timeout +IF ticks # 0 THEN ticks ELSE DefaultTimeout;
RETURN
END;
DisableTimeout: PUBLIC PROCEDURE [condition: POINTER TO CONDITION] •
BEGIN
LOOPHOLE[condition, POINTER TO Condition].timeout +- 0;
RETURN
END;
MsecToTicks: PUBLIC PROCEDURE ems: CARDINAL] RETURNS [Ticks] •
BEGIN
RETURN[(ms+TimerGrain-l)/TimerGrain]
END;
TicksToMsec: PUBLIC PROCEDURE [ticks: Ticks] RETURNS [CARDINAL] •
BEGIN
RETURN[ticks·TimerGrain]
END;
InitializeMonitor: PUBLIC PROCEDURE [monitor: POINTER TO MONITORLOCK] •
BEGIN
LOOPl10LE[monitor, POINTER TO MonitorLock]t +- UnlockedEmpty;
RETURN

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Process.mesa

Z-Sep-78 13:58:17

END;
InitializeCondition: PUBLIC PROCEDURE [
condition: POINTER TO CONDITION, ticks: CARDINAL] •
BEGIN
LOOPHOLE[condition, POINTER TO Condition]t ~ Condition[no, Empty, ticks];
RETURN
END;
ValidateProcess: PUBLIC PROCEDURE [p: ProcessHandle] •
BEGIN OPEN SDDefs;
sd: POINTER TO ARRAY [0 .. 0) OF UNSPECIFIED ~ SO;
c: CARDINAL a LOOPHOLE[p];
IF c < SD[sFirstProcess] OR c ) sd[sLastProcess] OR
(c - sd[sFirstProcess]) MOD SIZE[PSB] # a THEN SIGNAL InvalidProcess[p];
RETURN
END;
InvalidProcess: PUBLIC SIGNAL [process: ProcessHandle] • CODE;
InitializeProcesses: PROCEDURE •
BEGIN OPEN SDDefs;
sd: POINTER TO ARRAY [0 .. 0) OF UNSPECIFIED ~ SO;
firstPSB: ProcessHandle ~ sd[sFirstProcess];
lastPSB: ProcessHandle ~ sd[sLastProcess];
psb: ProcessHandle;
DisableTimeout[@dead];
DisableTimeout[@frameReady];
DisableTimeout[@frameTaken];
DisableTimeout[@rebirth];
SDCt ~ 0;
CurrentStatet ~ LOOPHOLE[sd[sFirstStateVector] +
DefaultPriority·SIZE[ControlDefs.StateVector]];
-- locate and initialize PSBs
sd[sProcessTrap] ~ ProcessTrap;
sd[sFork] ~ Fork;
sd[sJoin] ~ Join:
-- fabricate PSB for self
lastPSBt ~ PSB[
link: lastPSB,
cleanup: Clean,
timeout: 0,
enterFailed: FALSE,
detached: FALSE,
fill: OB,
state: alive,
timeoutAllowed:,
abortPending: FALSE,
timeoutPending: FALSE,
waitingOnCV: FALSE,
priority: DefaultPriority,
frame: REGISTER[ControlDefs.Lreg]]:
CurrentPSBt ~ ReadyListt ~ lastPSB:
-- set up free PSB pool ("rebirth" condition)
FOR psb ~ firstPSB, psb+SIZE[PSB]
UNTIL psb a lastPSB DO
psb t ~ PSB[
link: psb-SIZE[PSB],
cleanup: Clean,
timeout: 0,
enterFailed: FALSE,
detached: FALSE,
fill: OB,
state: dead,
timeoutAllowed:,
abortPending: FALSE,
timeoutPending: FALSE,
waitingOnCV: TRUE,
priority: DefaultPriority,
frame: ControlOefs.NullFrame]:
ENDLOOP:
LOOPHOLE[rebirth, Condition].queue ~
(firstPSB.link ~ lastPSB-SIZE[PSB])-PSBBase:
-- CVt already set up by Nova code
ActiveWordt ~ 77777B;
RETURN

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Process.mesa

2-Sep-78 13:58:17

END:
InitializeTimeouts: PROCEDURE·
BEGIN OPEN InlineDefs:
TimeoutMask: WORD· BITSHIFT[l,TimeoutLevel]:
Disablelnterrupts[];
-- Nova code has set up IntVec[TimeoutLevel]
DIWt ~ BITOR[DIWt, TimeoutMask]:
EnableInterrupts[]:
RETURN
END:
InitializeProcesses[];
InitializeTimeouts[]:
END.

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