
DIRECTORY
Atom USING [DottedPairNode, PropList],
CedarProcess USING [ForkableProc, ForkOptions, Priority, Process, ProcessList, ProcessRep, Status],
Process USING [CheckForAbort, Detach, GetCurrent, GetPriority, Priority, SetPriority],
ProcessProps USING [GetPropList, PushPropList];

CedarProcessImpl: CEDAR MONITOR
IMPORTS Process, ProcessProps
EXPORTS CedarProcess = {

ForkableProc: TYPE = CedarProcess.ForkableProc;
ForkOptions: TYPE = CedarProcess.ForkOptions;
Priority: TYPE = CedarProcess.Priority;
ProcessRef: TYPE = CedarProcess.Process;
ProcessList: TYPE = CedarProcess.ProcessList;
Status: TYPE = CedarProcess.Status;


busyList: CedarProcess.ProcessList м NIL;
busyCount: INT м 0;
statusChange: CONDITION;


SetPriority: PUBLIC PROC [priority: Priority] = {
Process.SetPriority[LOOPHOLE[priority]];
};

GetPriority: PUBLIC PROC RETURNS [priority: Priority] = {
RETURN [LOOPHOLE[Process.GetPriority[]]];
};
DoWithPriority: PUBLIC PROC [priority: Priority, action: PROC] = {
old: Priority м GetPriority[];
SetPriority[priority];
action[ ! UNWIND => SetPriority[old]];
SetPriority[old];
};

Fork: PUBLIC PROC [action: ForkableProc, data: REF м NIL, options: ForkOptions]
RETURNS [ProcessRef] = TRUSTED {
new: ProcessRef м NEW[CedarProcess.ProcessRep м [action: action, data: data]];
props: Atom.PropList м ProcessProps.GetPropList[];
Process.Detach[FORK CedarProcessBase[new, props, options]];
WaitForStarted[new];
RETURN [new];
};

GetStatus: PUBLIC ENTRY PROC [process: ProcessRef] RETURNS [Status] = {
IF (process м DefaultMe[process]) = NIL THEN RETURN [invalid];
RETURN [process.status];
};
Join: PUBLIC ENTRY PROC [process: ProcessRef, wait: BOOL м TRUE]
RETURNS [status: Status, results: REF] = {
IF process # NIL THEN {
IF wait THEN DO
SELECT process.status FROM
busy, debugging => WAIT statusChange;
ENDCASE => EXIT;
ENDLOOP;
RETURN [process.status, process.results];
};
RETURN [done, NIL];
};

Abort: PUBLIC ENTRY PROC [process: ProcessRef] = {
IF process # NIL THEN {
process.abortCount м process.abortCount + 1;
process.abortRequested м TRUE;
};
};

CheckAbort: PUBLIC PROC [process: ProcessRef] = {
Process.CheckForAbort[];
CheckAbortEntry[process];
};


GetBusyList: PUBLIC ENTRY PROC RETURNS [head: ProcessList м NIL] = {
FOR each: ProcessList м busyList, each.rest WHILE each # NIL DO
SELECT each.first.status FROM
busy, debugging => head м CONS[each.first, head];
ENDCASE;
ENDLOOP;
};

GetBusyCount: PUBLIC ENTRY PROC RETURNS [INT] = {
RETURN [busyCount];
};

CheckAbortEntry: ENTRY PROC [process: ProcessRef] = {
IF (process м DefaultMe[process]) # NIL AND process.abortRequested THEN {
process.abortRequested м FALSE;
RETURN WITH ERROR ABORTED;
};
};

DefaultMe: INTERNAL PROC [process: ProcessRef] RETURNS [ProcessRef] = TRUSTED {
IF process = NIL THEN {
me: PROCESS м LOOPHOLE[Process.GetCurrent[]];
FOR each: ProcessList м busyList, each.rest WHILE each # NIL DO
process м each.first;
IF process.process = me THEN RETURN [process];
ENDLOOP;
RETURN [NIL];
};
RETURN [process];
};

WaitForStarted: ENTRY PROC [process: ProcessRef] = {
WHILE process.process = NIL DO WAIT statusChange; ENDLOOP;
};

AdjustDebugCount: ENTRY PROC [process: ProcessRef, delta: INT] = {
process.debugCount м process.debugCount + delta;
};

CedarProcessBase: PROC [new: ProcessRef, props: Atom.PropList, options: ForkOptions] = {
innerProcessBase: PROC = TRUSTED {
me: PROCESS м LOOPHOLE[Process.GetCurrent[]];
AddToBusyList[new];
new.results м new.action[new.data
! 
ABORTED => GO TO abort;
];
RemFromBusyList[new, done];
EXITS abort => RemFromBusyList[new, aborted];
};
IF options.usePriority THEN Process.SetPriority[LOOPHOLE[options.priority]];
IF NOT options.inheritProperties THEN props м NIL;
props м CONS[NEW[Atom.DottedPairNode м [$CedarProcess, new]], props];
ProcessProps.PushPropList[props, innerProcessBase];
};
AddToBusyList: ENTRY PROC [process: ProcessRef] = TRUSTED {
busyList м CONS[process, busyList];
process.process м LOOPHOLE[Process.GetCurrent[]];
busyCount м busyCount + 1;
BROADCAST statusChange;
};

RemFromBusyList: ENTRY PROC [process: ProcessRef, status: Status] = {
SELECT TRUE FROM
busyList = NIL => {};
busyList.first = process => {
busyCount м busyCount - 1;
busyList м busyList.rest;
};
ENDCASE => {
lag: ProcessList м busyList;
DO
next: ProcessList м lag.rest;
IF next = NIL THEN EXIT;
IF next.first.process = process.process THEN {
busyCount м busyCount - 1;
lag.rest м next.rest;
EXIT;
};
lag м next;
ENDLOOP;
};
process.status м status;
BROADCAST statusChange;
};


}.
  8  
CedarProcessImpl.mesa
Copyright ╙ 1985, 1986, 1987, 1990, 1991 by Xerox Corporation.  All rights reserved.
Russ Atkinson (RRA) January 19, 1987 7:03:28 pm PST
Michael Plass, September 14, 1990 11:30 am PDT
AMEvents USING [Debugged, Debugging],
Loader USING [MakeGlobalFrameResident, MakeProcedureResident],
Global vars
Operations for the current process
Sets the priority of the current process to the given priority
Gets the priority of the current process

Performs the action using the given priority.  After the action completes the priority reverts to the priority before the call.

Operations for forked processes
Forks the action with the given callback data and the given options.  Note that the action must NOT be a nested procedure.
Monitored access to process.status.

wait = TRUE AND (process.status = debugging OR process.status = busy) =>
wait for (process.status = done OR process.status = aborted)
In all other cases, return the current results and status.
a monitored call to make process.abortRequested = TRUE
increments process.abortCount
a monitored call to make process.abortRequested = TRUE
raises ERROR ABORTED if process.abortRequested was TRUE when called
Operations for all busy forked processes
Returns a copy of the current busy list of processes.
Returns the number of processes forked through this interface that currently have status = busy or status = debugging.
Utilities

AMEvents.Debugging => AdjustDebugCount[new, 1];
AMEvents.Debugged => AdjustDebugCount[new, -1];

Temporary
Loader.MakeGlobalFrameResident[SetPriority];
Loader.MakeProcedureResident[SetPriority];
Loader.MakeProcedureResident[GetPriority];

CHANGE LOG

Russ Atkinson (RRA) August 19, 1985 2:35:11 pm PDT
in CedarProcessBase
old: IF options.inheritProperties THEN props _ NIL;
new: IF NOT options.inheritProperties THEN props _ NIL;

Russ Atkinson (RRA) August 19, 1985 10:12:26 pm PDT
in CedarProcessBase -
old: AMEvents.Debugging => AdjustDebugCount[new, -1];
new: AMEvents.Debugged => AdjustDebugCount[new, -1];

Michael Plass, September 14, 1990
Removed references to AMEvents and Loader.

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