<> <> <> <> <> <> DIRECTORY YggHostFS USING[Error, HostFile, RC, Read, Reason, Write], YggDummyProcess USING[Detach], YggFilePageMgrIO USING[IORequest, IOType, Who]; YggFilePageMgrIOImpl: CEDAR MONITOR IMPORTS YggHostFS, YggDummyProcess EXPORTS YggFilePageMgrIO = BEGIN requests: LIST OF IOMasterRequests _ NIL; nRequests: NAT _ 0; maxRequests: NAT _ 4; IOMasterRequests: TYPE = RECORD[controllingProcess: PROCESS, IOThreadAssigned: BOOLEAN, error: YggHostFS.RC, errorIORequest: YggFilePageMgrIO.IORequest, nIOsInProgress: NAT, io: YggFilePageMgrIO.IOType, file: YggHostFS.HostFile, list: LIST OF YggFilePageMgrIO.IORequest]; IOControllerAvail: CONDITION; IOThreadFinished: CONDITION; IOThreadNeeded: CONDITION; <> <> <> RegisterRequest: PUBLIC ENTRY PROCEDURE[controllingProcess: PROCESS, io: YggFilePageMgrIO.IOType, file: YggHostFS.HostFile, list: LIST OF YggFilePageMgrIO.IORequest] RETURNS[iORequest: YggFilePageMgrIO.IORequest] = BEGIN -- non system fatal errors: none. DO IF nRequests < maxRequests THEN EXIT; WAIT IOControllerAvail; ENDLOOP; nRequests _ nRequests + 1; requests _ CONS[[controllingProcess: controllingProcess, IOThreadAssigned: FALSE, error: ok, errorIORequest: , nIOsInProgress: 1, io: io, file: file, list: list.rest], requests]; IF list.rest # NIL THEN NOTIFY IOThreadNeeded; <> <> RETURN[list.first]; END; <> <> <> <> <> <> <> <> <> <> <> <> <> <> <> RegisterIOThread: ENTRY PROCEDURE RETURNS[workToDo: BOOLEAN, controllingProcess: PROCESS, io: YggFilePageMgrIO.IOType, file: YggHostFS.HostFile, iORequest: YggFilePageMgrIO.IORequest] = BEGIN -- non system fatal errors: none. FOR req: LIST OF IOMasterRequests _ requests, req.rest UNTIL req = NIL DO IF ((NOT req.first.IOThreadAssigned) AND (req.first.list # NIL)) THEN BEGIN workToDo _ TRUE; controllingProcess _ req.first.controllingProcess; io _ req.first.io; file _ req.first.file; iORequest _ req.first.list.first; req.first.list _ req.first.list.rest; req.first.IOThreadAssigned _ TRUE; IF (req.first.nIOsInProgress _ req.first.nIOsInProgress + 1) # 2 THEN ERROR; <> RETURN; END; ENDLOOP; workToDo _ FALSE; END; GetNext: PUBLIC ENTRY PROCEDURE[controllingProcess: PROCESS, who: YggFilePageMgrIO.Who] RETURNS[error: YggHostFS.RC, errorIORequest: YggFilePageMgrIO.IORequest, workToDo: BOOLEAN, iORequest: YggFilePageMgrIO.IORequest] = BEGIN -- non system fatal errors: none. prevReq, req: LIST OF IOMasterRequests; [prevReq, req] _ FindReqAndPrev[controllingProcess]; IF (((error _ req.first.error) # ok) OR ((workToDo _ (req.first.list # NIL)) = FALSE)) THEN BEGIN workToDo _ FALSE; <> <> [error, errorIORequest] _ FinishUp[controllingProcess, prevReq, req, who]; END ELSE BEGIN iORequest _ req.first.list.first; <> <> req.first.list _ req.first.list.rest; END; END; LogError: PUBLIC ENTRY PROCEDURE[controllingProcess: PROCESS, who: YggFilePageMgrIO.Who, why: YggHostFS.Reason, errorIORequest: YggFilePageMgrIO.IORequest] = BEGIN -- non system fatal errors: none. prevReq, req: LIST OF IOMasterRequests; [prevReq, req] _ FindReqAndPrev[controllingProcess]; req.first.error _ why; req.first.errorIORequest _ errorIORequest; [] _ FinishUp[controllingProcess, prevReq, req, who]; END; FindReqAndPrev: INTERNAL PROCEDURE[controllingProcess: PROCESS] RETURNS[prevReq, req: LIST OF IOMasterRequests] = BEGIN -- non system fatal errors: none. prevReq _ NIL; req _ requests; DO IF req.first.controllingProcess = controllingProcess THEN RETURN; prevReq _ req; IF (req _ req.rest) = NIL THEN ERROR; ENDLOOP; END; FinishUp: INTERNAL PROCEDURE[controllingProcess: PROCESS, prevReq, req: LIST OF IOMasterRequests, who: YggFilePageMgrIO.Who] RETURNS[error: YggHostFS.RC, errorIORequest: YggFilePageMgrIO.IORequest] = BEGIN -- non system fatal errors: none. req.first.nIOsInProgress _ req.first.nIOsInProgress - 1; <> IF who = IOThread THEN BEGIN IF req.first.nIOsInProgress = 0 THEN BROADCAST IOThreadFinished; END ELSE BEGIN IF req.first.nIOsInProgress # 0 THEN BEGIN DO WAIT IOThreadFinished; IF req.first.nIOsInProgress = 0 THEN EXIT; ENDLOOP; [prevReq, req] _ FindReqAndPrev[controllingProcess]; END; IF prevReq = NIL THEN requests _ req.rest ELSE prevReq.rest _ req.rest; nRequests _ nRequests - 1; NOTIFY IOControllerAvail; END; error _ req.first.error; errorIORequest _ req.first.errorIORequest; <> END; IOThread: PROCEDURE = BEGIN -- non system fatal errors: MonitoredIOThread: ENTRY PROCEDURE = BEGIN -- non system fatal errors: none. WAIT IOThreadNeeded; END; DoWork: PROCEDURE = BEGIN -- non system fatal errors: none. workToDo: BOOLEAN; controllingProcess: PROCESS; io: YggFilePageMgrIO.IOType; file: YggHostFS.HostFile; iORequest: YggFilePageMgrIO.IORequest; [workToDo, controllingProcess, io, file, iORequest] _ RegisterIOThread[]; DO IF (NOT workToDo) THEN RETURN; DoIO[io, file, iORequest ! YggHostFS.Error => BEGIN LogError[controllingProcess, IOThread, why, iORequest]; GOTO errorSeen; END]; [, , workToDo, iORequest] _ GetNext[controllingProcess: controllingProcess, who: IOThread]; REPEAT errorSeen => NULL; ENDLOOP; END; DO MonitoredIOThread[]; DoWork[]; ENDLOOP; END; DoIO: PUBLIC PROCEDURE[io: YggFilePageMgrIO.IOType, file: YggHostFS.HostFile, iORequest: YggFilePageMgrIO.IORequest] = BEGIN -- non system fatal errors: none. <> <> tiny: INT _ iORequest.filePageNumber; SELECT io FROM write => BEGIN file.Write[[iORequest.filePageNumber], iORequest.nPages, iORequest.vM]; END; read => TRUSTED BEGIN file.Read[[iORequest.filePageNumber], iORequest.nPages, iORequest.vM]; END; ENDCASE => ERROR; <> <> END; GenerateIOThread: PROCEDURE = BEGIN -- non system fatal errors: none. TRUSTED BEGIN YggDummyProcess.Detach[FORK IOThread[]]; END; END; <

> THROUGH [0..maxRequests) DO GenerateIOThread[]; ENDLOOP; END. Edit Log Initial: Kolling: August 25, 1983 3:12 pm: impl module for FilePageManager io. Nodified: Hauser: February 20, 1985 3:05:56 pm PST <> <> <<>>