DIRECTORY AlpineEnvironment, File, FileLock, FilePrivate, TransactionMap, VolumeGroup; VolumeGroupImpl: MONITOR IMPORTS File, FileLock, FilePrivate EXPORTS VolumeGroup = BEGIN OPEN VolumeGroup; Open: PUBLIC PROCEDURE [volumeGroupID: VolumeGroupID, volumes: LIST OF VolumeID, trans: TransactionMap.Handle] = BEGIN OpenEntry: ENTRY PROCEDURE = BEGIN IF Find[volumeGroupID]#NIL THEN RETURN WITH ERROR Failed[duplicateVolGroup]; FOR vol: LIST OF VolumeID _ volumes, vol.rest WHILE vol#NIL DO IF FindVolume[vol.first]#nullVolumeGroupID THEN RETURN WITH ERROR Failed[duplicateVol]; ENDLOOP; volumeGroups _ FilePrivate.stdPZone.CONS[[volumeGroupID: volumeGroupID, volumes: volumes], volumeGroups]; END; -- OpenEntry IF volumeGroupID=nullVolumeGroupID THEN ERROR Failed[nullVolGroupID]; IF volumes=NIL THEN ERROR Failed[empty]; IF trans#NIL THEN FileLock.AcquireVolumeGroupLock[volumeGroupID: volumeGroupID, trans: trans, requested: [write, fail], minimum: write]; OpenEntry[]; END; Close: PUBLIC PROCEDURE [volumeGroupID: VolumeGroupID, trans: TransactionMap.Handle] = BEGIN CloseEntry: ENTRY PROCEDURE = BEGIN IF ~Delete[volumeGroupID] THEN RETURN WITH ERROR Failed[unknownVolumeGroupID]; END; -- CloseEntry FileLock.AcquireVolumeGroupLock[volumeGroupID: volumeGroupID, trans: trans, requested: [write, fail], minimum: write]; CloseEntry[]; END; Identify: PUBLIC PROCEDURE [volID: VolOrVolGroupID, trans: TransactionMap.Handle _ TransactionMap.nullHandle, lock: LockOption _ [none, wait]] RETURNS [volumeID: VolumeID, volumeGroupID: VolumeGroupID] = BEGIN IdentifyEntry: ENTRY PROCEDURE = BEGIN volumes: LIST OF VolumeID = Find[[volID]]; IF volumes#NIL THEN {volumeID _ nullVolumeID; volumeGroupID _ [volID]; RETURN}; volumeGroupID _ FindVolume[[volID]]; IF volumeGroupID#nullVolumeGroupID THEN volumeID _ [volID] ELSE RETURN WITH ERROR Failed[unknownVolOrVolGroupID]; END; -- IdentifyEntry VerifyStillThere: ENTRY PROCEDURE = BEGIN IF Find[volumeGroupID]=NIL THEN RETURN WITH ERROR Failed[unknownVolOrVolGroupID]; END; -- VerifyStillThere IdentifyEntry[]; IF lock.mode#none THEN BEGIN FileLock.AcquireVolumeGroupLock[volumeGroupID: volumeGroupID, trans: trans, requested: lock, minimum: read]; VerifyStillThere[]; END; END; GetVolumes: PUBLIC PROCEDURE [volumeGroupID: VolumeGroupID, trans: TransactionMap.Handle _ TransactionMap.nullHandle, lock: LockOption _ [none, wait]] RETURNS [volumes: LIST OF VolumeID] = BEGIN GetVolumesEntry: ENTRY PROCEDURE = {volumes _ Find[volumeGroupID]}; IF lock.mode#none THEN FileLock.AcquireVolumeGroupLock[volumeGroupID: volumeGroupID, trans: trans, requested: lock, minimum: read]; GetVolumesEntry[]; IF volumes=NIL THEN ERROR Failed[unknownVolumeGroupID]; END; GetNext: PUBLIC PROCEDURE [volumeGroupID: VolumeGroupID, trans: TransactionMap.Handle _ TransactionMap.nullHandle, lock: LockOption _ [none, wait]] RETURNS [nextVolumeGroup: VolumeGroupID] = BEGIN GetNextEntry: ENTRY PROCEDURE RETURNS [VolumeGroupID] = BEGIN IF volumeGroupID=nullVolumeGroupID AND volumeGroups#NIL THEN RETURN [volumeGroups.first.volumeGroupID] ELSE FOR group: LIST OF VolumeGroupRecord _ volumeGroups, group.rest WHILE group#NIL DO IF volumeGroupID=group.first.volumeGroupID AND group.rest#NIL THEN RETURN [group.rest.first.volumeGroupID]; ENDLOOP; RETURN [nullVolumeGroupID]; END; -- GetNextEntry StillThere: ENTRY PROCEDURE RETURNS [BOOLEAN] = {RETURN[Find[volumeGroupID]#NIL]}; DO nextVolumeGroup _ GetNextEntry[]; IF lock.mode=none OR nextVolumeGroup=nullVolumeGroupID THEN EXIT; FileLock.AcquireVolumeGroupLock[volumeGroupID: nextVolumeGroup, trans: trans, requested: lock, minimum: read]; IF StillThere[] THEN EXIT; ENDLOOP; END; SelectVolumeForCreate: PUBLIC ENTRY PROCEDURE [volumeGroupID: VolumeGroupID, count: PageCount] RETURNS [volumeID: VolumeID] = BEGIN volumes: LIST OF VolumeID = Find[volumeGroupID]; maxFreePages: PageCount _ 0; IF volumes=NIL THEN RETURN WITH ERROR Failed[unknownVolumeGroupID]; FOR vol: LIST OF VolumeID _ volumes, vol.rest WHILE vol#NIL DO freePageCount: PageCount = File.LogicalInfo[File.FindVolumeFromID[vol.first]].free; IF freePageCount>maxFreePages THEN {maxFreePages _ freePageCount; volumeID _ vol.first}; ENDLOOP; IF count>maxFreePages THEN RETURN WITH ERROR Failed[insufficientSpace]; END; Lock: PUBLIC PROCEDURE [volumeGroupID: VolumeGroupID, trans: TransactionMap.Handle, lock: LockOption _ [read, wait]] = BEGIN VerifyStillThere: ENTRY PROCEDURE = BEGIN IF Find[volumeGroupID]=NIL THEN RETURN WITH ERROR Failed[unknownVolumeGroupID]; END; FileLock.AcquireVolumeGroupLock[volumeGroupID: volumeGroupID, trans: trans, requested: lock, minimum: read]; VerifyStillThere[]; END; Failed: PUBLIC ERROR [why: Failure] = CODE; VolumeGroupRecord: TYPE = RECORD [ volumeGroupID: VolumeGroupID, volumes: LIST OF VolumeID]; volumeGroups: LIST OF VolumeGroupRecord _ NIL; Find: INTERNAL PROCEDURE [volumeGroupID: VolumeGroupID] RETURNS [volumes: LIST OF VolumeID] = BEGIN FOR group: LIST OF VolumeGroupRecord _ volumeGroups, group.rest WHILE group#NIL DO IF volumeGroupID=group.first.volumeGroupID THEN RETURN [group.first.volumes]; ENDLOOP; RETURN [NIL]; END; FindVolume: INTERNAL PROCEDURE [volumeID: VolumeID] RETURNS [volumeGroupID: VolumeGroupID] = BEGIN FOR group: LIST OF VolumeGroupRecord _ volumeGroups, group.rest WHILE group#NIL DO FOR vol: LIST OF VolumeID _ group.first.volumes, vol.rest WHILE vol#NIL DO IF volumeID=vol.first THEN RETURN [group.first.volumeGroupID]; ENDLOOP; ENDLOOP; RETURN [nullVolumeGroupID]; END; Delete: INTERNAL PROCEDURE [volumeGroupID: VolumeGroupID] RETURNS [found: BOOLEAN] = BEGIN IF volumeGroups#NIL AND volumeGroupID=volumeGroups.first.volumeGroupID THEN {volumeGroups _ volumeGroups.rest; RETURN [TRUE]} ELSE FOR group: LIST OF VolumeGroupRecord _ volumeGroups, group.rest WHILE group#NIL DO IF group.rest#NIL AND volumeGroupID=volumeGroups.rest.first.volumeGroupID THEN {group.rest _ group.rest.rest; RETURN [TRUE]}; ENDLOOP; RETURN [FALSE]; END; END. ‏VolumeGroupImpl.mesa Last edited by: MBrown on January 31, 1984 3:41:56 pm PST Taft on April 10, 1983 4:35 pm Kolling on February 22, 1983 1:49 pm Loose ends: 1. Someday this should be coordinated with whatever AccessControl is doing to maintain its own VolumeGroup-related data structures. The module monitor protects the VolumeGroupImpl internal data structures and serves no other purpose visible to clients. VolumeGroup. This version just selects the emptiest unit. A cleverer algorithm might be desirable, perhaps with some caching of recent results as well. Internal stuff Returns NIL if not found, otherwise the list of volumes belonging to the group. 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