-- Scavenger.mesa (last edited by: McJones on: January 28, 1981 12:39 PM)

DIRECTORY

File USING [Capability, ID, PageCount, PageNumber, Type],

Space USING [PageNumber],

System USING [GreenwichMeanTime],

Volume USING [ID];

Scavenger: DEFINITIONS =

BEGIN

Error: ERROR [error: ErrorType];

ErrorType: TYPE = {cannotWriteLog, noSuchPage, orphanNotFound, volumeOpen, diskHardwareError, diskNotReady};

Header: TYPE = MACHINE DEPENDENT RECORD [

volume (0): Volume.ID,

date (5): System.GreenwichMeanTime,

incomplete (7: 0..14): BOOLEAN,

repaired (7: 15..15): BOOLEAN,

numberOfFiles (10B): LONG CARDINAL];

LogFormat: TYPE = MACHINE DEPENDENT RECORD [

header (0): Header,

files (SIZE [Header]): ARRAY [0..0) OF FileEntry];

Problem: TYPE = MACHINE DEPENDENT RECORD [

trouble (0): SELECT entryType (0: 0..15):* FROM -- "trouble" added due to compiler bug.

unreadable, missing => [

first (1): File.PageNumber,

count (3): File.PageCount],

duplicate, orphan => [

id (1): OrphanHandle]

ENDCASE];

FileEntry: TYPE = MACHINE DEPENDENT RECORD [

file (0): File.ID,

numberOfProblems (5): CARDINAL,

problems (6): ARRAY [0..0) OF Problem];

OrphanHandle: TYPE [2];

DeleteLog: PROCEDURE [volume: Volume.ID];

DeleteOrphanPage: PROCEDURE [volume: Volume.ID, id: OrphanHandle];

GetLog: PROCEDURE [volume: Volume.ID] RETURNS [logFile: File.Capability];

ReadBadPage: PROCEDURE [file: File.ID, page: File.PageNumber, destination: Space.PageNumber];

ReadOrphanPage: PROCEDURE [volume: Volume.ID, id: OrphanHandle, destination: Space.PageNumber]

RETURNS [file: File.ID, type: File.Type, pageNumber: File.PageNumber, readErrors: BOOLEAN];

RewritePage: PROCEDURE [file: File.ID, page: File.PageNumber, source: Space.PageNumber];

Scavenge: PROCEDURE [volume, logDestination: Volume.ID, repair: BOOLEAN] RETURNS [logFile: File.Capability];

END.

LOG

Time: June 17, 1980 10:06 AMBy: LuniewskiAction: Create file

Time: July 13, 1980 9:08 PMBy: ForrestAction: Add error: to ERROR declaration

Time: September 2, 1980 4:58 PMBy: LuniewskiAction: Make all records be Machine Dependent and use explicit word numbers within those records

Time: October 10, 1980 6:30 PMBy: LuniewskiAction: SIZE[] => #

Time: January 28, 1981 12:39 PMBy: McJonesAction: Add diskHardwareError, diskNotReady to ErrorType