DIRECTORYCedarSnapshot,	-- using lotsInputFocus USING [EnableInput],MessageWindow USING [Append, Blink, Confirm],SafeStorage USING [ReclaimCollectibleObjects],ViewerClasses USING [NotifyProc, Viewer],ViewerOps USING [EnumerateViewers, EnumProc, FindViewer],ViewersSnapshot,WindowManager USING [UnWaitCursor, WaitCursor];ViewersSnapshotImpl: CEDAR MONITORIMPORTS CedarSnapshot, InputFocus, MessageWindow, SafeStorage, ViewerOps, WindowManagerEXPORTS ViewersSnapshotSHARES InputFocus =BEGINworking: BOOL _ FALSE;Working: ENTRY PROC RETURNS [now: BOOL] = INLINE {now _ working; working _ TRUE};Done: ENTRY PROC = INLINE {working _ FALSE};Checkpoint: PUBLIC PROC RETURNS [outcome: CedarSnapshot.Outcome] =BEGIN OPEN CedarSnapshot;IF Working[] THEN RETURN [checkpointed];WindowManager.WaitCursor[];MessageWindow.Append["Trace and sweep of collectable storage...", TRUE];[] _ SafeStorage.ReclaimCollectibleObjects[TRUE, TRUE];	-- t&s collectionMessageWindow.Append["Processing checkpoint file...", TRUE];TRUSTED {outcome _ CedarSnapshot.Checkpoint[]};MessageWindow.Append[SELECT outcome FROMcheckpointed	=> "Checkpoint created successfully.",rolledBack	=> "State restored to previous checkpoint.",insufficientDiskSpace	=> "Insufficient disk space to make checkpoint!",transactionsInProgress => "Transaction in progress . . . checkpoint aborted.",overwrittenBcd => "OVERWRITTEN BCDS!  Strongly recommend you boot!",potentiallyDangerousCodeLinks => "Warning: Checkpoint has potentially dangerous code links!",ENDCASE	=> "Checkpoint or Rollback problem; see a system wizard!", TRUE];IF outcome = overwrittenBcd THEN {bootButton: ViewerClasses.Viewer;MessageWindow.Blink[];bootButton _ ViewerOps.FindViewer["Boot"];IF bootButton # NIL THEN bootButton.class.notify[bootButton, LIST[$Mark, $Hit]];MessageWindow.Blink[]};InputFocus.EnableInput[];WindowManager.UnWaitCursor[];Done[];END;RollBack: PUBLIC PROC = BEGINTRUSTED {CedarSnapshot.RollBack[]};	-- no return unless rollback fails!MessageWindow.Append["No previous Checkpoint to restore!"];MessageWindow.Blink[];END;NothingWorthSaving: PROC RETURNS[BOOLEAN] =BEGINdirty: BOOLEAN _ FALSE;CheckDirty: ViewerOps.EnumProc = {dirty _ v.newVersion OR v.newFile OR dirty};ViewerOps.EnumerateViewers[CheckDirty];IF dirty THEN {MessageWindow.Blink[];IF ~MessageWindow.Confirm[    "Confirm discard of edits ... "]     THEN {MessageWindow.Append["action aborted."];RETURN[FALSE]}};RETURN[TRUE];END;Notifier: PUBLIC ViewerClasses.NotifyProc = {FOR l: LIST OF REF ANY _ input, l.rest UNTIL l = NIL DOSELECT l.first FROM$Rollback => {IF NothingWorthSaving[] THEN RollBack[]};$CheckPoint => {IF NothingWorthSaving[] THEN [] _ Checkpoint[]};ENDCASE => ERROR;ENDLOOP;};END.   Є  ViewersSnapshotImpl.mesa; Written by S. McGregorlast edited by McGregor October 25, 1982 2:35 pmLast Edited by: Maxwell, January 27, 1983 12:42 pmLast Edited by: Pausch, August 26, 1983 5:54 pm[self: Viewer, input: LIST OF REF ANY]Э╩d  Ц"cedar" styleШ JЪ╧c0Щ0JЪЭ0Щ0JЩ2JЪ╧i/Щ/JШ Ъ╧k	Ш	JЪЬЭШJЪЬЯЬШJЪЬЯЬШ-JЪЬЯЬШ.JЪЬЯЬШ)JЪЬ
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