-- WalnutDBLog.Mesa
-- Contents: types and procedures for dealing with the log information in the database
-- Last Edited by: Willie-Sue, July 19, 1983 5:37 pm

DIRECTORY
  DB;
    
WalnutDBLog: CEDAR DEFINITIONS =

BEGIN OPEN DB;

SchemaVersionTime: DB.GMT;
-- schemaVersion is time found in database
SchemaMismatch: SIGNAL[schemaVersion: DB.GMT];

walnutLogInfo: Relation; -- used to keep current info about the log file
  wExpectedLength: Attribute;  -- int (how long the log file is)
  wExpectedDBPos: Attribute;  -- int (how much of the log has been parsed into Msgs)
  wStartExpungePos: Attribute;  -- int (where in log file the last/current expunge started)
  wCopyInProgress: Attribute;  -- bool (TRUE while Copying onto tail of log file)
  wSchemaVersion: Attribute;  -- time (for keeping track of changes in walnut's schema)
  wLogFileName: Attribute;  -- string (where to find the log file)

walnutInfoRelship: Relship;        -- need fetch & check only once

-- * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
 
GetCurrentLogFile: PROC RETURNS[ROPE];
 -- Retrieves name for current log file from database

-- SetCurrentLogFile: PROC[fileName: ROPE] is allowed only by Expunge

GetExpectedLogLength: PROC RETURNS[INT];
   -- Retrieves last stored log length from database (used for recovery from crash)
   
SetExpectedLogLength: PROC[INT];
    -- sets the log length in the database
    
SetExpectedDBLogPos: PROC[INT];
    -- sets the last stored DB log position
     
GetExpectedDBLogPos: PROC RETURNS[INT];
  -- Retrieves last stored DB log pos from database (used for recovery from crash)
 
GetStartExpungePos: PROC RETURNS[INT];
   -- Log file position at which current/last expunge began
   
SetStartExpungePos: PROC[INT];
    -- set the starting position of the next expunge

GetCopyInProgress: PROC RETURNS[BOOL];
   -- returns TRUE if a copy onto tail of log file is in progress
   
SetCopyInProgress: PROC[BOOL];
    -- set the copy in progress bit in the DB

END.