INTERFACE AppBackup;

<* PRAGMA LL *>

IMPORT App, Rd, Time, Wr;

After init is called, the read and write methods are called.

read is called once soon after init has returned and anytime SynchronousRead is called.

write is called after self.changed is signaled, but not more often than wait seconds after the last write (unless SynchronousWrite was called).

TYPE
  T <: TPublic;
  TPublic = MUTEX OBJECT
    name: TEXT;
    log: App.Log;
  METHODS
    init(fileName: TEXT; wait: Time.T; log: App.Log): T RAISES {App.Error};
    modified();
    (* called to indicate the related data structure has changed and the
       backup file should be written within "self.wait" seconds. *)
    read(rd: Rd.T; initial: BOOLEAN) RAISES {App.Error};
    <* LL = self *>
    write(wr: Wr.T) RAISES {App.Error};
    <* LL = self *>
  END;

PROCEDURE SynchronousRead(t: T; initial: BOOLEAN) RAISES {App.Error};
PROCEDURE SynchronousWrite(t: T) RAISES {App.Error};
  <* LL < t *>

END AppBackup.