Megatest

;; returns: db existed-prior-to-opening
;; RA => Returns a db handler; sets the lock if opened in writable mode
;;
;;(define *db-open-mutex* (make-mutex))

(define (db:lock-create-open fname initproc)
  (let* ((parent-dir   (or (pathname-directory fname)(current-directory))) ;; no parent? go local
         (raw-fname    (pathname-file fname))
	 (dir-writable (file-write-access? parent-dir))
	 (file-exists  (file-exists? fname))
	 (file-write   (if file-exists
			   (file-write-access? fname)
			   dir-writable )))
    ;;(mutex-lock! *db-open-mutex*) ;; tried this mutex, not clear it helped.
    (if file-write ;; dir-writable
	(condition-case
         (let* ((lockfname   (conc fname ".lock"))
                (readyfname  (conc parent-dir "/.ready-" raw-fname))
                (readyexists (file-exists? readyfname)))
           (if (not readyexists)
               (common:simple-file-lock-and-wait lockfname))
           (let ((db      (sqlite3:open-database fname)))
             (sqlite3:set-busy-handler! db (make-busy-timeout 136000))
             (sqlite3:execute db "PRAGMA synchronous = 0;")
             (if (not file-exists)
                 (begin
                   (if (and (configf:lookup *configdat* "setup" "use-wal")
                            (string-match "^/tmp/.*" fname)) ;; this is a file in /tmp
                       (sqlite3:execute db "PRAGMA journal_mode=WAL;")
                       (print "Creating " fname " in NON-WAL mode."))
                   (initproc db)))
             (if (not readyexists)
                 (begin
                   (common:simple-file-release-lock lockfname)
                   (with-output-to-file
                       readyfname
                     (lambda ()
                       (print "Ready at " 
                              (seconds->year-work-week/day-time 
                               (current-seconds)))))))
             db))
         (exn (io-error)  (debug:print 0 *default-log-port* "ERROR: i/o error with " fname ". Check permissions, disk space etc. and try again."))
         (exn (corrupt)   (debug:print 0 *default-log-port* "ERROR: database " fname " is corrupt. Repair it to proceed."))
         (exn (busy)      (debug:print 0 *default-log-port* "ERROR: database " fname " is locked. Try copying to another location, remove original and copy back."))
         (exn (permission)(debug:print 0 *default-log-port* "ERROR: database " fname " has some permissions problem."))
         (exn () (debug:print 0 *default-log-port* "ERROR: Unknown error with database " fname " message: " ((condition-property-accessor 'exn 'message) exn))))
        
	(condition-case
         (begin
           (debug:print 2 *default-log-port* "WARNING: opening db in non-writable dir " fname)
           (let ((db (sqlite3:open-database fname)))
             ;;(mutex-unlock! *db-open-mutex*)
             db))
         (exn (io-error)  (debug:print 0 *default-log-port* "ERROR: i/o error with " fname ". Check permissions, disk space etc. and try again."))
         (exn (corrupt)   (debug:print 0 *default-log-port* "ERROR: database " fname " is corrupt. Repair it to proceed."))
         (exn (busy)      (debug:print 0 *default-log-port* "ERROR: database " fname " is locked. Try copying to another location, remove original and copy back."))
         (exn (permission)(debug:print 0 *default-log-port* "ERROR: database " fname " has some permissions problem."))
         (exn () (debug:print 0 *default-log-port* "ERROR: Unknown error with database " fname " message: " ((condition-property-accessor 'exn 'message) exn))))
	)))