Megatest

;;   NOTE: returns a dbdat not a dbstruct!
;;
(define (dbfile:open-sqlite3-db dbpath init-proc)
  (let* ((dbexists     (file-exists? dbpath))
	 (write-access (file-write-access? dbpath))
	 (db           (dbfile:cautious-open-database dbpath init-proc))) #;(sqlite3:open-database dbpath)
    (dbfile:inc-db-open dbpath)
    (sqlite3:set-busy-handler! db (sqlite3:make-busy-timeout 10000))
    (sqlite3:execute db (conc "PRAGMA synchronous = 0;"))
    ;; (init-proc db)
    (make-dbr:dbdat dbfile: dbpath dbh: db read-only: (not write-access))))

(define (dbfile:print-and-exit . params)
  (with-output-to-port
      (current-error-port)
    (lambda ()

	 (delay-time (* (- 51 tries-left) 1.1))
      	 (write-access (file-write-access? fname))
         (dir-access (file-write-access? (pathname-directory fname)))
         (retry      (lambda ()
		       (thread-sleep! delay-time)
		       (if (> tries-left 0)
			   (dbfile:cautious-open-database fname init-proc (- tries-left 1))))))
    (assert (>= tries-left 0) (conc "FATAL: too many attempts in dbfile:cautious-open-database of "fname", giving up."))

    (if (and (file-write-access? fname)
	     (file-exists? busy-file))
	(begin
	  (dbfile:print-err "INFO: dbfile:cautious-open-database: journal file " busy-file " exists, trying again in few seconds.")
	  (thread-sleep! 1)
	  (if (eq? tries-left 2)
	      (begin
		(dbfile:print-err "INFO: forcing journal rollup "busy-file)
		(dbfile:brute-force-salvage-db fname)))
	  (dbfile:cautious-open-database fname init-proc (- tries-left 1)))

	(let* ((result (condition-case
		         (if dir-access
			   (dbfile:with-simple-file-lock
			    (conc fname ".lock")
			    (lambda ()
			      (let* ((db-exists (file-exists? fname))
				     (db        (sqlite3:open-database fname))) ;; creates an empty db if it did not already exist.


				(if (and init-proc (not db-exists))
				    (init-proc db))
				db)))
                            (begin
                               (if (file-exists? fname )
                                   (begin
                                      (sqlite3:open-database fname)

			      (retry))
			 (exn (permission)(dbfile:print-err exn "ERROR: database " fname " has some permissions problem.")
			      (retry))
			 (exn ()
			      (dbfile:print-err exn "ERROR: Unknown error with database " fname " message: "
						((condition-property-accessor 'exn 'message) exn))
			      (retry)))))
          #;(if (file-write-access? fname)
	  (dbfile:simple-file-release-lock lock-file))
	  result))))

(define (dbfile:brute-force-salvage-db fname)
  (let* ((backupfname (conc fname"-"(current-process-id)".bak"))
	 (cmd (conc "cp "fname" "backupfname";mv "fname" "(conc fname ".delme;")
		    "cp "backupfname" "fname)))
    (dbfile:print-err "WARNING: attempting recovery of file "fname" by running commands:\n"
		      "  "cmd)