Megatest

;; 
;;     You should have received a copy of the GNU General Public License
;;     along with Megatest.  If not, see <http://www.gnu.org/licenses/>.

;;======================================================================

(declare (unit dbfile))
;; (declare (uses debugprint))

;; (declare (uses commonmod))


(module dbfile
	*
	
(import scheme chicken data-structures extras)
(import (prefix sqlite3 sqlite3:)
	posix typed-records srfi-18
	srfi-69
	stack
	files
	ports

	;; commonmod
	)

;; (import debugprint)

;;======================================================================
;;  R E C O R D S
;;======================================================================

;;

;; Open the classic megatest.db file (defaults to open in toppath)
;;
;;   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)
    (sqlite3:set-busy-handler! db (sqlite3:make-busy-timeout 10000))
    ;; (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 ()
      (apply print params)))

    ;; (db:multi-db-sync subdb 'old2new))  ;; migrate data from megatest.db automatically
    tmpdb))
		
;;======================================================================
;; no-sync.db - small bits of data to be shared between servers
;;======================================================================

;; if we are not a server create a db handle. this is not finalized
;; so watch for problems. I'm still not clear if it is needed to manually
;; finalize sqlite3 dbs with the sqlite3 egg.
;;

(define (dbfile:cautious-open-database fname init-proc #!optional (tries-left 10))
  (let* ((lock-file (conc fname".lock"))
	 (retry (lambda ()
		  (thread-sleep! 1.1)
		  (if (> tries-left 0)
		      (dbfile:cautious-open-database fname init-proc (- tries-left 1))))))
    (assert (>= tries-left 0) (conc "FATAL: Five attempts in dbfile:cautious-open-database of "fname", giving up."))
    (if (and (file-write-access? fname) (not (dbfile:simple-file-lock lock-file)))
	(begin
	  (dbfile:print-err "INFO: lock file "lock-file" exists, trying again in 1 second.")
	  (thread-sleep! 1)
	  (dbfile:cautious-open-database fname init-proc (- tries-left 1)))
	(let* ((db-exists (file-exists? fname))
	       (result (condition-case
			   (let* ((db (sqlite3:open-database fname)))
			     (if (and init-proc (not db-exists))
				 (init-proc db))

			     db)
			(exn (io-error)
			     (dbfile:print-err exn "ERROR: i/o error with " fname ". Check permissions, disk space etc. and try again.")
			     (retry))
			(exn (corrupt)
			     (dbfile:print-err exn "ERROR: database " fname " is corrupt. Repair it to proceed.")
			     (retry))
			(exn (busy)
			     (dbfile:print-err exn "ERROR: database " fname
					       " is locked. Try copying to another location, remove original and copy back.")
			     (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:open-no-sync-db dbpath)
  (if *no-sync-db*
      *no-sync-db*
      (begin
	(if (not (file-exists? dbpath))
	    (create-directory dbpath #t))
	(let* ((dbname    (conc dbpath "/no-sync.db"))
	       (db-exists (file-exists? dbname))
	       (init-proc (lambda (db)

			    (if (not db-exists)
				(begin
				  (sqlite3:execute db "PRAGMA synchronous = 0;")
				  (sqlite3:execute db "CREATE TABLE IF NOT EXISTS no_sync_metadat (var TEXT,val TEXT, CONSTRAINT no_sync_metadat_constraint UNIQUE (var));"))
				)))
	       (db        (dbfile:cautious-open-database dbname init-proc))) ;; (sqlite3:open-database dbname)))
	  (sqlite3:set-busy-handler! db (sqlite3:make-busy-timeout 136000))
	  ;;(sqlite3:execute db "PRAGMA journal_mode=WAL;")
	  (set! *no-sync-db* db)
	  db))))

(define (db:no-sync-set db var val)
  (sqlite3:execute db "INSERT OR REPLACE INTO no_sync_metadat (var,val) VALUES (?,?);" var val))

(define (db:no-sync-del! db var)
  (sqlite3:execute db "DELETE FROM no_sync_metadat WHERE var=?;" var))

			'("/no/such/file")
			glob-list)))
  (apply max
	 (map
	  dbfile:lazy-modification-time 
	  file-list))))

;; dot-locking egg seems not to work, using this for now
;; if lock is older than expire-time then remove it and try again
;; to get the lock
;;
(define (dbfile:simple-file-lock fname #!key (expire-time 300))
  (let ((fmod-time (handle-exceptions
		       ext
		     (current-seconds)
		     (file-modification-time fname))))
    (if (file-exists? fname)
	(if (> (- (current-seconds) fmod-time) expire-time)
	    (begin
	      (handle-exceptions exn #f (delete-file* fname))	
	      (dbfile:simple-file-lock fname expire-time: expire-time))
	    #f)
	(let ((key-string (conc (get-host-name) "-" (current-process-id)))
	      (oup        (open-output-file fname)))
	  (with-output-to-port
	      oup
	    (lambda ()
	      (print key-string)))
	  (close-output-port oup)
	  #;(with-output-to-file fname ;; bizarre. with-output-to-file does not seem to be cleaning up after itself.
	    (lambda ()
	  (print key-string)))
	  (thread-sleep! 0.25)
	  (if (file-exists? fname)
	      (handle-exceptions exn
                #f 
                (with-input-from-file fname
	  	  (lambda ()
		    (equal? key-string (read-line)))))
	      #f)
       )
    )
  )
)

(define (dbfile:simple-file-lock-and-wait fname #!key (expire-time 300))
  (let ((end-time (+ expire-time (current-seconds))))
    (let loop ((got-lock (dbfile:simple-file-lock fname expire-time: expire-time)))
      (if got-lock
	  #t
	  (if (> end-time (current-seconds))
	      (begin
		(thread-sleep! 3)
		(loop (dbfile:simple-file-lock fname expire-time: expire-time)))
	      #f)))))

(define (dbfile:simple-file-release-lock fname)
  (handle-exceptions
      exn
      #f ;; I don't really care why this failed (at least for now)
    (delete-file* fname)))


)