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-
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(if (not (file-exists? dbpath))
(create-directory dbpath #t))
(debug:print-info 0 *default-log-port* "Opening "dbpath"/no-sync.db")
(let* ((dbname (conc dbpath "/no-sync.db"))
(db-exists (file-exists? dbname))
(init-proc (lambda (db)
(if (not db-exists)
(for-each
(lambda (stmt)
(sqlite3:execute db stmt))
(begin
(sqlite3:execute db "CREATE TABLE IF NOT EXISTS no_sync_metadat (var TEXT,val TEXT, CONSTRAINT no_sync_metadat_constraint UNIQUE (var));"))
(list
"CREATE TABLE IF NOT EXISTS no_sync_metadat
(var TEXT,
val TEXT,
CONSTRAINT no_sync_metadat_constraint UNIQUE (var));"
"CREATE TABLE IF NOT EXISTS no_sync_locks
(key TEXT,
val TEXT,
CONSTRAINT no_sync_metadat_constraint UNIQUE (var));")))))
)))
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(let ((newres (if (string? res)
(string->number res)
#f)))
(if newres
newres
res))
res)))
(define (db:extract-time-identifier instr)
(let ((tokens (string-split instr "+")))
(match tokens
((t i)(cons (string->number t) i))
((t) (cons (string->number t) #f))
(else
(assert #f "FATAL: db:extract-time-identifier handed bad data "instr)))))
;; transaction protected lock aquisition
;; either:
;; fails returns (#f . lock-creation-time)
;; succeeds (returns (#t . lock-creation-time)
;; use (db:no-sync-del! db keyname) to release the lock
;;
(define (db:no-sync-get-lock-with-id db keyname identifier)
(sqlite3:with-transaction
db
(lambda ()
(condition-case
(let* ((curr-val (db:no-sync-get/default db keyname #f)))
(if curr-val
(match (db:extract-time-identifier curr-val)
((timestamp ident)
(if (equal? ident identifier)
#t ;; this *is* my lock
#f)) ;; nope, not my lock
(else #f)) ;; nope, not my lock
(let ((lock-value (if identifier
(conc (current-seconds)"+"identifier)
(current-seconds))))
(sqlite3:execute db "INSERT OR REPLACE INTO no_sync_metadat (var,val) VALUES(?,?);" keyname lock-value)
#t)))
(exn (io-error) (dbfile:print-err "ERROR: i/o error with no-sync db. Check permissions, disk space etc. and try again."))
(exn (corrupt) (dbfile:print-err "ERROR: database no-sync db is corrupt. Repair it to proceed."))
(exn (busy) (dbfile:print-err "ERROR: database no-sync db is locked. Try copying to another location, remove original and copy back."))
(exn (permission)(dbfile:print-err "ERROR: database no-sync db has some permissions problem."))
(exn () ;; (status done) ;; I don't know how to detect status done but no data!
(dbfile:print-err "ERROR: Unknown error with database no-sync db message: exn="(condition->list exn)", \n"
((condition-property-accessor 'exn 'message) exn))
#f)))))
;; transaction protected lock aquisition
;; either:
;; fails returns (#f . lock-creation-time)
;; succeeds (returns (#t . lock-creation-time)
;; use (db:no-sync-del! db keyname) to release the lock
;;
;;
;;
(define (db:no-sync-get-lock db keyname . identification)
|