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;;; Guix Data Service -- Information about Guix over time
;;; Copyright © 2019 Christopher Baines <mail@cbaines.net>
;;;
;;; This program is free software: you can redistribute it and/or
;;; modify it under the terms of the GNU Affero General Public License
;;; as published by the Free Software Foundation, either version 3 of
;;; the License, or (at your option) any later version.
;;;
;;; This program is distributed in the hope that it will be useful,
;;; but WITHOUT ANY WARRANTY; without even the implied warranty of
;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
;;; Affero General Public License for more details.
;;;
;;; You should have received a copy of the GNU Affero General Public
;;; License along with this program. If not, see
;;; <http://www.gnu.org/licenses/>.
(define-module (guix-data-service database)
#:use-module (squee)
#:export (with-postgresql-connection
with-postgresql-transaction
with-advisory-session-lock
obtain-advisory-transaction-lock))
;; TODO This isn't exported for some reason
(define pg-conn-finish
(@@ (squee) pg-conn-finish))
(define* (with-postgresql-connection name f)
(define paramstring
(string-append
(or (getenv "GUIX_DATA_SERVICE_DATABASE_PARAMSTRING")
"dbname=guix_data_service user=guix_data_service")
" application_name='guix-data-service " name "'"))
(let* ((conn (connect-to-postgres-paramstring paramstring)))
(with-throw-handler
#t
(lambda ()
(let ((result (f conn)))
(pg-conn-finish conn)
result))
(lambda (key . args)
(pg-conn-finish conn)))))
(define* (with-postgresql-transaction conn f
#:key always-rollback?)
(exec-query conn "BEGIN;")
(with-throw-handler #t
(lambda ()
(let ((result (f conn)))
(exec-query conn (if always-rollback?
"ROLLBACK;"
"COMMIT;"))
result))
(lambda (key . args)
(exec-query conn "ROLLBACK;"))))
(define (with-advisory-session-lock conn lock f)
(let ((lock-number (number->string (symbol-hash lock))))
(exec-query conn
"SELECT pg_advisory_lock($1)"
(list lock-number))
(with-throw-handler #t
(lambda ()
(let ((result (f)))
(exec-query conn
"SELECT pg_advisory_unlock($1)"
(list lock-number))
result))
(lambda (key . args)
(exec-query conn
"SELECT pg_advisory_unlock($1)"
(list lock-number))))))
(define (obtain-advisory-transaction-lock conn lock)
(let ((lock-number (number->string (symbol-hash lock))))
(exec-query conn
"SELECT pg_advisory_xact_lock($1)"
(list lock-number))))
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