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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 (system foreign)
#:use-module (ice-9 match)
#:use-module (ice-9 threads)
#:use-module (squee)
#:use-module (guix-data-service config)
#:export (with-postgresql-connection
with-postgresql-connection-per-thread
with-thread-postgresql-connection
with-postgresql-transaction
check-test-database!
with-advisory-session-lock
obtain-advisory-transaction-lock
exec-query-with-null-handling))
;; TODO This isn't exported for some reason
(define pg-conn-finish
(@@ (squee) pg-conn-finish))
(define (open-postgresql-connection name statement-timeout)
(define paramstring
(string-append
(or (getenv "GUIX_DATA_SERVICE_DATABASE_PARAMSTRING")
(simple-format
#f "dbname=~A user=~A"
(%config 'database-name)
(%config 'database-user)))
" application_name='guix-data-service " name "'"))
(let* ((conn (connect-to-postgres-paramstring
(or (getenv "GUIX_DATA_SERVICE_DATABASE_URI")
paramstring))))
(when statement-timeout
(exec-query
conn
(simple-format #f "SET statement_timeout = ~A"
statement-timeout)))
conn))
(define* (with-postgresql-connection name f #:key (statement-timeout #f))
(let ((conn (open-postgresql-connection name statement-timeout)))
(with-throw-handler
#t
(lambda ()
(call-with-values
(lambda ()
(f conn))
(lambda vals
(pg-conn-finish conn)
(apply values vals))))
(lambda (key . args)
(pg-conn-finish conn)))))
(define %postgresql-connection-parameters
(make-parameter #f))
(define %postgresql-connections-hash-table
(make-parameter #f))
(define* (with-postgresql-connection-per-thread name thunk
#:key (statement-timeout #f))
(parameterize ((%postgresql-connection-parameters
(list name statement-timeout))
(%postgresql-connections-hash-table
(make-hash-table)))
(call-with-values
thunk
(lambda vals
(hash-for-each
(lambda (thread conn)
(pg-conn-finish conn))
(%postgresql-connections-hash-table))
(apply values vals)))))
(define %thread-postgresql-connection
(make-thread-local-fluid))
(define (with-thread-postgresql-connection f)
(define (set-current-thread-connection conn)
(if conn
(hash-set! (%postgresql-connections-hash-table)
(current-thread)
conn)
(hash-remove! (%postgresql-connections-hash-table)
(current-thread)))
(fluid-set! %thread-postgresql-connection
conn))
(let ((conn (fluid-ref %thread-postgresql-connection)))
(if conn
;; Assume an exception here could mean the connection has failed, so
;; close it
(with-exception-handler
(lambda (exn)
(pg-conn-finish conn)
(set-current-thread-connection #f)
(raise-exception exn))
(lambda ()
(f conn)))
(let ((conn (apply open-postgresql-connection
(%postgresql-connection-parameters))))
(set-current-thread-connection conn)
(f 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 (check-test-database! conn)
(match (exec-query conn "SELECT current_database()")
(((name))
(unless (string=? name "guix_data_service_test")
(error "tests being run against non test database")))))
(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))))
(define squee/libpq
(@@ (squee) libpq))
(define squee/unwrap-result-ptr
(@@ (squee) unwrap-result-ptr))
(define %PQgetisnull
(pointer->procedure int
(dynamic-func "PQgetisnull" squee/libpq)
(list '* int int)))
(define (result-serializer-simple-list-with-null-handling result-ptr)
"Get a simple list of lists representing the result of the query"
(let ((rows-range (iota (result-num-rows result-ptr)))
(cols-range (iota (result-num-cols result-ptr))))
(map
(lambda (row-i)
(map
(lambda (col-i)
(let ((val (result-get-value result-ptr row-i col-i)))
(cond
((eq? #f val) '())
((string-null? val)
(if (eq? 1 (%PQgetisnull
(squee/unwrap-result-ptr result-ptr) row-i col-i))
'()
val))
(else val))))
cols-range))
rows-range)))
(define* (exec-query-with-null-handling pg-conn command #:optional (params '()))
(exec-query pg-conn command params
#:serializer result-serializer-simple-list-with-null-handling))
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