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01/02: services: herd: Add 'wait-for-service'.
From: |
guix-commits |
Subject: |
01/02: services: herd: Add 'wait-for-service'. |
Date: |
Sat, 28 May 2022 17:24:46 -0400 (EDT) |
civodul pushed a commit to branch master
in repository guix.
commit b04ae71defe0bd2a5fbd2df07d55cfe3eb40cba9
Author: Ludovic Courtès <ludo@gnu.org>
AuthorDate: Sat May 28 23:03:45 2022 +0200
services: herd: Add 'wait-for-service'.
* gnu/services/herd.scm (wait-for-service): New procedure.
---
gnu/services/herd.scm | 36 +++++++++++++++++++++++++++++++++++-
1 file changed, 35 insertions(+), 1 deletion(-)
diff --git a/gnu/services/herd.scm b/gnu/services/herd.scm
index 80d08f849e..a7c845b4b0 100644
--- a/gnu/services/herd.scm
+++ b/gnu/services/herd.scm
@@ -58,7 +58,8 @@
load-services/safe
start-service
stop-service
- restart-service))
+ restart-service
+ wait-for-service))
;;; Commentary:
;;;
@@ -313,6 +314,39 @@ when passed a service with an already-registered name."
(with-shepherd-action name ('restart) result
result))
+(define* (wait-for-service name #:key (timeout 20))
+ "Wait for the service providing NAME, a symbol, to be up and running, and
+return its \"running value\". Give up after TIMEOUT seconds and raise a
+'&shepherd-error' exception. Raise a '&service-not-found-error' exception
+when NAME is not found."
+ (define (relevant-service? service)
+ (memq name (live-service-provision service)))
+
+ (define start
+ (car (gettimeofday)))
+
+ ;; Note: As of Shepherd 0.9.1, we cannot just call the 'start' method and
+ ;; wait for it: it would spawn an additional elogind process. Thus, poll.
+ (let loop ((attempts 0))
+ (define services
+ (current-services))
+
+ (define now
+ (car (gettimeofday)))
+
+ (when (>= (- now start) timeout)
+ (raise (condition (&shepherd-error)))) ;XXX: better exception?
+
+ (match (find relevant-service? services)
+ (#f
+ (raise (condition (&service-not-found-error
+ (service name)))))
+ (service
+ (or (live-service-running service)
+ (begin
+ (sleep 1)
+ (loop (+ attempts 1))))))))
+
;; Local Variables:
;; eval: (put 'alist-let* 'scheme-indent-function 2)
;; eval: (put 'with-shepherd 'scheme-indent-function 1)