[shepherd] 16/16: service: Add 'start-in-the-background'.

[Ludovic Courtès]

civodul pushed a commit to branch wip-fibers
in repository shepherd.

commit 4ef79ea1889ad7077005894b4d05b0862647df90
Author: Ludovic Courtès <ludo@gnu.org>
AuthorDate: Sun Mar 27 22:21:45 2022 +0200

    service: Add 'start-in-the-background'.
    
    * modules/shepherd/service.scm (start-in-the-background): New procedure.
    * doc/shepherd.texi (Service Convenience): Document it.
---
 doc/shepherd.texi            |  9 +++++++++
 modules/shepherd/service.scm | 18 ++++++++++++++++++
 2 files changed, 27 insertions(+)

diff --git a/doc/shepherd.texi b/doc/shepherd.texi
index fbda56b..8be7dc2 100644
--- a/doc/shepherd.texi
+++ b/doc/shepherd.texi
@@ -861,6 +861,15 @@ current value of the @code{running} slot of the service.
 Start a registered service providing @var{obj}.
 @end deffn
 
+@deffn {procedure} start-in-the-background @var{services}
+Start the services named by @var{services}, a list of symbols, in the
+background.  In other words, this procedure returns immediately without
+waiting until all of @var{services} have been started.
+
+This procedure can be useful in a configuration file because it lets you
+interact right away with shepherd using the @command{herd} command.
+@end deffn
+
 @deffn {method} stop (obj <symbol>)
 Stop a registered service providing @var{obj}.
 @end deffn
diff --git a/modules/shepherd/service.scm b/modules/shepherd/service.scm
index aa12461..db482f8 100644
--- a/modules/shepherd/service.scm
+++ b/modules/shepherd/service.scm
@@ -58,6 +58,7 @@
             enable
             disable
             start
+            start-in-the-background
             stop
             action
             enforce
@@ -675,6 +676,23 @@ results."
                (apply action service the-action args))
              which-services))))
 
+(define (start-in-the-background services)
+  "Start the services named by @var{services}, a list of symbols, in the
+background.  In other words, this procedure returns immediately without
+waiting until all of @var{services} have been started.
+
+This procedure can be useful in a configuration file because it lets you
+interact right away with shepherd using the @command{herd} command."
+  (spawn-fiber
+   (lambda ()
+     (for-each (lambda (service)
+                 ;; Keep going if one of SERVICES fails to start.
+                 (guard (c ((service-error? c)
+                            (local-output
+                             (l10n "Failed to start ~a in the background.")
+                             service)))
+                   (start service)))
+               services))))