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-rw-r--r--gnu/services/dmd.scm34
1 files changed, 33 insertions, 1 deletions
diff --git a/gnu/services/dmd.scm b/gnu/services/dmd.scm
index 7b6434a0ae..e87b9e4415 100644
--- a/gnu/services/dmd.scm
+++ b/gnu/services/dmd.scm
@@ -27,7 +27,9 @@
#:use-module (gnu services)
#:use-module (gnu packages admin)
#:use-module (ice-9 match)
+ #:use-module (ice-9 vlist)
#:use-module (srfi srfi-1)
+ #:use-module (srfi srfi-26)
#:use-module (srfi srfi-34)
#:use-module (srfi srfi-35)
#:export (dmd-root-service-type
@@ -42,7 +44,9 @@
dmd-service-respawn?
dmd-service-start
dmd-service-stop
- dmd-service-auto-start?))
+ dmd-service-auto-start?
+
+ dmd-service-back-edges))
;;; Commentary:
;;;
@@ -179,4 +183,32 @@ failure."
(gexp->file "dmd.conf" config)))
+(define (dmd-service-back-edges services)
+ "Return a procedure that, when given a <dmd-service> from SERVICES, returns
+the list of <dmd-service> that depend on it."
+ (define provision->service
+ (let ((services (fold (lambda (service result)
+ (fold (cut vhash-consq <> service <>)
+ result
+ (dmd-service-provision service)))
+ vlist-null
+ services)))
+ (lambda (name)
+ (match (vhash-assq name services)
+ ((_ . service) service)
+ (#f #f)))))
+
+ (define edges
+ (fold (lambda (service edges)
+ (fold (lambda (requirement edges)
+ (vhash-consq (provision->service requirement) service
+ edges))
+ edges
+ (dmd-service-requirement service)))
+ vlist-null
+ services))
+
+ (lambda (service)
+ (vhash-foldq* cons '() service edges)))
+
;;; dmd.scm ends here