forge: Limit number of parallel CI job runs.

* guix/forge/forge.scm (<forge-project>)[parallel-ci-job-runs]: New
field.
* guix/forge/forge.scm (forge-ci-jobs): Add project context to CI
jobs.
(forge-ci-job-contexts): New function.
(forge-ci-jobs-and-groups): Rename to
forge-ci-jobs+contexts+groups. Also return <forge-laminar-context>
objects.
(forge-service-type): Call forge-ci-jobs+contexts+groups instead of
forge-ci-jobs-and-groups.
* doc/forge.skb (Reference)[<forge-project>]{parallel-ci-job-runs}:
Document it.

2 files changed, 29 insertions, 5 deletions

diff --git a/doc/forge.skb b/doc/forge.skb
index 83b4100..99d1b86 100644
--- a/doc/forge.skb
+++ b/doc/forge.skb
@@ -555,6 +555,9 @@ jobs when a request is received on ,(samp "http://hostname:port/hooks/<name>") \
 specified, a cron job triggers the CI jobs once a day.]))]
          :default [,(code ['post-receive-hook]) for local repositories
 and ,(code ['cron]) for remote repositories])
+       (record-field "parallel-ci-job-runs"
+         [Number of CI job runs of this project to run
+simultaneously])
        (record-field "repository-branch"
          [Main branch of the repository. This field is currently
 unused unused, and may be deprecated in the future.]))
diff --git a/guix/forge/forge.scm b/guix/forge/forge.scm
index 7cf3ff3..6e24cbf 100644
--- a/guix/forge/forge.scm
+++ b/guix/forge/forge.scm
@@ -87,7 +87,9 @@
                               'post-receive-hook)
                              ;; 'cron for remote repositories
                              (else 'cron)))
-                   (thunked)))
+                   (thunked))
+  (parallel-ci-job-runs forge-project-parallel-ci-job-runs
+                        (default 1)))
 
 (define-record-type* <forge-configuration>
   forge-configuration make-forge-configuration
@@ -407,7 +409,24 @@ When @var{verbose?} is #true, verbose build logs are shown."
 (define (forge-ci-jobs config)
   "Return list of CI jobs for forge configuraion @var{config}. Each
 value of the returned list is a @code{<forge-laminar-job>} object."
-  (append-map forge-project-ci-jobs
+  (append-map (lambda (project)
+                ;; Add project context to CI jobs.
+                (map (lambda (job)
+                       (forge-laminar-job
+                        (inherit job)
+                        (contexts (cons (forge-project-name project)
+                                        (forge-laminar-job-contexts job)))))
+                     (forge-project-ci-jobs project)))
+              (forge-configuration-projects config)))
+
+(define (forge-ci-job-contexts config)
+  "Return list of CI job contexts for forge configuration
+@var{config}. Each element of the returned list is a
+@code{<forge-laminar-context>} object."
+  (filter-map (lambda (project)
+                (forge-laminar-context
+                 (name (forge-project-name project))
+                 (executors (forge-project-parallel-ci-job-runs project))))
               (forge-configuration-projects config)))
 
 (define (forge-ci-job-groups config)
@@ -427,11 +446,13 @@ value of the returned list is a @code{<forge-laminar-job>} object."
                                           ")$"))))))
               (forge-configuration-projects config)))
 
-(define (forge-ci-jobs-and-groups config)
+(define (forge-ci-jobs+contexts+groups config)
   "Return list of CI jobs and job groups for forge configuration
 @var{config}. Each element of the returned list is either a
-@code{<forge-laminar-job>} or a @code{<forge-laminar-group>} object."
+@code{<forge-laminar-job>}, @code{<forge-laminar-context>} or
+@code{<forge-laminar-group>} object."
   (append (forge-ci-jobs config)
+          (forge-ci-job-contexts config)
           (forge-ci-job-groups config)))
 
 (define (forge-cron-jobs config)
@@ -475,7 +496,7 @@ value is a list of @code{<webhook-hook>} objects."
    (extensions (list (service-extension activation-service-type
                                         forge-activation)
                      (service-extension forge-laminar-service-type
-                                        forge-ci-jobs-and-groups)
+                                        forge-ci-jobs+contexts+groups)
                      ;; TODO: Run CI job only if there are new commits
                      ;; in the remote repository.
                      (service-extension mcron-service-type