Add Guile GC related metrics

I'm seeing mmap(PROT_NONE) failed crashes, and maybe these metrics will help
in understanding what's going on.

1 files changed, 30 insertions, 1 deletions

diff --git a/guix-build-coordinator/utils.scm b/guix-build-coordinator/utils.scm
index fea9c1c..ee1fea3 100644
--- a/guix-build-coordinator/utils.scm
+++ b/guix-build-coordinator/utils.scm
@@ -23,6 +23,7 @@
   #:use-module (gcrypt hash)
   #:use-module (gcrypt random)
   #:use-module (json)
+  #:use-module (prometheus)
   #:use-module (guix pki)
   #:use-module (guix utils)
   #:use-module (guix config)
@@ -59,7 +60,9 @@
 
             get-load-average
 
-            running-on-the-hurd?))
+            running-on-the-hurd?
+
+            get-gc-metrics-updater))
 
 (eval-when (eval load compile)
   (begin
@@ -838,3 +841,29 @@ again."
     (unless cached-system
       (set! cached-system (utsname:sysname (uname))))
     (string=? cached-system "GNU")))
+
+(define (get-gc-metrics-updater registry)
+  (define metrics
+    `((gc-time-taken
+       . ,(make-gauge-metric registry "guile_gc_time_taken"))
+      (heap-size
+       . ,(make-gauge-metric registry "guile_heap_size"))
+      (heap-free-size
+       . ,(make-gauge-metric registry "guile_heap_free_size"))
+      (heap-total-allocated
+       . ,(make-gauge-metric registry "guile_heap_total_allocated"))
+      (heap-allocated-since-gc
+       . ,(make-gauge-metric registry "guile_allocated_since_gc"))
+      (protected-objects
+       . ,(make-gauge-metric registry "guile_gc_protected_objects"))
+      (gc-times
+       . ,(make-gauge-metric registry "guile_gc_times"))))
+
+  (lambda ()
+    (let ((stats (gc-stats)))
+      (for-each
+       (match-lambda
+         ((name . metric)
+          (let ((value (assq-ref stats name)))
+            (metric-set metric value))))
+       metrics))))