database: Add "db-get-build-percentage".

* src/cuirass/database.scm (db-get-build-percentage): New procedure.
* tests/database.scm ("db-get-build-percentage"): New test.

src/cuirass/database.scm

@@ -64,6 +64,7 @@
             db-get-output
             db-get-outputs
             db-get-time-since-previous-build
+            db-get-build-percentage
             db-register-builds
             db-update-build-status!
             db-update-build-worker!
@@ -667,6 +668,25 @@ WHERE job_name  = " job-name "AND specification = " specification
        (string->number time))
       (else #f))))
 
+(define (db-get-build-percentage build-id)
+  "Return the build completion percentage for BUILD-ID."
+  (with-db-worker-thread db
+    (match (expect-one-row
+            (exec-query/bind db "
+SELECT LEAST(duration::float/last_duration * 100, 100)::int AS percentage FROM
+(SELECT (extract(epoch from now())::int - starttime) as duration,
+last_build.duration AS last_duration FROM builds,
+(SELECT (stoptime - starttime) AS duration FROM Builds
+WHERE job_name IN
+(SELECT job_name from Builds WHERE id = " build-id ")
+AND status = 0
+ORDER BY Builds.timestamp DESC LIMIT 1) last_build
+where id = " build-id ") d;
+"))
+      ((time)
+       (string->number time))
+      (else #f))))
+
 (define (db-register-builds jobs eval-id specification)
   (define (new-outputs? outputs)
     (let ((new-outputs

tests/database.scm

@@ -402,6 +402,37 @@ timestamp, checkouttime, evaltime) VALUES ('guix', 0, 0, 0, 0);")
                                       #:outputs `(("out" . "/bar"))))
       (sort (db-get-pending-derivations) string<?)))
 
+  (test-assert "db-get-build-percentage"
+    (begin
+      (let* ((ts (time-second (current-time time-utc)))
+             (old `((#:derivation . "/last.drv")
+                    (#:eval-id . 2)
+                    (#:job-name . "job")
+                    (#:timestamp . ,(- ts 10))
+                    (#:status . 0)
+                    (#:starttime . 10)
+                    (#:stoptime . 20)
+                    (#:system . "x86_64-linux")
+                    (#:nix-name . "foo")
+                    (#:log . "log")
+                    (#:outputs . ())))
+             (new `((#:derivation . "/cur.drv")
+                    (#:eval-id . 2)
+                    (#:job-name . "job")
+                    (#:timestamp . ,(- ts 5))
+                    (#:starttime . ,(- ts 5))
+                    (#:system . "x86_64-linux")
+                    (#:nix-name . "foo")
+                    (#:log . "log")
+                    (#:outputs . ()))))
+        (db-add-build old)
+        (db-add-build new)
+        (let ((last-id
+               (match (expect-one-row
+                       (exec-query (%db) "SELECT MAX(id) FROM Builds;"))
+                 ((id) (string->number id)))))
+          (>= (db-get-build-percentage last-id) 50)))))
+
   (test-assert "db-close"
     (begin
       (exec-query (%db) (format #f "DROP OWNED BY CURRENT_USER;"))