Re-work how agents handle missing inputs

Don't start the build if there are missing inputs.

1 files changed, 30 insertions, 11 deletions

diff --git a/guix-build-coordinator/agent.scm b/guix-build-coordinator/agent.scm
index f091401..0db99eb 100644
--- a/guix-build-coordinator/agent.scm
+++ b/guix-build-coordinator/agent.scm
@@ -42,14 +42,33 @@
                        already-allocated-builds))))
     (for-each (lambda (build)
                 (let ((derivation-name (assoc-ref build "derivation-name")))
-                  (pre-build-process derivation-name)
-                  (let ((result (perform-build derivation-name)))
-                    (post-build uuid coordinator-uri password
-                                (assoc-ref build "uuid")
-                                derivation-name))))
+                  (let ((pre-build-status (pre-build-process derivation-name)))
+                    (if (eq? (assq-ref pre-build-status 'result) 'success)
+                        (let ((result (perform-build derivation-name)))
+                          (post-build uuid coordinator-uri password
+                                      (assoc-ref build "uuid")
+                                      derivation-name))
+                        (simple-format #t "failure: ~A\n" pre-build-status)))))
               builds)))
 
 (define (pre-build-process derivation-name)
+  (define (find-missing-inputs inputs)
+    (let ((output-paths
+           (append-map derivation-input-output-paths inputs)))
+
+      (with-store store
+        (fold (lambda (file result)
+                (if (file-exists? file)
+                    result
+                    (if (has-substitutes? store file)
+                        (begin
+                          (with-store store
+                            (build-things store output-paths))
+                          result)
+                        (cons file result))))
+              '()
+              output-paths))))
+
   (let ((derivation
          (if (file-exists? derivation-name)
              (read-derivation-from-file derivation-name)
@@ -63,12 +82,12 @@
         (with-store store
           (delete-paths store output-file-names)))
 
-      (let* ((inputs (derivation-inputs derivation))
-             (output-paths
-              (append-map derivation-input-output-paths inputs)))
-
-        (with-store store
-          (build-things store output-paths))))))
+      (let ((missing-inputs
+             (find-missing-inputs (derivation-inputs derivation))))
+        (if (null? missing-inputs)
+            '((result . success))
+            `((result         . failure)
+              (missing-inputs . ,missing-inputs)))))))
 
 (define (perform-build derivation-name)
   (with-store store