Remove workers hash table.

* src/cuirass/database.scm (db-add-worker): Rename ...
(db-add-or-update-worker): ... into this new procedure.
(db-get-worker, db-remove-unresponsive-workers): New procedures.
* src/cuirass/remote-server.scm (%workers): Remove it.
(pop-build): Adapt it.
(remove-unresponsive-workers!): Remove it.
(read-worker-exp): Adapt it.
(zmq-start-proxy): Ditto.
* tests/database.scm ("db-add-worker"): Rename ...
("db-add-or-update-worker"): ... into this new test.
("db-get-worker", "db-remove-unresponsive-workers"): New tests.

src/cuirass/database.scm

@@ -88,8 +88,10 @@
             db-get-builds-max
             db-get-evaluation-specification
             db-get-build-product-path
-            db-add-worker
+            db-add-or-update-worker
+            db-get-worker
             db-get-workers
+            db-remove-unresponsive-workers
             db-clear-workers
             db-clear-build-queue
             ;; Parameters.
@@ -1370,7 +1372,7 @@ WHERE id = " id))
       ((path) path)
       (else #f))))
 
-(define (db-add-worker worker)
+(define (db-add-or-update-worker worker)
   "Insert WORKER into Worker table."
   (with-db-worker-thread db
     (exec-query/bind db "\
@@ -1380,7 +1382,24 @@ VALUES ("
                      (worker-address worker) ", "
                      (worker-machine worker) ", "
                      (string-join (worker-systems worker) ",") ", "
-                     (worker-last-seen worker) ");")))
+                     (worker-last-seen worker) ")
+ON CONFLICT(name) DO UPDATE
+SET last_seen = " (worker-last-seen worker) ";")))
+
+(define (db-get-worker name)
+  "Return the worker with the given NAME."
+  (with-db-worker-thread db
+    (match (expect-one-row
+            (exec-query/bind db "
+SELECT name, address, machine, systems, last_seen from Workers
+WHERE name = " name ";"))
+      ((name address machine systems last-seen)
+       (worker
+        (name name)
+        (address address)
+        (machine machine)
+        (systems (string-split systems #\,))
+        (last-seen last-seen))))))
 
 (define (db-get-workers)
   "Return the workers in Workers table."
@@ -1401,6 +1420,11 @@ SELECT name, address, machine, systems, last_seen from Workers"))
                       (last-seen last-seen))
                      workers)))))))
 
+(define (db-remove-unresponsive-workers timeout)
+  (with-db-worker-thread db
+    (exec-query/bind db "DELETE FROM Workers WHERE
+(extract(epoch from now())::int - last_seen) > " timeout ";")))
+
 (define (db-clear-workers)
   "Remove all workers from Workers table."
   (with-db-worker-thread db

src/cuirass/remote-server.scm

@@ -158,15 +158,11 @@ Start a remote build server.\n"))
 ;;; Build workers.
 ;;;
 
-(define %workers
-  ;; Set of connected workers.
-  (make-hash-table))
-
 (define (pop-build name)
   (define (random-system systems)
     (list-ref systems (random (length systems))))
 
-  (let ((worker (hash-ref %workers name)))
+  (let ((worker (db-get-worker name)))
     (and worker
          (let ((system (random-system
                         (worker-systems worker))))
@@ -177,36 +173,18 @@ Start a remote build server.\n"))
              ((build) build)
              (() #f))))))
 
-(define (remove-unresponsive-workers!)
-  (let ((unresponsive
-         (hash-fold (lambda (key value old)
-                      (let* ((last-seen (worker-last-seen value))
-                             (diff (- (current-time) last-seen)))
-                        (if (> diff (%worker-timeout))
-                            (cons key old)
-                            old)))
-                    '()
-                    %workers)))
-    (for-each (lambda (worker)
-                (hash-remove! %workers worker))
-              unresponsive)))
-
 (define* (read-worker-exp exp #:key reply-worker)
   "Read the given EXP sent by a worker.  REPLY-WORKER is a procedure that can
 be used to reply to the worker."
-  (define (update-workers! base-worker proc)
+  (define (update-worker! base-worker)
     (let* ((worker* (worker
                      (inherit (sexp->worker base-worker))
-                     (last-seen (current-time))))
-           (name (worker-name worker*)))
-      (proc name)
-      (hash-set! %workers name worker*)))
+                     (last-seen (current-time)))))
+      (db-add-or-update-worker worker*)))
 
   (match (zmq-read-message exp)
     (('worker-ready worker)
-     (update-workers! worker
-                      (lambda (name)
-                        (log-message (G_ "Worker `~a' is ready.") name))))
+     (update-worker! worker))
     (('worker-request-work name)
      (let ((build (pop-build name)))
        (if build
@@ -224,11 +202,7 @@ be used to reply to the worker."
            (reply-worker
             (zmq-no-build-message)))))
     (('worker-ping worker)
-     (update-workers! worker (const #t))
-     (db-clear-workers)
-     (hash-for-each (lambda (key value)
-                      (db-add-worker value))
-                    %workers))
+     (update-worker! worker))
     (('build-started ('drv drv) ('worker worker))
      (let ((log-file (log-path (%cache-directory) drv)))
        (log-message "build started: '~a' on ~a." drv worker)
@@ -387,7 +361,7 @@ frontend to the workers connected through the TCP backend."
                    (zmq-send-bytevector fetch-socket rest)
                    (read-worker-exp (bv->string rest)
                                     #:reply-worker reply-worker))))))
-        (remove-unresponsive-workers!)
+        (db-remove-unresponsive-workers (%worker-timeout))
         (loop)))))
 
 

tests/database.scm

@@ -327,14 +327,26 @@ timestamp, checkouttime, evaltime) VALUES ('guix', 0, 0, 0, 0);")
     "path"
     (db-get-build-product-path 1))
 
-  (test-equal "db-add-worker"
+  (test-equal "db-add-or-update-worker"
     1
-    (db-add-worker %dummy-worker))
+    (begin
+      (db-add-or-update-worker %dummy-worker)
+      (db-add-or-update-worker %dummy-worker)))
+
+  (test-equal "db-get-worker"
+    %dummy-worker
+    (db-get-worker "worker"))
 
   (test-equal "db-get-workers"
     (list %dummy-worker)
     (db-get-workers))
 
+  (test-equal "db-remove-unresponsive-workers"
+    '()
+    (begin
+      (db-remove-unresponsive-workers 50)
+      (db-get-workers)))
+
   (test-equal "db-clear-workers"
     '()
     (begin