Feature 04 task 5: Async job runner and GET /api/v1/jobs/{id} (#29)

Co-authored-by: dev_agent <dev_agent@cubecraftlabs.com>
Co-committed-by: dev_agent <dev_agent@cubecraftlabs.com>

cmd/server/jobs_test.go

@@ -0,0 +1,62 @@
+package main
+
+import (
+	"context"
+	"io"
+	"log/slog"
+	"testing"
+	"time"
+
+	"code.cubecraftlabs.com/Maniacs_Mansion/Meal-Quest/internal/jobs"
+)
+
+// TestNewJobRunnerRunsNoop proves the runner run builds can execute a job:
+// a noop job enqueued before Start, as at boot, succeeds with its result.
+func TestNewJobRunnerRunsNoop(t *testing.T) {
+	ctx := context.Background()
+	db, err := openStore(ctx, t.TempDir())
+	if err != nil {
+		t.Fatal(err)
+	}
+	t.Cleanup(func() {
+		if err := db.Close(); err != nil {
+			t.Error(err)
+		}
+	})
+	runner, kinds, err := newJobRunner(db, slog.New(slog.NewTextHandler(io.Discard, nil)))
+	if err != nil {
+		t.Fatal(err)
+	}
+	id, err := kinds.builtins.Noop.Enqueue(ctx, jobs.NoopPayload{})
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	jobsCtx, stopJobs := context.WithCancel(ctx)
+	if err := runner.Start(jobsCtx); err != nil {
+		stopJobs()
+		t.Fatal(err)
+	}
+	t.Cleanup(func() {
+		stopJobs()
+		runner.Wait()
+	})
+
+	deadline := time.Now().Add(5 * time.Second)
+	for {
+		job, err := runner.Get(ctx, id)
+		if err != nil {
+			t.Fatal(err)
+		}
+		if job.Status == jobs.StatusSucceeded || job.Status == jobs.StatusFailed {
+			if job.Kind != jobs.KindNoop || job.Status != jobs.StatusSucceeded || string(job.Result) != `{"ok":true}` || job.Error != nil {
+				t.Fatalf("noop job = %+v (result %s), want succeeded with {\"ok\":true}", job, job.Result)
+			}
+			return
+		}
+		if time.Now().After(deadline) {
+			t.Fatalf("noop job never finished; last %+v", job)
+		}
+		time.Sleep(5 * time.Millisecond)
+	}
+}

cmd/server/main.go

@@ -18,6 +18,7 @@ import (
 	"code.cubecraftlabs.com/Maniacs_Mansion/Meal-Quest/internal/forwarded"
 	"code.cubecraftlabs.com/Maniacs_Mansion/Meal-Quest/internal/frontend"
 	"code.cubecraftlabs.com/Maniacs_Mansion/Meal-Quest/internal/household"
+	"code.cubecraftlabs.com/Maniacs_Mansion/Meal-Quest/internal/jobs"
 	"code.cubecraftlabs.com/Maniacs_Mansion/Meal-Quest/internal/secretbox"
 	"code.cubecraftlabs.com/Maniacs_Mansion/Meal-Quest/internal/server"
 	"code.cubecraftlabs.com/Maniacs_Mansion/Meal-Quest/internal/store"
@@ -27,6 +28,9 @@ import (
 // version is set at build time with -ldflags "-X main.version=<version>".
 var version = "dev"
 
+// jobWorkers is the number of background jobs run at once.
+const jobWorkers = 2
+
 func main() {
 	cfg, err := config.Load()
 	if err != nil {
@@ -63,6 +67,10 @@ func run(cfg config.Config, logger *slog.Logger) error {
 		return err
 	}
 	settings := household.NewSettingsService(db)
+	runner, _, err := newJobRunner(db, logger)
+	if err != nil {
+		return err
+	}
 
 	sessions, err := auth.NewSessionManager(db, cfg.SessionIdle, cfg.SessionMax)
 	if err != nil {
@@ -80,10 +88,22 @@ func run(cfg config.Config, logger *slog.Logger) error {
 		return err
 	}
 
-	router, err := server.NewRouter(logger, version, cfg.TrustedProxy, authFlow, sessions, settings, frontend.Assets())
+	router, err := server.NewRouter(logger, version, cfg.TrustedProxy, authFlow, sessions, settings, runner, frontend.Assets())
 	if err != nil {
 		return err
 	}
+
+	// Start fails the jobs a previous process left running before any
+	// worker runs. The workers stop, and are waited for, before the
+	// database closes.
+	jobsCtx, stopJobs := context.WithCancel(ctx)
+	defer func() {
+		stopJobs()
+		runner.Wait()
+	}()
+	if err := runner.Start(jobsCtx); err != nil {
+		return err
+	}
 	srv := &http.Server{
 		Addr:              cfg.HTTPAddr,
 		Handler:           router,
@@ -165,6 +185,35 @@ func seedDefaults(ctx context.Context, db *store.Store, defaultTZ string) error
 	return household.SeedNotificationPrefs(ctx, db)
 }
 
+// jobKinds enqueues every job kind the server runs.
+type jobKinds struct {
+	builtins *jobs.Builtins
+}
+
+// newJobRunner returns the job runner with every job kind registered, ready
+// to Start.
+func newJobRunner(db *store.Store, logger *slog.Logger) (*jobs.Runner, *jobKinds, error) {
+	runner, err := jobs.NewRunner(db, logger, jobWorkers)
+	if err != nil {
+		return nil, nil, err
+	}
+	kinds, err := registerJobKinds(runner)
+	if err != nil {
+		return nil, nil, err
+	}
+	return runner, kinds, nil
+}
+
+// registerJobKinds registers every job kind's handler on runner. Each
+// feature's job kinds are registered here.
+func registerJobKinds(runner *jobs.Runner) (*jobKinds, error) {
+	builtins, err := jobs.RegisterBuiltins(runner)
+	if err != nil {
+		return nil, err
+	}
+	return &jobKinds{builtins: builtins}, nil
+}
+
 // logListening logs the startup line. Only the public URL's origin is logged
 // so no credential-bearing URL component can reach the log.
 func logListening(logger *slog.Logger, cfg config.Config) {