feat: tokenization start, waitlist for background task graceful exit

projects/greenlight/cmd/api/helpers.go

@@ -178,8 +178,11 @@ func (app *application) readInt(qs url.Values, key string, defaultValue int, v *
 
 // The background() helper accepts an arbitrary function as a parameter.
 func (app *application) background(fn func()) {
+	app.wg.Add(1)
 	// Launch a background goroutine.
 	go func() {
+		// Use defer to decrement the WaitGroup counter before the goroutine returns.
+		defer app.wg.Done()
 		// Recover any panic.
 		defer func() {
 			if err := recover(); err != nil {

projects/greenlight/cmd/api/main.go

@@ -5,6 +5,7 @@ import (
 	"database/sql"
 	"flag"
 	"os"
+	"sync"
 	"time"
 
 	"github.com/joho/godotenv"
@@ -57,6 +58,7 @@ type application struct {
 	logger *jsonlog.Logger
 	models data.Models
 	mailer mailer.Mailer
+	wg     sync.WaitGroup
 }
 
 func main() {
@@ -94,7 +96,7 @@ func main() {
 	// make sure to replace the default values for smtp-username and smtp-password
 	// with your own Mailtrap credentials.
 	flag.StringVar(&cfg.smtp.host, "smtp-host", "sandbox.smtp.mailtrap.io", "SMTP host")
-	flag.IntVar(&cfg.smtp.port, "smtp-port", 25, "SMTP port")
+	flag.IntVar(&cfg.smtp.port, "smtp-port", 2525, "SMTP port")
 	flag.StringVar(&cfg.smtp.username, "smtp-username", "3d946287da35ea", "SMTP username")
 	flag.StringVar(&cfg.smtp.password, "smtp-password", "d06a774b484ca3", "SMTP password")
 	flag.StringVar(&cfg.smtp.sender, "smtp-sender", "Greenlight <no-reply@greenlight.debuggingjon.dev>", "SMTP sender")

projects/greenlight/cmd/api/server.go

@@ -20,31 +20,39 @@ func (app *application) serve() error {
 		WriteTimeout: 30 * time.Second,
 	}
 
-	// Create a shutdownError channel. We will use this to receive any errors returned
-	// by the graceful Shutdown() function.
 	shutdownError := make(chan error)
 
 	go func() {
 		quit := make(chan os.Signal, 1)
-		// Intercept the signals, as before.
 		signal.Notify(quit, syscall.SIGINT, syscall.SIGTERM)
 		s := <-quit
 
-		// Update the log entry to say "shutting down server" instead of "caught signal".
+		app.logger.PrintInfo("caught signal", map[string]string{
-		app.logger.PrintInfo("shutting down server", map[string]string{
 			"signal": s.String(),
 		})
 
-		// Create a context with a 5-second timeout.
 		ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
 		defer cancel()
 
-		// Call Shutdown() on our server, passing in the context we just made.
+		// Call Shutdown() on the server like before, but now we only send on the
-		// Shutdown() will return nil if the graceful shutdown was successful, or an
+		// shutdownError channel if it returns an error.
-		// error (which may happen because of a problem closing the listeners, or
+		err := srv.Shutdown(ctx)
-		// because the shutdown didn't complete before the 5-second context deadline is
+		if err != nil {
-		// hit). We relay this return value to the shutdownError channel.
+			shutdownError <- err
-		shutdownError <- srv.Shutdown(ctx)
+		}
+
+		// Log a message to say that we're waiting for any background goroutines to
+		// complete their tasks.
+		app.logger.PrintInfo("completing background tasks", map[string]string{
+			"addr": srv.Addr,
+		})
+
+		// Call Wait() to block until our WaitGroup counter is zero --- essentially
+		// blocking until the background goroutines have finished. Then we return nil on
+		// the shutdownError channel, to indicate that the shutdown completed without
+		// any issues.
+		app.wg.Wait()
+		shutdownError <- nil
 	}()
 
 	app.logger.PrintInfo("starting server", map[string]string{
@@ -52,25 +60,16 @@ func (app *application) serve() error {
 		"env":  app.config.env,
 	})
 
-	// Calling Shutdown() on our server will cause ListenAndServe() to immediately
-	// return a http.ErrServerClosed error. So if we see this error, it is actually a
-	// good thing and an indication that the graceful shutdown has started. So we check
-	// specifically for this, only returning the error if it is NOT http.ErrServerClosed.
 	err := srv.ListenAndServe()
 	if !errors.Is(err, http.ErrServerClosed) {
 		return err
 	}
 
-	// Otherwise, we wait to receive the return value from Shutdown() on the
-	// shutdownError channel. If return value is an error, we know that there was a
-	// problem with the graceful shutdown and we return the error.
 	err = <-shutdownError
 	if err != nil {
 		return err
 	}
 
-	// At this point we know that the graceful shutdown completed successfully and we
-	// log a "stopped server" message.
 	app.logger.PrintInfo("stopped server", map[string]string{
 		"addr": srv.Addr,
 	})

projects/greenlight/docs/api/greenlight-bruno/Users/Create User.yml

@@ -11,7 +11,7 @@ http:
     data: |-
       {
         "name": "Carol 3",
-        "email": "carol3@example.com",
+        "email": "carol5@example.com",
         "password": "pa55word"
       }
   auth: inherit

projects/greenlight/migrations/000005_create_tokens_table.down.sql

@@ -0,0 +1 @@
+DROP TABLE IF EXISTS tokens;

projects/greenlight/migrations/000005_create_tokens_table.up.sql

@@ -0,0 +1,7 @@
+CREATE TABLE IF NOT EXISTS tokens (
+    hash bytea PRIMARY KEY,
+    user_id bigint NOT NULL REFERENCES users ON DELETE CASCADE,
+    expiry timestamp(0) with time zone NOT NULL,
+    scope text NOT NULL
+);
+