Create an UpdateDispatcher interface to decouple Dispatcher and Updat…

…er components (#120)

* Make a new interface to abstract away the dispatcher, allowing for custom implementations

* Move dispatcher to be an interface

* fix lint

* fix tests and add comments

ext/common_test.go

@@ -1,6 +1,8 @@
 package ext
 
 import (
+	"errors"
+
 	"github.com/PaulSonOfLars/gotgbot/v2"
 )
 
@@ -21,11 +23,17 @@ func (d DummyHandler) Name() string {
 	return "dummy" + d.N
 }
 
+var ErrBadDispatcher = errors.New("can only inject updates if the dispatcher is of type *Dispatcher")
+
 func (u *Updater) InjectUpdate(token string, upd gotgbot.Update) error {
 	bData, ok := u.botMapping.getBot(token)
 	if !ok {
 		return ErrNotFound
 	}
 
-	return u.Dispatcher.ProcessUpdate(bData.bot, &upd, nil)
+	d, ok := u.Dispatcher.(*Dispatcher)
+	if !ok {
+		return ErrBadDispatcher
+	}
+	return d.ProcessUpdate(bData.bot, &upd, nil)
 }

ext/dispatcher.go

@@ -46,8 +46,18 @@ var (
 	ContinueGroups = errors.New("group iteration continued")
 )
 
+// The UpdateDispatcher interface is used to abstract away common Dispatcher implementations.
+// It assumes that all incoming updates come through a JSON channel.
+type UpdateDispatcher interface {
+	Start(b *gotgbot.Bot, updates <-chan json.RawMessage)
+	Stop()
+}
+
+// The Dispatcher struct is the default UpdateDispatcher implementation.
+// It supports grouping of update handlers, allowing for powerful update handling flows.
+// Customise the handling of updates by wrapping the Processor struct.
 type Dispatcher struct {
-	// Processor defines how to process the raw updates being processed by the Dispatcher.
+	// Processor defines how to process the raw updates being handled by the Dispatcher.
 	// This can be extended to include additional error handling, metrics, etc.
 	Processor Processor
 
@@ -80,6 +90,9 @@ type Dispatcher struct {
 	waitGroup sync.WaitGroup
 }
 
+// Ensure compile-time type safety.
+var _ UpdateDispatcher = &Dispatcher{}
+
 // DispatcherOpts can be used to configure or override default Dispatcher behaviours.
 type DispatcherOpts struct {
 	// Processor allows for providing custom Processor interfaces with different behaviours.
@@ -109,7 +122,7 @@ type DispatcherOpts struct {
 	MaxRoutines int
 }
 
-// NewDispatcher creates a new dispatcher, which process and handles incoming updates from the updates channel.
+// NewDispatcher creates a new Dispatcher, which process and handles incoming updates from the updates channel.
 func NewDispatcher(opts *DispatcherOpts) *Dispatcher {
 	var errHandler DispatcherErrorHandler
 	var panicHandler DispatcherPanicHandler
@@ -175,7 +188,7 @@ func (d *Dispatcher) MaxUsage() int {
 
 // Start to handle incoming updates.
 // This is a blocking method; it should be called as a goroutine, such that it can receive incoming updates.
-func (d *Dispatcher) Start(b *gotgbot.Bot, updates chan json.RawMessage) {
+func (d *Dispatcher) Start(b *gotgbot.Bot, updates <-chan json.RawMessage) {
 	// Listen to updates as they come in from the updater.
 	for upd := range updates {
 		d.waitGroup.Add(1)

ext/updater.go

@@ -26,7 +26,9 @@ type ErrorFunc func(error)
 
 type Updater struct {
 	// Dispatcher is where all the incoming updates are sent to be processed.
-	Dispatcher *Dispatcher
+	// The Dispatcher runs in a separate goroutine, allowing for parallel update processing and dispatching.
+	// Once the Updater has received an update, it sends it to the Dispatcher over a JSON channel.
+	Dispatcher UpdateDispatcher
 
 	// UnhandledErrFunc provides more flexibility for dealing with previously unhandled errors, such as failures to get
 	// updates (when long-polling), or failures to unmarshal.
@@ -54,23 +56,14 @@ type UpdaterOpts struct {
 	// ErrorLog specifies an optional logger for unexpected behavior from handlers.
 	// If nil, logging is done via the log package's standard logger.
 	ErrorLog *log.Logger
-	// The dispatcher instance to be used by the updater.
-	Dispatcher *Dispatcher
 }
 
-// NewUpdater Creates a new Updater, as well as the necessary structures required for the associated Dispatcher.
-func NewUpdater(opts *UpdaterOpts) *Updater {
+// NewUpdater Creates a new Updater, as well as a Dispatcher and any optional updater configurations (via UpdaterOpts).
+func NewUpdater(dispatcher UpdateDispatcher, opts *UpdaterOpts) *Updater {
 	var unhandledErrFunc ErrorFunc
 	var errLog *log.Logger
 
-	// Default dispatcher, no special settings.
-	dispatcher := NewDispatcher(nil)
-
 	if opts != nil {
-		if opts.Dispatcher != nil {
-			dispatcher = opts.Dispatcher
-		}
-
 		unhandledErrFunc = opts.UnhandledErrFunc
 		errLog = opts.ErrorLog
 	}

ext/updater_test.go

@@ -23,7 +23,7 @@ func TestUpdaterThrowsErrorWhenSameWebhookAddedTwice(t *testing.T) {
 	}
 
 	d := ext.NewDispatcher(&ext.DispatcherOpts{})
-	u := ext.NewUpdater(&ext.UpdaterOpts{Dispatcher: d})
+	u := ext.NewUpdater(d, nil)
 
 	err := u.AddWebhook(b, "test", ext.WebhookOpts{})
 	if err != nil {
@@ -47,7 +47,7 @@ func TestUpdaterSupportsWebhookReAdding(t *testing.T) {
 	}
 
 	d := ext.NewDispatcher(&ext.DispatcherOpts{})
-	u := ext.NewUpdater(&ext.UpdaterOpts{Dispatcher: d})
+	u := ext.NewUpdater(d, nil)
 
 	err := u.AddWebhook(b, "test", ext.WebhookOpts{})
 	if err != nil {
@@ -76,7 +76,7 @@ func TestUpdaterDisallowsEmptyWebhooks(t *testing.T) {
 	}
 
 	d := ext.NewDispatcher(&ext.DispatcherOpts{})
-	u := ext.NewUpdater(&ext.UpdaterOpts{Dispatcher: d})
+	u := ext.NewUpdater(d, nil)
 
 	err := u.AddWebhook(b, "", ext.WebhookOpts{})
 	if !errors.Is(err, ext.ErrEmptyPath) {
@@ -104,7 +104,7 @@ func TestUpdaterAllowsWebhookDeletion(t *testing.T) {
 	}
 
 	d := ext.NewDispatcher(&ext.DispatcherOpts{})
-	u := ext.NewUpdater(&ext.UpdaterOpts{Dispatcher: d})
+	u := ext.NewUpdater(d, nil)
 
 	err := u.StartPolling(b, &ext.PollingOpts{
 		EnableWebhookDeletion: true,
@@ -143,7 +143,7 @@ func TestUpdaterSupportsTwoPollingBots(t *testing.T) {
 	}
 
 	d := ext.NewDispatcher(&ext.DispatcherOpts{})
-	u := ext.NewUpdater(&ext.UpdaterOpts{Dispatcher: d})
+	u := ext.NewUpdater(d, nil)
 
 	err := u.StartPolling(b1, &ext.PollingOpts{
 		GetUpdatesOpts: &gotgbot.GetUpdatesOpts{
@@ -185,7 +185,7 @@ func TestUpdaterThrowsErrorWhenSameLongPollAddedTwice(t *testing.T) {
 	}
 
 	d := ext.NewDispatcher(&ext.DispatcherOpts{})
-	u := ext.NewUpdater(&ext.UpdaterOpts{Dispatcher: d})
+	u := ext.NewUpdater(d, nil)
 
 	err := u.StartPolling(b, &ext.PollingOpts{
 		GetUpdatesOpts: &gotgbot.GetUpdatesOpts{
@@ -228,7 +228,7 @@ func TestUpdaterSupportsLongPollReAdding(t *testing.T) {
 	}
 
 	d := ext.NewDispatcher(&ext.DispatcherOpts{})
-	u := ext.NewUpdater(&ext.UpdaterOpts{Dispatcher: d})
+	u := ext.NewUpdater(d, nil)
 
 	err := u.StartPolling(b, &ext.PollingOpts{
 		GetUpdatesOpts: &gotgbot.GetUpdatesOpts{RequestOpts: reqOpts},
@@ -303,7 +303,7 @@ func BenchmarkUpdaterMultibots(b *testing.B) {
 
 func benchmarkUpdaterWithNBots(b *testing.B, numBot int) {
 	d := ext.NewDispatcher(nil)
-	u := ext.NewUpdater(&ext.UpdaterOpts{Dispatcher: d})
+	u := ext.NewUpdater(d, nil)
 
 	wg := sync.WaitGroup{}
 	d.AddHandler(ext.DummyHandler{F: func(b *gotgbot.Bot, ctx *ext.Context) error {

samples/callbackqueryBot/main.go

@@ -28,17 +28,15 @@ func main() {
 	}
 
 	// Create updater and dispatcher.
-	updater := ext.NewUpdater(&ext.UpdaterOpts{
-		Dispatcher: ext.NewDispatcher(&ext.DispatcherOpts{
-			// If an error is returned by a handler, log it and continue going.
-			Error: func(b *gotgbot.Bot, ctx *ext.Context, err error) ext.DispatcherAction {
-				log.Println("an error occurred while handling update:", err.Error())
-				return ext.DispatcherActionNoop
-			},
-			MaxRoutines: ext.DefaultMaxRoutines,
-		}),
+	dispatcher := ext.NewDispatcher(&ext.DispatcherOpts{
+		// If an error is returned by a handler, log it and continue going.
+		Error: func(b *gotgbot.Bot, ctx *ext.Context, err error) ext.DispatcherAction {
+			log.Println("an error occurred while handling update:", err.Error())
+			return ext.DispatcherActionNoop
+		},
+		MaxRoutines: ext.DefaultMaxRoutines,
 	})
-	dispatcher := updater.Dispatcher
+	updater := ext.NewUpdater(dispatcher, nil)
 
 	// /start command to introduce the bot
 	dispatcher.AddHandler(handlers.NewCommand("start", start))

samples/commandBot/main.go

@@ -28,17 +28,15 @@ func main() {
 	}
 
 	// Create updater and dispatcher.
-	updater := ext.NewUpdater(&ext.UpdaterOpts{
-		Dispatcher: ext.NewDispatcher(&ext.DispatcherOpts{
-			// If an error is returned by a handler, log it and continue going.
-			Error: func(b *gotgbot.Bot, ctx *ext.Context, err error) ext.DispatcherAction {
-				log.Println("an error occurred while handling update:", err.Error())
-				return ext.DispatcherActionNoop
-			},
-			MaxRoutines: ext.DefaultMaxRoutines,
-		}),
+	dispatcher := ext.NewDispatcher(&ext.DispatcherOpts{
+		// If an error is returned by a handler, log it and continue going.
+		Error: func(b *gotgbot.Bot, ctx *ext.Context, err error) ext.DispatcherAction {
+			log.Println("an error occurred while handling update:", err.Error())
+			return ext.DispatcherActionNoop
+		},
+		MaxRoutines: ext.DefaultMaxRoutines,
 	})
-	dispatcher := updater.Dispatcher
+	updater := ext.NewUpdater(dispatcher, nil)
 
 	// /start command to introduce the bot
 	dispatcher.AddHandler(handlers.NewCommand("start", start))

samples/conversationBot/main.go

@@ -32,17 +32,15 @@ func main() {
 	}
 
 	// Create updater and dispatcher.
-	updater := ext.NewUpdater(&ext.UpdaterOpts{
-		Dispatcher: ext.NewDispatcher(&ext.DispatcherOpts{
-			// If an error is returned by a handler, log it and continue going.
-			Error: func(b *gotgbot.Bot, ctx *ext.Context, err error) ext.DispatcherAction {
-				log.Println("an error occurred while handling update:", err.Error())
-				return ext.DispatcherActionNoop
-			},
-			MaxRoutines: ext.DefaultMaxRoutines,
-		}),
+	dispatcher := ext.NewDispatcher(&ext.DispatcherOpts{
+		// If an error is returned by a handler, log it and continue going.
+		Error: func(b *gotgbot.Bot, ctx *ext.Context, err error) ext.DispatcherAction {
+			log.Println("an error occurred while handling update:", err.Error())
+			return ext.DispatcherActionNoop
+		},
+		MaxRoutines: ext.DefaultMaxRoutines,
 	})
-	dispatcher := updater.Dispatcher
+	updater := ext.NewUpdater(dispatcher, nil)
 
 	dispatcher.AddHandler(handlers.NewConversation(
 		[]ext.Handler{handlers.NewCommand("start", start)},

samples/echoBot/main.go

@@ -36,17 +36,15 @@ func main() {
 	}
 
 	// Create updater and dispatcher.
-	updater := ext.NewUpdater(&ext.UpdaterOpts{
-		Dispatcher: ext.NewDispatcher(&ext.DispatcherOpts{
-			// If an error is returned by a handler, log it and continue going.
-			Error: func(b *gotgbot.Bot, ctx *ext.Context, err error) ext.DispatcherAction {
-				log.Println("an error occurred while handling update:", err.Error())
-				return ext.DispatcherActionNoop
-			},
-			MaxRoutines: ext.DefaultMaxRoutines,
-		}),
+	dispatcher := ext.NewDispatcher(&ext.DispatcherOpts{
+		// If an error is returned by a handler, log it and continue going.
+		Error: func(b *gotgbot.Bot, ctx *ext.Context, err error) ext.DispatcherAction {
+			log.Println("an error occurred while handling update:", err.Error())
+			return ext.DispatcherActionNoop
+		},
+		MaxRoutines: ext.DefaultMaxRoutines,
 	})
-	dispatcher := updater.Dispatcher
+	updater := ext.NewUpdater(dispatcher, nil)
 
 	// Add echo handler to reply to all text messages.
 	dispatcher.AddHandler(handlers.NewMessage(message.Text, echo))

samples/echoMultiBot/main.go

@@ -32,18 +32,15 @@ func main() {
 	webhookSecret := os.Getenv("WEBHOOK_SECRET")
 
 	// Create updater and dispatcher.
-	updater := ext.NewUpdater(&ext.UpdaterOpts{
-		ErrorLog: nil,
-		Dispatcher: ext.NewDispatcher(&ext.DispatcherOpts{
-			// If an error is returned by a handler, log it and continue going.
-			Error: func(b *gotgbot.Bot, ctx *ext.Context, err error) ext.DispatcherAction {
-				log.Println("an error occurred while handling update:", err.Error())
-				return ext.DispatcherActionNoop
-			},
-			MaxRoutines: ext.DefaultMaxRoutines,
-		}),
+	dispatcher := ext.NewDispatcher(&ext.DispatcherOpts{
+		// If an error is returned by a handler, log it and continue going.
+		Error: func(b *gotgbot.Bot, ctx *ext.Context, err error) ext.DispatcherAction {
+			log.Println("an error occurred while handling update:", err.Error())
+			return ext.DispatcherActionNoop
+		},
+		MaxRoutines: ext.DefaultMaxRoutines,
 	})
-	dispatcher := updater.Dispatcher
+	updater := ext.NewUpdater(dispatcher, nil)
 
 	// Add stop handler to stop all bots gracefully.
 	dispatcher.AddHandler(handlers.NewCommand("stop", func(b *gotgbot.Bot, ctx *ext.Context) error {

samples/echoWebhookBot/main.go

@@ -45,17 +45,15 @@ func main() {
 	}
 
 	// Create updater and dispatcher.
-	updater := ext.NewUpdater(&ext.UpdaterOpts{
-		Dispatcher: ext.NewDispatcher(&ext.DispatcherOpts{
-			// If an error is returned by a handler, log it and continue going.
-			Error: func(b *gotgbot.Bot, ctx *ext.Context, err error) ext.DispatcherAction {
-				log.Println("an error occurred while handling update:", err.Error())
-				return ext.DispatcherActionNoop
-			},
-			MaxRoutines: ext.DefaultMaxRoutines,
-		}),
+	dispatcher := ext.NewDispatcher(&ext.DispatcherOpts{
+		// If an error is returned by a handler, log it and continue going.
+		Error: func(b *gotgbot.Bot, ctx *ext.Context, err error) ext.DispatcherAction {
+			log.Println("an error occurred while handling update:", err.Error())
+			return ext.DispatcherActionNoop
+		},
+		MaxRoutines: ext.DefaultMaxRoutines,
 	})
-	dispatcher := updater.Dispatcher
+	updater := ext.NewUpdater(dispatcher, nil)
 
 	// Add echo handler to reply to all text messages.
 	dispatcher.AddHandler(handlers.NewMessage(message.Text, echo))

samples/inlinequeryBot/main.go

@@ -33,17 +33,15 @@ func main() {
 	}
 
 	// Create updater and dispatcher.
-	updater := ext.NewUpdater(&ext.UpdaterOpts{
-		Dispatcher: ext.NewDispatcher(&ext.DispatcherOpts{
-			// If an error is returned by a handler, log it and continue going.
-			Error: func(b *gotgbot.Bot, ctx *ext.Context, err error) ext.DispatcherAction {
-				log.Println("an error occurred while handling update:", err.Error())
-				return ext.DispatcherActionNoop
-			},
-			MaxRoutines: ext.DefaultMaxRoutines,
-		}),
+	dispatcher := ext.NewDispatcher(&ext.DispatcherOpts{
+		// If an error is returned by a handler, log it and continue going.
+		Error: func(b *gotgbot.Bot, ctx *ext.Context, err error) ext.DispatcherAction {
+			log.Println("an error occurred while handling update:", err.Error())
+			return ext.DispatcherActionNoop
+		},
+		MaxRoutines: ext.DefaultMaxRoutines,
 	})
-	dispatcher := updater.Dispatcher
+	updater := ext.NewUpdater(dispatcher, nil)
 
 	// Create an inline query handler to reply to all inline queries
 	dispatcher.AddHandler(handlers.NewInlineQuery(inlinequery.All, source))

samples/metricsBot/main.go

@@ -48,7 +48,7 @@ func main() {
 	go monitorDispatcherBuffer(dispatcher)
 
 	// Create the updater with our customised dispatcher.
-	updater := ext.NewUpdater(&ext.UpdaterOpts{Dispatcher: dispatcher})
+	updater := ext.NewUpdater(dispatcher, nil)
 
 	// Add echo handler to reply to all text messages.
 	dispatcher.AddHandler(handlers.NewMessage(message.Text, echo))