feat: [wip] - implement storage

broker.go

@@ -38,6 +38,7 @@ type Broker struct {
 	queues     storage.IMap[string, *Queue]
 	consumers  storage.IMap[string, *consumer]
 	publishers storage.IMap[string, *publisher]
+	deadLetter storage.IMap[string, *Queue] // DLQ mapping for each queue
 	opts       *Options
 }
 
@@ -47,6 +48,7 @@ func NewBroker(opts ...Option) *Broker {
 		queues:     memory.New[string, *Queue](),
 		publishers: memory.New[string, *publisher](),
 		consumers:  memory.New[string, *consumer](),
+		deadLetter: memory.New[string, *Queue](),
 		opts:       options,
 	}
 }
@@ -422,6 +424,19 @@ func (b *Broker) dispatchWorker(queue *Queue) {
 				delay = b.backoffRetry(queue, task, delay)
 			}
 		}
+		if task.RetryCount > b.opts.maxRetries {
+			b.sendToDLQ(queue, task)
+		}
+	}
+}
+
+func (b *Broker) sendToDLQ(queue *Queue, task *QueuedTask) {
+	id, _ := jsonparser.GetString(task.Message.Payload, "id")
+	if dlq, ok := b.deadLetter.Get(queue.name); ok {
+		log.Printf("Sending task %s to dead-letter queue for %s", id, queue.name)
+		dlq.tasks <- task
+	} else {
+		log.Printf("No dead-letter queue for %s, discarding task %s", queue.name, id)
 	}
 }
 

ctx.go

@@ -4,11 +4,9 @@ import (
 	"context"
 	"crypto/tls"
 	"crypto/x509"
-	"encoding/json"
 	"fmt"
 	"net"
 	"os"
-	"time"
 
 	"github.com/oarkflow/xid"
 
@@ -17,17 +15,6 @@ import (
 	"github.com/oarkflow/mq/storage/memory"
 )
 
-type Task struct {
-	CreatedAt   time.Time       `json:"created_at"`
-	ProcessedAt time.Time       `json:"processed_at"`
-	Expiry      time.Time       `json:"expiry"`
-	Error       error           `json:"error"`
-	ID          string          `json:"id"`
-	Topic       string          `json:"topic"`
-	Status      string          `json:"status"`
-	Payload     json.RawMessage `json:"payload"`
-}
-
 type Handler func(context.Context, *Task) Result
 
 func IsClosed(conn net.Conn) bool {

dag/dag.go

@@ -2,7 +2,9 @@ package dag
 
 import (
 	"context"
+	"encoding/json"
 	"fmt"
+	"io"
 	"log"
 	"net/http"
 	"sync"
@@ -180,6 +182,35 @@ func (tm *DAG) GetStartNode() string {
 	return tm.startNode
 }
 
+func (tm *DAG) ServeHTTP(w http.ResponseWriter, r *http.Request) {
+	if r.Method != http.MethodPost {
+		http.Error(w, "Invalid request method", http.StatusMethodNotAllowed)
+		return
+	}
+	var payload []byte
+	if r.Body != nil {
+		defer r.Body.Close()
+		var err error
+		payload, err = io.ReadAll(r.Body)
+		if err != nil {
+			http.Error(w, "Failed to read request body", http.StatusBadRequest)
+			return
+		}
+	} else {
+		http.Error(w, "Empty request body", http.StatusBadRequest)
+		return
+	}
+	ctx := r.Context()
+	ctx = mq.SetHeaders(ctx, map[string]string{consts.AwaitResponseKey: "true"})
+	rs := tm.Process(ctx, payload)
+	if rs.Error != nil {
+		http.Error(w, fmt.Sprintf("[DAG Error] - %v", rs.Error), http.StatusInternalServerError)
+		return
+	}
+	w.Header().Set("Content-Type", "application/json")
+	json.NewEncoder(w).Encode(rs)
+}
+
 func (tm *DAG) Start(ctx context.Context, addr string) error {
 	if !tm.server.SyncMode() {
 		go func() {

examples/dag.go

@@ -4,10 +4,8 @@ import (
 	"context"
 	"encoding/json"
 	"fmt"
-	"io"
 	"net/http"
 
-	"github.com/oarkflow/mq/consts"
 	"github.com/oarkflow/mq/examples/tasks"
 	"github.com/oarkflow/mq/services"
 
@@ -16,8 +14,8 @@ import (
 )
 
 func main() {
-	sync()
+	Sync()
-	async()
+	aSync()
 }
 
 func setup(f *dag.DAG) {
@@ -46,7 +44,7 @@ func sendData(f *dag.DAG) {
 	fmt.Println(string(result.Payload))
 }
 
-func sync() {
+func Sync() {
 	f := dag.NewDAG("Sample DAG", "sample-dag", mq.WithSyncMode(true), mq.WithNotifyResponse(tasks.NotifyResponse))
 	setup(f)
 	fmt.Println(f.ExportDOT())
@@ -54,46 +52,10 @@ func sync() {
 	fmt.Println(f.SaveSVG("dag.svg"))
 }
 
-func async() {
+func aSync() {
 	f := dag.NewDAG("Sample DAG", "sample-dag", mq.WithNotifyResponse(tasks.NotifyResponse))
 	setup(f)
-
+	http.HandleFunc("POST /request", f.ServeHTTP)
-	requestHandler := func(requestType string) func(w http.ResponseWriter, r *http.Request) {
-		return func(w http.ResponseWriter, r *http.Request) {
-			if r.Method != http.MethodPost {
-				http.Error(w, "Invalid request method", http.StatusMethodNotAllowed)
-				return
-			}
-			var payload []byte
-			if r.Body != nil {
-				defer r.Body.Close()
-				var err error
-				payload, err = io.ReadAll(r.Body)
-				if err != nil {
-					http.Error(w, "Failed to read request body", http.StatusBadRequest)
-					return
-				}
-			} else {
-				http.Error(w, "Empty request body", http.StatusBadRequest)
-				return
-			}
-			ctx := r.Context()
-			if requestType == "request" {
-				ctx = mq.SetHeaders(ctx, map[string]string{consts.AwaitResponseKey: "true"})
-			}
-			// ctx = context.WithValue(ctx, "initial_node", "E")
-			rs := f.Process(ctx, payload)
-			if rs.Error != nil {
-				http.Error(w, fmt.Sprintf("[DAG Error] - %v", rs.Error), http.StatusInternalServerError)
-				return
-			}
-			w.Header().Set("Content-Type", "application/json")
-			json.NewEncoder(w).Encode(rs)
-		}
-	}
-
-	http.HandleFunc("POST /publish", requestHandler("publish"))
-	http.HandleFunc("POST /request", requestHandler("request"))
 	http.HandleFunc("/pause-consumer/{id}", func(writer http.ResponseWriter, request *http.Request) {
 		id := request.PathValue("id")
 		if id != "" {

examples/priority.go

@@ -11,12 +11,17 @@ import (
 func main() {
 	pool := mq.NewPool(2, 5, 1000, tasks.SchedulerHandler, tasks.SchedulerCallback, mq.NewMemoryTaskStorage(10*time.Minute))
 
-	time.Sleep(time.Millisecond)
+	for i := 0; i < 100; i++ {
+		if i%10 == 0 {
+			pool.EnqueueTask(context.Background(), &mq.Task{ID: "High Priority Task: I'm high"}, 10)
+		} else if i%15 == 0 {
+			pool.EnqueueTask(context.Background(), &mq.Task{ID: "Super High Priority Task: {}"}, 15)
+		} else {
 			pool.EnqueueTask(context.Background(), &mq.Task{ID: "Low Priority Task"}, 1)
-	pool.EnqueueTask(context.Background(), &mq.Task{ID: "Medium Priority Task"}, 5)
+		}
-	pool.EnqueueTask(context.Background(), &mq.Task{ID: "High Priority Task"}, 10)
+	}
 
-	time.Sleep(5 * time.Second)
+	time.Sleep(15 * time.Second)
 	pool.PrintMetrics()
 	pool.Stop()
 }

pool.go

@@ -29,19 +29,15 @@ type Pool struct {
 	numOfWorkers              int32
 	paused                    bool
 	scheduler                 *Scheduler
-	totalScheduledTasks       int
+	overflowBufferLock        sync.RWMutex
+	overflowBuffer            []*QueueTask
 }
 
-func NewPool(
+func NewPool(numOfWorkers, taskQueueSize int, maxMemoryLoad int64, handler Handler, callback Callback, storage TaskStorage) *Pool {
-	numOfWorkers, taskQueueSize int,
-	maxMemoryLoad int64,
-	handler Handler,
-	callback Callback,
-	storage TaskStorage) *Pool {
 	pool := &Pool{
 		taskQueue:     make(PriorityQueue, 0, taskQueueSize),
 		stop:          make(chan struct{}),
-		taskNotify:    make(chan struct{}, 1),
+		taskNotify:    make(chan struct{}, numOfWorkers), // Buffer for workers
 		maxMemoryLoad: maxMemoryLoad,
 		handler:       handler,
 		callback:      callback,
@@ -70,6 +66,7 @@ func (wp *Pool) Start(numWorkers int) {
 	}
 	atomic.StoreInt32(&wp.numOfWorkers, int32(numWorkers))
 	go wp.monitorWorkerAdjustments()
+	go wp.startOverflowDrainer()
 }
 
 func (wp *Pool) worker() {
@@ -77,6 +74,14 @@ func (wp *Pool) worker() {
 	for {
 		select {
 		case <-wp.taskNotify:
+			wp.processNextTask()
+		case <-wp.stop:
+			return
+		}
+	}
+}
+
+func (wp *Pool) processNextTask() {
 	wp.taskQueueLock.Lock()
 	var task *QueueTask
 	if len(wp.taskQueue) > 0 && !wp.paused {
@@ -87,11 +92,15 @@ func (wp *Pool) worker() {
 		var err error
 		task, err = wp.taskStorage.FetchNextTask()
 		if err != nil {
-
+			return
-					continue
 		}
 	}
 	if task != nil {
+		wp.handleTask(task)
+	}
+}
+
+func (wp *Pool) handleTask(task *QueueTask) {
 	taskSize := int64(utils.SizeOf(task.payload))
 	wp.totalMemoryUsed += taskSize
 	wp.totalTasks++
@@ -107,14 +116,9 @@ func (wp *Pool) worker() {
 		}
 	}
 	if err := wp.taskStorage.DeleteTask(task.payload.ID); err != nil {
-
+		// Handle deletion error
 	}
 	wp.totalMemoryUsed -= taskSize
-			}
-		case <-wp.stop:
-			return
-		}
-	}
 }
 
 func (wp *Pool) monitorWorkerAdjustments() {
@@ -162,9 +166,12 @@ func (wp *Pool) EnqueueTask(ctx context.Context, payload *Task, priority int) er
 		return fmt.Errorf("max memory load reached, cannot add task of size %d", taskSize)
 	}
 	heap.Push(&wp.taskQueue, task)
+
+	// Non-blocking task notification
 	select {
 	case wp.taskNotify <- struct{}{}:
 	default:
+		wp.storeInOverflow(task)
 	}
 	return nil
 }
@@ -177,6 +184,45 @@ func (wp *Pool) Resume() {
 	wp.paused = false
 }
 
+// Overflow Handling
+func (wp *Pool) storeInOverflow(task *QueueTask) {
+	wp.overflowBufferLock.Lock()
+	wp.overflowBuffer = append(wp.overflowBuffer, task)
+	wp.overflowBufferLock.Unlock()
+}
+
+// Drains tasks from the overflow buffer when taskNotify is not full
+func (wp *Pool) startOverflowDrainer() {
+	for {
+		wp.drainOverflowBuffer()
+		select {
+		case <-wp.stop:
+			return
+		default:
+			continue
+		}
+	}
+}
+
+func (wp *Pool) drainOverflowBuffer() {
+	wp.overflowBufferLock.Lock()
+	defer wp.overflowBufferLock.Unlock()
+
+	for len(wp.overflowBuffer) > 0 {
+		select {
+		case wp.taskNotify <- struct{}{}:
+			// Move the first task from the overflow buffer to the queue
+			wp.taskQueueLock.Lock()
+			heap.Push(&wp.taskQueue, wp.overflowBuffer[0])
+			wp.overflowBuffer = wp.overflowBuffer[1:]
+			wp.taskQueueLock.Unlock()
+		default:
+			// Stop if taskNotify is full
+			return
+		}
+	}
+}
+
 func (wp *Pool) Stop() {
 	close(wp.stop)
 	wp.wg.Wait()

queue.go

@@ -21,14 +21,24 @@ func newQueue(name string, queueSize int) *Queue {
 	}
 }
 
-func (b *Broker) NewQueue(qName string) *Queue {
+func (b *Broker) NewQueue(name string) *Queue {
-	q, ok := b.queues.Get(qName)
+	q := &Queue{
-	if ok {
+		name:      name,
-		return q
+		tasks:     make(chan *QueuedTask, b.opts.queueSize),
+		consumers: memory.New[string, *consumer](),
 	}
-	q = newQueue(qName, b.opts.queueSize)
+	b.queues.Set(name, q)
-	b.queues.Set(qName, q)
+
+	// Create DLQ for the queue
+	dlq := &Queue{
+		name:      name + "_dlq",
+		tasks:     make(chan *QueuedTask, b.opts.queueSize),
+		consumers: memory.New[string, *consumer](),
+	}
+	b.deadLetter.Set(name, dlq)
+
 	go b.dispatchWorker(q)
+	go b.dispatchWorker(dlq)
 	return q
 }
 

task.go

@@ -5,6 +5,17 @@ import (
 	"time"
 )
 
+type Task struct {
+	CreatedAt   time.Time       `json:"created_at"`
+	ProcessedAt time.Time       `json:"processed_at"`
+	Expiry      time.Time       `json:"expiry"`
+	Error       error           `json:"error"`
+	ID          string          `json:"id"`
+	Topic       string          `json:"topic"`
+	Status      string          `json:"status"`
+	Payload     json.RawMessage `json:"payload"`
+}
+
 func NewTask(id string, payload json.RawMessage, nodeKey string) *Task {
 	if id == "" {
 		id = NewID()