redis-sync-fanout-queue-go

What is it?

Priority queue with synchronous fanout delivery for each room based on Redis.

This queue is special by several key properties:

1. It delivers each message sent to a room to all subscribers of that room.
2. It does not deliver the next message until all subscribers of the room ACKnowledge the last message.
3. It is based entirely on Redis primitives.
4. Out-of-band messages are also available. They are immediately delivered to all subscribers with no regard to ACKs.

This allows building distributed systems where edges process messages in a coordinated lock-step with each other.

Queue guarantees

Synchronized Fanout

All clients must ACKnowledge processing of a message before any other client can see the next message, unless the message is sent Out-of-band.

At most once delivery

There are no message redelivery attempts built in. Either you get it or you do not.

(*) In case communication breaks, client must stop sending Ping() requests (preferably send an Unsubscribe() request), obtain a new Client ID, and Subscribe() after communication has been re-established.

High performance, low memory footprint

Most of the heavy lifting is done in Redis.

Infrastructure

The library leverages go-redis for communication with the Redis server.

Usage

Publishing messages

package main

import (
	"context"
	"fmt"
	"os"
	"os/signal"
	"time"

	"github.com/go-redis/redis/v8"

	redisSyncFanoutQueue "github.com/zavitax/redis-sync-fanout-queue-go"
)

var testMessageContent = "test message content"
var testRoomId = "GO-ROOM-TEST"

var redisOptions = &redis.Options{
	Addr:     "127.0.0.1:6379",
	Password: "",
	DB:       0,
}

func createApiOptions() *redisSyncFanoutQueue.ApiOptions {
	result := &redisSyncFanoutQueue.ApiOptions{
		RedisOptions:   redisOptions,
		ClientTimeout:  time.Second * 15,
		RedisKeyPrefix: fmt.Sprintf("{test-redis-sync-fanout-queue}::%v", "test"),
	}

	return result
}

func createApiClient(options *redisSyncFanoutQueue.ApiOptions) (redisSyncFanoutQueue.RedisQueueApiClient, error) {
	return redisSyncFanoutQueue.NewApiClient(context.TODO(), options)
}

func pub() {
	doneC := make(chan os.Signal, 1)
	signal.Notify(doneC)

	client, _ := createApiClient(createApiOptions())

	i := 0
	ticker := time.NewTicker(time.Second)
	done := false
	for !done {
		select {
		case <-doneC:
			done = true
		case <-ticker.C:
			i++

			client.Send(context.TODO(), "MSG_PRODUCER_ID", testRoomId, testMessageContent, 1)

			fmt.Printf("Send: %v\r", i)
		}
	}
	ticker.Stop()

	client.Close()
}

func main() {
	pub()
}

Subscribing and maintaining a client connection

package main

import (
	"context"
	"fmt"
	"os"
	"os/signal"
	"time"

	"github.com/go-redis/redis/v8"

	redisSyncFanoutQueue "github.com/zavitax/redis-sync-fanout-queue-go"
)

var testMessageContent = "test message content"
var testRoomId = "GO-ROOM-TEST"

var redisOptions = &redis.Options{
	Addr:     "127.0.0.1:6379",
	Password: "",
	DB:       0,
}

func createApiOptions() *redisSyncFanoutQueue.ApiOptions {
	result := &redisSyncFanoutQueue.ApiOptions{
		RedisOptions:   redisOptions,
		ClientTimeout:  time.Second * 15,
		RedisKeyPrefix: fmt.Sprintf("{test-redis-sync-fanout-queue}::%v", "test"),
	}

	return result
}

func createApiClient(options *redisSyncFanoutQueue.ApiOptions) (redisSyncFanoutQueue.RedisQueueApiClient, error) {
	return redisSyncFanoutQueue.NewApiClient(context.TODO(), options)
}

func sub(clientsCount int) {
	doneC := make(chan os.Signal, 1)
	signal.Notify(doneC)

	client, _ := createApiClient(createApiOptions())

	clientIds := []string{}
	for i := 0; i < clientsCount; i++ {
		clientId, _ := client.CreateClientID(context.Background())
		client.Subscribe(context.TODO(), clientId, testRoomId)
		clientIds = append(clientIds, clientId)
	}

	ticker := time.NewTicker(time.Second)
	done := false
	for !done {
		select {
		case <-doneC:
			done = true
		case <-ticker.C:
			for _, clientId := range clientIds {
				// Must call periodically for each Client ID & Room ID comibnation to keep
				// Client ID alive.
				client.Ping(context.Background(), clientId)
			}

			metrics, _ := client.GetMetrics(context.TODO(), &redisSyncFanoutQueue.GetApiMetricsOptions{
				TopRoomsLimit: 10,
			})

			fmt.Printf("Metrics: %v\n", metrics)
		}
	}
	ticker.Stop()

	for _, clientId := range clientIds {
		client.Unsubscribe(context.Background(), clientId, testRoomId)
	}

	client.Close()
}

func main() {
	sub(1)
}

Delivering and ACKnowledging messages (worker)

package main

import (
	"context"
	"fmt"
	"os"
	"os/signal"
	"time"

	"github.com/go-redis/redis/v8"

	redisSyncFanoutQueue "github.com/zavitax/redis-sync-fanout-queue-go"
)

var testMessageContent = "test message content"
var testRoomId = "GO-ROOM-TEST"

var redisOptions = &redis.Options{
	Addr:     "127.0.0.1:6379",
	Password: "",
	DB:       0,
}

func createApiOptions() *redisSyncFanoutQueue.ApiOptions {
	result := &redisSyncFanoutQueue.ApiOptions{
		RedisOptions:   redisOptions,
		ClientTimeout:  time.Second * 15,
		RedisKeyPrefix: fmt.Sprintf("{test-redis-sync-fanout-queue}::%v", "test"),
	}

	return result
}

func createWorkerOptions() *redisSyncFanoutQueue.WorkerOptions {
	result := &redisSyncFanoutQueue.WorkerOptions{
		RedisOptions:   redisOptions,
		RedisKeyPrefix: fmt.Sprintf("{test-redis-sync-fanout-queue}::%v", "test"),
	}

	return result
}

func createApiClient(options *redisSyncFanoutQueue.ApiOptions) (redisSyncFanoutQueue.RedisQueueApiClient, error) {
	return redisSyncFanoutQueue.NewApiClient(context.TODO(), options)
}

func worker() {
	doneC := make(chan os.Signal, 1)
	signal.Notify(doneC)

	// Used for ACKs
	client, _ := createApiClient(createApiOptions())

	wo := createWorkerOptions()
	wo.HandleRoomClientTimeout = func(ctx context.Context, clientId *string, roomId *string) error {
		return nil
	}
	wo.HandleMessage = func(ctx context.Context, clientId *string, msg *redisSyncFanoutQueue.Message) error {
		if msg.Data == nil {
			fmt.Printf("Received nil data\n")
			return nil
		}

		strData := (*msg.Data).(string)
		if strData != testMessageContent {
			fmt.Printf("Expected '%v' but received '%v'\n", testMessageContent, strData)
			return nil
		}

		fmt.Printf("Received: client[%s] room[%s]: %v\n", *clientId, msg.Room, strData)

		if msg.AckToken != nil {
			//time.Sleep(time.Second * 3)
			// This should be called by the actual client, when it's done processing the message
			client.AckMessage(ctx, *clientId, msg.AckToken)
		}

		return nil
	}

	worker, _ := createWorkerClient(wo)

	ticker := time.NewTicker(time.Second)
	done := false
	for !done {
		select {
		case <-doneC:
			done = true
		case <-ticker.C:
			metrics, _ := worker.GetMetrics(context.TODO(), &redisSyncFanoutQueue.GetWorkerMetricsOptions{})

			fmt.Printf("Metrics: %v\n", metrics)
		}
	}
	ticker.Stop()

	worker.Close()
	client.Close()
}

func main() {
	worker()
}

Peeking at room's queue head

package main

import (
	"context"
	"fmt"
	"os"
	"os/signal"
	"time"

	"github.com/go-redis/redis/v8"

	redisSyncFanoutQueue "github.com/zavitax/redis-sync-fanout-queue-go"
)

var testMessageContent = "test message content"
var testRoomId = "GO-ROOM-TEST"

var redisOptions = &redis.Options{
	Addr:     "127.0.0.1:6379",
	Password: "",
	DB:       0,
}

func createApiOptions() *redisSyncFanoutQueue.ApiOptions {
	result := &redisSyncFanoutQueue.ApiOptions{
		RedisOptions:   redisOptions,
		ClientTimeout:  time.Second * 15,
		RedisKeyPrefix: fmt.Sprintf("{test-redis-sync-fanout-queue}::%v", "test"),
	}

	return result
}

func createApiClient(options *redisSyncFanoutQueue.ApiOptions) (redisSyncFanoutQueue.RedisQueueApiClient, error) {
	return redisSyncFanoutQueue.NewApiClient(context.TODO(), options)
}

func peek() {
	doneC := make(chan os.Signal, 1)
	signal.Notify(doneC)

	client, _ := createApiClient(createApiOptions())

	ticker := time.NewTicker(time.Second)
	done := false
	for !done {
		select {
		case <-doneC:
			done = true
		case <-ticker.C:
			if msgs, err := client.Peek(context.TODO(), testRoomId, 0, 10); err != nil {
				panic(err)
			} else {
				for index, msg := range msgs {
					strData := (*msg.Data).(string)

					fmt.Printf("Peek: %d: %v\n", index, strData)
				}
			}
		}
	}
	ticker.Stop()

	client.Close()
}

func main() {
	peek()
}