forgejo/modules/queue/queue_redis.go

// Copyright 2019 The Gitea Authors. All rights reserved.
// Use of this source code is governed by a MIT-style
// license that can be found in the LICENSE file.

package queue

import (
	"context"
	"encoding/json"
	"errors"
	"fmt"
	"reflect"
	"strings"
	"sync"
	"time"

	"code.gitea.io/gitea/modules/log"

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

// RedisQueueType is the type for redis queue
const RedisQueueType Type = "redis"

type redisClient interface {
	RPush(key string, args ...interface{}) *redis.IntCmd
	LPop(key string) *redis.StringCmd
	Ping() *redis.StatusCmd
	Close() error
}

// RedisQueue redis queue
type RedisQueue struct {
	client      redisClient
	queueName   string
	handle      HandlerFunc
	batchLength int
	closed      chan struct{}
	exemplar    interface{}
	workers     int
}

// RedisQueueConfiguration is the configuration for the redis queue
type RedisQueueConfiguration struct {
	Addresses   string
	Password    string
	DBIndex     int
	BatchLength int
	QueueName   string
	Workers     int
}

// NewRedisQueue creates single redis or cluster redis queue
func NewRedisQueue(handle HandlerFunc, cfg, exemplar interface{}) (Queue, error) {
	configInterface, err := toConfig(RedisQueueConfiguration{}, cfg)
	if err != nil {
		return nil, err
	}
	config := configInterface.(RedisQueueConfiguration)

	dbs := strings.Split(config.Addresses, ",")
	var queue = RedisQueue{
		queueName:   config.QueueName,
		handle:      handle,
		batchLength: config.BatchLength,
		exemplar:    exemplar,
		closed:      make(chan struct{}),
		workers:     config.Workers,
	}
	if len(dbs) == 0 {
		return nil, errors.New("no redis host found")
	} else if len(dbs) == 1 {
		queue.client = redis.NewClient(&redis.Options{
			Addr:     strings.TrimSpace(dbs[0]), // use default Addr
			Password: config.Password,           // no password set
			DB:       config.DBIndex,            // use default DB
		})
	} else {
		queue.client = redis.NewClusterClient(&redis.ClusterOptions{
			Addrs: dbs,
		})
	}
	if err := queue.client.Ping().Err(); err != nil {
		return nil, err
	}
	return &queue, nil
}

// Run runs the redis queue
func (r *RedisQueue) Run(atShutdown, atTerminate func(context.Context, func())) {
	atShutdown(context.Background(), r.Shutdown)
	atTerminate(context.Background(), r.Terminate)
	wg := sync.WaitGroup{}
	for i := 0; i < r.workers; i++ {
		wg.Add(1)
		go func() {
			r.worker()
			wg.Done()
		}()
	}
	wg.Wait()
}

func (r *RedisQueue) worker() {
	var i int
	var datas = make([]Data, 0, r.batchLength)
	for {
		select {
		case <-r.closed:
			if len(datas) > 0 {
				log.Trace("Handling: %d data, %v", len(datas), datas)
				r.handle(datas...)
			}
			return
		default:
		}
		bs, err := r.client.LPop(r.queueName).Bytes()
		if err != nil && err != redis.Nil {
			log.Error("LPop failed: %v", err)
			time.Sleep(time.Millisecond * 100)
			continue
		}

		i++
		if len(datas) > r.batchLength || (len(datas) > 0 && i > 3) {
			log.Trace("Handling: %d data, %v", len(datas), datas)
			r.handle(datas...)
			datas = make([]Data, 0, r.batchLength)
			i = 0
		}

		if len(bs) == 0 {
			time.Sleep(time.Millisecond * 100)
			continue
		}

		var data Data
		if r.exemplar != nil {
			t := reflect.TypeOf(r.exemplar)
			n := reflect.New(t)
			ne := n.Elem()
			err = json.Unmarshal(bs, ne.Addr().Interface())
			data = ne.Interface().(Data)
		} else {
			err = json.Unmarshal(bs, &data)
		}
		if err != nil {
			log.Error("Unmarshal: %v", err)
			time.Sleep(time.Millisecond * 100)
			continue
		}

		log.Trace("RedisQueue: task found: %#v", data)

		datas = append(datas, data)
		select {
		case <-r.closed:
			if len(datas) > 0 {
				log.Trace("Handling: %d data, %v", len(datas), datas)
				r.handle(datas...)
			}
			return
		default:
		}
		time.Sleep(time.Millisecond * 100)
	}
}

// Push implements Queue
func (r *RedisQueue) Push(data Data) error {
	if r.exemplar != nil {
		// Assert data is of same type as r.exemplar
		value := reflect.ValueOf(data)
		t := value.Type()
		exemplarType := reflect.ValueOf(r.exemplar).Type()
		if !t.AssignableTo(exemplarType) || data == nil {
			return fmt.Errorf("Unable to assign data: %v to same type as exemplar: %v in %s", data, r.exemplar, r.name)
		}
	}
	bs, err := json.Marshal(data)
	if err != nil {
		return err
	}
	return r.client.RPush(r.queueName, bs).Err()
}

// Shutdown processing from this queue
func (r *RedisQueue) Shutdown() {
	select {
	case <-r.closed:
	default:
		close(r.closed)
	}
}

// Terminate this queue and close the queue
func (r *RedisQueue) Terminate() {
	r.Shutdown()
	if err := r.client.Close(); err != nil {
		log.Error("Error whilst closing internal redis client: %v", err)
	}
}

func init() {
	queuesMap[RedisQueueType] = NewRedisQueue
}