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asynq/internal/rdb/rdb.go

267 lines
8.3 KiB
Go

// Package rdb encapsulates the interactions with redis.
package rdb
import (
"encoding/json"
"errors"
"fmt"
"time"
"github.com/go-redis/redis/v7"
"github.com/rs/xid"
)
// Redis keys
const (
queuePrefix = "asynq:queues:" // LIST - asynq:queues:<qname>
defaultQ = queuePrefix + "default" // LIST
scheduledQ = "asynq:scheduled" // ZSET
retryQ = "asynq:retry" // ZSET
deadQ = "asynq:dead" // ZSET
inProgressQ = "asynq:in_progress" // LIST
)
var (
// ErrDequeueTimeout indicates that the blocking dequeue operation timed out.
ErrDequeueTimeout = errors.New("blocking dequeue operation timed out")
// ErrTaskNotFound indicates that a task that matches the given identifier was not found.
ErrTaskNotFound = errors.New("could not find a task")
)
// RDB is a client interface to query and mutate task queues.
type RDB struct {
client *redis.Client
}
// NewRDB returns a new instance of RDB.
func NewRDB(client *redis.Client) *RDB {
return &RDB{client}
}
// TaskMessage is the internal representation of a task with additional metadata fields.
// Serialized data of this type gets written in redis.
type TaskMessage struct {
//-------- Task fields --------
// Type represents the kind of task.
Type string
// Payload holds data needed to process the task.
Payload map[string]interface{}
//-------- Metadata fields --------
// ID is a unique identifier for each task
ID xid.ID
// Queue is a name this message should be enqueued to
Queue string
// Retry is the max number of retry for this task.
Retry int
// Retried is the number of times we've retried this task so far
Retried int
// ErrorMsg holds the error message from the last failure
ErrorMsg string
}
// Close closes the connection with redis server.
func (r *RDB) Close() error {
return r.client.Close()
}
// Enqueue inserts the given task to the end of the queue.
// It also adds the queue name to the "all-queues" list.
func (r *RDB) Enqueue(msg *TaskMessage) error {
bytes, err := json.Marshal(msg)
if err != nil {
return fmt.Errorf("could not marshal %+v to json: %v", msg, err)
}
qname := queuePrefix + msg.Queue
pipe := r.client.Pipeline()
pipe.LPush(qname, string(bytes))
_, err = pipe.Exec()
if err != nil {
return fmt.Errorf("could not enqueue the task %+v to %q: %v", msg, qname, err)
}
return nil
}
// Dequeue blocks until there is a task available to be processed,
// once a task is available, it adds the task to "in progress" list
// and returns the task.
func (r *RDB) Dequeue(timeout time.Duration) (*TaskMessage, error) {
data, err := r.client.BRPopLPush(defaultQ, inProgressQ, timeout).Result()
if err == redis.Nil {
return nil, ErrDequeueTimeout
}
if err != nil {
return nil, fmt.Errorf("command `BRPOPLPUSH %q %q %v` failed: %v", defaultQ, inProgressQ, timeout, err)
}
var msg TaskMessage
err = json.Unmarshal([]byte(data), &msg)
if err != nil {
return nil, fmt.Errorf("could not unmarshal %v to json: %v", data, err)
}
return &msg, nil
}
// Done removes the task from in-progress queue to mark the task as done.
func (r *RDB) Done(msg *TaskMessage) error {
bytes, err := json.Marshal(msg)
if err != nil {
return fmt.Errorf("could not marshal %+v to json: %v", msg, err)
}
// NOTE: count ZERO means "remove all elements equal to val"
err = r.client.LRem(inProgressQ, 0, string(bytes)).Err()
if err != nil {
return fmt.Errorf("command `LREM %s 0 %s` failed: %v", inProgressQ, string(bytes), err)
}
return nil
}
// Requeue moves the task from in-progress queue to the default
// queue.
func (r *RDB) Requeue(msg *TaskMessage) error {
bytes, err := json.Marshal(msg)
if err != nil {
return fmt.Errorf("could not marshal %+v to json: %v", msg, err)
}
// Note: Use RPUSH to push to the head of the queue.
// KEYS[1] -> asynq:in_progress
// KEYS[2] -> asynq:queues:default
// ARGV[1] -> taskMessage value
script := redis.NewScript(`
redis.call("LREM", KEYS[1], 0, ARGV[1])
redis.call("RPUSH", KEYS[2], ARGV[1])
return redis.status_reply("OK")
`)
_, err = script.Run(r.client, []string{inProgressQ, defaultQ}, string(bytes)).Result()
return err
}
// Schedule adds the task to the backlog queue to be processed in the future.
func (r *RDB) Schedule(msg *TaskMessage, processAt time.Time) error {
bytes, err := json.Marshal(msg)
if err != nil {
return fmt.Errorf("could not marshal %+v to json: %v", msg, err)
}
score := float64(processAt.Unix())
err = r.client.ZAdd(scheduledQ, &redis.Z{Member: string(bytes), Score: score}).Err()
if err != nil {
return fmt.Errorf("command `ZADD %s %.1f %s` failed: %v", scheduledQ, score, string(bytes), err)
}
return nil
}
// Retry moves the task from in-progress to retry queue, incrementing retry count
// and assigning error message to the task message.
func (r *RDB) Retry(msg *TaskMessage, processAt time.Time, errMsg string) error {
bytesToRemove, err := json.Marshal(msg)
if err != nil {
return fmt.Errorf("could not marshal %+v to json: %v", msg, err)
}
modified := *msg
modified.Retried++
modified.ErrorMsg = errMsg
bytesToAdd, err := json.Marshal(&modified)
if err != nil {
return fmt.Errorf("could not marshal %+v to json: %v", modified, err)
}
// KEYS[1] -> asynq:in_progress
// KEYS[2] -> asynq:retry
// ARGV[1] -> TaskMessage value to remove from InProgress queue
// ARGV[2] -> TaskMessage value to add to Retry queue
// ARGV[3] -> retry_at UNIX timestamp
script := redis.NewScript(`
redis.call("LREM", KEYS[1], 0, ARGV[1])
redis.call("ZADD", KEYS[2], ARGV[3], ARGV[2])
return redis.status_reply("OK")
`)
_, err = script.Run(r.client, []string{inProgressQ, retryQ},
string(bytesToRemove), string(bytesToAdd), processAt.Unix()).Result()
return err
}
// Kill sends the task to "dead" queue from in-progress queue, assigning
// the error message to the task.
// It also trims the set by timestamp and set size.
func (r *RDB) Kill(msg *TaskMessage, errMsg string) error {
const maxDeadTask = 10
const deadExpirationInDays = 90
bytesToRemove, err := json.Marshal(msg)
if err != nil {
return fmt.Errorf("could not marshal %+v to json: %v", msg, err)
}
modified := *msg
modified.ErrorMsg = errMsg
bytesToAdd, err := json.Marshal(&modified)
if err != nil {
return fmt.Errorf("could not marshal %+v to json: %v", modified, err)
}
now := time.Now()
limit := now.AddDate(0, 0, -deadExpirationInDays).Unix() // 90 days ago
// KEYS[1] -> asynq:in_progress
// KEYS[2] -> asynq:dead
// ARGV[1] -> TaskMessage value to remove from InProgress queue
// ARGV[2] -> TaskMessage value to add to Dead queue
// ARGV[3] -> died_at UNIX timestamp
// ARGV[4] -> cutoff timestamp (e.g., 90 days ago)
// ARGV[5] -> max number of tasks in dead queue (e.g., 100)
script := redis.NewScript(`
redis.call("LREM", KEYS[1], 0, ARGV[1])
redis.call("ZADD", KEYS[2], ARGV[3], ARGV[2])
redis.call("ZREMRANGEBYSCORE", KEYS[2], "-inf", ARGV[4])
redis.call("ZREMRANGEBYRANK", KEYS[2], 0, -ARGV[5])
return redis.status_reply("OK")
`)
_, err = script.Run(r.client, []string{inProgressQ, deadQ},
string(bytesToRemove), string(bytesToAdd), now.Unix(), limit, maxDeadTask).Result()
return err
}
// RestoreUnfinished moves all tasks from in-progress list to the queue
// and reports the number of tasks restored.
func (r *RDB) RestoreUnfinished() (int64, error) {
script := redis.NewScript(`
local len = redis.call("LLEN", KEYS[1])
for i = len, 1, -1 do
redis.call("RPOPLPUSH", KEYS[1], KEYS[2])
end
return len
`)
res, err := script.Run(r.client, []string{inProgressQ, defaultQ}).Result()
if err != nil {
return 0, err
}
n, ok := res.(int64)
if !ok {
return 0, fmt.Errorf("could not cast %v to int64", res)
}
return n, nil
}
// CheckAndEnqueue checks for all scheduled tasks and enqueues any tasks that
// have to be processed.
func (r *RDB) CheckAndEnqueue() error {
delayed := []string{scheduledQ, retryQ}
for _, zset := range delayed {
if err := r.forward(zset); err != nil {
return err
}
}
return nil
}
// forward moves all tasks with a score less than the current unix time
// from the given zset to the default queue.
func (r *RDB) forward(from string) error {
script := redis.NewScript(`
local msgs = redis.call("ZRANGEBYSCORE", KEYS[1], "-inf", ARGV[1])
for _, msg in ipairs(msgs) do
redis.call("ZREM", KEYS[1], msg)
redis.call("LPUSH", KEYS[2], msg)
end
return msgs
`)
now := float64(time.Now().Unix())
_, err := script.Run(r.client, []string{from, defaultQ}, now).Result()
return err
}