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poller.go
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/
poller.go
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package goworker
import (
"bytes"
"encoding/json"
"fmt"
"reflect"
"time"
"github.com/pkg/errors"
"github.com/redis/go-redis/v9"
)
var (
errorUnexpectedJob = errors.New("code expects exactly two items - queue name and task json")
errorCustomArgsAreNotASlice = errors.New("args from custom decoder must be a slice")
)
type poller struct {
process
isStrict bool
}
func newPoller(queues []string, isStrict bool) (*poller, error) {
process, err := newProcess("poller", queues)
if err != nil {
return nil, err
}
return &poller{
process: *process,
isStrict: isStrict,
}, nil
}
func (p *poller) getJob(c *redis.Client, interval time.Duration) (*Job, error) {
for _, queue := range p.queues(p.isStrict) {
logger.Debugf("Checking %s", queue)
results, err := c.BLPop(ctx, interval, fmt.Sprintf("%squeue:%s", workerSettings.Namespace, queue)).Result()
if err != nil {
// no jobs for now, continue on another queue
if err == redis.Nil {
continue
}
return nil, err
}
if len(results) > 0 {
if len(results) != 2 {
return nil, errorUnexpectedJob
}
// at 0 index we have a queue name
task := results[1]
logger.Debugf("Found job on %s", queue)
job := &Job{Queue: queue}
if customDecoder == nil {
decoder := json.NewDecoder(bytes.NewReader([]byte(task)))
if workerSettings.UseNumber {
decoder.UseNumber()
}
if err := decoder.Decode(&job.Payload); err != nil {
return nil, err
}
} else {
class, args, err := customDecoder(task)
if err != nil {
return nil, err
}
job.Payload.Class = class
// customDecoder has to have a fixed signature, so args are of
// type interface{}; here we check that it is actually a slice
val := reflect.ValueOf(args).Elem()
if val.Kind() != reflect.Slice {
return nil, errorCustomArgsAreNotASlice
}
// and then make it an explicit slice of interfaces
sliceLen := val.Len()
job.Payload.Args = make([]interface{}, sliceLen)
for i := 0; i < sliceLen; i++ {
job.Payload.Args[i] = val.Index(i).Interface()
}
}
return job, nil
}
}
return nil, nil
}
func (p *poller) poll(interval time.Duration, quit <-chan bool) (<-chan *Job, error) {
err := p.open(client)
if err != nil {
return nil, errors.WithStack(err)
}
err = p.start(client)
if err != nil {
return nil, errors.WithStack(err)
}
jobs := make(chan *Job)
go func() {
defer func() {
close(jobs)
err = p.finish(client)
if err != nil {
err = errors.WithStack(err)
_ = logger.Criticalf("Error on %v finishing working on %v: %+v", p, p.Queues, err)
return
}
err = p.close(client)
if err != nil {
err = errors.WithStack(err)
_ = logger.Criticalf("Error on %v closing client on %v: %+v", p, p.Queues, err)
return
}
}()
for {
select {
case <-quit:
return
default:
job, err := p.getJob(client, interval)
if err != nil {
err = errors.WithStack(err)
_ = logger.Criticalf("Error on %v getting job from %v: %+v", p, p.Queues, err)
return
}
if job != nil {
err = client.Incr(ctx, fmt.Sprintf("%sstat:processed:%v", workerSettings.Namespace, p)).Err()
if err != nil {
err = errors.WithStack(err)
_ = logger.Errorf("Error on %v incrementing stat on %v: %+v", p, p.Queues, err)
return
}
select {
case jobs <- job:
case <-quit:
buf, err := json.Marshal(job.Payload)
if err != nil {
err = errors.WithStack(err)
_ = logger.Criticalf("Error requeueing %v: %v", job, err)
return
}
err = client.LPush(ctx, fmt.Sprintf("%squeue:%s", workerSettings.Namespace, job.Queue), buf).Err()
if err != nil {
err = errors.WithStack(err)
_ = logger.Criticalf("Error requeueing %v: %v", job, err)
return
}
return
}
} else if workerSettings.ExitOnComplete {
return
}
}
}
}()
return jobs, nil
}