func (w *Worker) WorkOne() (didWork bool) {
j, err := w.c.LockJob(w.Queue)
if err != nil {
log.Printf("attempting to lock job: %v", err)
return
}
if j == nil {
return // no job was available
}
defer j.Done()
defer recoverPanic(j)
didWork = true
wf, ok := w.m[j.Type]
if !ok {
msg := fmt.Sprintf("unknown job type: %q", j.Type)
log.Println(msg)
if err = j.Error(msg); err != nil {
log.Printf("attempting to save error on job %d: %v", j.ID, err)
}
return
}
if err = wf(j); err != nil {
j.Error(err.Error())
return
}
if err = j.Delete(); err != nil {
log.Printf("attempting to delete job %d: %v", j.ID, err)
}
log.Printf("event=job_worked job_id=%d job_type=%s", j.ID, j.Type)
return
}
// recoverPanic tries to handle panics in job execution.
// A stacktrace is stored into Job last_error.
func recoverPanic(j *Job) {
if r := recover(); r != nil {
// record an error on the job with panic message and stacktrace
stackBuf := make([]byte, 1024)
n := runtime.Stack(stackBuf, false)
buf := &bytes.Buffer{}
fmt.Fprintf(buf, "%v\n", r)
fmt.Fprintln(buf, string(stackBuf[:n]))
fmt.Fprintln(buf, "[...]")
stacktrace := buf.String()
log.Printf("event=panic job_id=%d job_type=%s\n%s", j.ID, j.Type, stacktrace)
if err := j.Error(stacktrace); err != nil {
log.Printf("attempting to save error on job %d: %v", j.ID, err)
}
}
}