Go worker with MongoDB capped collection

worker_mongodb_queue.go

package main

import (
 "os"
 "log"
 "gopkg.in/mgo.v2"
 "gopkg.in/mgo.v2/bson"
 "time"
)

// Capped collection without index
type Job struct {
  Id bson.ObjectId `json:"_id" bson:"_id"`
  Name string `json:"name" bson:"name"`
  CreatedAt time.Time `json:"createdAt" bson:"createdAt"`
}

func main(){
  // change this to your capped collection name
  jobsCollectionName := "jobs"
  var job Job
  const tailTimeout time.Duration = 120 * time.Second

  // connect
  con, err := mgo.Dial(os.Getenv("MONGO_URL"))
  if err != nil {
    log.Printf("Error connecting to MongoDB: %v\n", err)
  }
  defer con.Close()

  dbSession := con.DB(jobsCollectionName)
  // find all the jobs
  jobsTail := dbSession.C(collectionName).Find(bson.M{}).Tail(tailTimeout)
  defer jobsTail.Close()
  for {
    for jobsTail.Next(&job){
      // do the work here
      log.Printf("Found job: %v created at %v\n", job.Name, job.CreatedAt)
    }

    if jobsTail.Err() != nil {
      jobsTail.Close()
    }
    if jobsTail.Timeout(){
      log.Println("Job timout")
      continue
    }

    // Restart and connect again to collection
    jobsTail = dbSession.C(collectionName).Find(bson.M{}).Tail(tailTimeout)
    log.Println("Reconnecting to the collection")
  }

}