go mongodb Iter迭代器樣本

func (this *Mongodb) StoreRecords(dbName, collection, storeDbName, tmpCollection string, queryMap, selecter bson.M) (err error) {session := this.GetSession()defer session.Close()iter := session.DB(dbName).C(collection).Find(queryMap).Select(selecter).Iter()oneMap := make(bson.M)historyMapSlice := make([]interface{}, 0, MAX_BULK_WRITE_FILE_LEN)flag := falsefor iter.Next(&oneMap) {tmpMap := DeepCopy(oneMap)//go深度拷貝historyMapSlice = append(historyMapSlice, tmpMap.(bson.M))if len(historyMapSlice) >= MAX_BULK_WRITE_FILE_LEN {//寫入最大長度this.BulkInsert(storeDbName, tmpCollection, historyMapSlice)historyMapSlice = make([]interface{}, 0, MAX_BULK_WRITE_FILE_LEN)flag = true}}if err = iter.Close(); err != nil {log.Error("StoreRecords,iter.Close() fail, db:", dbName,", Collection:", collection,", queryCondition:", queryMap,", selector:", selecter,", ErrInfo:", err)}if 0 == len(historyMapSlice) && !flag {err = errors.New("not found StoreRecords data")return}this.BulkInsert(storeDbName, tmpCollection, historyMapSlice)return}func (this *Mongodb) BulkInsert(dataBase, collection string, allRecords []interface{}) (err error) {    if 0 == len(allRecords) {        log.Info("bulkInsert: 0 == len(allRecords)! db:", dataBase, "collection:", collection)        return    }    bulkInsert := func(c *mgo.Collection) error {        bulk := c.Bulk()        bulk.Unordered()        bulk.Insert(allRecords...)        _, err := bulk.Run()        return err    }    err = this.WitchCollection(dataBase, collection, bulkInsert)    if err != nil {        log.Error("mongodb BulkInsert, BulkInsert Failed, db:", dataBase,            ", Collection:", collection,            ", ErrInfo:", err)    }    return}