GraphQL API and utilities for the rpdata project
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package counter
import (
"git.aiterp.net/rpdata/api/internal/store"
"github.com/globalsign/mgo"
"github.com/globalsign/mgo/bson"
)
var collection *mgo.Collection
type counter struct {
ID string `bson:"_id"`
Value int `bson:"value"`
}
// Next gets the next value of a counter, or an error if it hasn't.
func Next(category, name string) (int, error) {
id := category + "." + name
doc := counter{}
_, err := collection.Find(bson.M{"_id": id}).Apply(mgo.Change{
Update: bson.M{"$inc": bson.M{"value": 1}},
Upsert: true,
ReturnNew: true,
}, &doc)
if err != nil {
return -1, err
}
return doc.Value, nil
}
// NextMany gets the next value of a counter, or an error if it hasn't, and increments by a specified value.
// Any value `returned` to `returned+(increment-1)` should then be safe to use.
func NextMany(category, name string, increment int) (int, error) {
id := category + "." + name
doc := counter{}
_, err := collection.Find(bson.M{"_id": id}).Apply(mgo.Change{
Update: bson.M{"$inc": bson.M{"value": increment}},
Upsert: true,
ReturnNew: true,
}, &doc)
if err != nil {
return -1, err
}
return doc.Value, nil
}
func init() {
store.HandleInit(func(db *mgo.Database) {
collection = db.C("core.counters")
})
}