// Increment increments the named counter.
func Increment(ctx context.Context, name string) error {
// Get counter config.
var cfg counterConfig
ckey := datastore.NewKey(ctx, configKind, name, 0, nil)
err := datastore.RunInTransaction(ctx, func(ctx context.Context) error {
err := datastore.Get(ctx, ckey, &cfg)
if err == datastore.ErrNoSuchEntity {
cfg.Shards = defaultShards
_, err = datastore.Put(ctx, ckey, &cfg)
}
return err
}, nil)
if err != nil {
return err
}
var s shard
err = datastore.RunInTransaction(ctx, func(ctx context.Context) error {
shardName := fmt.Sprintf("%s-shard%d", name, rand.Intn(cfg.Shards))
key := datastore.NewKey(ctx, shardKind, shardName, 0, nil)
err := datastore.Get(ctx, key, &s)
// A missing entity and a present entity will both work.
if err != nil && err != datastore.ErrNoSuchEntity {
return err
}
s.Name = name
s.Count++
_, err = datastore.Put(ctx, key, &s)
return err
}, nil)
if err != nil {
return err
}
memcache.IncrementExisting(ctx, memcacheKey(name), 1)
return nil
}
func incrementSoldCounter(c context.Context) error {
_, err := memcache.IncrementExisting(c, "sold", 1)
if err != nil {
if err == datastore.ErrNoSuchEntity {
log.Infof(c, "[counter] Cache miss when incrementing")
} else {
return err
}
}
sold := new(Counter)
err = datastore.RunInTransaction(c, func(c context.Context) error {
key := datastore.NewKey(c, "Counter", "sold", 0, nil)
err := datastore.Get(c, key, sold)
if err != nil && err != datastore.ErrNoSuchEntity {
return err
}
sold.Value++
_, err = datastore.Put(c, key, sold)
if err != nil {
sold.Value--
return err
}
return nil
}, nil)
return err
}
func (m mcImpl) Increment(key string, delta int64, initialValue *uint64) (uint64, error) {
if initialValue == nil {
return memcache.IncrementExisting(m.aeCtx, key, delta)
}
return memcache.Increment(m.aeCtx, key, delta, *initialValue)
}
