// queryToIter takes a FinalizedQuery and returns an iterator function which
// will produce either *items or errors.
//
// - d is the raw datastore to run this query on
// - filter is a function which will return true if the given key should be
// excluded from the result set.
func queryToIter(stopChan chan struct{}, fq *ds.FinalizedQuery, d ds.RawInterface) func() (*item, error) {
c := make(chan *item)
go func() {
defer close(c)
err := d.Run(fq, func(k *ds.Key, pm ds.PropertyMap, _ ds.CursorCB) error {
i := &item{key: k, data: pm}
select {
case c <- i:
return nil
case <-stopChan:
return ds.Stop
}
})
if err != nil {
c <- &item{err: err}
}
}()
return func() (*item, error) {
itm := <-c
if itm == nil {
return nil, nil
}
if itm.err != nil {
return nil, itm.err
}
return itm, nil
}
}
func doRunInTransaction(base ds.RawInterface, f func(context.Context) error, opts *ds.TransactionOptions) error {
return base.RunInTransaction(func(ctx context.Context) error {
return withTxnBuf(ctx, f, opts)
}, opts)
}