// This kind of iterator expects to last more than 60s, which is when a regular datastore
// iterator will timeout (it thinks its view of the world is too stale)
// Instead, we just grab all the keys up front, and than instantiate them one at a time.
func (db FlightDB) LongIterWith(q *datastore.Query, flightProcFunc func(*f.Flight)) error {
keys, err := q.KeysOnly().GetAll(db.C, nil)
if err != nil {
return err
}
for _, key := range keys {
blob := f.FrozenFlight{}
if err := datastore.Get(db.C, key, &blob); err != nil {
return err
}
if flight, err := blob.Thaw(); err != nil {
return err
} else {
//flight.EnterUTC,flight.LeaveUTC = flight.Track.TimesInBox(sfo.KBoxSnarfingCatchment)
flight.SetDatastoreKey(key.Encode())
flightProcFunc(flight)
}
}
return nil
}
func GetAllKeys(c appengine.Context, q *ds.Query, limit int) ([]*ds.Key, ds.Cursor, bool, error) {
it := q.KeysOnly().Limit(limit + 1).Run(c)
keys := make([]*ds.Key, 0, limit)
hasMore := true
for i := 0; i < limit; i++ {
key, err := it.Next(nil)
if err == ds.Done {
hasMore = false
break
} else if err != nil {
return nil, ds.Cursor{}, false, err
}
keys = append(keys, key)
}
cursor, _ := it.Cursor()
if hasMore {
if _, err := it.Next(nil); err != nil {
hasMore = false
}
}
return keys, cursor, hasMore, nil
}
func (db FlightDB) countByQuery(q *datastore.Query) (int, error) {
q2 := q.KeysOnly()
keys, err := q2.GetAll(db.C, nil)
if err != nil {
return 0, err
}
return len(keys), nil
}
// USE: keys,ok := db.SelectKeys(qry)
func (db *Manager) SelectKeys(qry *datastore.Query) ([]string, bool) {
recs := new(interface{})
keys, err := qry.KeysOnly().GetAll(db.Context, recs)
skeys := []string{}
if err == nil {
for k := range keys {
skeys = append(skeys, keys[k].StringID())
}
}
return skeys, err == nil
}
func GetPage(c appengine.Context, query *datastore.Query, limit int, keysOnly bool, dst interface{}) (*Page, error) {
var dv reflect.Value
var mat multiArgType
var elemType reflect.Type
if !keysOnly {
dv = reflect.ValueOf(dst)
if dv.Kind() != reflect.Ptr || dv.IsNil() {
return nil, datastore.ErrInvalidEntityType
}
dv = dv.Elem()
mat, elemType = checkMultiArg(dv)
if mat == multiArgTypeInvalid || mat == multiArgTypeInterface {
return nil, datastore.ErrInvalidEntityType
}
}
var keys []*datastore.Key
var cursor datastore.Cursor
query = query.Limit(limit + 1)
if keysOnly {
query = query.KeysOnly()
}
t := query.Run(c)
more := true
for i := 0; i < limit; i++ {
var ev reflect.Value
if !keysOnly {
ev = reflect.New(elemType)
}
k, err := t.Next(ev.Interface())
if err == datastore.Done {
more = false
break
}
if err != nil {
return nil, err
}
if !keysOnly {
if mat != multiArgTypeStructPtr {
ev = ev.Elem()
}
dv.Set(reflect.Append(dv, ev))
}
keys = append(keys, k)
}
if more {
var err error
cursor, err = t.Cursor()
if err != nil {
return nil, err
}
var ei interface{}
if !keysOnly {
ei = reflect.New(elemType).Interface()
}
_, err = t.Next(ei)
if err == datastore.Done {
more = false
}
}
return &Page{
Keys: keys,
Start: cursor,
More: more,
}, nil
}
