// executeCmd runs Store.ExecuteCmd in a goroutine. A channel with
// element type equal to the reply type is created and returned
// immediately. The reply is sent to the channel once the cmd has been
// executed by the store. The store is looked up from the store map
// if specified by header.Replica; otherwise, the command is being
// executed locally, and the replica is determined via lookup of
// header.Key in the ranges slice.
func (db *LocalDB) executeCmd(method string, header *storage.RequestHeader, args, reply interface{}) interface{} {
chanVal := reflect.MakeChan(reflect.ChanOf(reflect.BothDir, reflect.TypeOf(reply)), 1)
replyVal := reflect.ValueOf(reply)
go func() {
// If the replica isn't specified in the header, look it up.
var err error
var store *storage.Store
// If we aren't given a Replica, then a little bending over backwards here. We need to find the Store, but all
// we have is the Key. So find its Range locally, and pull out its Replica which we use to find the Store.
// This lets us use the same codepath below (store.ExecuteCmd) for both locally and remotely originated
// commands.
if header.Replica.NodeID == 0 {
if repl := db.lookupReplica(header.Key); repl != nil {
header.Replica = *repl
} else {
err = util.Errorf("unable to lookup range replica for key %q", string(header.Key))
}
}
if err == nil {
store, err = db.GetStore(&header.Replica)
}
if err != nil {
reflect.Indirect(replyVal).FieldByName("Error").Set(reflect.ValueOf(err))
} else {
store.ExecuteCmd(method, header, args, reply)
}
chanVal.Send(replyVal)
}()
return chanVal.Interface()
}
// executeCmd runs Store.ExecuteCmd in a goroutine. A channel with
// element type equal to the reply type is created and returned
// immediately. The reply is sent to the channel once the cmd has been
// executed by the store. The store is looked up from the store map
// if specified by header.Replica; otherwise, the command is being
// executed locally, and the replica is determined via lookup of
// header.Key in the ranges slice.
func (db *LocalDB) executeCmd(method string, header *storage.RequestHeader, args, reply interface{}) interface{} {
chanVal := reflect.MakeChan(reflect.ChanOf(reflect.BothDir, reflect.TypeOf(reply)), 1)
replyVal := reflect.ValueOf(reply)
go func() {
// If the replica isn't specified in the header, look it up.
var err error
var store *storage.Store
if header.Replica.NodeID == 0 {
if repl := db.lookupReplica(header.Key); repl != nil {
header.Replica = *repl
} else {
err = util.Errorf("unable to lookup range replica for key %q", string(header.Key))
}
}
if err == nil {
store, err = db.GetStore(&header.Replica)
}
if err != nil {
reflect.Indirect(replyVal).FieldByName("Error").Set(reflect.ValueOf(err))
} else {
store.ExecuteCmd(method, header, args, reply)
}
chanVal.Send(replyVal)
}()
return chanVal.Interface()
}