func makeShards(src []*shardSource) ([]*shard.Shard, error) {
out := make([]*shard.Shard, len(src))
for i, sh := range src {
if strings.Index(sh.Pivot, "0x") != 0 {
return nil, errors.New("invalid pivot format")
}
pivot, err := strconv.ParseUint(sh.Pivot[2:], 16, 64)
if err != nil {
return nil, err
}
out[i] = &shard.Shard{
Pivot: xor.Key(pivot),
Addr: x.Addr(sh.Addr),
HTTP: sh.HTTP,
}
}
return out, nil
}
// Sum sends a SUM request to the sumr database and returns the value underlying key, or zero otherwise
func (cli *Client) Sum(key sumr.Key) (result float64) {
cli.lmtr.Open()
defer cli.lmtr.Close()
cli.lk.Lock()
server := cli.metric.Nearest(xor.Key(key), 1)[0].(*shard).Server
cli.lk.Unlock()
// Recover from dead shard panic
defer func() {
if err := recover(); err != nil {
log.Printf("dead shard: %s", err)
result = math.NaN()
}
}()
retrn := server.Call("Sum", key)
return retrn[0].(float64)
}
// Add sends an ADD request to the database to add value to key; if key does not exist, it is created with the given value.
// updateTime is the application-level timestamp of this request.
// Add returns the value of the key after the update.
func (cli *Client) Add(updateTime time.Time, key sumr.Key, value float64) (result float64) {
// Per-client rate-limiting
cli.lmtr.Open()
defer cli.lmtr.Close()
cli.lk.Lock()
server := cli.metric.Nearest(xor.Key(key), 1)[0].(*shard).Server
cli.lk.Unlock()
// Recover from dead shard panic
defer func() {
if err := recover(); err != nil {
log.Printf("dead shard: %s", err)
// XXX: Take a more comprehensive action here
result = math.NaN()
}
}()
retrn := server.Call("Add", updateTime, key, value)
return retrn[0].(float64)
}
func (s *shard) Key() xor.Key {
return xor.Key(s.ShardKey)
}
// ID returns the XOR-metric ID of the shard underlying this checkpoint
func (s *WorkerCheckpoint) Key() xor.Key {
return xor.Key(s.ShardKey)
}
func ShardKeyOf(timedashID int64) xor.Key {
h := fnv.New64a()
binary.Write(h, binary.BigEndian, timedashID)
return xor.Key(h.Sum64())
}
func (id SpaceID) ShardKey() xor.Key {
return xor.Key(id)
}