func (self *ClientPriorityList) SelectWrite() *ClientWeightWrapper {
if self.num == 1 {
logger.LogDebug("select writer ", self.clients[0].GetClient())
return self.clients[0]
}
for {
self.i = (self.i + 1) % self.num
if self.i == 0 {
self.cw -= self.gcd
if self.cw <= 0 {
self.cw = self.w_max
if self.cw == 0 {
return nil
}
}
}
if weight := self.clients[self.i].w; weight >= self.cw {
logger.LogDebug("select writer ", self.clients[self.i].GetClient())
return self.clients[self.i]
}
}
if self.lowerPriority != nil {
return self.lowerPriority.SelectWrite()
}
return nil
}
func (self *Selector) EndBalance() {
self.lock.Lock()
defer self.lock.Unlock()
self.scaling = false
self.runtime = self.scale
logger.LogDebug("balance finish")
}
// 有可能多写，所以这里group返回的是数组，那么上层应该双写
func (self *Selector) Shard(key string, isWrite bool) []*datasource.Group {
data := []byte(key)
ds := make([]*datasource.Group, 1)
if !isWrite || !self.scaling {
i := int(crc32.ChecksumIEEE(data)) % len(self.runtime)
ds[0] = self.runtime[i]
logger.LogDebug("selector runtime", self.runtime[i], "at", i)
} else {
oldIdx := int(crc32.ChecksumIEEE(data)) % len(self.runtime)
newIdx := int(crc32.ChecksumIEEE(data)) % len(self.scale)
// 实际上这部分扩容期间的写入是冗余的
ds[0] = self.runtime[oldIdx]
logger.LogDebug("selector runtime", self.runtime[oldIdx], "at", oldIdx)
if oldIdx != newIdx {
ds = append(ds, self.scale[newIdx])
logger.LogDebug("selector scale ", self.scale[newIdx], "at", newIdx)
}
}
return ds
}
func (self *DBAdapter) GenKey(key string, keyType int, client *mysql.MysqlClient) (int64, error) {
logger.LogDebug("gen key use client", client)
db := client.GetDB()
id := int64(-1)
db.QueryRow("SELECT `db`.`id` from `db` WHERE `db`.`key`=?", key).Scan(&id)
if id < 0 {
stmt, err := db.Prepare("INSERT INTO `db` (`id`, `type`, `key`) VALUES (NULL, ?, ?)")
defer stmt.Close()
if err != nil {
return -1, err
}
result, err := stmt.Exec(keyType, key)
if err != nil {
return -1, err
}
id, err = result.LastInsertId()
if err != nil {
return -1, err
}
}
return id, nil
}
func (self *MedisHandler) Mget(keys []string) ([][]byte, error) {
logger.LogDebug("mget", keys)
return self.stringAdapter.MGet(keys)
}
func (self *Selector) Balance() {
self.lock.Lock()
defer self.lock.Unlock()
self.scaling = true
logger.LogDebug("balancing datasource groups")
}