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package proxy
import (
"errors"
"sync"
)
var (
ErrEmptySrvSelectorName = errors.New("server selector name is empty")
)
var (
srvSelectors map[string]func(*ClientConn) (string, Server)
srvSelectorMu sync.RWMutex
srvSelectorOnce sync.Once
)
// RegisterSrvSelector registers a server selection handler
// which can be enabled using the `SrvSelector` config option.
// Empty names are an error.
// If the handler returns an empty server name,
// the regular server selection procedure is used.
// Only one server selector can be active at a time.
func RegisterSrvSelector(name string, sel func(*ClientConn) (string, Server)) error {
initSrvSelectors()
if name == "" {
return ErrEmptySrvSelectorName
}
srvSelectorMu.Lock()
defer srvSelectorMu.Unlock()
srvSelectors[name] = sel
return nil
}
func selectSrv(cc *ClientConn) (string, Server) {
sel := Conf().SrvSelector
if sel == "" {
return "", Server{}
}
initSrvSelectors()
srvSelectorMu.RLock()
defer srvSelectorMu.RUnlock()
handler, ok := srvSelectors[sel]
if !ok {
cc.Log("<-", "server selector not registered")
return "", Server{}
}
return handler(cc)
}
func initSrvSelectors() {
srvSelectorOnce.Do(func() {
srvSelectorMu.Lock()
defer srvSelectorMu.Unlock()
srvSelectors = make(map[string]func(*ClientConn) (string, Server))
})
}
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