91 lines
3.4 KiB
Go
91 lines
3.4 KiB
Go
/*
|
|
*
|
|
* Copyright 2016 gRPC authors.
|
|
*
|
|
* Licensed under the Apache License, Version 2.0 (the "License");
|
|
* you may not use this file except in compliance with the License.
|
|
* You may obtain a copy of the License at
|
|
*
|
|
* http://www.apache.org/licenses/LICENSE-2.0
|
|
*
|
|
* Unless required by applicable law or agreed to in writing, software
|
|
* distributed under the License is distributed on an "AS IS" BASIS,
|
|
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
|
|
* See the License for the specific language governing permissions and
|
|
* limitations under the License.
|
|
*
|
|
*/
|
|
|
|
package grpc
|
|
|
|
import (
|
|
"google.golang.org/grpc/balancer"
|
|
"google.golang.org/grpc/resolver"
|
|
)
|
|
|
|
// The parent ClientConn should re-resolve when grpclb loses connection to the
|
|
// remote balancer. When the ClientConn inside grpclb gets a TransientFailure,
|
|
// it calls lbManualResolver.ResolveNow(), which calls parent ClientConn's
|
|
// ResolveNow, and eventually results in re-resolve happening in parent
|
|
// ClientConn's resolver (DNS for example).
|
|
//
|
|
// parent
|
|
// ClientConn
|
|
// +-----------------------------------------------------------------+
|
|
// | parent +---------------------------------+ |
|
|
// | DNS ClientConn | grpclb | |
|
|
// | resolver balancerWrapper | | |
|
|
// | + + | grpclb grpclb | |
|
|
// | | | | ManualResolver ClientConn | |
|
|
// | | | | + + | |
|
|
// | | | | | | Transient | |
|
|
// | | | | | | Failure | |
|
|
// | | | | | <--------- | | |
|
|
// | | | <--------------- | ResolveNow | | |
|
|
// | | <--------- | ResolveNow | | | | |
|
|
// | | ResolveNow | | | | | |
|
|
// | | | | | | | |
|
|
// | + + | + + | |
|
|
// | +---------------------------------+ |
|
|
// +-----------------------------------------------------------------+
|
|
|
|
// lbManualResolver is used by the ClientConn inside grpclb. It's a manual
|
|
// resolver with a special ResolveNow() function.
|
|
//
|
|
// When ResolveNow() is called, it calls ResolveNow() on the parent ClientConn,
|
|
// so when grpclb client lose contact with remote balancers, the parent
|
|
// ClientConn's resolver will re-resolve.
|
|
type lbManualResolver struct {
|
|
scheme string
|
|
ccr resolver.ClientConn
|
|
|
|
ccb balancer.ClientConn
|
|
}
|
|
|
|
func (r *lbManualResolver) Build(_ resolver.Target, cc resolver.ClientConn, _ resolver.BuildOption) (resolver.Resolver, error) {
|
|
r.ccr = cc
|
|
return r, nil
|
|
}
|
|
|
|
func (r *lbManualResolver) Scheme() string {
|
|
return r.scheme
|
|
}
|
|
|
|
// ResolveNow calls resolveNow on the parent ClientConn.
|
|
func (r *lbManualResolver) ResolveNow(o resolver.ResolveNowOption) {
|
|
r.ccb.ResolveNow(o)
|
|
}
|
|
|
|
// Close is a noop for Resolver.
|
|
func (*lbManualResolver) Close() {}
|
|
|
|
// NewAddress calls cc.NewAddress.
|
|
func (r *lbManualResolver) NewAddress(addrs []resolver.Address) {
|
|
r.ccr.NewAddress(addrs)
|
|
}
|
|
|
|
// NewServiceConfig calls cc.NewServiceConfig.
|
|
func (r *lbManualResolver) NewServiceConfig(sc string) {
|
|
r.ccr.NewServiceConfig(sc)
|
|
}
|