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scheduler_resolver.go
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scheduler_resolver.go
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/*
* Copyright 2022 The Dragonfly 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 resolver
import (
"reflect"
"sync"
"google.golang.org/grpc/grpclog"
"google.golang.org/grpc/resolver"
"d7y.io/dragonfly/v2/client/config"
)
const (
// SchedulerScheme is the scheduler schema used by resolver.
SchedulerScheme = "sched"
)
var (
// SchedulerVirtualTarget is scheduler virtual target.
SchedulerVirtualTarget = SchedulerScheme + "://localhost"
)
var plogger = grpclog.Component("scheduler_resolver")
// SchedulerResolver implement resolver.Builder
type SchedulerResolver struct {
addrs []resolver.Address
cc resolver.ClientConn
dynconfig config.Dynconfig
mu *sync.Mutex
}
// RegisterScheduler registers the dragonfly resolver builder to the grpc with custom schema.
func RegisterScheduler(dynconfig config.Dynconfig) {
resolver.Register(&SchedulerResolver{dynconfig: dynconfig, mu: &sync.Mutex{}})
}
// Scheme returns the resolver scheme.
func (r *SchedulerResolver) Scheme() string {
return SchedulerScheme
}
// Build creates a new resolver for the given target.
//
// gRPC dial calls Build synchronously, and fails if the returned error is
// not nil.
func (r *SchedulerResolver) Build(target resolver.Target, cc resolver.ClientConn, opts resolver.BuildOptions) (resolver.Resolver, error) {
r.cc = cc
r.dynconfig.Register(r)
r.ResolveNow(resolver.ResolveNowOptions{})
return r, nil
}
// ResolveNow will be called by gRPC to try to resolve the target name again.
// gRPC will trigger resolveNow everytime SubConn connect fail. But we only need
// to refresh addresses from manager when all SubConn fail.
// So here we don't trigger resolving to reduce the pressure of manager.
func (r *SchedulerResolver) ResolveNow(resolver.ResolveNowOptions) {
// Avoid concurrent GetResolveSchedulerAddrs calls.
if !r.mu.TryLock() {
plogger.Warning("resolve addresses is running")
return
}
defer r.mu.Unlock()
addrs, err := r.dynconfig.GetResolveSchedulerAddrs()
if err != nil {
plogger.Errorf("resolve addresses error %v", err)
return
}
if reflect.DeepEqual(r.addrs, addrs) {
return
}
r.addrs = addrs
if err := r.cc.UpdateState(resolver.State{
Addresses: addrs,
}); err != nil {
plogger.Errorf("resolver update ClientConn error %v", err)
}
plogger.Infof("resolve addresses %v", addrs)
}
// Close closes the resolver.
func (r *SchedulerResolver) Close() {
r.dynconfig.Deregister(r)
}
// OnNotify is triggered and resolver address is updated.
func (r *SchedulerResolver) OnNotify(data *config.DynconfigData) {
r.ResolveNow(resolver.ResolveNowOptions{})
}