242 lines
7.1 KiB
Go
242 lines
7.1 KiB
Go
/*
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*
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* Copyright 2017 gRPC authors.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*
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*/
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package grpc
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import (
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"encoding/json"
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"errors"
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"fmt"
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"google.golang.org/grpc/balancer"
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"google.golang.org/grpc/connectivity"
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internalgrpclog "google.golang.org/grpc/internal/grpclog"
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"google.golang.org/grpc/internal/grpcrand"
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"google.golang.org/grpc/internal/pretty"
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"google.golang.org/grpc/resolver"
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"google.golang.org/grpc/serviceconfig"
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)
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const (
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// PickFirstBalancerName is the name of the pick_first balancer.
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PickFirstBalancerName = "pick_first"
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logPrefix = "[pick-first-lb %p] "
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)
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type pickfirstBuilder struct{}
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func (pickfirstBuilder) Build(cc balancer.ClientConn, opt balancer.BuildOptions) balancer.Balancer {
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b := &pickfirstBalancer{cc: cc}
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b.logger = internalgrpclog.NewPrefixLogger(logger, fmt.Sprintf(logPrefix, b))
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return b
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}
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func (pickfirstBuilder) Name() string {
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return PickFirstBalancerName
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}
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type pfConfig struct {
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serviceconfig.LoadBalancingConfig `json:"-"`
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// If set to true, instructs the LB policy to shuffle the order of the list
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// of addresses received from the name resolver before attempting to
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// connect to them.
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ShuffleAddressList bool `json:"shuffleAddressList"`
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}
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func (pickfirstBuilder) ParseConfig(js json.RawMessage) (serviceconfig.LoadBalancingConfig, error) {
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var cfg pfConfig
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if err := json.Unmarshal(js, &cfg); err != nil {
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return nil, fmt.Errorf("pickfirst: unable to unmarshal LB policy config: %s, error: %v", string(js), err)
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}
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return cfg, nil
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}
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type pickfirstBalancer struct {
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logger *internalgrpclog.PrefixLogger
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state connectivity.State
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cc balancer.ClientConn
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subConn balancer.SubConn
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}
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func (b *pickfirstBalancer) ResolverError(err error) {
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if b.logger.V(2) {
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b.logger.Infof("Received error from the name resolver: %v", err)
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}
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if b.subConn == nil {
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b.state = connectivity.TransientFailure
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}
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if b.state != connectivity.TransientFailure {
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// The picker will not change since the balancer does not currently
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// report an error.
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return
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}
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b.cc.UpdateState(balancer.State{
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ConnectivityState: connectivity.TransientFailure,
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Picker: &picker{err: fmt.Errorf("name resolver error: %v", err)},
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})
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}
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func (b *pickfirstBalancer) UpdateClientConnState(state balancer.ClientConnState) error {
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addrs := state.ResolverState.Addresses
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if len(addrs) == 0 {
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// The resolver reported an empty address list. Treat it like an error by
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// calling b.ResolverError.
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if b.subConn != nil {
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// Shut down the old subConn. All addresses were removed, so it is
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// no longer valid.
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b.subConn.Shutdown()
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b.subConn = nil
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}
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b.ResolverError(errors.New("produced zero addresses"))
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return balancer.ErrBadResolverState
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}
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// We don't have to guard this block with the env var because ParseConfig
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// already does so.
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cfg, ok := state.BalancerConfig.(pfConfig)
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if state.BalancerConfig != nil && !ok {
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return fmt.Errorf("pickfirst: received illegal BalancerConfig (type %T): %v", state.BalancerConfig, state.BalancerConfig)
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}
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if cfg.ShuffleAddressList {
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addrs = append([]resolver.Address{}, addrs...)
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grpcrand.Shuffle(len(addrs), func(i, j int) { addrs[i], addrs[j] = addrs[j], addrs[i] })
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}
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if b.logger.V(2) {
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b.logger.Infof("Received new config %s, resolver state %s", pretty.ToJSON(cfg), pretty.ToJSON(state.ResolverState))
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}
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if b.subConn != nil {
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b.cc.UpdateAddresses(b.subConn, addrs)
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return nil
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}
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var subConn balancer.SubConn
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subConn, err := b.cc.NewSubConn(addrs, balancer.NewSubConnOptions{
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StateListener: func(state balancer.SubConnState) {
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b.updateSubConnState(subConn, state)
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},
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})
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if err != nil {
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if b.logger.V(2) {
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b.logger.Infof("Failed to create new SubConn: %v", err)
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}
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b.state = connectivity.TransientFailure
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b.cc.UpdateState(balancer.State{
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ConnectivityState: connectivity.TransientFailure,
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Picker: &picker{err: fmt.Errorf("error creating connection: %v", err)},
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})
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return balancer.ErrBadResolverState
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}
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b.subConn = subConn
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b.state = connectivity.Idle
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b.cc.UpdateState(balancer.State{
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ConnectivityState: connectivity.Connecting,
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Picker: &picker{err: balancer.ErrNoSubConnAvailable},
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})
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b.subConn.Connect()
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return nil
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}
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// UpdateSubConnState is unused as a StateListener is always registered when
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// creating SubConns.
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func (b *pickfirstBalancer) UpdateSubConnState(subConn balancer.SubConn, state balancer.SubConnState) {
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b.logger.Errorf("UpdateSubConnState(%v, %+v) called unexpectedly", subConn, state)
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}
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func (b *pickfirstBalancer) updateSubConnState(subConn balancer.SubConn, state balancer.SubConnState) {
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if b.logger.V(2) {
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b.logger.Infof("Received SubConn state update: %p, %+v", subConn, state)
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}
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if b.subConn != subConn {
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if b.logger.V(2) {
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b.logger.Infof("Ignored state change because subConn is not recognized")
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}
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return
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}
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if state.ConnectivityState == connectivity.Shutdown {
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b.subConn = nil
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return
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}
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switch state.ConnectivityState {
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case connectivity.Ready:
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b.cc.UpdateState(balancer.State{
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ConnectivityState: state.ConnectivityState,
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Picker: &picker{result: balancer.PickResult{SubConn: subConn}},
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})
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case connectivity.Connecting:
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if b.state == connectivity.TransientFailure {
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// We stay in TransientFailure until we are Ready. See A62.
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return
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}
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b.cc.UpdateState(balancer.State{
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ConnectivityState: state.ConnectivityState,
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Picker: &picker{err: balancer.ErrNoSubConnAvailable},
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})
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case connectivity.Idle:
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if b.state == connectivity.TransientFailure {
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// We stay in TransientFailure until we are Ready. Also kick the
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// subConn out of Idle into Connecting. See A62.
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b.subConn.Connect()
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return
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}
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b.cc.UpdateState(balancer.State{
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ConnectivityState: state.ConnectivityState,
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Picker: &idlePicker{subConn: subConn},
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})
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case connectivity.TransientFailure:
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b.cc.UpdateState(balancer.State{
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ConnectivityState: state.ConnectivityState,
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Picker: &picker{err: state.ConnectionError},
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})
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}
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b.state = state.ConnectivityState
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}
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func (b *pickfirstBalancer) Close() {
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}
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func (b *pickfirstBalancer) ExitIdle() {
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if b.subConn != nil && b.state == connectivity.Idle {
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b.subConn.Connect()
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}
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}
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type picker struct {
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result balancer.PickResult
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err error
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}
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func (p *picker) Pick(balancer.PickInfo) (balancer.PickResult, error) {
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return p.result, p.err
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}
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// idlePicker is used when the SubConn is IDLE and kicks the SubConn into
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// CONNECTING when Pick is called.
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type idlePicker struct {
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subConn balancer.SubConn
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}
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func (i *idlePicker) Pick(balancer.PickInfo) (balancer.PickResult, error) {
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i.subConn.Connect()
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return balancer.PickResult{}, balancer.ErrNoSubConnAvailable
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}
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