forked from TrueCloudLab/distribution
90 lines
2.8 KiB
Go
90 lines
2.8 KiB
Go
/*
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*
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* Copyright 2020 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 serviceconfig contains utility functions to parse service config.
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package serviceconfig
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import (
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"encoding/json"
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"fmt"
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"google.golang.org/grpc/balancer"
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"google.golang.org/grpc/grpclog"
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externalserviceconfig "google.golang.org/grpc/serviceconfig"
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)
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// BalancerConfig is the balancer config part that service config's
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// loadBalancingConfig fields can be unmarshalled to. It's a json unmarshaller.
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//
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// https://github.com/grpc/grpc-proto/blob/54713b1e8bc6ed2d4f25fb4dff527842150b91b2/grpc/service_config/service_config.proto#L247
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type BalancerConfig struct {
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Name string
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Config externalserviceconfig.LoadBalancingConfig
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}
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type intermediateBalancerConfig []map[string]json.RawMessage
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// UnmarshalJSON implements json unmarshaller.
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func (bc *BalancerConfig) UnmarshalJSON(b []byte) error {
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var ir intermediateBalancerConfig
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err := json.Unmarshal(b, &ir)
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if err != nil {
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return err
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}
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for i, lbcfg := range ir {
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if len(lbcfg) != 1 {
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return fmt.Errorf("invalid loadBalancingConfig: entry %v does not contain exactly 1 policy/config pair: %q", i, lbcfg)
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}
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var (
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name string
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jsonCfg json.RawMessage
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)
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// Get the key:value pair from the map.
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for name, jsonCfg = range lbcfg {
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}
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builder := balancer.Get(name)
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if builder == nil {
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// If the balancer is not registered, move on to the next config.
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// This is not an error.
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continue
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}
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bc.Name = name
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parser, ok := builder.(balancer.ConfigParser)
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if !ok {
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if string(jsonCfg) != "{}" {
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grpclog.Warningf("non-empty balancer configuration %q, but balancer does not implement ParseConfig", string(jsonCfg))
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}
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// Stop at this, though the builder doesn't support parsing config.
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return nil
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}
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cfg, err := parser.ParseConfig(jsonCfg)
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if err != nil {
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return fmt.Errorf("error parsing loadBalancingConfig for policy %q: %v", name, err)
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}
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bc.Config = cfg
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return nil
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}
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// This is reached when the for loop iterates over all entries, but didn't
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// return. This means we had a loadBalancingConfig slice but did not
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// encounter a registered policy. The config is considered invalid in this
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// case.
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return fmt.Errorf("invalid loadBalancingConfig: no supported policies found")
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}
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