forked from toolshed/abra
85 lines
2.4 KiB
Go
85 lines
2.4 KiB
Go
/*
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*
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* Copyright 2024 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 gracefulswitch
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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/serviceconfig"
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)
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type lbConfig struct {
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serviceconfig.LoadBalancingConfig
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childBuilder balancer.Builder
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childConfig serviceconfig.LoadBalancingConfig
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}
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// ChildName returns the name of the child balancer of the gracefulswitch
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// Balancer.
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func ChildName(l serviceconfig.LoadBalancingConfig) string {
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return l.(*lbConfig).childBuilder.Name()
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}
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// ParseConfig parses a child config list and returns a LB config for the
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// gracefulswitch Balancer.
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//
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// cfg is expected to be a json.RawMessage containing a JSON array of LB policy
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// names + configs as the format of the "loadBalancingConfig" field in
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// ServiceConfig. It returns a type that should be passed to
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// UpdateClientConnState in the BalancerConfig field.
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func ParseConfig(cfg json.RawMessage) (serviceconfig.LoadBalancingConfig, error) {
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var lbCfg []map[string]json.RawMessage
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if err := json.Unmarshal(cfg, &lbCfg); err != nil {
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return nil, err
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}
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for i, e := range lbCfg {
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if len(e) != 1 {
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return nil, fmt.Errorf("expected a JSON struct with one entry; received entry %v at index %d", e, i)
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}
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var name string
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var jsonCfg json.RawMessage
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for name, jsonCfg = range e {
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}
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builder := balancer.Get(name)
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if builder == nil {
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// Skip unregistered balancer names.
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continue
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}
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parser, ok := builder.(balancer.ConfigParser)
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if !ok {
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// This is a valid child with no config.
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return &lbConfig{childBuilder: builder}, 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 nil, fmt.Errorf("error parsing config for policy %q: %v", name, err)
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}
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return &lbConfig{childBuilder: builder, childConfig: cfg}, nil
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}
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return nil, fmt.Errorf("no supported policies found in config: %v", string(cfg))
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}
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