| /* |
| * Licensed to the Apache Software Foundation (ASF) under one or more |
| * contributor license agreements. See the NOTICE file distributed with |
| * this work for additional information regarding copyright ownership. |
| * The ASF licenses this file to You 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 metadata collects and exposes information of all services for service discovery purpose. |
| package metadata |
| |
| import ( |
| "github.com/dubbogo/gost/log/logger" |
| |
| perrors "github.com/pkg/errors" |
| |
| "go.uber.org/atomic" |
| ) |
| |
| import ( |
| "dubbo.apache.org/dubbo-go/v3/common/constant" |
| "dubbo.apache.org/dubbo-go/v3/common/extension" |
| "dubbo.apache.org/dubbo-go/v3/metadata/service/exporter" |
| ) |
| |
| var ( |
| exporting = &atomic.Bool{} |
| ) |
| |
| func ExportMetadataService() { |
| ms, err := extension.GetLocalMetadataService(constant.DefaultKey) |
| if err != nil { |
| logger.Warnf("could not init metadata service", err) |
| return |
| } |
| |
| if exporting.Load() { |
| return |
| } |
| |
| // In theory, we can use sync.Once |
| // But sync.Once is not reentrant. |
| // Now the invocation chain is createRegistry -> tryInitMetadataService -> metadataServiceExporter.export |
| // -> createRegistry -> initMetadataService... |
| // So using sync.Once will result in dead lock |
| exporting.Store(true) |
| |
| expt := extension.GetMetadataServiceExporter(constant.DefaultKey, ms) |
| if expt == nil { |
| logger.Warnf("get metadata service exporter failed, pls check if you import _ \"dubbo.apache.org/dubbo-go/v3/metadata/service/exporter/configurable\"") |
| return |
| } |
| |
| err = expt.Export(nil) |
| if err != nil { |
| logger.Errorf("could not export the metadata service, err = %s", err.Error()) |
| return |
| } |
| |
| // report interface-app mapping |
| err = publishMapping(expt) |
| if err != nil { |
| logger.Errorf("Publish interface-application mapping failed, got error %#v", err) |
| } |
| } |
| |
| // OnEvent only handle ServiceConfigExportedEvent |
| func publishMapping(sc exporter.MetadataServiceExporter) error { |
| urls := sc.GetExportedURLs() |
| |
| for _, u := range urls { |
| err := extension.GetGlobalServiceNameMapping().Map(u) |
| if err != nil { |
| return perrors.WithMessage(err, "could not map the service: "+u.String()) |
| } |
| } |
| return nil |
| } |