1// Copyright 2017, OpenCensus Authors 2// 3// Licensed under the Apache License, Version 2.0 (the "License"); 4// you may not use this file except in compliance with the License. 5// You may obtain a copy of the License at 6// 7// http://www.apache.org/licenses/LICENSE-2.0 8// 9// Unless required by applicable law or agreed to in writing, software 10// distributed under the License is distributed on an "AS IS" BASIS, 11// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 12// See the License for the specific language governing permissions and 13// limitations under the License. 14 15package view 16 17import "sync" 18 19var ( 20 exportersMu sync.RWMutex // guards exporters 21 exporters = make(map[Exporter]struct{}) 22) 23 24// Exporter exports the collected records as view data. 25// 26// The ExportView method should return quickly; if an 27// Exporter takes a significant amount of time to 28// process a Data, that work should be done on another goroutine. 29// 30// It is safe to assume that ExportView will not be called concurrently from 31// multiple goroutines. 32// 33// The Data should not be modified. 34type Exporter interface { 35 ExportView(viewData *Data) 36} 37 38// RegisterExporter registers an exporter. 39// Collected data will be reported via all the 40// registered exporters. Once you no longer 41// want data to be exported, invoke UnregisterExporter 42// with the previously registered exporter. 43// 44// Binaries can register exporters, libraries shouldn't register exporters. 45func RegisterExporter(e Exporter) { 46 exportersMu.Lock() 47 defer exportersMu.Unlock() 48 49 exporters[e] = struct{}{} 50} 51 52// UnregisterExporter unregisters an exporter. 53func UnregisterExporter(e Exporter) { 54 exportersMu.Lock() 55 defer exportersMu.Unlock() 56 57 delete(exporters, e) 58} 59