Source: manager.go in package go.opencensus.io/metric/metricproducer

Copyright 2019, OpenCensus Authors Licensed 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 metricproducer

import (
	"sync"
)

Manager maintains a list of active producers. Producers can register with the manager to allow readers to read all metrics provided by them. Readers can retrieve all producers registered with the manager, read metrics from the producers and export them.

type Manager struct {
	mu        sync.RWMutex
	producers map[Producer]struct{}
}

var prodMgr *Manager
var once sync.Once

GlobalManager is a single instance of producer manager that is used by all producers and all readers.

func GlobalManager() *Manager {
	once.Do(func() {
		prodMgr = &Manager{}
		prodMgr.producers = make(map[Producer]struct{})
	})
	return prodMgr
}

AddProducer adds the producer to the Manager if it is not already present.

func (pm *Manager) AddProducer(producer Producer) {
	if producer == nil {
		return
	}
	pm.mu.Lock()
	defer pm.mu.Unlock()
	pm.producers[producer] = struct{}{}
}

DeleteProducer deletes the producer from the Manager if it is present.

func (pm *Manager) DeleteProducer(producer Producer) {
	if producer == nil {
		return
	}
	pm.mu.Lock()
	defer pm.mu.Unlock()
	delete(pm.producers, producer)
}

GetAll returns a slice of all producer currently registered with the Manager. For each call it generates a new slice. The slice should not be cached as registration may change at any time. It is typically called periodically by exporter to read metrics from the producers.

func (pm *Manager) GetAll() []Producer {
	pm.mu.Lock()
	defer pm.mu.Unlock()
	producers := make([]Producer, len(pm.producers))
	i := 0
	for producer := range pm.producers {
		producers[i] = producer
		i++
	}
	return producers