status-im/status-go

package peers

import (
    "sync"

    "github.com/ethereum/go-ethereum/log"
    "github.com/ethereum/go-ethereum/p2p/discv5"

    "github.com/status-im/status-go/common"
    "github.com/status-im/status-go/discovery"
)

// Register manages register topic queries
type Register struct {
    discovery discovery.Discovery
    topics    []discv5.Topic

    wg   sync.WaitGroup
    quit chan struct{}
}

// NewRegister creates instance of topic register
func NewRegister(discovery discovery.Discovery, topics ...discv5.Topic) *Register {
    return &Register{discovery: discovery, topics: topics}
}

// Start topic register query for every topic
func (r *Register) Start() error {
    if !r.discovery.Running() {
        return ErrDiscv5NotRunning
    }
    r.quit = make(chan struct{})
    for _, topic := range r.topics {
        r.wg.Add(1)
        go func(t discv5.Topic) {
            defer common.LogOnPanic()
            log.Debug("v5 register topic", "topic", t)
            if err := r.discovery.Register(string(t), r.quit); err != nil {
                log.Error("error registering topic", "topic", t, "error", err)
            }
            r.wg.Done()
        }(topic)
    }
    return nil
}

// Stop all register topic queries and waits for them to exit
func (r *Register) Stop() {
    if r.quit == nil {
        return
    }
    select {
    case <-r.quit:
        return
    default:
        close(r.quit)
    }
    log.Debug("waiting for register queries to exit")
    r.wg.Wait()
}