Deal with useless StopReceivingUpdates method

[PaulAnnekov]

StopReceivingUpdates method is useless for real cases. Let's take a code from README, remove non-relevant parts and add StopReceivingUpdates() to it:

package main

import (
        "os"
        "os/signal"
        "syscall"
        "log"

        "github.com/go-telegram-bot-api/telegram-bot-api"
)

func main() {
        bot, err := tgbotapi.NewBotAPI("MyAwesomeBotToken")
        if err != nil {
                log.Panic(err)
        }

        log.Printf("Authorized on account %s", bot.Self.UserName)

        u := tgbotapi.NewUpdate(0)
        u.Timeout = 60

        updates, err := bot.GetUpdatesChan(u)

        // Stop receiving updates when app receives shutdown signal.
        shutdown := make(chan os.Signal, 1)
        signal.Notify(shutdown, syscall.SIGINT, syscall.SIGTERM)
        go func() {
            s := <-shutdown
            signal.Stop(shutdown)
            log.Printf("Got a %s signal, stop receiving updates, app is closing...", s)
            bot.StopReceivingUpdates()
        }()

        for update := range updates {
            log.Printf("[%s] %s", update.Message.From.UserName, update.Message.Text)
        }
}

Calling StopReceivingUpdates() doesn't stop to receive updates, because it waits <60 seconds to return from bot.GetUpdates (https://github.com/go-telegram-bot-api/telegram-bot-api/blob/master/bot.go#L494). If bot.GetUpdates() will return some updates - they will be sent to update channel and you will see logs.

Also, sending SIGINT/SIGTERM to a process doesn't make it to shutdown. Calling StopReceivingUpdates() just stops to call bot.GetUpdates() in a loop, but doesn't close an update channel, which is totally useless after StopReceivingUpdates() call, because the goroutine which could send a message to it was already stopped.

This method should be removed or fixed. Fix must be the following: it should cancel current polling request and close update channel.

[tinti]

Does this help?

https://github.com/go-telegram-bot-api/telegram-bot-api/pull/218