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The short version: Is there a way to empty a go channel without recreating it, or looping through it?
The why: I'm using two channels to send and receive data, and I have an extra channel to signal that a reconnect is needed.
Now when the transport has been reset/reconnected I want to 'empty' the extra channel to make sure that there is not any lingering other reset requests which would cause the thing to reconnect again.
270
Closing a channel indicates that no more values will be sent on it. This can be useful to communicate completion to the channel's receivers. In this example we'll use a jobs channel to communicate work to be done from the main() goroutine to a worker goroutine.
The Channel Closing Principle One general principle of using Go channels is don't close a channel from the receiver side and don't close a channel if the channel has multiple concurrent senders. In other words, we should only close a channel in a sender goroutine if the sender is the only sender of the channel.
You needn't close every channel when you've finished with it. It's only necessary to close a channel when it is important to tell the receiving goroutines that all data have been sent.
Typically, you pass the goroutine a (possibly separate) signal channel. That signal channel is used to push a value into when you want the goroutine to stop. The goroutine polls that channel regularly. As soon as it detects a signal, it quits.
It is not possible to empty a channel without a loop. If you don't have any concurrent receivers, then you can use this simple loop:
for len(ch) > 0 {
<-ch
}
If you do have concurrent receivers, then use the loop:
L:
for {
select {
case <-c:
default:
break L
}
}
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