On Sat, 31 Aug 2019 at 10:02, T L <tapir....@gmail.com> wrote:
>
>
> On Saturday, August 31, 2019 at 4:04:29 AM UTC-4, T L wrote:
>>
>>
>>
>> On Saturday, August 31, 2019 at 2:32:26 AM UTC-4, rog wrote:
>>>
>>> The reason you're wanting priority select is because you are shutting
>>> down the data channel preemptively, but you can wait for an acknowledgement
>>> from the run goroutine instead:
>>>
>>> https://play.golang.org/p/qSWluYy4ifl
>>>
>>>
>> Your solution is clever. The Close method can be called multiple time
>> safely.
>> Is there such a beautiful solution for multiple senders?
>>
>>
>
> Translating a multi-senders problem to a single sender problem is the only
> way I can get:
> https://play.golang.org/p/dAppUxP96g4
>
The answer really depends on what you're actually trying to do. What are
the multiple senders? What's the actual problem you're trying to solve?
I'd fairly sure you'll be able do what you want without requiring a
prioritised select, which is what this thread was about.
cheers,
rog.
>
>>
>>> On Wed, 28 Aug 2019 at 18:06, T L <tapi...@gmail.com> wrote:
>>>
>>>> The old thread:
>>>> https://groups.google.com/forum/#!topic/golang-nuts/ZrVIhHCrR9o
>>>>
>>>> Go channels are flexible, but in practice, I often encountered some
>>>> situations in which channel are hard to use.
>>>> Given an example:
>>>>
>>>> import "math/rand"
>>>>
>>>> type Producer struct {
>>>> data chan int
>>>> closed chan struct{}
>>>> }
>>>>
>>>> func NewProducer() *Producer {
>>>> p := &Producer {
>>>> data: make(chan int),
>>>> closed: make(chan struct{}),
>>>> }
>>>>
>>>> go p.run()
>>>>
>>>> return p
>>>> }
>>>>
>>>> func (p *Produce) Stream() chan int {
>>>> return p.data
>>>> }
>>>>
>>>> func (p *Producer) run() {
>>>> for {
>>>> // If non-blocking cases are selected by their appearance order,
>>>> // then the following slect block is a perfect use.
>>>> select {
>>>> case(0) <-p.closed: return
>>>> case p.data <- rand.Int():
>>>> }
>>>> }
>>>> }
>>>>
>>>> func (p *Produce) Clsoe() {
>>>> close(p.closed)
>>>> close(p.data)
>>>> }
>>>>
>>>> func main() {
>>>> p := NewProducer()
>>>> for n := p.Stream() {
>>>> // use n ...
>>>> }
>>>> }
>>>>
>>>>
>>>> If the first case in the select block in the above example has a higher
>>>> priority than the second one,
>>>> then coding will be much happier for the use cases like the above one.
>>>>
>>>> In short, the above use case requires:
>>>> * for receivers, data streaming end is notified by the close of a
>>>> channel.
>>>> * for senders, data will never be sent to closed channel.
>>>>
>>>> But, as Go 1 doesn't support priority select cases, it is much tedious
>>>> to implement the code
>>>> satisfying the above listed requirements. The final implementation is
>>>> often very ugly and inefficient.
>>>>
>>>> Does anyone else also experience the pain?
>>>>
>>>> --
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>>>> .
>>>>
>>> --
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