Indeed, servers are easier, and if all you're looking to do is to issue a
cancellation signal which immediately closes every active connection, the
code you posted is perfectly adequate.
I don't expect calling SetDeadline to ever cause a panic, regardless of the
state of the connection.
On Wed, Jul 8, 2020 at 1:43 PM Brian Candler <b.cand...@pobox.com> wrote:
> On Wednesday, 8 July 2020 11:17:56 UTC+1, Andrei Tudor Călin wrote:
>>
>> I think this works for some cases, but it is potentially wasteful (and
>> even leaky) in terms of resource usage.
>>
>> For example, if ctx is context.Background(), it leaks a goroutine for
>> every connection
>>
>
> If this is a network server, that's easily fixed: you make a new ctx for
> each connection (derived from the main one), and cancel it just before the
> connection is closed. I think it's useful anyway to have a context which
> covers the lifetime of that connection.
>
> > It also keeps the additional goroutine around for the entire lifetime
> of the connection.
>
> Goroutines are cheap.
>
> How about the following?
>
> type Deadliner interface {
> SetDeadline(t time.Time) error
> }
>
> func addContext(ctx context.Context, d Deadliner) {
> go func() {
> <-ctx.Done()
> d.SetDeadline(time.Now())
> }()
> }
>
> func handleConnection(ctx context.Context, conn net.Conn) {
> ctx, cancel := context.WithCancel(ctx)
> defer cancel()
> addContext(ctx, conn)
>
> ... rest of code goes here
> }
>
> That seems pretty clean to me. My only concern is there's a possibility
> of calling SetDeadline on an already-closed connection, and whether that
> would cause a panic.
>
>> --
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>
--
Andrei Călin
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