I agree with Dave Cheney and Michal Strba that Context should not be used
for storage of any kind and only serve the purpose of cancelation.
In effect, the original purpose of Context, I think, was avoiding cascading
failure in chains of *network* calls, where the result of one call would
be used as argument to the next call. In effect, a kill switch on the whole
chain.
A deeper analysis of this feature makes me think that this is not so much
about goroutines (hence not so much about thread local storage) as much as
network failures.
And finally, I think the last thing anybody wants is to pollute the whole
stdlib with Contexts.
To me, given these requirements, context should become embedded in all
network functions, just like a timeout is.
Only difference, when creating a network function (client or server) one
would (optionally) call SetContextName("MyContext") on it (I think the
namespace suggestion from plan 9 is excellent), so a chain of network calls
would belong to the same named context.
So when code owning that chain of network calls would need to cancel (in
effect kill) the chain, it would just call a lib function called Cancel(ctx
string) and the whole chain of calls would be killed: every network
functions must obey a Cancel() call.
As far as extending it to Reader, it does not make sense to me. The reason
why there is a Context today is that failures in chained network calls are
difficult to detect and correct, because of inherent network
characteristics. That is not a general case for a Reader.
On Monday, August 7, 2017 at 3:40:05 PM UTC+2, Michal Strba wrote:
>
> Hi everyone!
>
> I've written a blog post called 'Context should go away for Go 2':
>
> https://faiface.github.io/post/context-should-go-away-go2/
>
> The post is about the cancelation problem in Go, how context package
> solves it, why context package is bad anyway, and that Go 2 should do
> something about it. Hope you enjoy reading ;)
>
> PS: I'm not sure if this post is acceptable for an experience report. If
> you think it is / isn't, let me know.
>
> Michal Štrba
>
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