W3C home > Mailing lists > Public > public-web-perf@w3.org > December 2013

Re: [beacon] no limits, no retry, no batching, post only

From: Jonas Sicking <jonas@sicking.cc>
Date: Tue, 10 Dec 2013 09:37:53 -0800
Message-ID: <CA+c2ei_F9O7RN9qMn4erW6ckPu-ZJopJ3Rhgjoax_aT5fXTYMA@mail.gmail.com>
To: Arvind Jain <arvind@google.com>
Cc: Ilya Grigorik <igrigorik@google.com>, Jatinder Mann <jmann@microsoft.com>, "public-web-perf@w3.org" <public-web-perf@w3.org>
On Mon, Dec 9, 2013 at 10:46 PM, Arvind Jain <arvind@google.com> wrote:
>
> Is it preferable to keep the return value void but throw a quota exceeded
> exception if the queue limit would be exceeded or change the return value to
> a boolean?

No. Throwing exceptions in intermittent conditions is a bad idea. It
can cause hard-to-reproduce bugs where important functionality
implemented in code that's run after the throwing function call
sometimes breaks with little help for the author to figure out why.

Keep in mind that the exception might never happen on the developer's
computer, but only on the end user's computer. At worst, there might
even be an exception handler higher up in the callstack which prevents
the exception from getting logged through window.onerror.

So returning true/false is a safer syntax.

/ Jonas

>
>
> On Mon, Dec 9, 2013 at 5:55 PM, Jonas Sicking <jonas@sicking.cc> wrote:
>>
>> On Sun, Dec 8, 2013 at 4:04 PM, Arvind Jain <arvind@google.com> wrote:
>> > I'm continuing to make changes to the current document. I think we
>> > should
>> > finalize the behavior and then we can debate whether to retrofit to XHR.
>>
>> Agreed.
>>
>> > We still need to nail down the size/queue limits. There is no mention of
>> > queue limits in the document yet.
>>
>> The more I think about it, the more I think that having strict limits
>> in the spec won't help us that much. Given that we need to have
>> max-queued-per-origin limits, we still need a way to signal to the
>> page if it bumped into those limits or not.
>>
>> That said, I think it would be good if we who are doing the initial
>> implementation of these specs could have an implementor-agreement on
>> what limits to use for now. And maybe even put such a limit as an
>> non-normative note in the spec, mostly as a documentation for web
>> developers.
>>
>> So we still need to have a way to signal to the author if a request
>> was queued or not. The two ways I can think of are:
>>
>> 1. Have a way to query the status of old requests. I.e. you can see if
>> old requests success/fail and failure reason (size too large, network
>> problems, etc).
>> 2. Synchronously return true/false at the time when the request is queued.
>>
>> 1 is more feature full, but more work to implement.
>>
>> 2 has the downside that implementing a synchronous true/false is more
>> work if you want to avoid synchronous communication between the
>> child-rendering-process and the parent-management-process.
>>
>> One implementation strategy would be to asynchronously signal to all
>> child processes how much data is currently queued for a given origin.
>> Then the child can just compare against that whenever a new request is
>> queued. This does introduce a small race if two or more child
>> processes attempt to queue requests at the same time. However the only
>> harm is that slightly more than allowed data would be queued, which
>> isn't really a big deal.
>>
>> There's no way to queue unlimited data anyway, at least not without
>> opening infinite number of child processes which I suspect would be a
>> bigger problem anyway if that was possible :)
>>
>> So I think 2 gets my vote.
>>
>> / Jonas
>
>
Received on Tuesday, 10 December 2013 17:38:52 UTC

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