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Re: Batching WA changes? (Was Re: Audio Workers - please review)

From: Robert O'Callahan <robert@ocallahan.org>
Date: Fri, 12 Sep 2014 15:10:15 +1200
Message-ID: <CAOp6jLa8=zRBq1L0gWvHHyRz7zX5hLOAW7hJKDTOEJjB9gdzyA@mail.gmail.com>
To: Raymond Toy <rtoy@google.com>
Cc: Chris Wilson <cwilso@google.com>, Norbert Schnell <Norbert.Schnell@ircam.fr>, Jussi Kalliokoski <jussi.kalliokoski@gmail.com>, Ehsan Akhgari <ehsan@mozilla.com>, "public-audio@w3.org" <public-audio@w3.org>
On Fri, Sep 12, 2014 at 9:44 AM, Raymond Toy <rtoy@google.com> wrote:

> On Thu, Sep 11, 2014 at 7:51 AM, Chris Wilson <cwilso@google.com> wrote:
>
>> I don't know how it is possible to do this, unless all WA changes are
>> batched up into a single postMessage.
>>
>
> I don't understand how this would work. How do you know when to batch up
> all WA changes?
> How would this work when you're dynamically creating source nodes and
> connections?
>

In Gecko all changes made by a single HTML5 task are grouped into a batch
and applied atomically when (or more accurately, after, since application
is async) the HTML5 task ends. ( "Task" is defined in the HTML5 spec. For
example, the execution of a setTimeout callback is a single HTML5 task.)

And it seems to me that if you wnat node1.start(now) and node2.start(now)
> to actually start at the same time, don't do expensive things between the
> two calls to start.  And given the fact that GC can happen at any time,
> something that wouldn't take a long time may suddenly take a long time.
>
> Aren't these things that developers must be aware of in the normal course
> of operation?
>

There are some unavoidable issues but this is not one of them. If you take
the Gecko approach, then if node1.start(N) and node2.start(N) are called in
the same HTML5 task, they will start playing at exactly the same time
(after that task ends).

Rob
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Received on Friday, 12 September 2014 03:10:43 UTC

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