On 07/27/2013 06:06 AM, Mark Hammond wrote:
On 27/07/2013 2:53 AM, Justin Lebar wrote:
...
>
Whether or not we totally succeed in this endeavor is another question
entirely. You could instrument your build to count the number of live
nsFrameMessageManager objects and report the number of message
listeners in each -- one way to do this would be with a patch very
similar to this one [1].
Thanks for following up. I'll add some hacks to count the message listeners as
you suggest and followup here with what I find.
Just to be clear though, if I find they are *not* all being removed, I should
open a bug on that rather than just removing the listeners myself and
calling it done? ie, is it accurate to say that it *should* not be necessary
to remove these handlers (and, if I verify that is true, that I could
explicitly add a note to this effect on the relevant MDN pages?)
Yes, one shouldn't have to remove message listeners. Message listeners should
in most cases work like event listeners.
But, as with event listeners, remember that the callback may keep stuff alive.
So after you have handled the message/event
you're expecting, and don't need to handle more such messages/events, you
perhaps want to remove the listener manually.
Thanks,
Mark
[1] https://bug893242.bugzilla.mozilla.org/attachment.cgi?id=774978
On Thu, Jul 25, 2013 at 6:51 PM, Mark Hammond <mhamm...@skippinet.com.au> wrote:
Felipe and I were having a discussion around a patch that uses
nsIMessageManager. Specifically, we create a <browser> element, then call
browser.messageManager.addMessageListener() with the requirement that the
listener live for as long as the browser element itself.
The question we had was whether it was necessary to explicitly call
removeMessageListener, or whether we can rely on automatic cleanup when the
browser element dies? It seems obvious to us that it *should* be safe to
rely on automatic cleanup, but searching both docs and mxr didn't make it
clear, so I figured it was better to ask rather than to cargo-cult the
addition of explicit cleanup code that wasn't necessary.
Thanks,
Mark
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