Add-ons that are not yet marked multi-process compatible will use our shimming layer, which allows usage of unsafe CPOWs within add-on code / compartments.
At least part of the problem here appears to be that FireGestures has "multiprocessCompatible" set to true in its install.rdf: https://github.com/gomita/firegestures/blob/7bd7db329c985dece9717105b07ede6303827a3d/install.rdf#L317 This will cause it to bypass our shim layer, which means it doesn't get a free pass on using CPOWs anymore. I'll see if I can make some recommendations to that add-on author in the associated GitHub issue: https://github.com/gomita/firegestures/issues/116 On 28 January 2016 at 11:57, Dave Townsend <dtowns...@mozilla.com> wrote: > I don't think that this is meant to impact add-on code at all, unless > it is calling browser code and making it do something unsafe, in which > case it would be up to the add-on developer to fix that. It's probably > worth filing a bug to track what is going on there though. > > On Thu, Jan 28, 2016 at 6:36 AM, Honza Bambas <hbam...@mozilla.com> wrote: > > Do we have any agenda for extensions? I'm using FireGestures and it's > broken > > since this has landed, just shouting out a lot of "unsafe CPOW usage" > > (missing the "forbidden" tho). > > > > Is the action here limited to just file a bug on the add-on side to fix > this > > or can we do anything on our side? (I presume and also support that > add-ons > > should be fixed here.) > > > > Thanks. > > > > -hb- > > > > > > On 1/27/2016 17:42, Mike Conley wrote: > >> > >> The spaghetti was put in the machine last night - this work has now > >> landed on mozilla-central. > >> > >> If you start seeing "unsafe CPOW usage forbidden" in the Browser Console > >> for various things, please mark them blocking bug 1233497. > >> > >> Thanks all, > >> > >> -Mike > >> > >> On 20/01/2016 3:54 PM, Mike Conley wrote: > >>> > >>> (cross-posted to both dev-platform and firefox-dev) > >>> * > >>> * > >>> TL;DR: Shortly, I’ll be flipping a pref to outlaw unsafe CPOWs in > almost > >>> all browser code. Unsafe CPOWs inside add-on scopes should continue to > >>> work properly. If you start seeing "unsafe CPOW usage forbidden” errors > >>> being throw for a feature you’re working on in the Browser Console, > it’s > >>> because unsafe CPOWs have been outlawed and you should stop using them. > >>> Talk to me if you run into problems. > >>> > >>> Details: > >>> > >>> “unsafe” CPOWs[1][2] are CPOWs that are accessed when the other process > >>> is not currently blocked waiting for information from you. For example, > >>> if you access gBrowser.selectedBrowser.contentDocumentAsCPOW.body when > >>> the content process is garbage collecting, the parent will be blocked > >>> until the child decides that it has a moment to service the synchronous > >>> message and return the information that the parent needs. Unsafe CPOWS > >>> are generally pretty horrible for performance, especially because we > >>> cannot know what state the other process is in. > >>> > >>> “safe” CPOWs are when the other process is in a known blocked state - > >>> for example, the content process sends a synchronous message to the > >>> parent asking for some information, and is blocked waiting for a > >>> response. The parent then accesses CPOWs in the content process safely, > >>> because the content process is in a known state. The only overhead here > >>> is the IPC traffic. > >>> > >>> “unsafe” CPOWs are often used by add-ons to synchronously manipulate > >>> content. A year or so back, a bunch of browser code also used unsafe > >>> CPOWs in this way, but we’ve been slowly but surely weeding them out. > >>> We’re at the state now where we believe we’ve eliminated most of the > >>> in-browser unsafe CPOW uses[3]. > >>> > >>> Within the next day or so, I’m going to be landing bug 1233497[4] which > >>> will cause unsafe CPOW usage in non-addon browser code to throw. In the > >>> event that this breaks things horribly, there is a pref[5] that we can > >>> flip to turn unsafe CPOWs back on while we fix things. > >>> > >>> Again, this work is occurring in bug 1233497[4]. If there are any major > >>> concerns, please bring them up here before I throw the spaghetti into > >>> the machine. > >>> > >>> For more details on unsafe CPOWs, please read [1] and/or [2]. > >>> > >>> [1]: > >>> > https://mikeconley.ca/blog/2015/02/17/on-unsafe-cpow-usage-in-firefox-desktop-and-why-is-my-nightly-so-sluggish-with-e10s-enabled/ > >>> > >>> [2]: http://blog.lassey.us/2015/01/10/unsafe-cpow-usage/ > >>> [3]: Outside of tests, and a few other little things that there are > >>> follow-ups for. > >>> [4]: https://bugzilla.mozilla.org/show_bug.cgi?id=1233497 > >>> [5]: dom.ipc.cpows.forbid-unsafe-from-browser > >>> > >> _______________________________________________ > >> dev-platform mailing list > >> dev-platform@lists.mozilla.org > >> https://lists.mozilla.org/listinfo/dev-platform > > > > > > > > _______________________________________________ > > dev-platform mailing list > > dev-platform@lists.mozilla.org > > https://lists.mozilla.org/listinfo/dev-platform > _______________________________________________ > dev-platform mailing list > dev-platform@lists.mozilla.org > https://lists.mozilla.org/listinfo/dev-platform > _______________________________________________ dev-platform mailing list dev-platform@lists.mozilla.org https://lists.mozilla.org/listinfo/dev-platform
