PSA: new helper class for MozPromise in DOM code
Hi all,
I pushed a new helper class to inbound today to make it easier to work with
MozPromise in DOM code. Specifically, it allows you to auto-disconnect a
Thenable request when the global dies.
The class is called DOMMozPromiseRequestHolder. Here is an example using
it:
#include "mozilla/dom/DOMMozPromiseRequestHolder.h"
// some method...
nsIGlobalObject* aGlobal = GetParentObject();
NS_ENSURE_TRUE(aGlobal, NS_ERROR_DOM_INVALID_STATE_ERR);
RefPtr> holder =
new DOMMozPromiseRequestHolder(global);
SomeAsyncWork()->Then(
global->EventTargetFor(TaskCategory::Other), __func__,
[holder] {
holder->Complete();
// do resolve stuff
}, [holder] {
holder->Compelte();
// do rejection stuff
})->Track(*holder);
This code supports multiple overlapping async operations at once. It also
works on both window and worker globals.
Disconnecting on workers is particularly important since the worker
shutdown may prevent the promise from dispatching a runnable. This can in
turn trigger assertions in the Thenable's destructor. The helper class
correctly disconnects the Thenable during worker shutdown without any
additional runnable dispatch.
This is landing in:
https://bugzilla.mozilla.org/show_bug.cgi?id=1457187
Please let me know if you run into any problems with it.
Thanks.
Ben
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Re: PSA: new helper class for MozPromise in DOM code
On Thu, Apr 26, 2018 at 04:12:09PM -0400, Ben Kelly wrote: I pushed a new helper class to inbound today to make it easier to work with MozPromise in DOM code. Specifically, it allows you to auto-disconnect a Thenable request when the global dies. Thank you! I've been worried about these kinds of footguns for a while. We could probably use something similar for JS... RefPtr> holder = new DOMMozPromiseRequestHolder(global); Note, this can be written a bit more concisely as: auto holder = MakeRefPtr>(global); -- Kris Maglione Senior Firefox Add-ons Engineer Mozilla Corporation All the hundreds of millions of people who, in their time, believed the Earth was flat never succeeded in unrounding it by an inch. --Isaac Asimov ___ dev-platform mailing list dev-platform@lists.mozilla.org https://lists.mozilla.org/listinfo/dev-platform
Re: PSA: new helper class for MozPromise in DOM code
Hi > On 26 Apr 2018, at 10:12 pm, Ben Kelly wrote: > > Hi all, > > I pushed a new helper class to inbound today to make it easier to work with > MozPromise in DOM code. Specifically, it allows you to auto-disconnect a > Thenable request when the global dies. > > The class is called DOMMozPromiseRequestHolder. Here is an example using > it: is that just a refcounted version of MozPromiseRequestHolder? smime.p7s Description: S/MIME cryptographic signature ___ dev-platform mailing list dev-platform@lists.mozilla.org https://lists.mozilla.org/listinfo/dev-platform
Re: PSA: new helper class for MozPromise in DOM code
On Fri, Apr 27, 2018, 3:13 AM Jean-Yves Avenard wrote: > > The class is called DOMMozPromiseRequestHolder. Here is an example using > > it: > > is that just a refcounted version of MozPromiseRequestHolder? > No. It binds to the global and calls DisconnectIfExists() when the global invokes DisconnectFromOwner() on it. ___ dev-platform mailing list dev-platform@lists.mozilla.org https://lists.mozilla.org/listinfo/dev-platform
