A soft reminder of using AbstractThread::GetCurrent()/MainThread() after some design change for Quantum-DOM.
If this message/callback is to be handled on *the main thread of the content process*, please use the replacement called AbstractMainThreadFor <https://wiki.mozilla.org/Quantum/DOM#AbstractThread::MainThread> instead. If you're in background thread or not in content process, you are totally fine to use AbstractThread::GetCurrent()/MainThread(). Regards, Bevis Tseng On Thu, Apr 20, 2017 at 2:54 AM, Kan-Ru Chen <kc...@mozilla.com> wrote: > Hello! > > With bug 1313200 landed, async IPC messages can now return data via > MozPromises. > > The IPDL syntax: > > protocol PFoo { > child: > async Bar() returns (bool param); > }; > > will generate IPC code that allow the send method like this: > > SendBar()->Then(AbstractThread::GetCurrent(), __func__, > [](bool param) { > // do something > }, > [](PromiseRejectReason aReason) { > // handle send failure > }); > > For a message named Foo it will receive a promise resolver with type > FooPromise. For example the receiving side of previous message > PFoo::Bar the handler looks like this: > > mozilla::ipc::IPCResult > FooChild::RecvBarMessage(RefPtr<BarMessagePromise>&& aPromise) > { > bool result; > // do some computation > aPromise->Resolve(result); > } > > If there are multiple return values, they will be wrapped in a > mozilla::Tuple. > > The usual MozPromise rule applies. You can store the promise and > resolve it later. You can direct the ThenFunction to be run on other > threads. If the channel is closed before all promises are resolved, > the pending promises will be rejected with > PromiseRejectReason::ChannelClosed. Promises resolved after channel > close are ignored. > > It is discouraged for the receiving handler to reject the promise. It > should be reserved for the IPC system to signal errors. If you must > reject the promise, only PromiseRejectReason::HandlerRejected is valid > value. > > Please give it a try. In theory this should work for all IPC actors. If > you encountered issues or have ideas to > improve this, please file a bug in Core :: IPC. > > Thanks, > Kanru > > P.S. Note that async constructor or destructor does not support return > promises because the semantic is still not clear. > _______________________________________________ > 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
