914974 - Allow MessagePorts to be sent via nsIFrameMessageManager

Status: NEW

(Core :: DOM: Core & HTML, defect, P5)

Description

[Mark Hammond [:markh] [:mhammond]]

Bug 677638 gave us MessagePorts and bug 516752 is giving us e10s.  Bug 914451 wants both of these, so wants a way to transfer a message port from the chrome process to a content process via nsIFrameMessageManager.

A complication here is that sendAsyncMessage etc have already "stolen" the 3rd arg for CPOW objects - ideally it could morph into something like "cpowsAndTransferables" so CPOWs *and* other transferrable objects could be specified.  Seeing sendAsyncMessage isn't a web api, it would also be OK for the port to be passed in msg.data, although it would need special casing as a MessagePort can't be copied, only transferred.

My testing shows the port object actually *can* be specified in the message data, but the receiving end doesn't actually see a MessagePort, just an [object Object] that doesn't work as a port - but that might just be bug 912456, which I expect might stop even that much working.

Comment 1

[David Anderson [:dvander] - inactive, e-mail if emergency]

Yeah, ideally we could figure out how to marshal it along with msg.data. Is it only going to be used with sendAsyncMessage? If so, you could also consider adding a sendMessagePort.

Comment 2

[Irakli Gozalishvili [:irakli] [:gozala] [@gozala]]

(In reply to David Anderson [:dvander] (inactive, r?/f?/ni? to ping) from comment #1)
> Yeah, ideally we could figure out how to marshal it along with msg.data. Is
> it only going to be used with sendAsyncMessage? If so, you could also
> consider adding a sendMessagePort.

For our use case we would rather have it as separate argument on the `sendAsyncMessage` because port may be sent with an associated message. Having different method will require coordination of the message and associated port manually.

Comment 3

[SUN Haitao]

Maybe we can get rid of all these troubles by adding a `sendAsyncMessageEx(name, data, transferables, cpows)` method.

Comment 4

[Chris Peterson [:cpeterson]]

Mass tracking-e10s flag change. Filter bugmail on "2be0fcce-e36a-4e2c-aa80-0e3d33eb5406".