1550560 - Allow marking an IPC actor as RefCounted

Status: RESOLVED FIXED

(Core :: IPC, enhancement, P2)

Comment 1

[Nika Layzell [:nika] (ni? for response)]

Attachment: Bug 1550560 - Part 1: Parse refcounted protocols in IPDL,

The syntax for the new construct looks like the following, and re-uses the
refcounted keyword from refcounted using statements:

async refcounted protocol PFoo { ... }

Comment 2

[Nika Layzell [:nika] (ni? for response)]

Attachment: Bug 1550560 - Part 2: Generate logic for refcounted IPDL actors,

This takes the approach of directly tying the AddRef() and Release() calls
on the underlying actor object to the lifecycle of the ActorLifecycleProxy
object, by adding another virtual ActorAlloc() method as the counterpart to
ActorDealloc().

The changes to the methods called from C++ are relatively minimal:

1. The SendPFooConstructor(...) methods have the same signature, but now will
   AddRef() internally (through ActorAlloc()), so an do_AddRef(foo).take()
   isn't needed. Same with the {Bind,Open}PFooEndpoint methods.

   This was done to reduce the number of invasive internal changes in the
   codegen which were required to pipe a passed-in already_AddRefed to the
   underlying ActorLifecycleProxy which is created by generic code.

2. The AllocPFoo{Parent,Child} methods have been modified to return an
   already_AddRefed by default, and the callsites will store the result in a
   RefPtr<T> if the type is refcounted.

3. No DeallocPFoo... method is called anymore. Unfortunately due to
   devirtualization, it won't be an error if an unused method is still present,
   though it won't be called.

Comment 3

[Nika Layzell [:nika] (ni? for response)]

Attachment: Bug 1550560 - Part 3: Make BrowserBridgeParent refcounted in IPDL,

This is an example refcounted actor which was easy enough to port over as an
initial test. More can be ported in the future, potentially alongside removing
mIPCOpen.

Comment 4

[Nika Layzell [:nika] (ni? for response)]

Attachment: Bug 1550560 - Part 4: Don't generate helper ctors for refcounted actors,

Comment 5

[Nika Layzell [:nika] (ni? for response)]

Attachment: Bug 1550560 - Part 5: Remove unnecessary Alloc method for PBrowserBridge,

Comment 6

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/1c6fd8c0baeb
Part 1: Parse refcounted protocols in IPDL, r=mccr8
https://hg.mozilla.org/integration/autoland/rev/997252eb5071
Part 2: Generate logic for refcounted IPDL actors, r=mccr8
https://hg.mozilla.org/integration/autoland/rev/dad8b9f72267
Part 3: Make BrowserBridgeParent refcounted in IPDL, r=mccr8
https://hg.mozilla.org/integration/autoland/rev/d771fa8b9289
Part 4: Don't generate helper ctors for refcounted actors, r=mccr8
https://hg.mozilla.org/integration/autoland/rev/7977d9421ecd
Part 5: Remove unnecessary Alloc method for PBrowserBridge, r=mccr8

Comment 7

[Andreea Pavel [:apavel]]

https://hg.mozilla.org/mozilla-central/rev/1c6fd8c0baeb
https://hg.mozilla.org/mozilla-central/rev/997252eb5071
https://hg.mozilla.org/mozilla-central/rev/dad8b9f72267
https://hg.mozilla.org/mozilla-central/rev/d771fa8b9289
https://hg.mozilla.org/mozilla-central/rev/7977d9421ecd