1192043 - Add mechanism to proxy native calls to Gecko thread

Status: RESOLVED FIXED

(Core Graveyard :: Widget: Android, defect)

Description

[(inactive) Jim Chen [:jchen] [:darchons]]

Currently GeckoEvents are all handled on the Gecko thread. When we switch them to native calls, we are going to want some kind of automatic mechanism to forward the native call to the Gecko thread.

Comment 1

[(inactive) Jim Chen [:jchen] [:darchons]]

Attachment: Add more JNIEnv support and null-check refs in JNI ref classs (v1)

Add more constructors in LocalRef and GlobalRef to accommodate use cases
where a JNIEnv is already available for performance reasons. Also add
more null-checks when creating references for performance reasons.

Comment 2

[(inactive) Jim Chen [:jchen] [:darchons]]

Attachment: Clean up NativeStubImpl template parameters (v1)

The mangled name of a NativeStubImpl instantiation is longer than
necessary because of the ReturnType arg. This patch turns it into a bool
parameter. It also reorders the parameters for cleanness.

Comment 3

[(inactive) Jim Chen [:jchen] [:darchons]]

Attachment: Fix compile errors in Natives.h (v1)

This patch fixes a compile error when using WeakPtr, where Impl* was
expected but SupportsWeakPtr<Impl>* was given.

This patch also fixes a compile error when using the DisposeNative
implementation provided by the autogenerated Natives class. e.g.,

> struct Foo : Bar::Natives<Foo> {
>     using Bar::Natives<Foo>::DisposeNative;
> };

This uses a default implementation of DisposeNative instead of a custom
implementation, and resulted in a compile error that this patch fixes.

Comment 4

[(inactive) Jim Chen [:jchen] [:darchons]]

Attachment: Add support for proxying native calls (v1)

If a C++ class implements native calls that all return void, it can
choose to have those calls go through a custom proxy function by
inheriting from mozilla::jni::UsesNativeCallProxy and override the
ProxyNativeCall member.

ProxyNativeCall accepts a rvalue reference to a
functor object specific to each call, and can alter the calling
environment (e.g. dispatch the call to another thread) before issuing
the actual native call through the functor's operator().

Any JNI refs contained in the call are automatically turned into global
refs so that the call can continue to work outside of the original JNI
call.

Native call proxy will be used to implement automatic dispatching of
native calls from the main thread to run on the Gecko thread.

Comment 5

[James Willcox (:snorp) ([e-mail]) (he/him)]

Comment on attachment 8650077 [details] [diff] [review]
Add more JNIEnv support and null-check refs in JNI ref classs (v1)

Review of attachment 8650077 [details] [diff] [review]:
-----------------------------------------------------------------

::: widget/android/jni/Refs.h
@@ +506,5 @@
> +    }
> +
> +    // Get the raw JNI reference that can be used as a return value.
> +    // Returns the same JNI type (jobject, jstring, etc.) as the underlying Ref.
> +    auto Forget() -> decltype(Ref<Cls>(nullptr).Get())

I seriously cannot parse this. Can you explain?

Comment 6

[James Willcox (:snorp) ([e-mail]) (he/him)]

Comment on attachment 8650081 [details] [diff] [review]
Add support for proxying native calls (v1)

Review of attachment 8650081 [details] [diff] [review]:
-----------------------------------------------------------------

I don't think I really understand this wizardry, but alright.

::: tools/profiler/core/GeckoSampler.cpp
@@ +548,5 @@
>    #if defined(SPS_OS_android) && !defined(MOZ_WIDGET_GONK)
>        if (ProfileJava()) {
>          mozilla::widget::GeckoJavaSampler::PauseJavaProfiling();
>  
> +        aWriter.Start();

Was this left in by accident?

Comment 7

[James Willcox (:snorp) ([e-mail]) (he/him)]

Comment on attachment 8650077 [details] [diff] [review]
Add more JNIEnv support and null-check refs in JNI ref classs (v1)

Review of attachment 8650077 [details] [diff] [review]:
-----------------------------------------------------------------

We discussed on irc, so I get it now.

Comment 8

[Pulsebot]

https://hg.mozilla.org/integration/mozilla-inbound/rev/e25900da1968
https://hg.mozilla.org/integration/mozilla-inbound/rev/bf759946aa72
https://hg.mozilla.org/integration/mozilla-inbound/rev/8cd372463964
https://hg.mozilla.org/integration/mozilla-inbound/rev/450d1f83b001

Comment 9

[Ryan VanderMeulen [:RyanVM]]

https://hg.mozilla.org/mozilla-central/rev/e25900da1968
https://hg.mozilla.org/mozilla-central/rev/bf759946aa72
https://hg.mozilla.org/mozilla-central/rev/8cd372463964
https://hg.mozilla.org/mozilla-central/rev/450d1f83b001