Hi Darin,
I do embed v8 on android on a regular basis.
Unlike you, I run v8 bound to gl thread, and as a rule of thumb for
performance reasons always on a different than the main thread.
I need to, at least, run `v8::platform::PumpMessageLoop(&platform,
isolate_);` to have promises executed.
In my case, this is executed consistently once every gl thread tick, 60
times a sec.
Your webassembly example, throws this btw: "TypeError:
WebAssembly.instantiate(): Imports argument must be present and must be an
object"
Hope that helps.
El viernes, 17 de enero de 2020, 16:29:12 (UTC+1), Darin Dimitrov escribió:
>
> Thanks Clemens. I would be very happy if someone more familiar could
> provide some insight.
>
> Any pointers in the Google Chrome source code for Android would also be
> helpful. I suppose they have already faced this problem and implemented it
> properly.
>
>
> On Thursday, January 16, 2020 at 3:41:22 PM UTC+2, Clemens Backes wrote:
>>
>> On Thu, Jan 16, 2020 at 2:23 PM Darin Dimitrov <darin....@gmail.com>
>> wrote:
>>
>>> Thanks Clemens.
>>>
>>> This works fine but it blocks the main thread. What would be the best
>>> approach to handle this in an Android app? Would writing a custom platform
>>> help in this case?
>>>
>>
>> I don't know about Android development, and I am not a platform expert,
>> so maybe others can chime in.
>> I guess that your own platform implementation would help because you
>> would get notified of new tasks that get scheduled.
>>
>> On Wednesday, January 15, 2020 at 5:12:39 PM UTC+2, Clemens Hammacher
>>> wrote:
>>>>
>>>> Hi Darin,
>>>>
>>>> WebAssembly.instantiate works asynchronously, so you have to keep your
>>>> program running for a while to wait for the asynchronous result, and keep
>>>> pumping the message loop and running microtasks to actually execute the
>>>> compilation tasks and promise resolution tasks that get added from the
>>>> background.
>>>>
>>>
>>>>
>>>> This is probably not the most elegant solution, but it works:
>>>> [...]
>>>> script->Run(context).ToLocal(&result);
>>>> // Keep running for 10 seconds, pumping the message loop and running
>>>> // microtasks.
>>>> auto start = std::chrono::system_clock::now();
>>>> do {
>>>> v8::platform::PumpMessageLoop(platform.get(), isolate);
>>>> isolate->RunMicrotasks();
>>>> } while (std::chrono::duration_cast<std::chrono::seconds>(
>>>> std::chrono::system_clock::now() - start)
>>>> .count() < 10);
>>>>
>>>> Hope that helps,
>>>> Clemens
>>>>
>>>>
>>>> On Wed, Jan 15, 2020 at 9:15 AM Darin Dimitrov <darin....@gmail.com>
>>>> wrote:
>>>>
>>>>> I have embedded V8 (7.8.279.19) inside my Android application and
>>>>> tried executing a script that compiles a WebAssembly module.
>>>>>
>>>>> Unfortunately the promise returned by the "WebAssembly.compile" method
>>>>> is never completed (neither the "then" or the "catch" methods are
>>>>> invoked).
>>>>> The same happens with the "WebAssembly.instantiate" method:
>>>>>
>>>>> std::unique_ptr<v8::Platform> platform = v8::platform::
>>>>> NewDefaultPlatform();
>>>>> v8::V8::InitializePlatform(platform.get());
>>>>> v8::V8::Initialize();
>>>>>
>>>>> v8::Isolate::CreateParams create_params;
>>>>> create_params.array_buffer_allocator = v8::ArrayBuffer::Allocator::
>>>>> NewDefaultAllocator();
>>>>> v8::Isolate* isolate = v8::Isolate::New(create_params);
>>>>> v8::Isolate::Scope isolate_scope(isolate);
>>>>> v8::HandleScope scope(isolate);
>>>>> auto global_template = v8::ObjectTemplate::New(isolate);
>>>>> global_template->Set(v8::String::NewFromUtf8(isolate, "log", v8::
>>>>> NewStringType::kNormal).ToLocalChecked(), v8::FunctionTemplate::New(
>>>>> isolate, [](const v8::FunctionCallbackInfo<v8::Value>& info) {
>>>>> v8::Isolate* isolate = info.GetIsolate();
>>>>> v8::String::Utf8Value utf(isolate, info[0].As<v8::String>());
>>>>> __android_log_print(ANDROID_LOG_DEBUG, "V8Native", "%s",*utf);
>>>>> }));
>>>>>
>>>>> v8::Local<v8::Context> context = v8::Context::New(isolate, nullptr,
>>>>> global_template);
>>>>> v8::Context::Scope context_scope(context);
>>>>> const char* csource = R"(
>>>>> let bytes = new Uint8Array([
>>>>> 0,97,115,109,1,0,0,0,1,8,2,96,1,127,0,96,0,0,2,8,1,2,106,
>>>>> 115,1,95,0,0,3,2,1,1,8,1,1,10,9,1,7,0,65,185,10,16,0,11
>>>>> ]);
>>>>> log('before the call');
>>>>> WebAssembly
>>>>> .instantiate(bytes)
>>>>> .then(obj => log('success'))
>>>>> .catch(err => log('log'));
>>>>> )";
>>>>> v8::Local<v8::String> source = v8::String::NewFromUtf8(isolate,
>>>>> csource, v8::NewStringType::kNormal).ToLocalChecked();
>>>>> v8::Local<v8::Script> script = v8::Script::Compile(context, source).
>>>>> ToLocalChecked();
>>>>> v8::Local<v8::Value> result;
>>>>> script->Run(context).ToLocal(&result);
>>>>>
>>>>>
>>>>>
>>>>> Do you have any idea what I might be missing here? The same javascript
>>>>> code works fine in the desktop browser.
>>>>>
>>>>> --
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>>>>> .
>>>>>
>>>>
>>>>
>>>> --
>>>>
>>>> Clemens Backes
>>>>
>>>> Software Engineer
>>>>
>>>> clem...@google.com
>>>>
>>>>
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>>> .
>>>
>>
>> --
>>
>> Clemens Backes
>>
>> Software Engineer
>>
>> clem...@google.com
>>
>>
>> Google Germany GmbH
>>
>> Erika-Mann-Straße 33
>>
>> 80636 München
>>
>> Geschäftsführer: Paul Manicle, Halimah DeLaine Prado
>>
>> Registergericht und -nummer: Hamburg, HRB 86891
>>
>> Sitz der Gesellschaft: Hamburg
>>
>> Diese E-Mail ist vertraulich. Falls sie diese fälschlicherweise erhalten
>> haben sollten, leiten Sie diese bitte nicht an jemand anderes weiter,
>> löschen Sie alle Kopien und Anhänge davon und lassen Sie mich bitte wissen,
>> dass die E-Mail an die falsche Person gesendet wurde.
>>
>>
>> This e-mail is confidential. If you received this communication by
>> mistake, please don't forward it to anyone else, please erase all copies
>> and attachments, and please let me know that it has gone to the wrong
>> person.
>>
>>
>>
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