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
> <javascript:>> 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 <javascript:>
>
>
> 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
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>
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