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Made flutter startup faster by allowing initialization to be parallelized #10182

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gaaclarke merged 10 commits into from
Sep 16, 2019
Merged

Made flutter startup faster by allowing initialization to be parallelized #10182

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c0ce97f
Made flutter startup faster by allowing initialization to be parallel…
gaaclarke Jul 26, 2019
13d3875
Merge branch 'master' into boost-flutter-startup-gaaclarke
gaaclarke Sep 16, 2019
7edae58
Moved shell construction to futures.
gaaclarke Sep 16, 2019
b51dc21
Fixed multiple std::move's from one unique_ptr future.
gaaclarke Sep 16, 2019
e8a6e40
fixed formatting
gaaclarke Sep 16, 2019
5f842b9
Merge branch 'master' into boost-flutter-startup-gaaclarke
gaaclarke Sep 16, 2019
9d6b813
added _future postfix
gaaclarke Sep 16, 2019
1b62816
simplified promise setter
gaaclarke Sep 16, 2019
4541f9a
Moved rasterization creation earlier to help parallelization.
gaaclarke Sep 16, 2019
799d314
fixed race condition where we were capturing a unique_ptr
gaaclarke Sep 16, 2019
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75 changes: 35 additions & 40 deletions shell/common/shell.cc
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Original file line number Diff line number Diff line change
Expand Up @@ -67,58 +67,57 @@ std::unique_ptr<Shell> Shell::CreateShellOnPlatformThread(
// first because it has state that the other subsystems depend on. It must
// first be booted and the necessary references obtained to initialize the
// other subsystems.
fml::AutoResetWaitableEvent io_latch;
std::unique_ptr<ShellIOManager> io_manager;
std::promise<std::unique_ptr<ShellIOManager>> io_manager_promise;
auto io_manager = io_manager_promise.get_future();

@chinmaygarde chinmaygarde Sep 16, 2019

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Here and elsewhere, please append _future to the ivars or locals that are now futures.

@gaaclarke gaaclarke Sep 16, 2019

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done

std::promise<fml::WeakPtr<ShellIOManager>> weak_io_manager_promise;
auto weak_io_manager = weak_io_manager_promise.get_future();
auto io_task_runner = shell->GetTaskRunners().GetIOTaskRunner();
fml::TaskRunner::RunNowOrPostTask(
io_task_runner,
[&io_latch, //
&io_manager, //
&platform_view, //
io_task_runner //
[&io_manager_promise, //
&weak_io_manager_promise, //
&platform_view, //
io_task_runner //
]() {
TRACE_EVENT0("flutter", "ShellSetupIOSubsystem");
io_manager = std::make_unique<ShellIOManager>(
auto io_manager = std::make_unique<ShellIOManager>(
platform_view->CreateResourceContext(), io_task_runner);
io_latch.Signal();
weak_io_manager_promise.set_value(io_manager->GetWeakPtr());
io_manager_promise.set_value(std::move(io_manager));
});
io_latch.Wait();

// Create the rasterizer on the GPU thread.
fml::AutoResetWaitableEvent gpu_latch;
std::unique_ptr<Rasterizer> rasterizer;
std::promise<std::unique_ptr<Rasterizer>> rasterizer_promise;

@chinmaygarde chinmaygarde Sep 16, 2019

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Please move this before the platform view creation call. You don't have to wait for the platform view to be created before this can be kicked off as there is no dependency. This can be kicked off eagerly so that platform view creation can be concurrent with rasterizer creation as well.

@gaaclarke gaaclarke Sep 16, 2019

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done

auto rasterizer = rasterizer_promise.get_future();
fml::TaskRunner::RunNowOrPostTask(
task_runners.GetGPUTaskRunner(), [&gpu_latch, //
&rasterizer, //
task_runners.GetGPUTaskRunner(), [&rasterizer_promise, //
on_create_rasterizer, //
shell = shell.get() //
]() {
TRACE_EVENT0("flutter", "ShellSetupGPUSubsystem");
if (auto new_rasterizer = on_create_rasterizer(*shell)) {
rasterizer = std::move(new_rasterizer);
rasterizer_promise.set_value(std::move(new_rasterizer));

@chinmaygarde chinmaygarde Sep 16, 2019

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This can just be condensed to one line now: rasterizer_promise.set_value(on_create_rasterizer(...))

@gaaclarke gaaclarke Sep 16, 2019

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done

} else {
rasterizer_promise.set_value(std::unique_ptr<Rasterizer>());
}
gpu_latch.Signal();
});

gpu_latch.Wait();

// Send dispatcher_maker to the engine constructor because shell won't have
// platform_view set until Shell::Setup is called later.
auto dispatcher_maker = platform_view->GetDispatcherMaker();

// Create the engine on the UI thread.
fml::AutoResetWaitableEvent ui_latch;
std::unique_ptr<Engine> engine;
std::promise<std::unique_ptr<Engine>> engine_promise;
auto engine = engine_promise.get_future();
fml::TaskRunner::RunNowOrPostTask(
shell->GetTaskRunners().GetUITaskRunner(),
fml::MakeCopyable([&ui_latch, //
&engine, //
fml::MakeCopyable([&engine_promise, //
shell = shell.get(), //
&dispatcher_maker, //
isolate_snapshot = std::move(isolate_snapshot), //
shared_snapshot = std::move(shared_snapshot), //
vsync_waiter = std::move(vsync_waiter), //
io_manager = io_manager->GetWeakPtr() //
&weak_io_manager //
]() mutable {
TRACE_EVENT0("flutter", "ShellSetupUISubsystem");
const auto& task_runners = shell->GetTaskRunners();
Expand All @@ -128,27 +127,23 @@ std::unique_ptr<Shell> Shell::CreateShellOnPlatformThread(
auto animator = std::make_unique<Animator>(*shell, task_runners,
std::move(vsync_waiter));

engine = std::make_unique<Engine>(*shell, //
dispatcher_maker, //
*shell->GetDartVM(), //
std::move(isolate_snapshot), //
std::move(shared_snapshot), //
task_runners, //
shell->GetSettings(), //
std::move(animator), //
std::move(io_manager) //
);
ui_latch.Signal();
engine_promise.set_value(std::make_unique<Engine>(
*shell, //
dispatcher_maker, //
*shell->GetDartVM(), //
std::move(isolate_snapshot), //
std::move(shared_snapshot), //
task_runners, //
shell->GetSettings(), //
std::move(animator), //
weak_io_manager.get() //
));
}));

ui_latch.Wait();
// We are already on the platform thread. So there is no platform latch to
// wait on.

if (!shell->Setup(std::move(platform_view), //
std::move(engine), //
std::move(rasterizer), //
std::move(io_manager)) //
engine.get(), //
rasterizer.get(), //
io_manager.get()) //
) {
return nullptr;
}
Expand Down