flutter_flutter/runtime/dart_isolate.h
Chinmay Garde 20c805c973
Ensure that Scene::toImage renders texture backed images. (#6636)
TL;DR: Offscreen surface is created on the render thread and device to host
transfer performed there before task completion on the UI thread.

While attempting to snapshot layer trees, the engine was attempting to use the
IO thread context. The reasoning was that this would be safe to do because any
textures uploaded to the GPU as a result of async texture upload would have
originated from this context and hence the handles would be valid in either
context. As it turns out, while the handles are valid, Skia does not support
this use-case because cross-context images transfer ownership of the image from
one context to another. So, when we made the hop from the UI thread to the IO
thread (for snapshotting), if either the UI or GPU threads released the last
reference to the texture backed image, the image would be invalid. This led to
such images being absent from the layer tree snapshot.

Simply referencing the images as they are being used on the IO thread is not
sufficient because accessing images on one context after their ownership has
already been transferred to another is not safe behavior (from Skia's
perspective, the handles are still valid in the sharegroup).

To work around these issues, it was decided that an offscreen render target
would be created on the render thread. The color attachment of this render
target could then be transferred as a cross context image to the IO thread for
the device to host tranfer.

Again, this is currently not quite possible because the only way to create
cross context images is from encoded data. Till Skia exposes the functionality
to create cross-context images from textures in one context, we do a device to
host transfer on the GPU thread. The side effect of this is that this is now
part of the frame workload (image compression, which dominate the wall time,
is still done of the IO thread).

A minor side effect of this patch is that the GPU latch needs to be waited on
before the UI thread tasks can be completed before shell initialization.
2018-10-22 17:40:24 -07:00

177 lines
5.3 KiB
C++

// Copyright 2017 The Flutter Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef FLUTTER_RUNTIME_DART_ISOLATE_H_
#define FLUTTER_RUNTIME_DART_ISOLATE_H_
#include <set>
#include <string>
#include "flutter/common/task_runners.h"
#include "flutter/fml/compiler_specific.h"
#include "flutter/fml/macros.h"
#include "flutter/fml/mapping.h"
#include "flutter/lib/ui/snapshot_delegate.h"
#include "flutter/lib/ui/ui_dart_state.h"
#include "flutter/lib/ui/window/window.h"
#include "flutter/runtime/dart_snapshot.h"
#include "third_party/dart/runtime/include/dart_api.h"
#include "third_party/tonic/dart_state.h"
namespace blink {
class DartVM;
class DartIsolate : public UIDartState {
public:
enum class Phase {
Unknown,
Uninitialized,
Initialized,
LibrariesSetup,
Ready,
Running,
Shutdown,
};
using ChildIsolatePreparer = std::function<bool(DartIsolate*)>;
// The root isolate of a Flutter application is special because it gets Window
// bindings. From the VM's perspective, this isolate is not special in any
// way.
static std::weak_ptr<DartIsolate> CreateRootIsolate(
DartVM* vm,
fml::RefPtr<DartSnapshot> isolate_snapshot,
fml::RefPtr<DartSnapshot> shared_snapshot,
TaskRunners task_runners,
std::unique_ptr<Window> window,
fml::WeakPtr<SnapshotDelegate> snapshot_delegate,
fml::WeakPtr<GrContext> resource_context,
fml::RefPtr<flow::SkiaUnrefQueue> unref_queue,
std::string advisory_script_uri,
std::string advisory_script_entrypoint,
Dart_IsolateFlags* flags = nullptr);
DartIsolate(DartVM* vm,
fml::RefPtr<DartSnapshot> isolate_snapshot,
fml::RefPtr<DartSnapshot> shared_snapshot,
TaskRunners task_runners,
fml::WeakPtr<SnapshotDelegate> snapshot_delegate,
fml::WeakPtr<GrContext> resource_context,
fml::RefPtr<flow::SkiaUnrefQueue> unref_queue,
std::string advisory_script_uri,
std::string advisory_script_entrypoint,
ChildIsolatePreparer child_isolate_preparer);
~DartIsolate() override;
Phase GetPhase() const;
FML_WARN_UNUSED_RESULT
bool PrepareForRunningFromPrecompiledCode();
FML_WARN_UNUSED_RESULT
bool PrepareForRunningFromKernel(std::shared_ptr<const fml::Mapping> kernel,
bool last_piece = true);
FML_WARN_UNUSED_RESULT
bool Run(const std::string& entrypoint);
FML_WARN_UNUSED_RESULT
bool RunFromLibrary(const std::string& library_name,
const std::string& entrypoint);
FML_WARN_UNUSED_RESULT
bool Shutdown();
void AddIsolateShutdownCallback(fml::closure closure);
DartVM* GetDartVM() const;
fml::RefPtr<DartSnapshot> GetIsolateSnapshot() const;
fml::RefPtr<DartSnapshot> GetSharedSnapshot() const;
std::weak_ptr<DartIsolate> GetWeakIsolatePtr();
private:
bool LoadKernel(std::shared_ptr<const fml::Mapping> mapping, bool last_piece);
class AutoFireClosure {
public:
AutoFireClosure(fml::closure closure) : closure_(std::move(closure)) {}
~AutoFireClosure() {
if (closure_) {
closure_();
}
}
private:
fml::closure closure_;
FML_DISALLOW_COPY_AND_ASSIGN(AutoFireClosure);
};
friend class DartVM;
DartVM* const vm_ = nullptr;
Phase phase_ = Phase::Unknown;
const fml::RefPtr<DartSnapshot> isolate_snapshot_;
const fml::RefPtr<DartSnapshot> shared_snapshot_;
std::vector<std::shared_ptr<const fml::Mapping>> kernel_buffers_;
std::vector<std::unique_ptr<AutoFireClosure>> shutdown_callbacks_;
ChildIsolatePreparer child_isolate_preparer_;
FML_WARN_UNUSED_RESULT
bool Initialize(Dart_Isolate isolate, bool is_root_isolate);
FML_WARN_UNUSED_RESULT
bool LoadLibraries(bool is_root_isolate);
bool UpdateThreadPoolNames() const;
FML_WARN_UNUSED_RESULT
bool MarkIsolateRunnable();
// |Dart_IsolateCreateCallback|
static Dart_Isolate DartIsolateCreateCallback(
const char* advisory_script_uri,
const char* advisory_script_entrypoint,
const char* package_root,
const char* package_config,
Dart_IsolateFlags* flags,
std::shared_ptr<DartIsolate>* embedder_isolate,
char** error);
static Dart_Isolate DartCreateAndStartServiceIsolate(
const char* advisory_script_uri,
const char* advisory_script_entrypoint,
const char* package_root,
const char* package_config,
Dart_IsolateFlags* flags,
char** error);
static std::pair<Dart_Isolate /* vm */,
std::weak_ptr<DartIsolate> /* embedder */>
CreateDartVMAndEmbedderObjectPair(
const char* advisory_script_uri,
const char* advisory_script_entrypoint,
const char* package_root,
const char* package_config,
Dart_IsolateFlags* flags,
std::shared_ptr<DartIsolate>* parent_embedder_isolate,
bool is_root_isolate,
char** error);
// |Dart_IsolateShutdownCallback|
static void DartIsolateShutdownCallback(
std::shared_ptr<DartIsolate>* embedder_isolate);
// |Dart_IsolateCleanupCallback|
static void DartIsolateCleanupCallback(
std::shared_ptr<DartIsolate>* embedder_isolate);
FML_DISALLOW_COPY_AND_ASSIGN(DartIsolate);
};
} // namespace blink
#endif // FLUTTER_RUNTIME_DART_ISOLATE_H_