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// Copyright 2013 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 SHELL_COMMON_SHELL_H_
#define SHELL_COMMON_SHELL_H_
#include <functional>
#include <mutex>
#include <string_view>
#include <unordered_map>
#include "flutter/common/settings.h"
#include "flutter/common/task_runners.h"
#include "flutter/flow/texture.h"
#include "flutter/fml/closure.h"
#include "flutter/fml/macros.h"
#include "flutter/fml/memory/ref_ptr.h"
#include "flutter/fml/memory/thread_checker.h"
#include "flutter/fml/memory/weak_ptr.h"
#include "flutter/fml/status.h"
#include "flutter/fml/synchronization/sync_switch.h"
#include "flutter/fml/synchronization/waitable_event.h"
#include "flutter/fml/thread.h"
#include "flutter/fml/time/time_point.h"
#include "flutter/lib/ui/semantics/custom_accessibility_action.h"
#include "flutter/lib/ui/semantics/semantics_node.h"
#include "flutter/lib/ui/window/platform_message.h"
#include "flutter/runtime/dart_vm_lifecycle.h"
#include "flutter/runtime/service_protocol.h"
#include "flutter/shell/common/animator.h"
#include "flutter/shell/common/engine.h"
#include "flutter/shell/common/platform_view.h"
#include "flutter/shell/common/rasterizer.h"
#include "flutter/shell/common/shell_io_manager.h"
#include "flutter/shell/common/surface.h"
namespace flutter {
/// Error exit codes for the Dart isolate.
enum class DartErrorCode {
/// No error has occurred.
NoError = 0,
/// The Dart error code for an API error.
ApiError = 253,
/// The Dart error code for a compilation error.
CompilationError = 254,
/// The Dart error code for an unkonwn error.
UnknownError = 255
};
//------------------------------------------------------------------------------
/// Perhaps the single most important class in the Flutter engine repository.
/// When embedders create a Flutter application, they are referring to the
/// creation of an instance of a shell. Creation and destruction of the shell is
/// synchronous and the embedder only holds a unique pointer to the shell. The
/// shell does not create the threads its primary components run on. Instead, it
/// is the embedder's responsibility to create threads and give the shell task
/// runners for those threads. Due to deterministic destruction of the shell,
/// the embedder can terminate all threads immediately after collecting the
/// shell. The shell must be created and destroyed on the same thread, but,
/// different shells (i.e. a separate instances of a Flutter application) may be
/// run on different threads simultaneously. The task runners themselves do not
/// have to be unique. If all task runner references given to the shell during
/// shell creation point to the same task runner, the Flutter application is
/// effectively single threaded.
///
/// The shell is the central nervous system of the Flutter application. None of
/// the shell components are thread safe and must be created, accessed and
/// destroyed on the same thread. To interact with one another, the various
/// components delegate to the shell for communication. Instead of using back
/// pointers to the shell, a delegation pattern is used by all components that
/// want to communicate with one another. Because of this, the shell implements
/// the delegate interface for all these components.
///
/// All shell methods accessed by the embedder may only be called on the
/// platform task runner. In case the embedder wants to directly access a shell
/// subcomponent, it is the embedder's responsibility to acquire a weak pointer
/// to that component and post a task to the task runner used by the component
/// to access its methods. The shell must also be destroyed on the platform
/// task runner.
///
/// There is no explicit API to bootstrap and shutdown the Dart VM. The first
/// instance of the shell in the process bootstraps the Dart VM and the
/// destruction of the last shell instance destroys the same. Since different
/// shells may be created and destroyed on different threads. VM bootstrap may
/// happen on one thread but its collection on another. This behavior is thread
/// safe.
///
class Shell final : public PlatformView::Delegate,
public Animator::Delegate,
public Engine::Delegate,
public Rasterizer::Delegate,
public ServiceProtocol::Handler {
public:
template <class T>
using CreateCallback = std::function<std::unique_ptr<T>(Shell&)>;
//----------------------------------------------------------------------------
/// @brief Creates a shell instance using the provided settings. The
/// callbacks to create the various shell subcomponents will be
/// called on the appropriate threads before this method returns.
/// If this is the first instance of a shell in the process, this
/// call also bootstraps the Dart VM.
///
/// @param[in] task_runners The task runners
/// @param[in] settings The settings
/// @param[in] on_create_platform_view The callback that must return a
/// platform view. This will be called on
/// the platform task runner before this
/// method returns.
/// @param[in] on_create_rasterizer That callback that must provide a
/// valid rasterizer. This will be called
/// on the render task runner before this
/// method returns.
///
/// @return A full initialized shell if the settings and callbacks are
/// valid. The root isolate has been created but not yet launched.
/// It may be launched by obtaining the engine weak pointer and
/// posting a task onto the UI task runner with a valid run
/// configuration to run the isolate. The embedder must always
/// check the validity of the shell (using the IsSetup call)
/// immediately after getting a pointer to it.
///
static std::unique_ptr<Shell> Create(
TaskRunners task_runners,
Settings settings,
const CreateCallback<PlatformView>& on_create_platform_view,
const CreateCallback<Rasterizer>& on_create_rasterizer);
//----------------------------------------------------------------------------
/// @brief Creates a shell instance using the provided settings. The
/// callbacks to create the various shell subcomponents will be
/// called on the appropriate threads before this method returns.
/// Unlike the simpler variant of this factory method, this method
/// allows for specification of window data. If this is the first
/// instance of a shell in the process, this call also bootstraps
/// the Dart VM.
///
/// @param[in] task_runners The task runners
/// @param[in] window_data The default data for setting up
/// ui.Window that attached to this
/// intance.
/// @param[in] settings The settings
/// @param[in] on_create_platform_view The callback that must return a
/// platform view. This will be called on
/// the platform task runner before this
/// method returns.
/// @param[in] on_create_rasterizer That callback that must provide a
/// valid rasterizer. This will be called
/// on the render task runner before this
/// method returns.
///
/// @return A full initialized shell if the settings and callbacks are
/// valid. The root isolate has been created but not yet launched.
/// It may be launched by obtaining the engine weak pointer and
/// posting a task onto the UI task runner with a valid run
/// configuration to run the isolate. The embedder must always
/// check the validity of the shell (using the IsSetup call)
/// immediately after getting a pointer to it.
///
static std::unique_ptr<Shell> Create(
TaskRunners task_runners,
const WindowData window_data,
Settings settings,
CreateCallback<PlatformView> on_create_platform_view,
CreateCallback<Rasterizer> on_create_rasterizer);
//----------------------------------------------------------------------------
/// @brief Creates a shell instance using the provided settings. The
/// callbacks to create the various shell subcomponents will be
/// called on the appropriate threads before this method returns.
/// Unlike the simpler variant of this factory method, this method
/// allows for the specification of an isolate snapshot that
/// cannot be adequately described in the settings. This call also
/// requires the specification of a running VM instance.
///
/// @param[in] task_runners The task runners
/// @param[in] window_data The default data for setting up
/// ui.Window that attached to this
/// intance.
/// @param[in] settings The settings
/// @param[in] isolate_snapshot A custom isolate snapshot. Takes
/// precedence over any snapshots
/// specified in the settings.
/// @param[in] on_create_platform_view The callback that must return a
/// platform view. This will be called on
/// the platform task runner before this
/// method returns.
/// @param[in] on_create_rasterizer That callback that must provide a
/// valid rasterizer. This will be called
/// on the render task runner before this
/// method returns.
/// @param[in] vm A running VM instance.
///
/// @return A full initialized shell if the settings and callbacks are
/// valid. The root isolate has been created but not yet launched.
/// It may be launched by obtaining the engine weak pointer and
/// posting a task onto the UI task runner with a valid run
/// configuration to run the isolate. The embedder must always
/// check the validity of the shell (using the IsSetup call)
/// immediately after getting a pointer to it.
///
static std::unique_ptr<Shell> Create(
TaskRunners task_runners,
const WindowData window_data,
Settings settings,
fml::RefPtr<const DartSnapshot> isolate_snapshot,
const CreateCallback<PlatformView>& on_create_platform_view,
const CreateCallback<Rasterizer>& on_create_rasterizer,
DartVMRef vm);
//----------------------------------------------------------------------------
/// @brief Destroys the shell. This is a synchronous operation and
/// synchronous barrier blocks are introduced on the various
/// threads to ensure shutdown of all shell sub-components before
/// this method returns.
///
~Shell();
//----------------------------------------------------------------------------
/// @brief Starts an isolate for the given RunConfiguration.
///
void RunEngine(RunConfiguration run_configuration);
//----------------------------------------------------------------------------
/// @brief Starts an isolate for the given RunConfiguration. The
/// result_callback will be called with the status of the
/// operation.
///
void RunEngine(RunConfiguration run_configuration,
const std::function<void(Engine::RunStatus)>& result_callback);
//------------------------------------------------------------------------------
/// @return The settings used to launch this shell.
///
const Settings& GetSettings() const;
//------------------------------------------------------------------------------
/// @brief If callers wish to interact directly with any shell
/// subcomponents, they must (on the platform thread) obtain a
/// task runner that the component is designed to run on and a
/// weak pointer to that component. They may then post a task to
/// that task runner, do the validity check on that task runner
/// before performing any operation on that component. This
/// accessor allows callers to access the task runners for this
/// shell.
///
/// @return The task runners current in use by the shell.
///
const TaskRunners& GetTaskRunners() const;
//----------------------------------------------------------------------------
/// @brief Rasterizers may only be accessed on the GPU task runner.
///
/// @return A weak pointer to the rasterizer.
///
fml::WeakPtr<Rasterizer> GetRasterizer() const;
//------------------------------------------------------------------------------
/// @brief Engines may only be accessed on the UI thread. This method is
/// deprecated, and implementers should instead use other API
/// available on the Shell or the PlatformView.
///
/// @return A weak pointer to the engine.
///
fml::WeakPtr<Engine> GetEngine();
//----------------------------------------------------------------------------
/// @brief Platform views may only be accessed on the platform task
/// runner.
///
/// @return A weak pointer to the platform view.
///
fml::WeakPtr<PlatformView> GetPlatformView();
// Embedders should call this under low memory conditions to free up
// internal caches used.
//
// This method posts a task to the raster threads to signal the Rasterizer to
// free resources.
//----------------------------------------------------------------------------
/// @brief Used by embedders to notify that there is a low memory
/// warning. The shell will attempt to purge caches. Current, only
/// the rasterizer cache is purged.
void NotifyLowMemoryWarning() const;
//----------------------------------------------------------------------------
/// @brief Used by embedders to check if all shell subcomponents are
/// initialized. It is the embedder's responsibility to make this
/// call before accessing any other shell method. A shell that is
/// not setup must be discarded and another one created with
/// updated settings.
///
/// @return Returns if the shell has been setup. Once set up, this does
/// not change for the life-cycle of the shell.
///
bool IsSetup() const;
//----------------------------------------------------------------------------
/// @brief Captures a screenshot and optionally Base64 encodes the data
/// of the last layer tree rendered by the rasterizer in this
/// shell.
///
/// @param[in] type The type of screenshot to capture.
/// @param[in] base64_encode If the screenshot data should be base64
/// encoded.
///
/// @return The screenshot result.
///
Rasterizer::Screenshot Screenshot(Rasterizer::ScreenshotType type,
bool base64_encode);
//----------------------------------------------------------------------------
/// @brief Pauses the calling thread until the first frame is presented.
///
/// @return 'kOk' when the first frame has been presented before the timeout
/// successfully, 'kFailedPrecondition' if called from the GPU or UI
/// thread, 'kDeadlineExceeded' if there is a timeout.
///
fml::Status WaitForFirstFrame(fml::TimeDelta timeout);
//----------------------------------------------------------------------------
/// @brief Used by embedders to reload the system fonts in
/// FontCollection.
/// It also clears the cached font families and send system
/// channel message to framework to rebuild affected widgets.
///
/// @return Returns if shell reloads system fonts successfully.
///
bool ReloadSystemFonts();
//----------------------------------------------------------------------------
/// @brief Used by embedders to get the last error from the Dart UI
/// Isolate, if one exists.
///
/// @return Returns the last error code from the UI Isolate.
///
std::optional<DartErrorCode> GetUIIsolateLastError() const;
//----------------------------------------------------------------------------
/// @brief Used by embedders to check if the Engine is running and has
/// any live ports remaining. For example, the Flutter tester uses
/// this method to check whether it should continue to wait for
/// a running test or not.
///
/// @return Returns if the shell has an engine and the engine has any live
/// Dart ports.
///
bool EngineHasLivePorts() const;
//----------------------------------------------------------------------------
/// @brief Accessor for the disable GPU SyncSwitch
std::shared_ptr<fml::SyncSwitch> GetIsGpuDisabledSyncSwitch() const;
//----------------------------------------------------------------------------
/// @brief Get a pointer to the Dart VM used by this running shell
/// instance.
///
/// @return The Dart VM pointer.
///
DartVM* GetDartVM();
private:
using ServiceProtocolHandler =
std::function<bool(const ServiceProtocol::Handler::ServiceProtocolMap&,
rapidjson::Document&)>;
const TaskRunners task_runners_;
const Settings settings_;
DartVMRef vm_;
mutable std::mutex time_recorder_mutex_;
std::optional<fml::TimePoint> latest_frame_target_time_;
std::unique_ptr<PlatformView> platform_view_; // on platform task runner
std::unique_ptr<Engine> engine_; // on UI task runner
std::unique_ptr<Rasterizer> rasterizer_; // on GPU task runner
std::unique_ptr<ShellIOManager> io_manager_; // on IO task runner
std::shared_ptr<fml::SyncSwitch> is_gpu_disabled_sync_switch_;
fml::WeakPtr<Engine> weak_engine_; // to be shared across threads
fml::WeakPtr<Rasterizer> weak_rasterizer_; // to be shared across threads
fml::WeakPtr<PlatformView>
weak_platform_view_; // to be shared across threads
std::unordered_map<std::string_view, // method
std::pair<fml::RefPtr<fml::TaskRunner>,
ServiceProtocolHandler> // task-runner/function
// pair
>
service_protocol_handlers_;
bool is_setup_ = false;
uint64_t next_pointer_flow_id_ = 0;
bool first_frame_rasterized_ = false;
std::atomic<bool> waiting_for_first_frame_ = true;
std::mutex waiting_for_first_frame_mutex_;
std::condition_variable waiting_for_first_frame_condition_;
// Written in the UI thread and read from the raster thread. Hence make it
// atomic.
std::atomic<bool> needs_report_timings_{false};
// Whether there's a task scheduled to report the timings to Dart through
// ui.Window.onReportTimings.
bool frame_timings_report_scheduled_ = false;
// Vector of FrameTiming::kCount * n timestamps for n frames whose timings
// have not been reported yet. Vector of ints instead of FrameTiming is stored
// here for easier conversions to Dart objects.
std::vector<int64_t> unreported_timings_;
// A cache of `Engine::GetDisplayRefreshRate` (only callable in the UI thread)
// so we can access it from `Rasterizer` (in the raster thread).
//
// The atomic is for extra thread safety as this is written in the UI thread
// and read from the raster thread.
std::atomic<float> display_refresh_rate_ = 0.0f;
// How many frames have been timed since last report.
size_t UnreportedFramesCount() const;
Shell(DartVMRef vm, TaskRunners task_runners, Settings settings);
static std::unique_ptr<Shell> CreateShellOnPlatformThread(
DartVMRef vm,
TaskRunners task_runners,
const WindowData window_data,
Settings settings,
fml::RefPtr<const DartSnapshot> isolate_snapshot,
const Shell::CreateCallback<PlatformView>& on_create_platform_view,
const Shell::CreateCallback<Rasterizer>& on_create_rasterizer);
bool Setup(std::unique_ptr<PlatformView> platform_view,
std::unique_ptr<Engine> engine,
std::unique_ptr<Rasterizer> rasterizer,
std::unique_ptr<ShellIOManager> io_manager);
void ReportTimings();
// |PlatformView::Delegate|
void OnPlatformViewCreated(std::unique_ptr<Surface> surface) override;
// |PlatformView::Delegate|
void OnPlatformViewDestroyed() override;
// |PlatformView::Delegate|
void OnPlatformViewSetViewportMetrics(
const ViewportMetrics& metrics) override;
// |PlatformView::Delegate|
void OnPlatformViewDispatchPlatformMessage(
fml::RefPtr<PlatformMessage> message) override;
// |PlatformView::Delegate|
void OnPlatformViewDispatchPointerDataPacket(
std::unique_ptr<PointerDataPacket> packet) override;
// |PlatformView::Delegate|
void OnPlatformViewDispatchSemanticsAction(
int32_t id,
SemanticsAction action,
std::vector<uint8_t> args) override;
// |PlatformView::Delegate|
void OnPlatformViewSetSemanticsEnabled(bool enabled) override;
// |shell:PlatformView::Delegate|
void OnPlatformViewSetAccessibilityFeatures(int32_t flags) override;
// |PlatformView::Delegate|
void OnPlatformViewRegisterTexture(
std::shared_ptr<flutter::Texture> texture) override;
// |PlatformView::Delegate|
void OnPlatformViewUnregisterTexture(int64_t texture_id) override;
// |PlatformView::Delegate|
void OnPlatformViewMarkTextureFrameAvailable(int64_t texture_id) override;
// |PlatformView::Delegate|
void OnPlatformViewSetNextFrameCallback(const fml::closure& closure) override;
// |Animator::Delegate|
void OnAnimatorBeginFrame(fml::TimePoint frame_target_time) override;
// |Animator::Delegate|
void OnAnimatorNotifyIdle(int64_t deadline) override;
// |Animator::Delegate|
void OnAnimatorDraw(
fml::RefPtr<Pipeline<flutter::LayerTree>> pipeline) override;
// |Animator::Delegate|
void OnAnimatorDrawLastLayerTree() override;
// |Engine::Delegate|
void OnEngineUpdateSemantics(
SemanticsNodeUpdates update,
CustomAccessibilityActionUpdates actions) override;
// |Engine::Delegate|
void OnEngineHandlePlatformMessage(
fml::RefPtr<PlatformMessage> message) override;
void HandleEngineSkiaMessage(fml::RefPtr<PlatformMessage> message);
// |Engine::Delegate|
void OnPreEngineRestart() override;
// |Engine::Delegate|
void UpdateIsolateDescription(const std::string isolate_name,
int64_t isolate_port) override;
// |Engine::Delegate|
void SetNeedsReportTimings(bool value) override;
// |Rasterizer::Delegate|
void OnFrameRasterized(const FrameTiming&) override;
// |Rasterizer::Delegate|
fml::Milliseconds GetFrameBudget() override;
// |Rasterizer::Delegate|
fml::TimePoint GetLatestFrameTargetTime() const override;
// |ServiceProtocol::Handler|
fml::RefPtr<fml::TaskRunner> GetServiceProtocolHandlerTaskRunner(
std::string_view method) const override;
// |ServiceProtocol::Handler|
bool HandleServiceProtocolMessage(
std::string_view method, // one if the extension names specified above.
const ServiceProtocolMap& params,
rapidjson::Document& response) override;
// |ServiceProtocol::Handler|
ServiceProtocol::Handler::Description GetServiceProtocolDescription()
const override;
// Service protocol handler
bool OnServiceProtocolScreenshot(
const ServiceProtocol::Handler::ServiceProtocolMap& params,
rapidjson::Document& response);
// Service protocol handler
bool OnServiceProtocolScreenshotSKP(
const ServiceProtocol::Handler::ServiceProtocolMap& params,
rapidjson::Document& response);
// Service protocol handler
bool OnServiceProtocolRunInView(
const ServiceProtocol::Handler::ServiceProtocolMap& params,
rapidjson::Document& response);
// Service protocol handler
bool OnServiceProtocolFlushUIThreadTasks(
const ServiceProtocol::Handler::ServiceProtocolMap& params,
rapidjson::Document& response);
// Service protocol handler
bool OnServiceProtocolSetAssetBundlePath(
const ServiceProtocol::Handler::ServiceProtocolMap& params,
rapidjson::Document& response);
// Service protocol handler
bool OnServiceProtocolGetDisplayRefreshRate(
const ServiceProtocol::Handler::ServiceProtocolMap& params,
rapidjson::Document& response);
// Service protocol handler
//
// The returned SkSLs are base64 encoded. Decode before storing them to files.
bool OnServiceProtocolGetSkSLs(
const ServiceProtocol::Handler::ServiceProtocolMap& params,
rapidjson::Document& response);
fml::WeakPtrFactory<Shell> weak_factory_;
// For accessing the Shell via the raster thread, necessary for various
// rasterizer callbacks.
std::unique_ptr<fml::WeakPtrFactory<Shell>> weak_factory_gpu_;
friend class testing::ShellTest;
FML_DISALLOW_COPY_AND_ASSIGN(Shell);
};
} // namespace flutter
#endif // SHELL_COMMON_SHELL_H_