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flutter_flutter/engine/src/flutter/shell/common/engine.h
yaakovschectman e2908808b6 Add callback to Embedder API to respond to new channel listeners, and use for Windows lifecycle (flutter/engine#44827) 
Supplant the temporary solution
https://github.com/flutter/engine/pull/44238 with a more elegant
solution with am embedder API callback. The windows engine provides a
callback that enables graceful exit and app lifecycle when the platform
and lifecycle channels are listened to, respectively.

https://github.com/flutter/flutter/issues/131616

## Pre-launch Checklist

- [x] I read the [Contributor Guide] and followed the process outlined
there for submitting PRs.
- [x] I read the [Tree Hygiene] wiki page, which explains my
responsibilities.
- [x] I read and followed the [Flutter Style Guide] and the [C++,
Objective-C, Java style guides].
- [x] I listed at least one issue that this PR fixes in the description
above.
- [x] I added new tests to check the change I am making or feature I am
adding, or Hixie said the PR is test-exempt. See [testing the engine]
for instructions on writing and running engine tests.
- [x] I updated/added relevant documentation (doc comments with `///`).
- [ ] I signed the [CLA].
- [x] All existing and new tests are passing.

If you need help, consider asking for advice on the #hackers-new channel
on [Discord].

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[Tree Hygiene]: https://github.com/flutter/flutter/wiki/Tree-hygiene
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[testing the engine]:
https://github.com/flutter/flutter/wiki/Testing-the-engine
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---------

Co-authored-by: Chris Bracken <chris@bracken.jp>
2023-08-29 16:12:35 -04:00

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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_ENGINE_H_
#define SHELL_COMMON_ENGINE_H_
#include <memory>
#include <string>
#include "flutter/assets/asset_manager.h"
#include "flutter/common/task_runners.h"
#include "flutter/fml/macros.h"
#include "flutter/fml/mapping.h"
#include "flutter/fml/memory/weak_ptr.h"
#include "flutter/lib/ui/painting/image_decoder.h"
#include "flutter/lib/ui/painting/image_generator_registry.h"
#include "flutter/lib/ui/semantics/custom_accessibility_action.h"
#include "flutter/lib/ui/semantics/semantics_node.h"
#include "flutter/lib/ui/snapshot_delegate.h"
#include "flutter/lib/ui/text/font_collection.h"
#include "flutter/lib/ui/volatile_path_tracker.h"
#include "flutter/lib/ui/window/platform_message.h"
#include "flutter/lib/ui/window/viewport_metrics.h"
#include "flutter/runtime/dart_vm.h"
#include "flutter/runtime/runtime_controller.h"
#include "flutter/runtime/runtime_delegate.h"
#include "flutter/shell/common/animator.h"
#include "flutter/shell/common/display_manager.h"
#include "flutter/shell/common/platform_view.h"
#include "flutter/shell/common/pointer_data_dispatcher.h"
#include "flutter/shell/common/rasterizer.h"
#include "flutter/shell/common/run_configuration.h"
#include "flutter/shell/common/shell_io_manager.h"
namespace flutter {
//------------------------------------------------------------------------------
/// The engine is a component owned by the shell that resides on the UI task
/// runner and is responsible for managing the needs of the root isolate and its
/// runtime. The engine can only be created, accessed and collected on the UI
/// task runner. Each shell owns exactly one instance of the engine.
///
/// The root isolate of Flutter application gets "window" bindings. Using these
/// bindings, the application can schedule frames, post layer-trees for
/// rendering, ask to decompress images and upload them to the GPU, etc..
/// Non-root isolates of the VM do not get any of these capabilities and are run
/// in a VM managed thread pool (so if they did have "window", the threading
/// guarantees needed for engine operation would be violated).
///
/// The engine is responsible for the entire life-cycle of the root isolate.
/// When the engine is collected, its owner assumes that the root isolate has
/// been shutdown and appropriate resources collected. While each engine
/// instance can only manage a single instance of a root isolate, it may restart
/// that isolate on request. This is how the cold-restart development scenario
/// is supported.
///
/// When the engine instance is initially created, the root isolate is created
/// but it is not in the |DartIsolate::Phase::Running| phase yet. It only moves
/// into that phase when a successful call to `Engine::Run` is made.
///
/// @see `Shell`
///
/// @note This name of this class is perhaps a bit unfortunate and has
/// sometimes been the cause of confusion. For a class named "Engine"
/// in the Flutter "Engine" repository, its responsibilities are
/// decidedly unremarkable. But, it does happen to be the primary
/// entry-point used by components higher up in the Flutter tech stack
/// (usually in Dart code) to peer into the lower level functionality.
/// Besides, the authors haven't been able to come up with a more apt
/// name and it does happen to be one of the older classes in the
/// repository.
///
class Engine final : public RuntimeDelegate, PointerDataDispatcher::Delegate {
public:
//----------------------------------------------------------------------------
/// @brief Indicates the result of the call to `Engine::Run`.
///
enum class RunStatus {
//--------------------------------------------------------------------------
/// The call to |Engine::Run| was successful and the root isolate is in the
/// `DartIsolate::Phase::Running` phase with its entry-point invocation
/// already pending in the task queue.
///
Success,
//--------------------------------------------------------------------------
/// The engine can only manage a single instance of a root isolate. If a
/// previous call to run the root isolate was successful, subsequent calls
/// to run the isolate (even if the new run configuration is different) will
/// be rejected.
///
/// It is up to the caller to decide to re-purpose the running isolate,
/// terminate it, or use another shell to host the new isolate. This is
/// mostly used by embedders which have a fire-and-forget strategy to root
/// isolate launch. For example, the application may try to "launch" an
/// isolate when the embedders launches or resumes from a paused state. That
/// the isolate is running is not necessarily a failure condition for them.
/// But from the engine's perspective, the run configuration was rejected.
///
FailureAlreadyRunning,
//--------------------------------------------------------------------------
/// Used to indicate to the embedder that a root isolate was not already
/// running but the run configuration was not valid and root isolate could
/// not be moved into the `DartIsolate::Phase::Running` phase.
///
/// The caller must attempt the run call again with a valid configuration.
/// The set of all failure modes is massive and can originate from a variety
/// of sub-components. The engine will attempt to log the same when
/// possible. With the aid of logs, the common causes of failure are:
///
/// * AOT assets were given to JIT/DBC mode VM's and vice-versa.
/// * The assets could not be found in the asset manager. Callers must make
/// sure their run configuration asset managers have been correctly set
/// up.
/// * The assets themselves were corrupt or invalid. Callers must make sure
/// their asset delivery mechanisms are sound.
/// * The application entry-point or the root library of the entry-point
/// specified in the run configuration was invalid. Callers must make sure
/// that the entry-point is present in the application. If the name of the
/// entrypoint is not "main" in the root library, callers must also ensure
/// that the snapshotting process has not tree-shaken away this
/// entrypoint. This requires the decoration of the entrypoint with the
/// `@pragma('vm:entry-point')` directive. This problem will manifest in
/// AOT mode operation of the Dart VM.
///
Failure,
};
//----------------------------------------------------------------------------
/// @brief While the engine operates entirely on the UI task runner, it
/// needs the capabilities of the other components to fulfill the
/// requirements of the root isolate. The shell is the only class
/// that implements this interface as no other component has
/// access to all components in a thread safe manner. The engine
/// delegates these tasks to the shell via this interface.
///
class Delegate {
public:
//--------------------------------------------------------------------------
/// @brief When the accessibility tree has been updated by the Flutter
/// application, this new information needs to be conveyed to
/// the underlying platform. The engine delegates this task to
/// the shell via this call. The engine cannot access the
/// underlying platform directly because of threading
/// considerations. Most platform specific APIs to convey
/// accessibility information are only safe to access on the
/// platform task runner while the engine is running on the UI
/// task runner.
///
/// @see `SemanticsNode`, `SemanticsNodeUpdates`,
/// `CustomAccessibilityActionUpdates`,
/// `PlatformView::UpdateSemantics`
///
/// @param[in] updates A map with the stable semantics node identifier as
/// key and the node properties as the value.
/// @param[in] actions A map with the stable semantics node identifier as
/// key and the custom node action as the value.
///
virtual void OnEngineUpdateSemantics(
SemanticsNodeUpdates updates,
CustomAccessibilityActionUpdates actions) = 0;
//--------------------------------------------------------------------------
/// @brief When the Flutter application has a message to send to the
/// underlying platform, the message needs to be forwarded to
/// the platform on the appropriate thread (via the platform
/// task runner). The engine delegates this task to the shell
/// via this method.
///
/// @see `PlatformView::HandlePlatformMessage`
///
/// @param[in] message The message from the Flutter application to send to
/// the underlying platform.
///
virtual void OnEngineHandlePlatformMessage(
std::unique_ptr<PlatformMessage> message) = 0;
//--------------------------------------------------------------------------
/// @brief Notifies the delegate that the root isolate of the
/// application is about to be discarded and a new isolate with
/// the same runtime started in its place. This should only
/// happen in the Flutter "debug" runtime mode in the
/// cold-restart scenario. The embedder may need to reset native
/// resource in response to the restart.
///
/// @see `PlatformView::OnPreEngineRestart`
///
virtual void OnPreEngineRestart() = 0;
//--------------------------------------------------------------------------
/// @brief Notifies the shell that the root isolate is created.
/// Currently, this information is to add to the service
/// protocol list of available root isolates running in the VM
/// and their names so that the appropriate isolate can be
/// selected in the tools for debugging and instrumentation.
///
virtual void OnRootIsolateCreated() = 0;
//--------------------------------------------------------------------------
/// @brief Notifies the shell of the name of the root isolate and its
/// port when that isolate is launched, restarted (in the
/// cold-restart scenario) or the application itself updates the
/// name of the root isolate (via
/// `PlatformDispatcher.setIsolateDebugName` in
/// `platform_dispatcher.dart`). The name of the isolate is
/// meaningless to the engine but is used in instrumentation and
/// tooling. Currently, this information is to update the
/// service protocol list of available root isolates running in
/// the VM and their names so that the appropriate isolate can
/// be selected in the tools for debugging and instrumentation.
///
/// @param[in] isolate_name The isolate name
/// @param[in] isolate_port The isolate port
///
virtual void UpdateIsolateDescription(const std::string isolate_name,
int64_t isolate_port) = 0;
//--------------------------------------------------------------------------
/// @brief Notifies the shell that the application has an opinion about
/// whether its frame timings need to be reported backed to it.
/// Due to the asynchronous nature of rendering in Flutter, it
/// is not possible for the application to determine the total
/// time it took to render a specific frame. While the
/// layer-tree is constructed on the UI thread, it needs to be
/// rendering on the raster thread. Dart code cannot execute on
/// this thread. So any instrumentation about the frame times
/// gathered on this thread needs to be aggregated and sent back
/// to the UI thread for processing in Dart.
///
/// When the application indicates that frame times need to be
/// reported, it collects this information till a specified
/// number of data points are gathered. Then this information is
/// sent back to Dart code via `Engine::ReportTimings`.
///
/// This option is engine counterpart of the
/// `Window._setNeedsReportTimings` in `window.dart`.
///
/// @param[in] needs_reporting If reporting information should be
/// collected and send back to Dart.
///
virtual void SetNeedsReportTimings(bool needs_reporting) = 0;
//--------------------------------------------------------------------------
/// @brief Directly invokes platform-specific APIs to compute the
/// locale the platform would have natively resolved to.
///
/// @param[in] supported_locale_data The vector of strings that represents
/// the locales supported by the app.
/// Each locale consists of three
/// strings: languageCode, countryCode,
/// and scriptCode in that order.
///
/// @return A vector of 3 strings languageCode, countryCode, and
/// scriptCode that represents the locale selected by the
/// platform. Empty strings mean the value was unassigned. Empty
/// vector represents a null locale.
///
virtual std::unique_ptr<std::vector<std::string>>
ComputePlatformResolvedLocale(
const std::vector<std::string>& supported_locale_data) = 0;
//--------------------------------------------------------------------------
/// @brief Invoked when the Dart VM requests that a deferred library
/// be loaded. Notifies the engine that the deferred library
/// identified by the specified loading unit id should be
/// downloaded and loaded into the Dart VM via
/// `LoadDartDeferredLibrary`
///
/// Upon encountering errors or otherwise failing to load a
/// loading unit with the specified id, the failure should be
/// directly reported to dart by calling
/// `LoadDartDeferredLibraryFailure` to ensure the waiting dart
/// future completes with an error.
///
/// @param[in] loading_unit_id The unique id of the deferred library's
/// loading unit. This id is to be passed
/// back into LoadDartDeferredLibrary
/// in order to identify which deferred
/// library to load.
///
virtual void RequestDartDeferredLibrary(intptr_t loading_unit_id) = 0;
//--------------------------------------------------------------------------
/// @brief Returns the current fml::TimePoint.
/// This method is primarily provided to allow tests to control
/// Any methods that rely on advancing the clock.
virtual fml::TimePoint GetCurrentTimePoint() = 0;
//----------------------------------------------------------------------------
/// @brief Returns the delegate object that handles PlatformMessage's from
/// Flutter to the host platform (and its responses).
virtual const std::shared_ptr<PlatformMessageHandler>&
GetPlatformMessageHandler() const = 0;
//--------------------------------------------------------------------------
/// @brief Invoked when a listener is registered on a platform channel.
///
/// @param[in] name The name of the platform channel to which a
/// listener has been registered or cleared.
///
/// @param[in] listening Whether the listener has been set (true) or
/// cleared (false).
///
virtual void OnEngineChannelUpdate(std::string name, bool listening) = 0;
//--------------------------------------------------------------------------
/// @brief Synchronously invokes platform-specific APIs to apply the
/// system text scaling on the given unscaled font size.
///
/// Platforms that support this feature (currently it's only
/// implemented for Android SDK level 34+) will send a valid
/// configuration_id to potential callers, before this method
/// can be called.
///
/// @param[in] unscaled_font_size The unscaled font size specified by the
/// app developer. The value is in logical
/// pixels, and is guaranteed to be finite
/// and non-negative.
/// @param[in] configuration_id The unique id of the configuration to
/// use for computing the scaled font size.
///
/// @return The scaled font size in logical pixels, or -1 when the given
/// configuration_id did not match a valid configuration.
///
virtual double GetScaledFontSize(double unscaled_font_size,
int configuration_id) const = 0;
};
//----------------------------------------------------------------------------
/// @brief Creates an instance of the engine with a supplied
/// `RuntimeController`. Use the other constructor except for
/// tests.
///
Engine(Delegate& delegate,
const PointerDataDispatcherMaker& dispatcher_maker,
std::shared_ptr<fml::ConcurrentTaskRunner> image_decoder_task_runner,
const TaskRunners& task_runners,
const Settings& settings,
std::unique_ptr<Animator> animator,
fml::WeakPtr<IOManager> io_manager,
const std::shared_ptr<FontCollection>& font_collection,
std::unique_ptr<RuntimeController> runtime_controller,
const std::shared_ptr<fml::SyncSwitch>& gpu_disabled_switch);
//----------------------------------------------------------------------------
/// @brief Creates an instance of the engine. This is done by the Shell
/// on the UI task runner.
///
/// @param delegate The object used by the engine to perform
/// tasks that require access to components
/// that cannot be safely accessed by the
/// engine. This is the shell.
/// @param dispatcher_maker The callback provided by `PlatformView` for
/// engine to create the pointer data
/// dispatcher. Similar to other engine
/// resources, this dispatcher_maker and its
/// returned dispatcher is only safe to be
/// called from the UI thread.
/// @param vm An instance of the running Dart VM.
/// @param[in] isolate_snapshot The snapshot used to create the root
/// isolate. Even though the isolate is not
/// `DartIsolate::Phase::Running` phase, it is
/// created when the engine is created. This
/// requires access to the isolate snapshot
/// upfront.
// TODO(chinmaygarde): This is probably redundant now that the IO manager is
// it's own object.
/// @param[in] task_runners The task runners used by the shell that
/// hosts this engine.
/// @param[in] settings The settings used to initialize the shell
/// and the engine.
/// @param[in] animator The animator used to schedule frames.
// TODO(chinmaygarde): Move this to `Engine::Delegate`
/// @param[in] snapshot_delegate The delegate used to fulfill requests to
/// snapshot a specified scene. The engine
/// cannot snapshot a scene on the UI thread
/// directly because the scene (described via
/// a `DisplayList`) may reference resources on
/// the GPU and there is no GPU context current
/// on the UI thread. The delegate is a
/// component that has access to all the
/// requisite GPU resources.
/// @param[in] io_manager The IO manager used by this root isolate to
/// schedule tasks that manage resources on the
/// GPU.
///
Engine(Delegate& delegate,
const PointerDataDispatcherMaker& dispatcher_maker,
DartVM& vm,
fml::RefPtr<const DartSnapshot> isolate_snapshot,
const TaskRunners& task_runners,
const PlatformData& platform_data,
const Settings& settings,
std::unique_ptr<Animator> animator,
fml::WeakPtr<IOManager> io_manager,
fml::RefPtr<SkiaUnrefQueue> unref_queue,
fml::TaskRunnerAffineWeakPtr<SnapshotDelegate> snapshot_delegate,
std::shared_ptr<VolatilePathTracker> volatile_path_tracker,
const std::shared_ptr<fml::SyncSwitch>& gpu_disabled_switch);
//----------------------------------------------------------------------------
/// @brief Create a Engine that shares as many resources as
/// possible with the calling Engine such that together
/// they occupy less memory and be created faster.
/// @details This should only be called on running Engines.
/// @return A new Engine with a running isolate.
/// @see Engine::Engine
/// @see DartIsolate::SpawnIsolate
///
std::unique_ptr<Engine> Spawn(
Delegate& delegate,
const PointerDataDispatcherMaker& dispatcher_maker,
const Settings& settings,
std::unique_ptr<Animator> animator,
const std::string& initial_route,
const fml::WeakPtr<IOManager>& io_manager,
fml::TaskRunnerAffineWeakPtr<SnapshotDelegate> snapshot_delegate,
const std::shared_ptr<fml::SyncSwitch>& gpu_disabled_switch) const;
//----------------------------------------------------------------------------
/// @brief Destroys the engine engine. Called by the shell on the UI task
/// runner. The running root isolate is terminated and will no
/// longer access the task runner after this call returns. This
/// allows the embedder to tear down the thread immediately if
/// needed.
///
~Engine() override;
//----------------------------------------------------------------------------
/// @return The pointer to this instance of the engine. The engine may
/// only be accessed safely on the UI task runner.
///
fml::WeakPtr<Engine> GetWeakPtr() const;
//----------------------------------------------------------------------------
/// @brief Moves the root isolate to the `DartIsolate::Phase::Running`
/// phase on a successful call to this method.
///
/// The isolate itself is created when the engine is created, but
/// it is not yet in the running phase. This is done to amortize
/// initial time taken to launch the root isolate. The isolate
/// snapshots used to run the isolate can be fetched on another
/// thread while the engine itself is launched on the UI task
/// runner.
///
/// Repeated calls to this method after a successful run will be
/// rejected even if the run configuration is valid (with the
/// appropriate error returned).
///
/// @param[in] configuration The configuration used to run the root isolate.
/// The configuration must be valid.
///
/// @return The result of the call to run the root isolate.
///
[[nodiscard]] RunStatus Run(RunConfiguration configuration);
//----------------------------------------------------------------------------
/// @brief Tears down an existing root isolate, reuses the components of
/// that isolate and attempts to launch a new isolate using the
/// given the run configuration. This is only used in the
/// "debug" Flutter runtime mode in the cold-restart scenario.
///
/// @attention This operation must be performed with care as even a
/// non-successful restart will still tear down any existing root
/// isolate. In such cases, the engine and its shell must be
/// discarded.
///
/// @param[in] configuration The configuration used to launch the new
/// isolate.
///
/// @return Whether the restart was successful. If not, the engine and its
/// shell must be discarded.
///
[[nodiscard]] bool Restart(RunConfiguration configuration);
//----------------------------------------------------------------------------
/// @brief Setup default font manager according to specific platform.
///
void SetupDefaultFontManager();
//----------------------------------------------------------------------------
/// @brief Updates the asset manager referenced by the root isolate of a
/// Flutter application. This happens implicitly in the call to
/// `Engine::Run` and `Engine::Restart` as the asset manager is
/// referenced from the run configuration provided to those calls.
/// In addition to the `Engine::Run` and `Engine::Restart`
/// calls, the tooling may need to update the assets available to
/// the application as the user adds them to their project. For
/// example, these assets may be referenced by code that is newly
/// patched in after a hot-reload. Neither the shell or the
/// isolate in relaunched in such cases. The tooling usually
/// patches in the new assets in a temporary location and updates
/// the asset manager to point to that location.
///
/// @param[in] asset_manager The new asset manager to use for the running
/// root isolate.
///
/// @return If the asset manager was successfully replaced. This may fail
/// if the new asset manager is invalid.
///
bool UpdateAssetManager(const std::shared_ptr<AssetManager>& asset_manager);
//----------------------------------------------------------------------------
/// @brief Notifies the engine that it is time to begin working on a new
/// frame previously scheduled via a call to
/// `Engine::ScheduleFrame`. This call originates in the animator.
///
/// The frame time given as the argument indicates the point at
/// which the current frame interval began. It is very slightly
/// (because of scheduling overhead) in the past. If a new layer
/// tree is not produced and given to the raster task runner
/// within one frame interval from this point, the Flutter
/// application will jank.
///
/// If a root isolate is running, this method calls the
/// `::_beginFrame` method in `hooks.dart`. If a root isolate is
/// not running, this call does nothing.
///
/// This method encapsulates the entire UI thread frame workload.
/// The following (mis)behavior in the functioning of the method
/// will cause the jank in the Flutter application:
/// * The time taken by this method to create a layer-tree exceeds
/// one frame interval (for example, 16.66 ms on a 60Hz
/// display).
/// * The time take by this method to generate a new layer-tree
/// causes the current layer-tree pipeline depth to change. To
/// illustrate this point, note that maximum pipeline depth used
/// by layer tree in the engine is 2. If both the UI and GPU
/// task runner tasks finish within one frame interval, the
/// pipeline depth is one. If the UI thread happens to be
/// working on a frame when the raster thread is still not done
/// with the previous frame, the pipeline depth is 2. When the
/// pipeline depth changes from 1 to 2, animations and UI
/// interactions that cause the generation of the new layer tree
/// appropriate for (frame_time + one frame interval) will
/// actually end up at (frame_time + two frame intervals). This
/// is not what code running on the UI thread expected would
/// happen. This causes perceptible jank.
///
/// @param[in] frame_time The point at which the current frame interval
/// began. May be used by animation interpolators,
/// physics simulations, etc..
///
/// @param[in] frame_number The frame number recorded by the animator. Used
/// by the framework to associate frame specific
/// debug information with frame timings and timeline
/// events.
void BeginFrame(fml::TimePoint frame_time, uint64_t frame_number);
//----------------------------------------------------------------------------
/// @brief Notifies the engine that the UI task runner is not expected to
/// undertake a new frame workload till a specified timepoint. The
/// timepoint is measured in microseconds against the system's
/// monotonic clock. It is recommended that the clock be accessed
/// via `Dart_TimelineGetMicros` from `dart_api.h` for
/// consistency. In reality, the clocks used by Dart, FML and
/// std::steady_clock are all the same and the timepoints can be
/// converted from on clock type to another.
///
/// The Dart VM uses this notification to schedule book-keeping
/// tasks that may include a garbage collection. In this way, it
/// is less likely for the VM to perform such (potentially long
/// running) tasks in the middle of a frame workload.
///
/// This notification is advisory. That is, not providing this
/// notification does not mean garbage collection is postponed
/// till this call is made. If this notification is not provided,
/// garbage collection will happen based on the usual heuristics
/// used by the Dart VM.
///
/// Currently, this idle notification is delivered to the engine
/// at two points. Once, the deadline is calculated based on how
/// much time in the current frame interval is left on the UI task
/// runner. Since the next frame workload cannot begin till at
/// least the next callback from the vsync waiter, this period may
/// be used to used as a "small" idle notification. On the other
/// hand, if no more frames are scheduled, a large (but arbitrary)
/// idle notification deadline is chosen for a "big" idle
/// notification. Again, this notification does not guarantee
/// collection, just gives the Dart VM more hints about opportune
/// moments to perform collections.
///
///
/// @param[in] deadline The deadline is used by the VM to determine if the
/// corresponding sweep can be performed within the
/// deadline.
///
void NotifyIdle(fml::TimeDelta deadline);
//----------------------------------------------------------------------------
/// @brief Notifies the engine that the attached flutter view has been
/// destroyed.
/// This enables the engine to notify the Dart VM so it can do
/// some cleanp activities.
void NotifyDestroyed();
//----------------------------------------------------------------------------
/// @brief Dart code cannot fully measure the time it takes for a
/// specific frame to be rendered. This is because Dart code only
/// runs on the UI task runner. That is only a small part of the
/// overall frame workload. The raster task runner frame workload
/// is executed on a thread where Dart code cannot run (and hence
/// instrument). Besides, due to the pipelined nature of rendering
/// in Flutter, there may be multiple frame workloads being
/// processed at any given time. However, for non-Timeline based
/// profiling, it is useful for trace collection and processing to
/// happen in Dart. To do this, the raster task runner frame
/// workloads need to be instrumented separately. After a set
/// number of these profiles have been gathered, they need to be
/// reported back to Dart code. The shell reports this extra
/// instrumentation information back to Dart code running on the
/// engine by invoking this method at predefined intervals.
///
/// @see `FrameTiming`
///
// TODO(chinmaygarde): The use `int64_t` is added for ease of conversion to
// Dart but hurts readability. The phases and the units of the timepoints are
// not obvious without some sleuthing. The conversion can happen at the
// native interface boundary instead.
///
/// @param[in] timings Collection of `FrameTiming::kCount` * `n` timestamps
/// for `n` frames whose timings have not been reported
/// yet. A collection of integers is reported here for
/// easier conversions to Dart objects. The timestamps
/// are measured against the system monotonic clock
/// measured in microseconds.
///
void ReportTimings(std::vector<int64_t> timings);
//----------------------------------------------------------------------------
/// @brief Gets the main port of the root isolate. Since the isolate is
/// created immediately in the constructor of the engine, it is
/// possible to get its main port immediately (even before a call
/// to `Run` can be made). This is useful in registering the port
/// in a race free manner with a port nameserver.
///
/// @return The main port of the root isolate.
///
Dart_Port GetUIIsolateMainPort();
//----------------------------------------------------------------------------
/// @brief Gets the debug name of the root isolate. By default, the
/// debug name of the isolate is derived from its advisory script
/// URI, advisory main entrypoint and its main port name. For
/// example, "main.dart$main-1234" where the script URI is
/// "main.dart", the entrypoint is "main" and the port name
/// "1234". Once launched, the isolate may re-christen itself
/// using a name it selects via `setIsolateDebugName` in
/// `platform_dispatcher.dart`. This name is purely advisory and
/// only used by instrumentation and reporting purposes.
///
/// @return The debug name of the root isolate.
///
std::string GetUIIsolateName();
//----------------------------------------------------------------------------
/// @brief It is an unexpected challenge to determine when a Dart
/// application is "done". The application cannot simply terminate
/// the native process (and perhaps return an exit code) because
/// it does not have that power. After all, Flutter applications
/// reside within a host process that may have other
/// responsibilities besides just running Flutter applications.
/// Also, the `main` entry-points are run on an event loop and
/// returning from "main" (unlike in C/C++ applications) does not
/// mean termination of the process. Besides, the return value of
/// the main entrypoint is discarded.
///
/// One technique used by embedders to determine "liveness" is to
/// count the outstanding live ports dedicated to the application.
/// These ports may be live as a result of pending timers,
/// scheduled tasks, pending IO on sockets, channels open with
/// other isolates, etc.. At regular intervals (sometimes as often
/// as after the UI task runner processes any task), embedders may
/// check for the "liveness" of the application and perform
/// teardown of the embedder when no more ports are live.
///
/// @return Check if the root isolate has any live ports.
///
bool UIIsolateHasLivePorts();
//----------------------------------------------------------------------------
/// @brief Errors that are unhandled on the Dart message loop are kept
/// for further inspection till the next unhandled error comes
/// along. This accessor returns the last unhandled error
/// encountered by the root isolate.
///
/// @return The ui isolate last error.
///
tonic::DartErrorHandleType GetUIIsolateLastError();
//----------------------------------------------------------------------------
/// @brief As described in the discussion for `UIIsolateHasLivePorts`,
/// the "done-ness" of a Dart application is tricky to ascertain
/// and the return value from the main entrypoint is discarded
/// (because the Dart isolate is still running after the main
/// entrypoint returns). But, the concept of an exit code akin to
/// those returned by native applications is still useful. Short
/// lived Dart applications (usually tests), emulate this by
/// setting a per isolate "return value" and then indicating their
/// "done-ness" (usually via closing all live ports). This
/// accessor returns that "return value" is present.
///
/// @see `UIIsolateHasLivePorts`
///
/// @return The return code (if specified) by the isolate.
///
std::optional<uint32_t> GetUIIsolateReturnCode();
//----------------------------------------------------------------------------
/// @brief Notify the Flutter application that a new view is available.
///
/// A view must be added before other methods can refer to it,
/// including the implicit view. Adding a view that already exists
/// triggers an assertion.
///
/// @param[in] view_id The ID of the new view.
/// @param[in] viewport_metrics The initial viewport metrics for the view.
///
void AddView(int64_t view_id, const ViewportMetrics& view_metrics);
//----------------------------------------------------------------------------
/// @brief Notify the Flutter application that a view is no
/// longer available.
///
/// Removing a view that does not exist triggers an assertion.
///
/// The implicit view (kFlutterImplicitViewId) should never be
/// removed. Doing so triggers an assertion.
///
/// @param[in] view_id The ID of the view.
///
void RemoveView(int64_t view_id);
//----------------------------------------------------------------------------
/// @brief Updates the viewport metrics for a view. The viewport metrics
/// detail the size of the rendering viewport in texels as well as
/// edge insets if present.
///
/// @see `ViewportMetrics`
///
/// @param[in] view_id The ID for the view that `metrics` describes.
/// @param[in] metrics The metrics.
///
void SetViewportMetrics(int64_t view_id, const ViewportMetrics& metrics);
//----------------------------------------------------------------------------
/// @brief Updates the display metrics for the currently running Flutter
/// application.
///
/// @param[in] displays A complete list of displays
///
void SetDisplays(const std::vector<DisplayData>& displays);
//----------------------------------------------------------------------------
/// @brief Notifies the engine that the embedder has sent it a message.
/// This call originates in the platform view and has been
/// forwarded to the engine on the UI task runner here.
///
/// @param[in] message The message sent from the embedder to the Dart
/// application.
///
void DispatchPlatformMessage(std::unique_ptr<PlatformMessage> message);
//----------------------------------------------------------------------------
/// @brief Notifies the engine that the embedder has sent it a pointer
/// data packet. A pointer data packet may contain multiple
/// input events. This call originates in the platform view and
/// the shell has forwarded the same to the engine on the UI task
/// runner here.
///
/// @param[in] packet The pointer data packet containing multiple
/// input events.
/// @param[in] trace_flow_id The trace flow identifier associated with the
/// pointer data packet. The engine uses this trace
/// identifier to connect trace flows in the
/// timeline from the input event to the
/// frames generated due to those input events.
/// These flows are tagged as "PointerEvent" in the
/// timeline and allow grouping frames and input
/// events into logical chunks.
///
void DispatchPointerDataPacket(std::unique_ptr<PointerDataPacket> packet,
uint64_t trace_flow_id);
//----------------------------------------------------------------------------
/// @brief Notifies the engine that the embedder encountered an
/// accessibility related action on the specified node. This call
/// originates on the platform view and has been forwarded to the
/// engine here on the UI task runner by the shell.
///
/// @param[in] node_id The identifier of the accessibility node.
/// @param[in] action The accessibility related action performed on the
/// node of the specified ID.
/// @param[in] args Optional data that applies to the specified action.
///
void DispatchSemanticsAction(int node_id,
SemanticsAction action,
fml::MallocMapping args);
//----------------------------------------------------------------------------
/// @brief Notifies the engine that the embedder has expressed an opinion
/// about whether the accessibility tree should be generated or
/// not. This call originates in the platform view and is
/// forwarded to the engine here on the UI task runner by the
/// shell.
///
/// @param[in] enabled Whether the accessibility tree is enabled or
/// disabled.
///
void SetSemanticsEnabled(bool enabled);
//----------------------------------------------------------------------------
/// @brief Notifies the engine that the embedder has expressed an opinion
/// about where the flags to set on the accessibility tree. This
/// flag originates in the platform view and is forwarded to the
/// engine here on the UI task runner by the shell.
///
/// The engine does not care about the accessibility feature flags
/// as all it does is forward this information from the embedder
/// to the framework. However, curious readers may refer to
/// `AccessibilityFeatures` in `window.dart` for currently
/// supported accessibility feature flags.
///
/// @param[in] flags The features to enable in the accessibility tree.
///
void SetAccessibilityFeatures(int32_t flags);
// |RuntimeDelegate|
void ScheduleFrame(bool regenerate_layer_tree) override;
/// Schedule a frame with the default parameter of regenerating the layer
/// tree.
void ScheduleFrame() { ScheduleFrame(true); }
// |RuntimeDelegate|
FontCollection& GetFontCollection() override;
// |RuntimeDelegate|
std::shared_ptr<AssetManager> GetAssetManager() override;
// Return the weak_ptr of ImageDecoder.
fml::WeakPtr<ImageDecoder> GetImageDecoderWeakPtr();
//----------------------------------------------------------------------------
/// @brief Get the `ImageGeneratorRegistry` associated with the current
/// engine.
///
/// @return The engine's `ImageGeneratorRegistry`.
///
fml::WeakPtr<ImageGeneratorRegistry> GetImageGeneratorRegistry();
// |PointerDataDispatcher::Delegate|
void DoDispatchPacket(std::unique_ptr<PointerDataPacket> packet,
uint64_t trace_flow_id) override;
// |PointerDataDispatcher::Delegate|
void ScheduleSecondaryVsyncCallback(uintptr_t id,
const fml::closure& callback) override;
//----------------------------------------------------------------------------
/// @brief Get the last Entrypoint that was used in the RunConfiguration
/// when |Engine::Run| was called.
///
const std::string& GetLastEntrypoint() const;
//----------------------------------------------------------------------------
/// @brief Get the last Entrypoint Library that was used in the
/// RunConfiguration when |Engine::Run| was called.
///
const std::string& GetLastEntrypointLibrary() const;
//----------------------------------------------------------------------------
/// @brief Get the last Entrypoint Arguments that was used in the
/// RunConfiguration when |Engine::Run| was called.This is only
/// valid in debug mode.
///
const std::vector<std::string>& GetLastEntrypointArgs() const;
//----------------------------------------------------------------------------
/// @brief Getter for the initial route. This can be set with a platform
/// message.
///
const std::string& InitialRoute() const { return initial_route_; }
//--------------------------------------------------------------------------
/// @brief Loads the Dart shared library into the Dart VM. When the
/// Dart library is loaded successfully, the Dart future
/// returned by the originating loadLibrary() call completes.
///
/// The Dart compiler may generate separate shared libraries
/// files called 'loading units' when libraries are imported
/// as deferred. Each of these shared libraries are identified
/// by a unique loading unit id. Callers should open and resolve
/// a SymbolMapping from the shared library. The Mappings should
/// be moved into this method, as ownership will be assumed by the
/// dart root isolate after successful loading and released after
/// shutdown of the root isolate. The loading unit may not be
/// used after isolate shutdown. If loading fails, the mappings
/// will be released.
///
/// This method is paired with a RequestDartDeferredLibrary
/// invocation that provides the embedder with the loading unit id
/// of the deferred library to load.
///
///
/// @param[in] loading_unit_id The unique id of the deferred library's
/// loading unit, as passed in by
/// RequestDartDeferredLibrary.
///
/// @param[in] snapshot_data Dart snapshot data of the loading unit's
/// shared library.
///
/// @param[in] snapshot_data Dart snapshot instructions of the loading
/// unit's shared library.
///
void LoadDartDeferredLibrary(
intptr_t loading_unit_id,
std::unique_ptr<const fml::Mapping> snapshot_data,
std::unique_ptr<const fml::Mapping> snapshot_instructions);
//--------------------------------------------------------------------------
/// @brief Indicates to the dart VM that the request to load a deferred
/// library with the specified loading unit id has failed.
///
/// The dart future returned by the initiating loadLibrary() call
/// will complete with an error.
///
/// @param[in] loading_unit_id The unique id of the deferred library's
/// loading unit, as passed in by
/// RequestDartDeferredLibrary.
///
/// @param[in] error_message The error message that will appear in the
/// dart Future.
///
/// @param[in] transient A transient error is a failure due to
/// temporary conditions such as no network.
/// Transient errors allow the dart VM to
/// re-request the same deferred library and
/// loading_unit_id again. Non-transient
/// errors are permanent and attempts to
/// re-request the library will instantly
/// complete with an error.
void LoadDartDeferredLibraryError(intptr_t loading_unit_id,
const std::string& error_message,
bool transient);
//--------------------------------------------------------------------------
/// @brief Accessor for the RuntimeController.
///
const RuntimeController* GetRuntimeController() const {
return runtime_controller_.get();
}
const std::weak_ptr<VsyncWaiter> GetVsyncWaiter() const;
private:
// |RuntimeDelegate|
std::string DefaultRouteName() override;
// |RuntimeDelegate|
void Render(std::unique_ptr<flutter::LayerTree> layer_tree,
float device_pixel_ratio) override;
// |RuntimeDelegate|
void UpdateSemantics(SemanticsNodeUpdates update,
CustomAccessibilityActionUpdates actions) override;
// |RuntimeDelegate|
void HandlePlatformMessage(std::unique_ptr<PlatformMessage> message) override;
// |RuntimeDelegate|
void OnRootIsolateCreated() override;
// |RuntimeDelegate|
void UpdateIsolateDescription(const std::string isolate_name,
int64_t isolate_port) override;
// |RuntimeDelegate|
std::unique_ptr<std::vector<std::string>> ComputePlatformResolvedLocale(
const std::vector<std::string>& supported_locale_data) override;
// |RuntimeDelegate|
void RequestDartDeferredLibrary(intptr_t loading_unit_id) override;
// |RuntimeDelegate|
std::weak_ptr<PlatformMessageHandler> GetPlatformMessageHandler()
const override;
// |RuntimeDelegate|
void SendChannelUpdate(std::string name, bool listening) override;
// |RuntimeDelegate|
double GetScaledFontSize(double unscaled_font_size,
int configuration_id) const override;
void SetNeedsReportTimings(bool value) override;
bool HandleLifecyclePlatformMessage(PlatformMessage* message);
bool HandleNavigationPlatformMessage(
std::unique_ptr<PlatformMessage> message);
bool HandleLocalizationPlatformMessage(PlatformMessage* message);
void HandleSettingsPlatformMessage(PlatformMessage* message);
void HandleAssetPlatformMessage(std::unique_ptr<PlatformMessage> message);
bool GetAssetAsBuffer(const std::string& name, std::vector<uint8_t>* data);
friend class testing::ShellTest;
Engine::Delegate& delegate_;
const Settings settings_;
std::unique_ptr<Animator> animator_;
std::unique_ptr<RuntimeController> runtime_controller_;
// The pointer_data_dispatcher_ depends on animator_ and runtime_controller_.
// So it should be defined after them to ensure that pointer_data_dispatcher_
// is destructed first.
std::unique_ptr<PointerDataDispatcher> pointer_data_dispatcher_;
std::string last_entry_point_;
std::string last_entry_point_library_;
std::vector<std::string> last_entry_point_args_;
std::string initial_route_;
std::shared_ptr<AssetManager> asset_manager_;
std::shared_ptr<FontCollection> font_collection_;
const std::unique_ptr<ImageDecoder> image_decoder_;
ImageGeneratorRegistry image_generator_registry_;
TaskRunners task_runners_;
fml::WeakPtrFactory<Engine> weak_factory_; // Must be the last member.
FML_DISALLOW_COPY_AND_ASSIGN(Engine);
};
} // namespace flutter
#endif // SHELL_COMMON_ENGINE_H_
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