#include <v8-platform.h>

Public Types
typedef void(*	StackTracePrinter) ()

Public Member Functions
virtual	~Platform ()=default

virtual PageAllocator *	GetPageAllocator ()

virtual ThreadIsolatedAllocator *	GetThreadIsolatedAllocator ()

virtual void	OnCriticalMemoryPressure ()

virtual int	NumberOfWorkerThreads ()=0

std::shared_ptr< v8::TaskRunner >	GetForegroundTaskRunner (Isolate *isolate)

virtual std::shared_ptr< v8::TaskRunner >	GetForegroundTaskRunner (Isolate *isolate, TaskPriority priority)=0

void	CallOnWorkerThread (std::unique_ptr< Task > task, SourceLocation location=SourceLocation::Current())

void	CallBlockingTaskOnWorkerThread (std::unique_ptr< Task > task, SourceLocation location=SourceLocation::Current())

void	CallLowPriorityTaskOnWorkerThread (std::unique_ptr< Task > task, SourceLocation location=SourceLocation::Current())

void	CallDelayedOnWorkerThread (std::unique_ptr< Task > task, double delay_in_seconds, SourceLocation location=SourceLocation::Current())

void	PostTaskOnWorkerThread (TaskPriority priority, std::unique_ptr< Task > task, SourceLocation location=SourceLocation::Current())

void	PostDelayedTaskOnWorkerThread (TaskPriority priority, std::unique_ptr< Task > task, double delay_in_seconds, SourceLocation location=SourceLocation::Current())

virtual bool	IdleTasksEnabled (Isolate *isolate)

std::unique_ptr< JobHandle >	PostJob (TaskPriority priority, std::unique_ptr< JobTask > job_task, SourceLocation location=SourceLocation::Current())

std::unique_ptr< JobHandle >	CreateJob (TaskPriority priority, std::unique_ptr< JobTask > job_task, SourceLocation location=SourceLocation::Current())

virtual std::unique_ptr< ScopedBlockingCall >	CreateBlockingScope (BlockingType blocking_type)

virtual double	MonotonicallyIncreasingTime ()=0

virtual int64_t	CurrentClockTimeMilliseconds ()

virtual double	CurrentClockTimeMillis ()=0

virtual double	CurrentClockTimeMillisecondsHighResolution ()

virtual StackTracePrinter	GetStackTracePrinter ()

virtual TracingController *	GetTracingController ()=0

virtual void	DumpWithoutCrashing ()

virtual HighAllocationThroughputObserver *	GetHighAllocationThroughputObserver ()

Protected Member Functions
virtual std::unique_ptr< JobHandle >	CreateJobImpl (TaskPriority priority, std::unique_ptr< JobTask > job_task, const SourceLocation &location)=0

virtual void	PostTaskOnWorkerThreadImpl (TaskPriority priority, std::unique_ptr< Task > task, const SourceLocation &location)=0

virtual void	PostDelayedTaskOnWorkerThreadImpl (TaskPriority priority, std::unique_ptr< Task > task, double delay_in_seconds, const SourceLocation &location)=0

Static Protected Member Functions
static V8_EXPORT double	SystemClockTimeMillis ()

Detailed Description

V8 Platform abstraction layer.

The embedder has to provide an implementation of this interface before initializing the rest of V8.

Definition at line 1123 of file v8-platform.h.

Member Typedef Documentation

◆ StackTracePrinter

typedef void(* StackTracePrinter) ()

Definition at line 1381 of file v8-platform.h.

Constructor & Destructor Documentation

◆ ~Platform()

virtual ~Platform ( )

virtualdefault

Member Function Documentation

◆ CallBlockingTaskOnWorkerThread()

void CallBlockingTaskOnWorkerThread	(	std::unique_ptr< Task >	task,
		SourceLocation	location = `SourceLocation::Current()`
	)

inline

Schedules a task that blocks the main thread to be invoked with high-priority on a worker thread. Embedders should override PostTaskOnWorkerThreadImpl() instead of CallBlockingTaskOnWorkerThread().

Definition at line 1198 of file v8-platform.h.

◆ CallDelayedOnWorkerThread()

void CallDelayedOnWorkerThread	(	std::unique_ptr< Task >	task,
		double	delay_in_seconds,
		SourceLocation	location = `SourceLocation::Current()`
	)

inline

Schedules a task to be invoked on a worker thread after |delay_in_seconds| expires. Embedders should override PostDelayedTaskOnWorkerThreadImpl() instead of CallDelayedOnWorkerThread().

Definition at line 1229 of file v8-platform.h.

◆ CallLowPriorityTaskOnWorkerThread()

void CallLowPriorityTaskOnWorkerThread	(	std::unique_ptr< Task >	task,
		SourceLocation	location = `SourceLocation::Current()`
	)

inline

Schedules a task to be invoked with low-priority on a worker thread. Embedders should override PostTaskOnWorkerThreadImpl() instead of CallLowPriorityTaskOnWorkerThread().

Definition at line 1213 of file v8-platform.h.

◆ CallOnWorkerThread()

void CallOnWorkerThread	(	std::unique_ptr< Task >	task,
		SourceLocation	location = `SourceLocation::Current()`
	)

inline

Schedules a task to be invoked on a worker thread. Embedders should override PostTaskOnWorkerThreadImpl() instead of CallOnWorkerThread().

Definition at line 1185 of file v8-platform.h.

◆ CreateBlockingScope()

virtual std::unique_ptr< ScopedBlockingCall > CreateBlockingScope ( BlockingType blocking_type )

inlinevirtual

Instantiates a ScopedBlockingCall to annotate a scope that may/will block.

Definition at line 1344 of file v8-platform.h.

◆ CreateJob()

std::unique_ptr< JobHandle > CreateJob	(	TaskPriority	priority,
		std::unique_ptr< JobTask >	job_task,
		SourceLocation	location = `SourceLocation::Current()`
	)

inline

Creates and returns a JobHandle associated with a Job. Unlike PostJob(), this doesn't immediately schedules |worker_task| to run; the Job is then scheduled by calling either NotifyConcurrencyIncrease() or Join().

A sufficient CreateJob() implementation that uses the default Job provided in libplatform looks like: std::unique_ptr<JobHandle> CreateJob( TaskPriority priority, std::unique_ptr<JobTask> job_task) override { return v8::platform::NewDefaultJobHandle( this, priority, std::move(job_task), NumberOfWorkerThreads()); }

Embedders should override CreateJobImpl() instead of CreateJob().

Definition at line 1335 of file v8-platform.h.

◆ CreateJobImpl()

virtual std::unique_ptr< JobHandle > CreateJobImpl	(	TaskPriority	priority,
		std::unique_ptr< JobTask >	job_task,
		const SourceLocation &	location
	)

protectedpure virtual

Creates and returns a JobHandle associated with a Job.

◆ CurrentClockTimeMillis()

virtual double CurrentClockTimeMillis ( )

pure virtual

This function is deprecated and will be deleted. Use either CurrentClockTimeMilliseconds() or CurrentClockTimeMillisecondsHighResolution().

Referenced by Platform::CurrentClockTimeMilliseconds(), and Platform::CurrentClockTimeMillisecondsHighResolution().

◆ CurrentClockTimeMilliseconds()

virtual int64_t CurrentClockTimeMilliseconds ( )

inlinevirtual

Current wall-clock time in milliseconds since epoch. Use CurrentClockTimeMillisHighResolution() when higher precision is required.

Definition at line 1363 of file v8-platform.h.

References Platform::CurrentClockTimeMillis().

◆ CurrentClockTimeMillisecondsHighResolution()

virtual double CurrentClockTimeMillisecondsHighResolution ( )

inlinevirtual

Same as CurrentClockTimeMilliseconds(), but with more precision.

Definition at line 1377 of file v8-platform.h.

References Platform::CurrentClockTimeMillis().

◆ DumpWithoutCrashing()

virtual void DumpWithoutCrashing ( )

inlinevirtual

Tells the embedder to generate and upload a crashdump during an unexpected but non-critical scenario.

Definition at line 1398 of file v8-platform.h.

◆ GetForegroundTaskRunner() [1/2]

std::shared_ptr< v8::TaskRunner > GetForegroundTaskRunner ( Isolate * isolate )

inline

Returns a TaskRunner which can be used to post a task on the foreground. The TaskRunner's NonNestableTasksEnabled() must be true. This function should only be called from a foreground thread.

Definition at line 1167 of file v8-platform.h.

References Platform::GetForegroundTaskRunner(), and v8::kUserBlocking.

◆ GetForegroundTaskRunner() [2/2]

virtual std::shared_ptr< v8::TaskRunner > GetForegroundTaskRunner	(	Isolate *	isolate,
		TaskPriority	priority
	)

pure virtual

Returns a TaskRunner with a specific |priority| which can be used to post a task on the foreground thread. The TaskRunner's NonNestableTasksEnabled() must be true. This function should only be called from a foreground thread.

Referenced by Platform::GetForegroundTaskRunner().

◆ GetHighAllocationThroughputObserver()

virtual HighAllocationThroughputObserver * GetHighAllocationThroughputObserver ( )

inlinevirtual

Allows the embedder to observe sections with high throughput allocation operations.

Definition at line 1405 of file v8-platform.h.

◆ GetPageAllocator()

virtual PageAllocator * GetPageAllocator ( )

inlinevirtual

Allows the embedder to manage memory page allocations. Returning nullptr will cause V8 to use the default page allocator.

Definition at line 1131 of file v8-platform.h.

◆ GetStackTracePrinter()

virtual StackTracePrinter GetStackTracePrinter ( )

inlinevirtual

Returns a function pointer that print a stack trace of the current stack on invocation. Disables printing of the stack trace if nullptr.

Definition at line 1387 of file v8-platform.h.

◆ GetThreadIsolatedAllocator()

virtual ThreadIsolatedAllocator * GetThreadIsolatedAllocator ( )

inlinevirtual

Allows the embedder to provide an allocator that uses per-thread memory permissions to protect allocations. Returning nullptr will cause V8 to disable protections that rely on this feature.

Definition at line 1139 of file v8-platform.h.

◆ GetTracingController()

virtual TracingController * GetTracingController ( )

pure virtual

Returns an instance of a v8::TracingController. This must be non-nullptr.

◆ IdleTasksEnabled()

virtual bool IdleTasksEnabled ( Isolate * isolate )

inlinevirtual

Returns true if idle tasks are enabled for the given |isolate|.

Definition at line 1265 of file v8-platform.h.

◆ MonotonicallyIncreasingTime()

virtual double MonotonicallyIncreasingTime ( )

pure virtual

Monotonically increasing time in seconds from an arbitrary fixed point in the past. This function is expected to return at least millisecond-precision values. For this reason, it is recommended that the fixed point be no further in the past than the epoch.

◆ NumberOfWorkerThreads()

virtual int NumberOfWorkerThreads ( )

pure virtual

Gets the max number of worker threads that may be used to execute concurrent work scheduled for any single TaskPriority by Call(BlockingTask)OnWorkerThread() or PostJob(). This can be used to estimate the number of tasks a work package should be split into. A return value of 0 means that there are no worker threads available. Note that a value of 0 won't prohibit V8 from posting tasks using |CallOnWorkerThread|.

◆ OnCriticalMemoryPressure()

virtual void OnCriticalMemoryPressure ( )

inlinevirtual

Enables the embedder to respond in cases where V8 can't allocate large blocks of memory. V8 retries the failed allocation once after calling this method. On success, execution continues; otherwise V8 exits with a fatal error. Embedder overrides of this function must NOT call back into V8.

Definition at line 1150 of file v8-platform.h.

◆ PostDelayedTaskOnWorkerThread()

void PostDelayedTaskOnWorkerThread	(	TaskPriority	priority,
		std::unique_ptr< Task >	task,
		double	delay_in_seconds,
		SourceLocation	location = `SourceLocation::Current()`
	)

inline

Schedules a task to be invoked on a worker thread after |delay_in_seconds| expires. Embedders should override PostDelayedTaskOnWorkerThreadImpl() instead of PostDelayedTaskOnWorkerThread().

Definition at line 1254 of file v8-platform.h.

◆ PostDelayedTaskOnWorkerThreadImpl()

virtual void PostDelayedTaskOnWorkerThreadImpl	(	TaskPriority	priority,
		std::unique_ptr< Task >	task,
		double	delay_in_seconds,
		const SourceLocation &	location
	)

protectedpure virtual

Schedules a task with |priority| to be invoked on a worker thread after |delay_in_seconds| expires.

◆ PostJob()

std::unique_ptr< JobHandle > PostJob	(	TaskPriority	priority,
		std::unique_ptr< JobTask >	job_task,
		SourceLocation	location = `SourceLocation::Current()`
	)

inline

Posts |job_task| to run in parallel. Returns a JobHandle associated with the Job, which can be joined or canceled. This avoids degenerate cases:

Calling CallOnWorkerThread() for each work item, causing significant overhead.
Fixed number of CallOnWorkerThread() calls that split the work and might run for a long time. This is problematic when many components post "num cores" tasks and all expect to use all the cores. In these cases, the scheduler lacks context to be fair to multiple same-priority requests and/or ability to request lower priority work to yield when high priority work comes in. A canonical implementation of |job_task| looks like: class MyJobTask : public JobTask { public: MyJobTask(...) : worker_queue_(...) {} // JobTask: void Run(JobDelegate* delegate) override { while (!delegate->ShouldYield()) { // Smallest unit of work. auto work_item = worker_queue_.TakeWorkItem(); // Thread safe. if (!work_item) return; ProcessWork(work_item); } }

size_t GetMaxConcurrency() const override { return worker_queue_.GetSize(); // Thread safe. } }; auto handle = PostJob(TaskPriority::kUserVisible, std::make_unique<MyJobTask>(...)); handle->Join();

PostJob() and methods of the returned JobHandle/JobDelegate, must never be called while holding a lock that could be acquired by JobTask::Run or JobTask::GetMaxConcurrency – that could result in a deadlock. This is because [1] JobTask::GetMaxConcurrency may be invoked while holding internal lock (A), hence JobTask::GetMaxConcurrency can only use a lock (B) if that lock is never held while calling back into JobHandle from any thread (A=>B/B=>A deadlock) and [2] JobTask::Run or JobTask::GetMaxConcurrency may be invoked synchronously from JobHandle (B=>JobHandle::foo=>B deadlock). Embedders should override CreateJobImpl() instead of PostJob().

Definition at line 1312 of file v8-platform.h.

◆ PostTaskOnWorkerThread()

void PostTaskOnWorkerThread	(	TaskPriority	priority,
		std::unique_ptr< Task >	task,
		SourceLocation	location = `SourceLocation::Current()`
	)

inline

Schedules a task to be invoked on a worker thread. Embedders should override PostTaskOnWorkerThreadImpl() instead of PostTaskOnWorkerThread().

Definition at line 1242 of file v8-platform.h.

◆ PostTaskOnWorkerThreadImpl()

virtual void PostTaskOnWorkerThreadImpl	(	TaskPriority	priority,
		std::unique_ptr< Task >	task,
		const SourceLocation &	location
	)

protectedpure virtual

Schedules a task with |priority| to be invoked on a worker thread.

◆ SystemClockTimeMillis()

static V8_EXPORT double SystemClockTimeMillis ( )

staticprotected

Default implementation of current wall-clock time in milliseconds since epoch. Useful for implementing |CurrentClockTimeMillis| if nothing special needed.

The documentation for this class was generated from the following file:

include/v8-platform.h

Public Types

Public Member Functions

Protected Member Functions

Static Protected Member Functions

Detailed Description

Member Typedef Documentation

◆ StackTracePrinter

Constructor & Destructor Documentation

◆ ~Platform()

Member Function Documentation

◆ CallBlockingTaskOnWorkerThread()

◆ CallDelayedOnWorkerThread()

◆ CallLowPriorityTaskOnWorkerThread()

◆ CallOnWorkerThread()

◆ CreateBlockingScope()

◆ CreateJob()

◆ CreateJobImpl()

◆ CurrentClockTimeMillis()

◆ CurrentClockTimeMilliseconds()

◆ CurrentClockTimeMillisecondsHighResolution()

◆ DumpWithoutCrashing()

◆ GetForegroundTaskRunner() [1/2]

◆ GetForegroundTaskRunner() [2/2]

◆ GetHighAllocationThroughputObserver()

◆ GetPageAllocator()

◆ GetStackTracePrinter()

◆ GetThreadIsolatedAllocator()

◆ GetTracingController()

◆ IdleTasksEnabled()

◆ MonotonicallyIncreasingTime()

◆ NumberOfWorkerThreads()

◆ OnCriticalMemoryPressure()

◆ PostDelayedTaskOnWorkerThread()

◆ PostDelayedTaskOnWorkerThreadImpl()

◆ PostJob()

◆ PostTaskOnWorkerThread()

◆ PostTaskOnWorkerThreadImpl()

◆ SystemClockTimeMillis()