#include <v8-platform.h>

Public Types
typedef void(*	StackTracePrinter) ()

Public Member Functions
virtual	~Platform ()=default

virtual PageAllocator *	GetPageAllocator ()=0

virtual ThreadIsolatedAllocator *	GetThreadIsolatedAllocator ()

virtual ZoneBackingAllocator *	GetZoneBackingAllocator ()

virtual void	OnCriticalMemoryPressure ()

virtual int	NumberOfWorkerThreads ()=0

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

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

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

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

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

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

virtual bool	IdleTasksEnabled (Isolate *isolate)

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

std::unique_ptr< JobHandle >	CreateJob (TaskPriority priority, std::unique_ptr< JobTask > job_task, const 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 1052 of file v8-platform.h.

Member Typedef Documentation

◆ StackTracePrinter

typedef void(* StackTracePrinter) ()

Definition at line 1296 of file v8-platform.h.

Constructor & Destructor Documentation

◆ ~Platform()

virtual ~Platform ( )

virtualdefault

Member Function Documentation

◆ CallBlockingTaskOnWorkerThread()

void CallBlockingTaskOnWorkerThread	(	std::unique_ptr< Task >	task,
		const 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 1140 of file v8-platform.h.

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

◆ CallDelayedOnWorkerThread()

void CallDelayedOnWorkerThread	(	std::unique_ptr< Task >	task,
		double	delay_in_seconds,
		const 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 1169 of file v8-platform.h.

References v8::kUserVisible, and Platform::PostDelayedTaskOnWorkerThreadImpl().

◆ CallLowPriorityTaskOnWorkerThread()

void CallLowPriorityTaskOnWorkerThread	(	std::unique_ptr< Task >	task,
		const 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 1154 of file v8-platform.h.

References v8::kBestEffort, and Platform::PostTaskOnWorkerThreadImpl().

◆ CallOnWorkerThread()

void CallOnWorkerThread	(	std::unique_ptr< Task >	task,
		const 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 1127 of file v8-platform.h.

References v8::kUserVisible, and Platform::PostTaskOnWorkerThreadImpl().

◆ 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 1259 of file v8-platform.h.

◆ CreateJob()

std::unique_ptr< JobHandle > CreateJob	(	TaskPriority	priority,
		std::unique_ptr< JobTask >	job_task,
		const 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 1250 of file v8-platform.h.

References Platform::CreateJobImpl().

Referenced by Platform::PostJob().

◆ 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.

Referenced by Platform::CreateJob().

◆ 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 1278 of file v8-platform.h.

References Platform::CurrentClockTimeMillis().

◆ CurrentClockTimeMillisecondsHighResolution()

virtual double CurrentClockTimeMillisecondsHighResolution ( )

inlinevirtual

Same as CurrentClockTimeMilliseconds(), but with more precision.

Definition at line 1292 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 1313 of file v8-platform.h.

◆ GetForegroundTaskRunner() [1/2]

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

inlinevirtual

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. TODO(chromium:1448758): Deprecate once |GetForegroundTaskRunner(Isolate*, TaskPriority)| is ready.

Definition at line 1106 of file v8-platform.h.

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

Referenced by Platform::GetForegroundTaskRunner().

◆ GetForegroundTaskRunner() [2/2]

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

inlinevirtual

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. TODO(chromium:1448758): Make pure virtual once embedders implement it.

Definition at line 1117 of file v8-platform.h.

◆ GetHighAllocationThroughputObserver()

virtual HighAllocationThroughputObserver * GetHighAllocationThroughputObserver ( )

inlinevirtual

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

Definition at line 1320 of file v8-platform.h.

◆ GetPageAllocator()

virtual PageAllocator * GetPageAllocator ( )

pure virtual

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

◆ 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 1302 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 1068 of file v8-platform.h.

◆ GetTracingController()

virtual TracingController * GetTracingController ( )

pure virtual

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

◆ GetZoneBackingAllocator()

virtual ZoneBackingAllocator * GetZoneBackingAllocator ( )

inlinevirtual

Allows the embedder to specify a custom allocator used for zones.

Definition at line 1075 of file v8-platform.h.

◆ IdleTasksEnabled()

virtual bool IdleTasksEnabled ( Isolate * isolate )

inlinevirtual

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

Definition at line 1180 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 1087 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.

Referenced by Platform::CallDelayedOnWorkerThread().

◆ PostJob()

std::unique_ptr< JobHandle > PostJob	(	TaskPriority	priority,
		std::unique_ptr< JobTask >	job_task,
		const 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 1227 of file v8-platform.h.

References Platform::CreateJob().

◆ 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.

Referenced by Platform::CallBlockingTaskOnWorkerThread(), Platform::CallLowPriorityTaskOnWorkerThread(), and Platform::CallOnWorkerThread().

◆ 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()

◆ GetZoneBackingAllocator()

◆ IdleTasksEnabled()

◆ MonotonicallyIncreasingTime()

◆ NumberOfWorkerThreads()

◆ OnCriticalMemoryPressure()

◆ PostDelayedTaskOnWorkerThreadImpl()

◆ PostJob()

◆ PostTaskOnWorkerThreadImpl()

◆ SystemClockTimeMillis()