v8  6.2.414(node8.16.0)
V8 is Google's open source JavaScript engine
Platform Class Referenceabstract

#include <v8-platform.h>

Public Types

enum  ExpectedRuntime { kShortRunningTask, kLongRunningTask }
 
typedef void(* StackTracePrinter) ()
 

Public Member Functions

virtual ~Platform ()=default
 
virtual void OnCriticalMemoryPressure ()
 
virtual size_t NumberOfAvailableBackgroundThreads ()
 
virtual void CallOnBackgroundThread (Task *task, ExpectedRuntime expected_runtime)=0
 
virtual void CallOnForegroundThread (Isolate *isolate, Task *task)=0
 
virtual void CallDelayedOnForegroundThread (Isolate *isolate, Task *task, double delay_in_seconds)=0
 
virtual void CallIdleOnForegroundThread (Isolate *isolate, IdleTask *task)
 
virtual bool IdleTasksEnabled (Isolate *isolate)
 
virtual double MonotonicallyIncreasingTime ()=0
 
virtual double CurrentClockTimeMillis ()
 
virtual StackTracePrinter GetStackTracePrinter ()
 
virtual TracingControllerGetTracingController ()=0
 

Static Protected Member Functions

static 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 121 of file v8-platform.h.

Member Typedef Documentation

◆ StackTracePrinter

typedef void(* StackTracePrinter) ()

Definition at line 217 of file v8-platform.h.

Member Enumeration Documentation

◆ ExpectedRuntime

This enum is used to indicate whether a task is potentially long running, or causes a long wait. The embedder might want to use this hint to decide whether to execute the task on a dedicated thread.

Enumerator
kShortRunningTask 
kLongRunningTask 

Definition at line 128 of file v8-platform.h.

Constructor & Destructor Documentation

◆ ~Platform()

virtual ~Platform ( )
virtualdefault

Member Function Documentation

◆ CallDelayedOnForegroundThread()

virtual void CallDelayedOnForegroundThread ( Isolate isolate,
Task task,
double  delay_in_seconds 
)
pure virtual

Schedules a task to be invoked on a foreground thread wrt a specific |isolate| after the given number of seconds |delay_in_seconds|. Tasks posted for the same isolate should be execute in order of scheduling. The definition of "foreground" is opaque to V8.

◆ CallIdleOnForegroundThread()

virtual void CallIdleOnForegroundThread ( Isolate isolate,
IdleTask task 
)
inlinevirtual

Schedules a task to be invoked on a foreground thread wrt a specific |isolate| when the embedder is idle. Requires that SupportsIdleTasks(isolate) is true. Idle tasks may be reordered relative to other task types and may be starved for an arbitrarily long time if no idle time is available. The definition of "foreground" is opaque to V8.

Definition at line 187 of file v8-platform.h.

◆ CallOnBackgroundThread()

virtual void CallOnBackgroundThread ( Task task,
ExpectedRuntime  expected_runtime 
)
pure virtual

Schedules a task to be invoked on a background thread. |expected_runtime| indicates that the task will run a long time. The Platform implementation takes ownership of |task|. There is no guarantee about order of execution of tasks wrt order of scheduling, nor is there a guarantee about the thread the task will be run on.

◆ CallOnForegroundThread()

virtual void CallOnForegroundThread ( Isolate isolate,
Task task 
)
pure virtual

Schedules a task to be invoked on a foreground thread wrt a specific |isolate|. Tasks posted for the same isolate should be execute in order of scheduling. The definition of "foreground" is opaque to V8.

◆ CurrentClockTimeMillis()

virtual double CurrentClockTimeMillis ( )
inlinevirtual

Current wall-clock time in milliseconds since epoch. This function is expected to return at least millisecond-precision values.

Definition at line 212 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 223 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 194 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.

◆ NumberOfAvailableBackgroundThreads()

virtual size_t NumberOfAvailableBackgroundThreads ( )
inlinevirtual

Gets the number of threads that are used to execute background tasks. Is used to estimate the number of tasks a work package should be split into. A return value of 0 means that there are no background threads available. Note that a value of 0 won't prohibit V8 from posting tasks using |CallOnBackgroundThread|.

Definition at line 151 of file v8-platform.h.

◆ 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 142 of file v8-platform.h.

◆ SystemClockTimeMillis()

static 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: