v8  5.1.281(node6.17.1)
V8 is Google's open source JavaScript engine
Platform Class Referenceabstract

#include <v8-platform.h>

Public Types

enum  ExpectedRuntime { kShortRunningTask, kLongRunningTask }

Public Member Functions

virtual ~Platform ()
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 const uint8_t * GetCategoryGroupEnabled (const char *name)
virtual const char * GetCategoryGroupName (const uint8_t *category_enabled_flag)
virtual uint64_t AddTraceEvent (char phase, const uint8_t *category_enabled_flag, const char *name, const char *scope, uint64_t id, uint64_t bind_id, int32_t num_args, const char **arg_names, const uint8_t *arg_types, const uint64_t *arg_values, unsigned int flags)
virtual void UpdateTraceEventDuration (const uint8_t *category_enabled_flag, const char *name, uint64_t handle)

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 45 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.


Definition at line 52 of file v8-platform.h.

Constructor & Destructor Documentation

◆ ~Platform()

virtual ~Platform ( )

Definition at line 57 of file v8-platform.h.

Member Function Documentation

◆ AddTraceEvent()

virtual uint64_t AddTraceEvent ( char  phase,
const uint8_t *  category_enabled_flag,
const char *  name,
const char *  scope,
uint64_t  id,
uint64_t  bind_id,
int32_t  num_args,
const char **  arg_names,
const uint8_t *  arg_types,
const uint64_t *  arg_values,
unsigned int  flags 

Adds a trace event to the platform tracing system. This function call is usually the result of a TRACE_* macro from trace_event_common.h when tracing and the category of the particular trace are enabled. It is not advisable to call this function on its own; it is really only meant to be used by the trace macros. The returned handle can be used by UpdateTraceEventDuration to update the duration of COMPLETE events.

Definition at line 153 of file v8-platform.h.

◆ 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 

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 102 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.

◆ GetCategoryGroupEnabled()

virtual const uint8_t* GetCategoryGroupEnabled ( const char *  name)

Called by TRACE_EVENT* macros, don't call this directly. The name parameter is a category group for example: TRACE_EVENT0("v8,parse", "V8.Parse") The pointer returned points to a value with zero or more of the bits defined in CategoryGroupEnabledFlags.

Definition at line 130 of file v8-platform.h.

◆ GetCategoryGroupName()

virtual const char* GetCategoryGroupName ( const uint8_t *  category_enabled_flag)

Gets the category group name of the given category_enabled_flag pointer. Usually used while serliazing TRACE_EVENTs.

Definition at line 139 of file v8-platform.h.

◆ IdleTasksEnabled()

virtual bool IdleTasksEnabled ( Isolate isolate)

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

Definition at line 109 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 ( )

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 66 of file v8-platform.h.

◆ UpdateTraceEventDuration()

virtual void UpdateTraceEventDuration ( const uint8_t *  category_enabled_flag,
const char *  name,
uint64_t  handle 

Sets the duration field of a COMPLETE trace event. It must be called with the handle returned from AddTraceEvent().

Definition at line 165 of file v8-platform.h.

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