v8::V8 Class Reference

#include <v8-initialization.h>

Public Types
enum class	WasmMemoryType { kMemory32 , kMemory64 }

Static Public Member Functions
static void	SetSnapshotDataBlob (StartupData *startup_blob)
static void	SetDcheckErrorHandler (DcheckErrorCallback that)
static void	SetFatalErrorHandler (V8FatalErrorCallback that)
static void	SetFlagsFromString (const char *str)
static void	SetFlagsFromString (const char *str, size_t length)
static void	SetFlagsFromCommandLine (int *argc, char **argv, bool remove_flags)
static const char *	GetVersion ()
static bool	Initialize ()
static void	SetEntropySource (EntropySource source)
static void	SetReturnAddressLocationResolver (ReturnAddressLocationResolver return_address_resolver)
static bool	Dispose ()
static bool	InitializeICU (const char *icu_data_file=nullptr)
static bool	InitializeICUDefaultLocation (const char *exec_path, const char *icu_data_file=nullptr)
static void	InitializeExternalStartupData (const char *directory_path)
static void	InitializeExternalStartupDataFromFile (const char *snapshot_blob)
static void	InitializePlatform (Platform *platform)
static void	DisposePlatform ()
static size_t	GetWasmMemoryReservationSizeInBytes (WasmMemoryType type, size_t byte_capacity)
static bool	EnableWebAssemblyTrapHandler (bool use_v8_signal_handler)
static void	SetFatalMemoryErrorCallback (OOMErrorCallback callback)
static void	GetSharedMemoryStatistics (SharedMemoryStatistics *statistics)

Friends
class	Context
template<class K , class V , class T >
class	PersistentValueMapBase

Detailed Description

Container class for static utility functions.

Member Enumeration Documentation

WasmMemoryType

enum class v8::V8::WasmMemoryType

strong

Enumerator
kMemory32
kMemory64

Member Function Documentation

Dispose()

static bool v8::V8::Dispose ( )

static

Releases any resources used by v8 and stops any utility threads that may be running. Note that disposing v8 is permanent, it cannot be reinitialized.

It should generally not be necessary to dispose v8 before exiting a process, this should happen automatically. It is only necessary to use if the process needs the resources taken up by v8.

Examples

shell.cc.

DisposePlatform()

static void v8::V8::DisposePlatform ( )

static

Clears all references to the v8::Platform. This should be invoked after V8 was disposed.

Examples

shell.cc.

EnableWebAssemblyTrapHandler()

static bool v8::V8::EnableWebAssemblyTrapHandler ( bool  use_v8_signal_handler )

static

Activate trap-based bounds checking for WebAssembly.

Parameters

use_v8_signal_handler

Whether V8 should install its own signal handler or rely on the embedder's.

GetSharedMemoryStatistics()

static void v8::V8::GetSharedMemoryStatistics ( SharedMemoryStatistics *  statistics )

static

Get statistics about the shared memory usage.

GetVersion()

static const char * v8::V8::GetVersion ( )

static

Get the version string.

Examples

shell.cc.

GetWasmMemoryReservationSizeInBytes()

static size_t v8::V8::GetWasmMemoryReservationSizeInBytes ( WasmMemoryType  type, size_t  byte_capacity  )

static

Returns the virtual address space reservation size (in bytes) needed for one WebAssembly memory instance of the given capacity.

Parameters

type	Whether this is a memory32 or memory64 instance.
byte_capacity	The maximum size, in bytes, of the WebAssembly memory. Values exceeding the engine's maximum allocatable memory size for the given type (determined by max_mem32_pages or max_mem64_pages) are clamped.

When trap-based bounds checking is enabled by EnableWebAssemblyTrapHandler(), the amount of virtual address space that V8 needs to reserve for each WebAssembly memory instance can be much bigger than the requested size. If the process does not have enough virtual memory available, WebAssembly memory allocation would fail. During the initialization of V8, embedders can use this method to estimate whether the process has enough virtual memory for their usage of WebAssembly, and decide whether to enable the trap handler via EnableWebAssemblyTrapHandler(), or to skip it and reduce the amount of virtual memory required to keep the application running.

Initialize()

static bool v8::V8::Initialize ( )

inlinestatic

Initializes V8. This function needs to be called before the first Isolate is created. It always returns true.

Examples

process.cc, and shell.cc.

InitializeExternalStartupData()

static void v8::V8::InitializeExternalStartupData ( const char *  directory_path )

static

Initialize the external startup data. The embedder only needs to invoke this method when external startup data was enabled in a build.

If V8 was compiled with the startup data in an external file, then V8 needs to be given those external files during startup. There are three ways to do this:

• InitializeExternalStartupData(const char*) This will look in the given directory for the file "snapshot_blob.bin".
• InitializeExternalStartupDataFromFile(const char*) As above, but will directly use the given file name.
• Call SetSnapshotDataBlob. This will read the blobs from the given data structure and will not perform any file IO.

Examples

process.cc, and shell.cc.

InitializeExternalStartupDataFromFile()

static void v8::V8::InitializeExternalStartupDataFromFile ( const char *  snapshot_blob )

static

InitializeICU()

static bool v8::V8::InitializeICU ( const char *  icu_data_file = nullptr )

static

Initialize the ICU library bundled with V8. The embedder should only invoke this method when using the bundled ICU. Returns true on success.

If V8 was compiled with the ICU data in an external file, the location of the data file has to be provided.

InitializeICUDefaultLocation()

static bool v8::V8::InitializeICUDefaultLocation ( const char *  exec_path, const char *  icu_data_file = nullptr  )

static

Initialize the ICU library bundled with V8. The embedder should only invoke this method when using the bundled ICU. If V8 was compiled with the ICU data in an external file and when the default location of that file should be used, a path to the executable must be provided. Returns true on success.

The default is a file called icudtl.dat side-by-side with the executable.

Optionally, the location of the data file can be provided to override the default.

Examples

process.cc, and shell.cc.

InitializePlatform()

static void v8::V8::InitializePlatform ( Platform *  platform )

static

Sets the v8::Platform to use. This should be invoked before V8 is initialized.

Examples

process.cc, and shell.cc.

SetDcheckErrorHandler()

static void v8::V8::SetDcheckErrorHandler ( DcheckErrorCallback  that )

static

Set the callback to invoke in case of Dcheck failures.

SetEntropySource()

static void v8::V8::SetEntropySource ( EntropySource  source )

static

Allows the host application to provide a callback which can be used as a source of entropy for random number generators.

SetFatalErrorHandler()

static void v8::V8::SetFatalErrorHandler ( V8FatalErrorCallback  that )

static

Set the callback to invoke in the case of CHECK failures or fatal errors. This is distinct from Isolate::SetFatalErrorHandler, which is invoked in response to API usage failures.

SetFatalMemoryErrorCallback()

static void v8::V8::SetFatalMemoryErrorCallback ( OOMErrorCallback  callback )

static

Allows the host application to provide a callback that will be called when v8 has encountered a fatal failure to allocate memory and is about to terminate.

SetFlagsFromCommandLine()

static void v8::V8::SetFlagsFromCommandLine ( int *  argc, char **  argv, bool  remove_flags  )

static

Sets V8 flags from the command line.

Examples

shell.cc.

SetFlagsFromString() [1/2]

static void v8::V8::SetFlagsFromString ( const char *  str )

static

Sets V8 flags from a string.

SetFlagsFromString() [2/2]

static void v8::V8::SetFlagsFromString ( const char *  str, size_t  length  )

static

SetReturnAddressLocationResolver()

static void v8::V8::SetReturnAddressLocationResolver ( ReturnAddressLocationResolver  return_address_resolver )

static

Allows the host application to provide a callback that allows v8 to cooperate with a profiler that rewrites return addresses on stack.

SetSnapshotDataBlob()

static void v8::V8::SetSnapshotDataBlob ( StartupData *  startup_blob )

static

Hand startup data to V8, in case the embedder has chosen to build V8 with external startup data.

Note:

• By default the startup data is linked into the V8 library, in which case this function is not meaningful.
• If this needs to be called, it needs to be called before V8 tries to make use of its built-ins.
• To avoid unnecessary copies of data, V8 will point directly into the given data blob, so pretty please keep it around until V8 exit.
• Compression of the startup blob might be useful, but needs to handled entirely on the embedders' side.
• The call will abort if the data is invalid.

Friends And Related Function Documentation

Context

friend class Context

friend

PersistentValueMapBase

template<class K , class V , class T >

friend class PersistentValueMapBase

friend

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

• include/v8-initialization.h