V8 is the JavaScript engine used in Google Chrome. It is open source and written in C++ with some parts implemented in embedded JavaScript. V8 uses just-in-time compilation, precise garbage collection, inline caching, and hidden classes to optimize performance. It supports 64-bit versions and has advantages like C-like syntax and bit operations. While documentation is limited, it allows embedding JavaScript in C++ applications and extending it with user libraries.

1. V8 javascript engine
이혁재
2011.06.1
2

2. 목차
• 소개
• 장단점
• 빌드
• 사용 예제
• v8 엔진이 빠른 이유

3. 소개
• 구글 크롬에 사용된 자바스크립트 엔진
• open source( New BSD License )
• c++ 구현됨 ( 일부는 내장 javascript 로 구
현 )
• windows / *nix / mac os X
• x86 / ARM

4. 장점
• 속도 : lua < v8 < lua-jit
• 64bit version 지원
• javascript 의 언어적 장점
– C 와 비슷
– Bit operation( <<, >> )
– 당연하게도 switch 가 있다 .
• google 에서 작성
– 안전성 , 업데이트 주기
• 인력 구하기
– 게임업계 외에서는 javascript 인력이 많다

5. 단점
• 문서 ( 예제 )
• 유저 라이브러리 확장
• corutine 같은 기능이 없음
• binder

6. 빌드
• 컴파일된 버젼이 없으니 받아서 빌드해야 함
• 선행 조건
– python 과 scon(make 같은 것 )
– python 부터 설치 하는게 편함
• 빌드 ( vc2008 기준 )
– Vcvarsall.bat
– scons env="PATH:%PATH%,INCLUDE:%INCLUDE
%,LIB:%LIB%" msvcrt=shared mode=debug
library=shared snapshot=off

7. dll 버전 사용하기
• USING_V8_SHARED
– dll 을 사용하는 응용프로그램에서 전역적으로
define 해야 함
– debug 버전
 v8_g.lib, v8_g.dll
– release 버전
 v8.lib, v8.dll

8. hello world
#include <v8.h>
using namespace v8;
int main(int argc, char* argv[]) {
HandleScope handle_scope;
Persistent<Context> context = Context::New();
Context::Scope context_scope(context);
Handle<String> source = String::New("'Hello' + ', World!'");
Handle<Script> script = Script::Compile(source);
Handle<Value> result = script->Run();
context.Dispose();
String::AsciiValue ascii(result);
printf("%sn", *ascii);
return 0;
}

9. hello world
#include <v8.h>
using namespace v8;
int main(int argc, char* argv[]) {
HandleScope handle_scope;
Persistent<Context> context = Context::New();
Context::Scope context_scope(context);
Handle<String> source = String::New("'Hello' + ', World!'");
Handle<Script> script = Script::Compile(source);
Handle<Value> result = script->Run();
context.Dispose();
String::AsciiValue ascii(result);
printf("%sn", *ascii);
return 0;
}

10. hello world
#include <v8.h>
using namespace v8;
int main(int argc, char* argv[]) {
HandleScope handle_scope;
Persistent<Context> context = Context::New();
Context::Scope context_scope(context);
Handle<String> source = String::New("'Hello' + ', World!'");
Handle<Script> script = Script::Compile(source);
Handle<Value> result = script->Run();
context.Dispose();
String::AsciiValue ascii(result);
printf("%sn", *ascii);
return 0;
}

11. hello world
#include <v8.h>
using namespace v8;
int main(int argc, char* argv[]) {
HandleScope handle_scope;
Persistent<Context> context = Context::New();
Context::Scope context_scope(context);
Handle<String> source = String::New("'Hello' + ', World!'");
Handle<Script> script = Script::Compile(source);
Handle<Value> result = script->Run();
context.Dispose();
String::AsciiValue ascii(result);
printf("%sn", *ascii);
return 0;
}

12. hello world
#include <v8.h>
using namespace v8;
int main(int argc, char* argv[]) {
HandleScope handle_scope;
Persistent<Context> context = Context::New();
Context::Scope context_scope(context);
Handle<String> source = String::New("'Hello' + ', World!'");
Handle<Script> script = Script::Compile(source);
Handle<Value> result = script->Run();
context.Dispose();
String::AsciiValue ascii(result);
printf("%sn", *ascii);
return 0;
}

13. javascript 에서 c++ 함수를 호출
static Handle<Value> LogCallback(const Arguments& args)
{
HandleScope scope;
printf("LogCallback calledn");
return v8::Undefined();
}
void Function()
{
HandleScope handle_scope;
Handle<ObjectTemplate> global = ObjectTemplate::New();
global->Set(String::New("log"), FunctionTemplate::New(LogCallback));
Persistent<Context> context = Context::New( NULL, global );
Context::Scope context_scope(context);
Handle<String> source = String::New("log();");
Handle<Script> script = Script::Compile(source);
script->Run();
context.Dispose();
}

14. javascript 에서 c++ 함수를 호출
static Handle<Value> LogCallback(const Arguments& args)
{
HandleScope scope;
printf("LogCallback calledn");
return v8::Undefined();
}
void Function()
{
HandleScope handle_scope;
Handle<ObjectTemplate> global = ObjectTemplate::New();
global->Set(String::New("log"), FunctionTemplate::New(LogCallback));
Persistent<Context> context = Context::New( NULL, global );
Context::Scope context_scope(context);
Handle<String> source = String::New("log();");
Handle<Script> script = Script::Compile(source);
script->Run();
context.Dispose();
}

15. javascript 에서 c++ 함수를 호출
static Handle<Value> LogCallback(const Arguments& args)
{
HandleScope scope;
printf("LogCallback calledn");
return v8::Undefined();
}
void Function()
{
HandleScope handle_scope;
Handle<ObjectTemplate> global = ObjectTemplate::New();
global->Set(String::New("log"), FunctionTemplate::New(LogCallback));
Persistent<Context> context = Context::New( NULL, global );
Context::Scope context_scope(context);
Handle<String> source = String::New("log();");
Handle<Script> script = Script::Compile(source);
script->Run();
context.Dispose();
}

16. javascript 에서 c++ 함수를 호출
static Handle<Value> LogCallback(const Arguments& args)
{
HandleScope scope;
printf("LogCallback calledn");
return v8::Undefined();
}
void Function()
{
HandleScope handle_scope;
Handle<ObjectTemplate> global = ObjectTemplate::New();
global->Set(String::New("log"), FunctionTemplate::New(LogCallback));
Persistent<Context> context = Context::New( NULL, global );
Context::Scope context_scope(context);
Handle<String> source = String::New("log();");
Handle<Script> script = Script::Compile(source);
script->Run();
context.Dispose();
}

17. javascript 에서 c++ 전역 변수 읽고 / 쓰기
int x, y;
Handle<Value> XGetter(Local<String> property, const AccessorInfo& info)
{
return Integer::New(x);
}
void XSetter(Local<String> property, Local<Value> value, const AccessorInfo& info
{
x = value->Int32Value();
}

18. javascript 에서 c++ 전역 변수 읽고 / 쓰기
void GlobalVar()
{
HandleScope handle_scope;
Handle<ObjectTemplate> global_templ = ObjectTemplate::New();
global_templ->SetAccessor(String::New("x"), XGetter, XSetter);
global_templ->SetAccessor(String::New("y"), YGetter, YSetter);
Persistent<Context> context = Context::New(NULL, global_templ);
Context::Scope context_scope(context);
Handle<String> source = String::New("x = 10; y = 10; x = y + 20;");
Handle<Script> script = Script::Compile(source);
Handle<Value> result = script->Run();
context.Dispose();
String::AsciiValue ascii(result);
printf("%sn", *ascii);
}

19. javascript 에서 c++ 전역 변수 읽고 / 쓰기
void GlobalVar()
{
HandleScope handle_scope;
Handle<ObjectTemplate> global_templ = ObjectTemplate::New();
global_templ->SetAccessor(String::New("x"), XGetter, XSetter);
global_templ->SetAccessor(String::New("y"), YGetter, YSetter);
Persistent<Context> context = Context::New(NULL, global_templ);
Context::Scope context_scope(context);
Handle<String> source = String::New("x = 10; y = 10; x = y + 20;");
Handle<Script> script = Script::Compile(source);
Handle<Value> result = script->Run();
context.Dispose();
String::AsciiValue ascii(result);
printf("%sn", *ascii);
}

20. javascript 에서 c++ class 접근
lass Point
ublic:
Point(int x, int y) : x_(x), y_(y) { }
int x_, y_;
;

21. javascript 에서 c++ class 접근
HandleScope handle_scope;
Handle<FunctionTemplate> point_templ = FunctionTemplate::New();
Handle<ObjectTemplate> point_inst = point_templ->InstanceTemplate();
point_inst->SetInternalFieldCount(1);
point_inst->SetAccessor(String::New("x"), GetPointX, SetPointX);
point_inst->SetAccessor(String::New("y"), GetPointY, SetPointY);
Persistent<Context> context = Context::New();
Context::Scope context_scope(context);
Point* p = new Point(0, 0);
Handle<Function> point_ctor = point_templ->GetFunction();
Local<Object> obj = point_ctor->NewInstance();
obj->SetInternalField(0, External::New(p));
context->Global()->Set(String::New("point"), obj);
Handle<String> source = String::New("point.x = 200;");
Handle<Script> script = Script::Compile(source);
Handle<Value> result = script->Run();
context.Dispose();

22. javascript 에서 c++ class 접근
HandleScope handle_scope;
Handle<FunctionTemplate> point_templ = FunctionTemplate::New();
Handle<ObjectTemplate> point_inst = point_templ->InstanceTemplate();
point_inst->SetInternalFieldCount(1);
point_inst->SetAccessor(String::New("x"), GetPointX, SetPointX);
point_inst->SetAccessor(String::New("y"), GetPointY, SetPointY);
Persistent<Context> context = Context::New();
Context::Scope context_scope(context);
Point* p = new Point(0, 0);
Handle<Function> point_ctor = point_templ->GetFunction();
Local<Object> obj = point_ctor->NewInstance();
obj->SetInternalField(0, External::New(p));
context->Global()->Set(String::New("point"), obj);
Handle<String> source = String::New("point.x = 200;");
Handle<Script> script = Script::Compile(source);
Handle<Value> result = script->Run();
context.Dispose();

23. javascript 에서 c++ class 접근
HandleScope handle_scope;
Handle<FunctionTemplate> point_templ = FunctionTemplate::New();
Handle<ObjectTemplate> point_inst = point_templ->InstanceTemplate();
point_inst->SetInternalFieldCount(1);
point_inst->SetAccessor(String::New("x"), GetPointX, SetPointX);
point_inst->SetAccessor(String::New("y"), GetPointY, SetPointY);
Persistent<Context> context = Context::New();
Context::Scope context_scope(context);
Point* p = new Point(0, 0);
Handle<Function> point_ctor = point_templ->GetFunction();
Local<Object> obj = point_ctor->NewInstance();
obj->SetInternalField(0, External::New(p));
context->Global()->Set(String::New("point"), obj);
Handle<String> source = String::New("point.x = 200;");
Handle<Script> script = Script::Compile(source);
Handle<Value> result = script->Run();
context.Dispose();

24. javascript 에서 c++ class 접근
HandleScope handle_scope;
Handle<FunctionTemplate> point_templ = FunctionTemplate::New();
Handle<ObjectTemplate> point_inst = point_templ->InstanceTemplate();
point_inst->SetInternalFieldCount(1);
point_inst->SetAccessor(String::New("x"), GetPointX, SetPointX);
point_inst->SetAccessor(String::New("y"), GetPointY, SetPointY);
Persistent<Context> context = Context::New();
Context::Scope context_scope(context);
Point* p = new Point(0, 0);
Handle<Function> point_ctor = point_templ->GetFunction();
Local<Object> obj = point_ctor->NewInstance();
obj->SetInternalField(0, External::New(p));
context->Global()->Set(String::New("point"), obj);
Handle<String> source = String::New("point.x = 200;");
Handle<Script> script = Script::Compile(source);
Handle<Value> result = script->Run();
context.Dispose();

25. javascript 에서 c++ class 접근
HandleScope handle_scope;
Handle<FunctionTemplate> point_templ = FunctionTemplate::New();
Handle<ObjectTemplate> point_inst = point_templ->InstanceTemplate();
point_inst->SetInternalFieldCount(1);
point_inst->SetAccessor(String::New("x"), GetPointX, SetPointX);
point_inst->SetAccessor(String::New("y"), GetPointY, SetPointY);
Persistent<Context> context = Context::New();
Context::Scope context_scope(context);
Point* p = new Point(0, 0);
Handle<Function> point_ctor = point_templ->GetFunction();
Local<Object> obj = point_ctor->NewInstance();
obj->SetInternalField(0, External::New(p));
context->Global()->Set(String::New("point"), obj);
Handle<String> source = String::New("point.x = 200;");
Handle<Script> script = Script::Compile(source);
Handle<Value> result = script->Run();
context.Dispose();

26. javascript 에서 c++ class 접근
HandleScope handle_scope;
Handle<FunctionTemplate> point_templ = FunctionTemplate::New();
Handle<ObjectTemplate> point_inst = point_templ->InstanceTemplate();
point_inst->SetInternalFieldCount(1);
point_inst->SetAccessor(String::New("x"), GetPointX, SetPointX);
point_inst->SetAccessor(String::New("y"), GetPointY, SetPointY);
Persistent<Context> context = Context::New();
Context::Scope context_scope(context);
Point* p = new Point(0, 0);
Handle<Function> point_ctor = point_templ->GetFunction();
Local<Object> obj = point_ctor->NewInstance();
obj->SetInternalField(0, External::New(p));
context->Global()->Set(String::New("point"), obj);
Handle<String> source = String::New("point.x = 200;");
Handle<Script> script = Script::Compile(source);
Handle<Value> result = script->Run();
context.Dispose();

27. javascript 에서 c++ class 접근
Handle<Value> GetPointX(Local<String> property, const AccessorInfo &info)
{
Local<Object> self = info.Holder();
Local<External> wrap = Local<External>::Cast(self->GetInternalField(0));
void* ptr = wrap->Value();
int value = static_cast<Point*>(ptr)->x_;
return Integer::New(value);
}
void SetPointX(Local<String> property, Local<Value> value, const AccessorInfo& in
{
Local<Object> self = info.Holder();
Local<External> wrap = Local<External>::Cast(self->GetInternalField(0));
void* ptr = wrap->Value();
static_cast<Point*>(ptr)->x_ = value->Int32Value();
}

28. 한글 처리 ( 1 )
• class String
– 3 가지 nested class 를 가짐
class String {
class AsciiValue { … }; // ASCII
class Value { … }; // UTF-16
class Utf8Value { … }; // UTF-8
};

29. 한글처리 ( 2 )
• String 클래스 내부 클래스 중에서 Value 를 사
용
– input: unicode
– output: unicode
Handle<String> source = String::New(L"' 한 ' + ' 글 '");
Handle<Script> script = Script::Compile(source);
Handle<Value> result = script->Run();
String::Value str(result);
wchar_t* p = *str;

30. v8 이 빠른 이유 ?
• Just-In-Time Compile
• Garbage Collection
– precise GC ( 자바가 사용한 gc 방식 )
– 더 진보됨
• Inline Cache
– property 찾은 결과 보관하여 cache
• Hidden Classes

31. JIT

32. Hidden Classes( 1 )

33. Hidden Classes( 2 )

34. reference
• 빌드
– http://code.google.com/p/v8/wiki/BuildingOnWind
ows
• embeding
– http://code.google.com/intl/ko-
KR/apis/v8/embed.html
• cproxyv8
– http://code.google.com/p/cproxyv8/
• 질답 게시판
– http://groups.google.com/group/v8-users/topics
• 왜 빠른가 ?
– http://techon.nikkeibp.co.jp/article/HONSHI/20090106/163617/

35. Q&A