I changed the line to
v8::Local<v8::Context> context(instance->context->Get(instance->isolate));
It is compiling also working fine.
However when I execute this executable with valgrind, I get lot of
"*Conditional
jump or move depends on uninitialised value(s)*"
One such conditional jump is given below.
==5158== Conditional jump or move depends on uninitialised value(s)
==5158== at 0x8F0868:
v8::internal::DeclarationScope::CheckConflictingVarDeclarations() (in
/home/user/mjse)
==5158== by 0x4D8F68:
v8::internal::PreParser::PreParseFunction(v8::internal::AstRawString
const*, v8::internal::FunctionKind,
v8::internal::FunctionLiteral::FunctionType,
v8::internal::DeclarationScope*, int*,
v8::internal::ProducedPreparseData**, int) (in /home/user/mjse)
==5158== by 0x4B7935:
v8::internal::Parser::SkipFunction(v8::internal::AstRawString const*,
v8::internal::FunctionKind, v8::internal::FunctionLiteral::FunctionType,
v8::internal::DeclarationScope*, int*, int*,
v8::internal::ProducedPreparseData**) (in /home/user/mjse)
==5158== by 0x4AB715:
v8::internal::Parser::ParseFunctionLiteral(v8::internal::AstRawString
const*, v8::internal::Scanner::Location,
v8::internal::FunctionNameValidity, v8::internal::FunctionKind, int,
v8::internal::FunctionLiteral::FunctionType, v8::internal::LanguageMode,
v8::internal::ZoneList<v8::internal::AstRawString const*>*) (in
/home/user/mjse)
==5158== by 0x4D1EFA:
v8::internal::ParserBase<v8::internal::Parser>::ParseHoistableDeclaration(int,
v8::base::Flags<v8::internal::ParseFunctionFlag, int>,
v8::internal::ZoneList<v8::internal::AstRawString const*>*, bool) (in
/home/user/mjse)
==5158== by 0x4AA266:
v8::internal::Parser::DoParseProgram(v8::internal::Isolate*,
v8::internal::ParseInfo*) (in /home/user/mjse)
==5158== by 0x4A9958:
v8::internal::Parser::ParseProgram(v8::internal::Isolate*,
v8::internal::ParseInfo*) (in /home/user/mjse)
==5158== by 0x4D5759:
v8::internal::parsing::ParseProgram(v8::internal::ParseInfo*,
v8::internal::Isolate*) (in /home/user/mjse)
==5158== by 0x22A835: v8::internal::(anonymous
namespace)::CompileToplevel(v8::internal::ParseInfo*,
v8::internal::Isolate*, v8::internal::IsCompiledScope*) (in /home/user/mjse)
==5158== by 0x22C128:
v8::internal::Compiler::GetSharedFunctionInfoForScript(v8::internal::Isolate*,
v8::internal::Handle<v8::internal::String>,
v8::internal::Compiler::ScriptDetails const&, v8::ScriptOriginOptions,
v8::Extension*, v8::internal::ScriptData*,
v8::ScriptCompiler::CompileOptions, v8::ScriptCompiler::NoCacheReason,
v8::internal::NativesFlag) (in /home/user/mjse)
==5158== by 0x1F0EE4:
v8::ScriptCompiler::CompileUnboundInternal(v8::Isolate*,
v8::ScriptCompiler::Source*, v8::ScriptCompiler::CompileOptions,
v8::ScriptCompiler::NoCacheReason) (in /home/user/mjse)
==5158== by 0x1F15D6:
v8::ScriptCompiler::Compile(v8::Local<v8::Context>,
v8::ScriptCompiler::Source*, v8::ScriptCompiler::CompileOptions,
v8::ScriptCompiler::NoCacheReason) (in /home/user/mjse)
==5158==
What could be the issue?
Thanks
Austin
On Thu, Jun 27, 2019 at 5:34 PM Austin Einter <austin.ein...@gmail.com>
wrote:
> Thanks Ben. I followed your suggestion.
> I added *v8::Global<v8::Context> *context; *member in instance structure.
>
> I put the code as below.
>
>
>
>
>
>
> * if(instance->context == nullptr) { v8::Local<v8::Context>
> context = v8::Context::New(instance->isolate); instance->context =
> new v8::Global<v8::Context>(instance->isolate, context); }*
>
> * v8::Local<v8::Context> context(instance->isolate, instance->context);*
>
> * For last line (in red) I am getting below compilation error.*
>
> error: no matching function for call to
> ‘v8::Local<v8::Context>::Local(v8::Isolate*&, v8::Global<v8::Context>*&)’
>
> Please let me know what I need to do to avoid this error.
>
> Thanks
> Austin
>
>
> On Thu, Jun 27, 2019 at 2:09 PM Ben Noordhuis <i...@bnoordhuis.nl> wrote:
>
>> On Thu, Jun 27, 2019 at 5:05 AM Austin Einter <austin.ein...@gmail.com>
>> wrote:
>> >
>> > Dear All
>> > I am quite new to v8. I am a c developer, with limited c++ knowledge.
>> Sorry if I ask very basic questions.
>> >
>> > I have a C application, that interacts with web servers. Gets
>> javascript. Need to execute javascript.
>> > Imagine a situation, where I get total 2 javascript files from server.
>> >
>> > js1.js
>> >
>> > function js_add_elements(var1, var2)
>> > {
>> > var var3 = parseInt(var1) + parseInt(var2);
>> > var result = 'Addition of ' + var1 + ' and ' + var2 + ' results ' +
>> var3;
>> > return result;
>> > }
>> >
>> >
>> > js2.js
>> >
>> > js_add_elements(2, 3);
>> >
>> >
>> >
>> > I have my c code as below.
>> >
>> > Header file
>> > typedef struct
>> > {
>> > std::unique_ptr<v8::Platform> platform;
>> > v8::Isolate::CreateParams create_params;
>> > v8::Isolate *isolate;
>> > v8::Isolate::Scope *isolate_scope;
>> > }MJSEInstance;
>> >
>> > #ifdef __cplusplus
>> > extern "C" {
>> > #endif
>> >
>> > /**
>> > * @brief Create MJSE instance
>> > */
>> > void *mjse_create_instance(char **argv);
>> >
>> > /**
>> > * @brief Destroy MJSE instance
>> > * @param instance -> MJSE instance
>> > */
>> > void mjse_destroy_instance(void *instance);
>> >
>> > /**
>> > * @brief Executes a script
>> > * @param minstance - MJSE instance
>> > * @param jscript - the javascript
>> > * @param scriptlen - Length of script
>> > */
>> > void mjse_execute_script(void *instance, char *jscript);
>> >
>> > #ifdef __cplusplus
>> > }
>> > #endif
>> >
>> > CPP File
>> > #include <stdio.h>
>> > #include <stdlib.h>
>> > #include <string.h>
>> > #include "include/libplatform/libplatform.h"
>> > #include "include/v8.h"
>> > #include "mjse.h"
>> > #include "mjse_int.h"
>> > #include <new>
>> >
>> > extern "C" {
>> > using namespace v8;
>> >
>> > void *mjse_create_instance(char **argv)
>> > {
>> > MJSEInstance *instance = (MJSEInstance *)calloc(1,
>> sizeof(MJSEInstance));
>> >
>> > v8::V8::InitializeICUDefaultLocation(argv[0]);
>> > v8::V8::InitializeExternalStartupData(argv[0]);
>> > instance->platform = v8::platform::NewDefaultPlatform();
>> >
>> > v8::V8::InitializePlatform(instance->platform.get());
>> > v8::V8::Initialize();
>> >
>> > instance->create_params.array_buffer_allocator =
>> v8::ArrayBuffer::Allocator::NewDefaultAllocator();
>> > instance->isolate = v8::Isolate::New(instance->create_params);
>> > instance->isolate_scope = new
>> v8::Isolate::Scope(instance->isolate);
>> >
>> > return instance;
>> > }
>> >
>> > void mjse_destroy_instance(void *minstance)
>> > {
>> > MJSEInstance *instance = (MJSEInstance *)minstance;
>> >
>> > if(instance == NULL)
>> > return;
>> >
>> > if(instance->isolate_scope)
>> > {
>> > delete instance->isolate_scope;
>> > }
>> >
>> > if(instance->isolate)
>> > {
>> > instance->isolate->Dispose();
>> > }
>> >
>> > v8::V8::Dispose();
>> > v8::V8::ShutdownPlatform();
>> >
>> > if(instance->create_params.array_buffer_allocator)
>> > {
>> > delete instance->create_params.array_buffer_allocator;
>> > }
>> >
>> > instance->~MJSEInstance();
>> > free(instance);
>> > }
>> >
>> >
>> > void mjse_execute_script(void *minstance, char *jscript)
>> > {
>> > MJSEInstance *instance = (MJSEInstance *)minstance;
>> >
>> > // Create a stack-allocated handle scope.
>> > v8::HandleScope handle_scope(instance->isolate);
>> >
>> > // Create a new context.
>> > v8::Local<v8::Context> context =
>> v8::Context::New(instance->isolate);
>> >
>> > // Enter the context for compiling and running the hello world
>> script.
>> > v8::Context::Scope context_scope(context);
>> >
>> > {
>> >
>> > // Create a string containing the JavaScript source code.
>> > v8::Local<v8::String> source =
>> > v8::String::NewFromUtf8(instance->isolate, jscript,
>> > v8::NewStringType::kNormal).ToLocalChecked();
>> >
>> > // Compile the source code.
>> > v8::Local<v8::Script> script =
>> > v8::Script::Compile(context, source).ToLocalChecked();
>> >
>> > // Run the script to get the result.
>> > v8::Local<v8::Value> result =
>> script->Run(context).ToLocalChecked();
>> >
>> > // Convert the result to an UTF8 string and print it.
>> > v8::String::Utf8Value utf8(instance->isolate, result);
>> > printf("%s\n", *utf8);
>> > }
>> > }
>> > }
>> >
>> > Main File
>> > int main(int argc, char **argv)
>> > {
>> > char *script;
>> > void *instance;
>> >
>> > instance = mjse_create_instance(argv);
>> >
>> > script = "function js_add_elements(var1, var2) \
>> > { \
>> > var var3 = parseInt(var1) + parseInt(var2); \
>> > var result = 'Addition of ' + var1 + ' and ' + var2
>> + ' results ' + var3; \
>> > return result; \
>> > };";
>> > mjse_execute_script(instance, script);
>> >
>> > script = "js_add_elements(2, 3);";
>> > mjse_execute_script(instance, script);
>> >
>> > mjse_destroy_instance(instance);
>> > return 0;
>> > }
>> >
>> > Now whats happening, while executing javascript first time it executes
>> fine. But while trying to execute second time (letter in red), it gets
>> exception.
>> >
>> > I understand, it is creating new v8 Local context each time, and does
>> not have js1.js details, hence getting exception. I also found in web we
>> can have v8 Global context and refer the context while executing for second
>> time.
>> >
>> > However I have not been able to find, how to declare v8 global context
>> and store / move v8 local context there and refer it during second time
>> execution. Please let me know with a sample/example code.
>> >
>> > Thanks
>> > Austin
>>
>> You can make the context persistent like this:
>>
>> if (instance->context == nullptr) {
>> v8::Local<v8::Context> context = v8::Context::New(instance->isolate);
>> instance->context = new v8::Global<v8::Context>(instance->isolate,
>> context);
>> }
>>
>> v8::Local<v8::Context> context(instance->isolate, instance->context);
>> v8::Context::Scope context_scope(context);
>>
>> --
>> --
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