mini_racer/ext/mini_racer_extension/mini_racer_extension.cc

#include <stdio.h>
#include <ruby.h>
#include <ruby/thread.h>
#include <v8.h>
#include <libplatform/libplatform.h>
#include <ruby/encoding.h>
#include <pthread.h>

using namespace v8;

class ArrayBufferAllocator : public v8::ArrayBuffer::Allocator {
 public:
  virtual void* Allocate(size_t length) {
    void* data = AllocateUninitialized(length);
    return data == NULL ? data : memset(data, 0, length);
  }
  virtual void* AllocateUninitialized(size_t length) { return malloc(length); }
  virtual void Free(void* data, size_t) { free(data); }
};

typedef struct {
    Isolate* isolate;
    Persistent<Context>* context;
    ArrayBufferAllocator* allocator;
} ContextInfo;

typedef struct {
    bool parsed;
    bool executed;
    Persistent<Value>* value;
    Persistent<Value>* message;
    Persistent<Value>* backtrace;
} EvalResult;

typedef struct {
    ContextInfo* context_info;
    Local<String>* eval;
    useconds_t timeout;
    EvalResult* result;
} EvalParams;

Platform* current_platform = NULL;
static VALUE rb_eJavaScriptError;

static void init_v8() {
    if (current_platform == NULL) {
	V8::InitializeICU();
	current_platform = platform::CreateDefaultPlatform();
	V8::InitializePlatform(current_platform);
	V8::Initialize();
    }
}

void* breaker(void *d) {
  EvalParams* data = (EvalParams*)d;
  usleep(data->timeout*1000);
  pthread_setcancelstate(PTHREAD_CANCEL_DISABLE, NULL);
  V8::TerminateExecution(data->context_info->isolate);
  return NULL;
}

void*
nogvl_context_eval(void* arg) {
    EvalParams* eval_params = (EvalParams*)arg;
    EvalResult* result = eval_params->result;
    Isolate* isolate = eval_params->context_info->isolate;
    Isolate::Scope isolate_scope(isolate);
    HandleScope handle_scope(isolate);

    TryCatch trycatch(isolate);

    Local<Context> context = eval_params->context_info->context->Get(isolate);

    Context::Scope context_scope(context);

    MaybeLocal<Script> parsed_script = Script::Compile(context, *eval_params->eval);
    result->parsed = !parsed_script.IsEmpty();
    result->executed = false;
    result->value = NULL;

    if (!result->parsed) {
	result->message = new Persistent<Value>();
	result->message->Reset(isolate, trycatch.Exception());
    } else {

	pthread_t breaker_thread;

	if (eval_params->timeout > 0) {
	   pthread_create(&breaker_thread, NULL, breaker, (void*)eval_params);
	}

	MaybeLocal<Value> maybe_value = parsed_script.ToLocalChecked()->Run(context);

	if (eval_params->timeout > 0) {
	    pthread_cancel(breaker_thread);
	    pthread_join(breaker_thread, NULL);
	}

	result->executed = !maybe_value.IsEmpty();

	if (!result->executed) {
	    if (trycatch.HasCaught()) {
		if (!trycatch.Exception()->IsNull()) {
		    result->message = new Persistent<Value>();
		    result->message->Reset(isolate, trycatch.Exception()->ToString());
		} else if(trycatch.HasTerminated()) {
		    result->message = new Persistent<Value>();
		    Local<String> tmp = String::NewFromUtf8(isolate, "JavaScript was terminated (either by timeout or explicitly)");
		    result->message->Reset(isolate, tmp);
		}

		if (!trycatch.StackTrace().IsEmpty()) {
		    result->backtrace = new Persistent<Value>();
		    result->backtrace->Reset(isolate, trycatch.StackTrace()->ToString());
		}
	    }
	} else {
	    Persistent<Value>* persistent = new Persistent<Value>();
	    persistent->Reset(isolate, maybe_value.ToLocalChecked());
	    result->value = persistent;
	}
    }

    return NULL;
}

static VALUE convert_v8_to_ruby(Isolate* isolate, Handle<Value> &value) {

    HandleScope scope(isolate);

    if (value->IsNull() || value->IsUndefined()){
	return Qnil;
    }

    if (value->IsInt32()) {
     return INT2FIX(value->Int32Value());
    }

    if (value->IsNumber()) {
      return rb_float_new(value->NumberValue());
    }

    if (value->IsTrue()) {
      return Qtrue;
    }

    if (value->IsFalse()) {
      return Qfalse;
    }

    if (value->IsArray()) {
      VALUE rb_array = rb_ary_new();
      Local<Array> arr = Local<Array>::Cast(value);
      for(int i=0; i<arr->Length(); i++) {
	  Local<Value> element = arr->Get(i);
	  VALUE rb_elem = convert_v8_to_ruby(isolate, element);
          rb_ary_push(rb_array, rb_elem);
      }
      return rb_array;
    }

    Local<String> rstr = value->ToString();
    return rb_enc_str_new(*v8::String::Utf8Value(rstr), rstr->Utf8Length(), rb_enc_find("utf-8"));
}

static Handle<Value> convert_ruby_to_v8(Isolate* isolate, VALUE value) {
    EscapableHandleScope scope(isolate);

    switch (TYPE(value)) {
    case T_FIXNUM:
	return scope.Escape(Integer::New(isolate, NUM2INT(value)));
    case T_FLOAT:
	return scope.Escape(Number::New(isolate, NUM2DBL(value)));
    case T_STRING:
	return scope.Escape(String::NewFromUtf8(isolate, RSTRING_PTR(value), NewStringType::kNormal, (int)RSTRING_LEN(value)).ToLocalChecked());
    case T_NIL:
	return scope.Escape(Null(isolate));
    case T_TRUE:
	return scope.Escape(True(isolate));
    case T_FALSE:
	return scope.Escape(False(isolate));
    case T_DATA:
    case T_OBJECT:
    case T_CLASS:
    case T_ICLASS:
    case T_MODULE:
    case T_REGEXP:
    case T_MATCH:
    case T_ARRAY:
    case T_HASH:
    case T_STRUCT:
    case T_BIGNUM:
    case T_FILE:
    case T_SYMBOL:
    case T_UNDEF:
    case T_NODE:
    default:
     // rb_warn("unknown conversion to V8 for: %s", RSTRING_PTR(rb_inspect(value)));
      return scope.Escape(String::NewFromUtf8(isolate, "Undefined Conversion"));
    }

}

static VALUE rb_context_eval_unsafe(VALUE self, VALUE str) {

    EvalParams eval_params;
    EvalResult eval_result;
    ContextInfo* context_info;
    VALUE result;

    VALUE message = Qnil;
    VALUE backtrace = Qnil;

    Data_Get_Struct(self, ContextInfo, context_info);

    {
	Locker lock(context_info->isolate);
	Isolate::Scope isolate_scope(context_info->isolate);
	HandleScope handle_scope(context_info->isolate);

	Local<String> eval = String::NewFromUtf8(context_info->isolate, RSTRING_PTR(str),
						  NewStringType::kNormal, (int)RSTRING_LEN(str)).ToLocalChecked();

	eval_params.context_info = context_info;
	eval_params.eval = &eval;
	eval_params.result = &eval_result;
	eval_params.timeout = 0;
	VALUE timeout = rb_iv_get(self, "@timeout");
	if (timeout != Qnil) {
	    eval_params.timeout = (useconds_t)NUM2LONG(timeout);
	}

	eval_result.message = NULL;
	eval_result.backtrace = NULL;

	rb_thread_call_without_gvl(nogvl_context_eval, &eval_params, RUBY_UBF_IO, 0);

	if (eval_result.message != NULL) {
	    Local<Value> tmp = Local<Value>::New(context_info->isolate, *eval_result.message);
	    message = convert_v8_to_ruby(context_info->isolate, tmp);
	    eval_result.message->Reset();
	    delete eval_result.message;
	}

	if (eval_result.backtrace != NULL) {
	    Local<Value> tmp = Local<Value>::New(context_info->isolate, *eval_result.backtrace);
	    backtrace = convert_v8_to_ruby(context_info->isolate, tmp);
	    eval_result.backtrace->Reset();
	    delete eval_result.backtrace;
	}
    }

    // NOTE: this is very important, we can not do an rb_raise from within
    // a v8 scope, if we do the scope is never cleaned up properly and we leak
    if (!eval_result.parsed) {
	if(TYPE(message) == T_STRING) {
	    rb_raise(rb_eJavaScriptError, "%s", RSTRING_PTR(message));
	} else {
	    rb_raise(rb_eJavaScriptError, "Unknown JavaScript Error during parse");
	}
    }

    if (!eval_result.executed) {

	VALUE ruby_exception = rb_iv_get(self, "@current_exception");
	if (ruby_exception == Qnil) {
	    // exception report about what happened
	    if(TYPE(message) == T_STRING && TYPE(backtrace) == T_STRING) {
		rb_raise(rb_eJavaScriptError, "%s/n%s", RSTRING_PTR(message), RSTRING_PTR(backtrace));
	    } else if(TYPE(message) == T_STRING) {
		rb_raise(rb_eJavaScriptError, "%s", RSTRING_PTR(message));
	    } else {
		rb_raise(rb_eJavaScriptError, "Unknown JavaScript Error during execution");
	    }
	} else {
	    rb_raise(CLASS_OF(ruby_exception), RSTRING_PTR(rb_funcall(ruby_exception, rb_intern("to_s"), 0)));
	}
    }

    // New scope for return value
    {
	Locker lock(context_info->isolate);
	Isolate::Scope isolate_scope(context_info->isolate);
	HandleScope handle_scope(context_info->isolate);

	Local<Value> tmp = Local<Value>::New(context_info->isolate, *eval_result.value);
	result = convert_v8_to_ruby(context_info->isolate, tmp);

	eval_result.value->Reset();
	delete eval_result.value;
    }

    return result;
}

typedef struct {
    VALUE callback;
    int length;
    VALUE* args;
    bool failed;
} protected_callback_data;

static
VALUE protected_callback(VALUE rdata) {
    protected_callback_data* data = (protected_callback_data*)rdata;
    VALUE result;

    if (data->length > 0) {
	result = rb_funcall2(data->callback, rb_intern("call"), data->length, data->args);
    } else {
	result = rb_funcall(data->callback, rb_intern("call"), 0);
    }
    return result;
}

static
VALUE rescue_callback(VALUE rdata, VALUE exception) {
    protected_callback_data* data = (protected_callback_data*)rdata;
    data->failed = true;
    return exception;
}

void*
gvl_ruby_callback(void* data) {

    FunctionCallbackInfo<Value>* args = (FunctionCallbackInfo<Value>*)data;
    VALUE* ruby_args;
    int length = args->Length();
    VALUE callback;
    VALUE result;
    VALUE self;

    {
	HandleScope scope(args->GetIsolate());
	Handle<External> external = Handle<External>::Cast(args->Data());

	VALUE* self_pointer = (VALUE*)(external->Value());
	self = *self_pointer;
	callback = rb_iv_get(self, "@callback");

	if (length > 0) {
	    ruby_args = ALLOC_N(VALUE, length);
	}


	for (int i = 0; i < length; i++) {
	    Local<Value> value = ((*args)[i]).As<Value>();
	    ruby_args[i] = convert_v8_to_ruby(args->GetIsolate(), value);
	}
    }

    // may raise exception stay clear of handle scope
    protected_callback_data callback_data;
    callback_data.length = length;
    callback_data.callback = callback;
    callback_data.args = ruby_args;
    callback_data.failed = false;

    result = rb_rescue(protected_callback, (VALUE)(&callback_data),
			rescue_callback, (VALUE)(&callback_data));

    if(callback_data.failed) {
	VALUE parent = rb_iv_get(self, "@parent");
	rb_iv_set(parent, "@current_exception", result);
	args->GetIsolate()->ThrowException(String::NewFromUtf8(args->GetIsolate(), "Ruby exception"));
    }
    else {
	HandleScope scope(args->GetIsolate());
	Handle<Value> v8_result = convert_ruby_to_v8(args->GetIsolate(), result);
	args->GetReturnValue().Set(v8_result);
    }

    if (length > 0) {
	xfree(ruby_args);
    }

    return NULL;
}

static void ruby_callback(const FunctionCallbackInfo<Value>& args) {
    rb_thread_call_with_gvl(gvl_ruby_callback, (void*)(&args));
}


static VALUE rb_external_function_notify_v8(VALUE self) {

    ContextInfo* context_info;

    VALUE parent = rb_iv_get(self, "@parent");
    VALUE name = rb_iv_get(self, "@name");

    Data_Get_Struct(parent, ContextInfo, context_info);

    Locker lock(context_info->isolate);
    Isolate::Scope isolate_scope(context_info->isolate);
    HandleScope handle_scope(context_info->isolate);

    Local<Context> context = context_info->context->Get(context_info->isolate);
    Context::Scope context_scope(context);

    Local<String> v8_str = String::NewFromUtf8(context_info->isolate, RSTRING_PTR(name),
					      NewStringType::kNormal, (int)RSTRING_LEN(name)).ToLocalChecked();


    // copy self so we can access from v8 external
    VALUE* self_copy;
    Data_Get_Struct(self, VALUE, self_copy);
    *self_copy = self;

    Local<Value> external = External::New(context_info->isolate, self_copy);
    context->Global()->Set(v8_str, FunctionTemplate::New(context_info->isolate, ruby_callback, external)->GetFunction());

    return Qnil;
}

void deallocate(void * data) {
    ContextInfo* context_info = (ContextInfo*)data;
    {
	Locker lock(context_info->isolate);
    }

    {
	context_info->context->Reset();
	delete context_info->context;
    }

    {
	context_info->isolate->Dispose();
    }

    delete context_info->allocator;
    xfree(context_info);
}

void deallocate_external_function(void * data) {
    xfree(data);
}

VALUE allocate_external_function(VALUE klass) {
    VALUE* self = ALLOC(VALUE);
    return Data_Wrap_Struct(klass, NULL, deallocate_external_function, (void*)self);
}


VALUE allocate(VALUE klass) {
    init_v8();

    ContextInfo* context_info = ALLOC(ContextInfo);

    context_info->allocator = new ArrayBufferAllocator();

    Isolate::CreateParams create_params;
    create_params.array_buffer_allocator = context_info->allocator;
    context_info->isolate = Isolate::New(create_params);

    Locker lock(context_info->isolate);
    Isolate::Scope isolate_scope(context_info->isolate);
    HandleScope handle_scope(context_info->isolate);

    Local<Context> context = Context::New(context_info->isolate);

    context_info->context = new Persistent<Context>();
    context_info->context->Reset(context_info->isolate, context);

    return Data_Wrap_Struct(klass, NULL, deallocate, (void*)context_info);
}

static VALUE
rb_context_stop(VALUE self) {
    ContextInfo* context_info;
    Data_Get_Struct(self, ContextInfo, context_info);
    V8::TerminateExecution(context_info->isolate);
    return Qnil;
}

extern "C" {

    void Init_mini_racer_extension ( void )
    {
	VALUE rb_mMiniRacer = rb_define_module("MiniRacer");
	VALUE rb_cContext = rb_define_class_under(rb_mMiniRacer, "Context", rb_cObject);
	rb_eJavaScriptError = rb_define_class_under(rb_mMiniRacer, "JavaScriptError", rb_eStandardError);
	VALUE rb_cExternalFunction = rb_define_class_under(rb_cContext, "ExternalFunction", rb_cObject);
	rb_define_method(rb_cContext, "stop", (VALUE(*)(...))&rb_context_stop, 0);
	rb_define_alloc_func(rb_cContext, allocate);

	rb_define_private_method(rb_cContext, "eval_unsafe",(VALUE(*)(...))&rb_context_eval_unsafe, 1);
	rb_define_private_method(rb_cExternalFunction, "notify_v8", (VALUE(*)(...))&rb_external_function_notify_v8, 0);
	rb_define_alloc_func(rb_cExternalFunction, allocate_external_function);
    }

}