在node.js0.12.x中使用libuv函数
发布于 6 年前 作者 yunnysunny 3936 次浏览 最后一次编辑是 5 年前 来自 问答

我曾经写过一个node.js的c++扩展,它在0.10.x版本上可以顺利编译。但是当把它迁移到0.12.x上时,就会编译出错,报出类似error C2065: “uv_work_t”:undeclared identifier的错误。我想知道在0.12.x中是否可以访问libuv的函数。 代码如下:

#include <node.h>
#include <string>
#include <v8.h>

#ifdef WINDOWS_SPECIFIC_DEFINE
#include <windows.h>
typedef DWORD ThreadId;
#else
#include <unistd.h>
#include <pthread.h>
typedef unsigned int ThreadId;
#endif
using namespace v8;

void async_hello(const FunctionCallbackInfo<Value>& args);

//not in main thread,called in uv thread pool
void call_work(uv_work_t* req);

//the callback function
void call_work_after(uv_work_t* req);

static ThreadId __getThreadId() {
	ThreadId nThreadID;
#ifdef WINDOWS_SPECIFIC_DEFINE
	
	nThreadID = GetCurrentProcessId();
	nThreadID = (nThreadID << 16) + GetCurrentThreadId();
#else
	nThreadID = getpid();
	nThreadID = (nThreadID << 16) + pthread_self();
#endif
	return nThreadID;
}

static void __tsleep(unsigned int millisecond) {
#ifdef WINDOWS_SPECIFIC_DEFINE
	::Sleep(millisecond);
#else
	usleep(millisecond*1000);
#endif
}

//defined a struct to storage the async reqution information
struct Baton {

    //must be declared as the type of Persistent,when callback finished successfully,execute the function dispose to release.
    Persistent<Function> callback;
    
    // 
    bool error;
    std::string error_message;
        
    //save the string passed from js
    std::string input_string;
            
    //save the string return to js
    std::string result;
        
};


void async_hello(const Arguments& args) {
    printf("\n%s Thread id : gettid() == %d\n",__FUNCTION__,__getThreadId());
    Isolate* isolate = Isolate::GetCurrent();
	HandleScope scope(isolate);
    if(args.Length() < 2) { 
        ThrowException(Exception::TypeError(String::New("Wrong number of arguments"))); 
        return; 
      } 
  
  
    if (!args[0]->IsString() || !args[1]->IsFunction()) {
        ThrowException(Exception::TypeError(
            String::New("Wrong number of arguments")));
		return;
    }
    

    Local<Function> callback = Local<Function>::Cast(args[1]);
   
    Baton* baton = new Baton();
    baton->error = false;
    baton->callback = Persistent<Function>::New(callback);
    v8::String::Utf8Value param1(args[0]->ToString());
    baton->input_string = std::string(*param1); 
        
    uv_work_t *req = new uv_work_t();
    req->data = baton;
    
    int status = uv_queue_work(uv_default_loop(), req, call_work,
                               (uv_after_work_cb)call_work_after);
    assert(status == 0);
    return 
}

//not in main thread
void call_work(uv_work_t* req) {
    printf("\n%s Thread id : gettid() == %d\n",__FUNCTION__,__getThreadId());
    Baton* baton = static_cast<Baton*>(req->data);
	for (int i=0;i<15;i++) {
		__tsleep(1000);
		printf("sleep 1 seconds in uv_work\n");
	}
	
	
    baton->result = baton->input_string+ "--->hello world from c++";
  
}


//return to main thread
void call_work_after(uv_work_t* req) {
	printf("\n%s Thread id : gettid() == %d\n",__FUNCTION__,__getThreadId());    
    Isolate* isolate = Isolate::GetCurrent();
	HandleScope scope(isolate);
    Baton* baton = static_cast<Baton*>(req->data);
    if (baton->error) {
        Local<Value> err = Exception::Error(String::New(baton->error_message.c_str()));

        //
        const unsigned argc = 1;
        Local<Value> argv[argc] = { err };

        //
        TryCatch try_catch;

        baton->callback->Call(Context::GetCurrent()->Global(), argc, argv);
        if (try_catch.HasCaught()) {
            node::FatalException(try_catch);
        }
    } else {
         
        const unsigned argc = 2;
        Local<Value> argv[argc] = {
            Local<Value>::New(Null()),
            Local<Value>::New(String::New(baton->result.c_str()))
        };
        TryCatch try_catch;
        baton->callback->Call(Context::GetCurrent()->Global(), argc, argv);
        if (try_catch.HasCaught()) {
            node::FatalException(try_catch);
        }
    }
    
    //relase Persistent callback
    baton->callback.Dispose();
    // release the memory space
    delete baton;
    delete req;
}

void RegisterModule(Handle<Object> target) {
    target->Set(String::NewSymbol("async_hello"),FunctionTemplate::New(async_hello)->GetFunction());
}

NODE_MODULE(binding, RegisterModule);

鉴于最新的node API文档中,使用FunctionCallbackInfo(而不是0.10.x中的Arguments)来接受js参数,我把async_hello的参数给改掉了。原始的代码存储在这里,它可以在0.10.x中被成功编译。

4 回复

没包含头文件。 #include “uv.h”

推荐看下 nan 这个项目。对 V8底下做了抽象。

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