在node.js0.12.x中使用libuv函数
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。