nodejs使用C++扩展实现监听文件目录变化

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实现 nodejs代码能够监听文件目录变化，C++扩展代码如下

#include <iostream>
#include <nan.h>
#include <map>
#include "../deps/efsw/include/efsw/efsw.hpp"namespace __watch__ {using v8::Array;
using v8::Local;
using v8::Value;
using v8::Isolate;
using v8::Context;
using namespace std;#define Watch watch
#define AddWatch addWatch
#define HandleFileAction handleFileAction
#define GetLastErrorLog getLastErrorLogefsw::FileWatcher* file_watcher;struct AsyncArgs {efsw::WatchID watch_id;std::string dir;std::string filename;efsw::Action action;std::string old_filename;uv_async_t handle;Nan::Callback* callback;
};void OnAsyncClosed(uv_handle_t* handle)
{uv_async_t* async = (uv_async_t*)handle;AsyncArgs* data = (AsyncArgs*)async->data;delete data;
}void OnEvent(uv_async_t* handle)
{printf("in OnEvent1\n");Nan::HandleScope scope;AsyncArgs* data = (AsyncArgs*)handle->data;Local<Value> argv[] = {Nan::New((int)data->watch_id),Nan::New(data->dir.c_str()).ToLocalChecked(),Nan::New(data->filename.c_str()).ToLocalChecked(),Nan::New(data->action),Nan::New(data->old_filename.c_str()).ToLocalChecked()};data->callback->Call(5, argv);uv_close((uv_handle_t*)handle, OnAsyncClosed);printf("in OnEvent2\n");
}class UpdateListener : public efsw::FileWatchListener {
public:UpdateListener(Nan::Callback* callback) :callback(callback){}~UpdateListener(){Nan::HandleScope scope;delete callback;}void HandleFileAction(efsw::WatchID watchid,const std::string& dir,const std::string& filename,efsw::Action action,std::string old_filename){printf("in HandleFileAction1\n");AsyncArgs* args = new AsyncArgs();args->watch_id = watchid;args->dir = dir;args->filename = filename;args->action = action;args->old_filename = old_filename;args->callback = callback;uv_async_init(uv_default_loop(), &args->handle, OnEvent);args->handle.data = (void*)args;//  _sleep(3*1000);int res = uv_async_send(&args->handle);std::cout << res;printf("\n");printf("in HandleFileAction2\n");}private:Nan::Callback* callback;
};std::map<std::string, std::vector<UpdateListener*> > listeners;NAN_METHOD(Watch)
{if(info.Length() < 2 || !info[0]->IsString() || !info[1]->IsFunction()){return Nan::ThrowError("Wrong argument");}Isolate* isolate = Isolate::GetCurrent();Local<Context> context = isolate->GetCurrentContext();Nan::Utf8String path(info[0]->ToString(context).ToLocalChecked());Nan::Callback* callback = new Nan::Callback(info[1].As<v8::Function>());UpdateListener* listener = new UpdateListener(callback);listeners[*path].push_back(listener);efsw::WatchID watch_id = file_watcher->AddWatch(*path, listener, true);if(watch_id < 0){return Nan::ThrowError(efsw::Errors::Log::GetLastErrorLog().c_str());}info.GetReturnValue().Set(Nan::New((int)watch_id));
}NAN_MODULE_INIT(Init)
{file_watcher = new efsw::FileWatcher();file_watcher->Watch();Nan::Export(target, "watch", Watch);
}NODE_MODULE(watch, Init)}

nodejs调用代码

const obj = require("./build/Release/watch");
const fs = require('fs');
console.log('obj',obj);obj.watch('/tmp',function(){//监听/tmp目录变化，如果目录中文件改变则执行回调debugger;console.log('tmp is call....');console.log(arguments);
});function second()
{// 写回文件fs.writeFile("D:/tmp/1.txt", "777", 'utf8', (writeErr) => {if (writeErr) {return console.error(writeErr);}console.log('文件已修改');});
}setTimeout(second,2000);function abc()
{console.log("abc=================================");
}setTimeout(abc,3000);//JS主线程退出了，则不会执行到第6行代码 这里延迟要大于上面setTimeout的延迟// console.log("111111111111111111111111112");// while(true){//这种JS主线程卡住了，无法回调// }// obj.watch('/tmp/sdfkjl',function(){
//     console.log(arguments);
// });//流程
//监听目录文件变化-->目录文件发生改变-->c++代码回调JS函数-->JS主线程执行回调函数（JS主线程退出或卡住则无法执行回调）

测试结果