厚街建设网站,信息流优化师需要具备哪些能力,外贸网站框架,网页开发者模式快捷键方式一#xff08;传统读取文件#xff0c;一直监听循环读取文件#xff09;
非阻塞打开文件#xff0c;用read循环定时读取#xff0c;性能不好
代码如下#xff1a;
#include iostream
#include fstream
#include functional
#include …方式一传统读取文件一直监听循环读取文件
非阻塞打开文件用read循环定时读取性能不好
代码如下
#include iostream
#include fstream
#include functional
#include thread
#include chrono
#include sys/stat.h
#include fcntl.h
#include unistd.h
#include cstringconstexpr int kBufferSize 256;class FileDescriptor {
public:explicit FileDescriptor(int fd) : fd_(fd) {}~FileDescriptor() {if (fd_ 0) {::close(fd_);}}int get() const {return fd_;}private:int fd_;
};class PipeListener {
public:using DataCallback std::functionvoid(std::string);PipeListener(const std::string pipePath) : pipePath_(pipePath), stopListening_(false) {if (access(pipePath.c_str(), F_OK) -1) {if (mkfifo(pipePath.c_str(), 0666) -1) {std::cerr Failed to create the pipe file: pipePath_ . Error: strerror(errno) std::endl;}}}~PipeListener() {stopListening();}void setDataCallback(DataCallback callback) {dataCallback_ std::move(callback);}void startListening() {stopListening_ false;listeningThread_ std::thread(PipeListener::listenThread, this);std::cout Listening for data on pipe: pipePath_ std::endl;}void stopListening() {stopListening_ true;if (listeningThread_.joinable()) {listeningThread_.join();std::cout Stopped listening on pipe: pipePath_ std::endl;}}private:void listenThread() {auto fd std::make_uniqueFileDescriptor(::open(pipePath_.c_str(), O_RDONLY | O_NONBLOCK));if (fd-get() 0) {std::cerr Failed to open the pipe file: pipePath_ . Error: strerror(errno) std::endl;return;}char buffer[kBufferSize];while (!stopListening_) {ssize_t bytesRead ::read(fd-get(), buffer, sizeof(buffer));if (bytesRead 0) {std::string data(buffer, bytesRead);if (!data.empty() dataCallback_) {dataCallback_(std::move(data));}}std::this_thread::sleep_for(std::chrono::milliseconds(100));}}private:std::string pipePath_;DataCallback dataCallback_;std::thread listeningThread_;bool stopListening_;
};int main() {PipeListener pipeListener(/home/hello/tmp/test_pipe); // 测试方式启动程序之后在终端用 echo bt_upgrade /home/hello/tmp/test_pipe 命令就能触发pipeListener.setDataCallback([](std::string data) {std::cout Received size: data.size() std::endl;std::cout Received data: data std::endl;std::cout Received data (hex): ;for (char c : data) {std::cout std::hex (int)(unsigned char)c ;}std::cout std::dec std::endl;});pipeListener.startListening();std::cout main std::endl;std::this_thread::sleep_for(std::chrono::seconds(100));pipeListener.stopListening();return 0;
}方式二用epoll监听管道文件内容
但是要停止程序时会阻塞在epoll_wait等待管道消息之后才能正常退出
代码如下
#include iostream
#include fstream
#include functional
#include thread
#include chrono
#include sys/stat.h
#include fcntl.h
#include unistd.h
#include sys/epoll.h
#include cstring constexpr int kBufferSize 256;class FileDescriptor {
public:explicit FileDescriptor(int fd) : fd_(fd) {}~FileDescriptor() {if (fd_ 0) {std::cout close fd_ std::endl;::close(fd_);}}int get() const {return fd_;}private:int fd_;
};class PipeListener {
public:using DataCallback std::functionvoid(std::string);PipeListener(const std::string pipePath) : pipePath_(pipePath), stopListening_(false) {if (access(pipePath.c_str(), F_OK) -1) {if (mkfifo(pipePath.c_str(), 0666) -1) {std::cerr Failed to create the pipe file: pipePath_ . Error: strerror(errno) std::endl;}}}~PipeListener() {stopListening();std::cout close epollfd_ std::endl;close(epollfd_);}void setDataCallback(DataCallback callback) {dataCallback_ std::move(callback);}void startListening() {stopListening_ false;listeningThread_ std::thread(PipeListener::listenThread, this);std::cout Listening for data on pipe: pipePath_ std::endl;}void stopListening() {stopListening_ true;if (listeningThread_.joinable()) {std::cout wait Stopped listening on pipe: pipePath_ std::endl;listeningThread_.join();std::cout Stopped listening on pipe: pipePath_ std::endl;}}private:void listenThread() {auto fd std::make_uniqueFileDescriptor(::open(pipePath_.c_str(), O_RDONLY | O_NONBLOCK));if (fd-get() 0) {std::cerr Failed to open the pipe file: pipePath_ . Error: strerror(errno) std::endl;return;}int epollfd_ epoll_create(1);if (epollfd_ -1) {std::cerr Failed to create epoll instance. Error: strerror(errno) std::endl;return;}struct epoll_event event;event.events EPOLLIN | EPOLLET; // Enable edge-triggered modeevent.data.fd fd-get();if (epoll_ctl(epollfd_, EPOLL_CTL_ADD, fd-get(), event) -1) {std::cerr Failed to add file descriptor to epoll. Error: strerror(errno) std::endl;return;}char buffer[kBufferSize];while (!stopListening_) {struct epoll_event events[1];int nfds epoll_wait(epollfd_, events, 1, -1);if (nfds -1) {std::cerr epoll_wait failed. Error: strerror(errno) std::endl;break;}for (int i 0; i nfds; i) {if (events[i].events EPOLLIN) {ssize_t bytesRead ::read(fd-get(), buffer, sizeof(buffer));if (bytesRead 0) {std::string data(buffer, bytesRead);if (!data.empty() dataCallback_) {dataCallback_(std::move(data));}}}}}}private:std::string pipePath_;DataCallback dataCallback_;std::thread listeningThread_;bool stopListening_;int epollfd_; // 新增的成员变量用于保存 epollfd_
};int main() {PipeListener pipeListener(/home/hello/tmp/test_pipe);// 测试方式启动程序之后在终端用 echo bt_upgrade /home/hello/tmp/test_pipe 命令就能触发pipeListener.setDataCallback([](std::string data) {std::cout Received size: data.size() std::endl;std::cout Received data: data std::endl;std::cout Received data (hex): ;for (char c : data) {std::cout std::hex (int)(unsigned char)c ;}std::cout std::dec std::endl;});pipeListener.startListening();std::cout main std::endl;std::this_thread::sleep_for(std::chrono::seconds(1));// pipeListener.stopListening();std::cout main return std::endl;return 0;
}方式三用epoll监听管道文件内容
用epoll监听管道文件内容对象析构或者退出时会通过epoll唤醒epoll_wait,释放资源正常退出
代码如下
#include iostream
#include fstream
#include functional
#include thread
#include chrono
#include csignal
#include sys/stat.h
#include fcntl.h
#include unistd.h
#include sys/epoll.h
#include condition_variable
#include sys/eventfd.h
#include cstring constexpr int kBufferSize 256;class PipeListener {
public:using DataCallback std::functionvoid(std::string);PipeListener(const std::string pipePath) : pipePath_(pipePath), stopListening_(true), epollfd_(0) {if (access(pipePath.c_str(), F_OK) -1) {if (mkfifo(pipePath.c_str(), 0666) -1) {std::cerr Failed to create the pipe file: pipePath_ . Error: strerror(errno) std::endl;}}}~PipeListener() {stopListening();}void setDataCallback(DataCallback callback) {dataCallback_ std::move(callback);}void startListening() {if (stopListening_ false) {std::cout already start Listening std::endl;return;}stopListening_ false;pipe_fd_ open(pipePath_.c_str(), O_RDONLY | O_NONBLOCK);std::cout startListening pipe_fd_ [ pipe_fd_ ] std::endl;if (!pipe_fd_) {std::cerr Failed to open the pipe file: pipePath_ . Error: strerror(errno) std::endl;return;}epollfd_ epoll_create(1);std::cout startListening epollfd_ [ epollfd_ ] std::endl;if (epollfd_ -1) {std::cerr Failed to create epoll instance. Error: strerror(errno) std::endl;return;}struct epoll_event event;event.events EPOLLIN | EPOLLET; // Enable edge-triggered modeevent.data.fd pipe_fd_;if (epoll_ctl(epollfd_, EPOLL_CTL_ADD, pipe_fd_, event) -1) {std::cerr Failed to add file descriptor to epoll. Error: strerror(errno) std::endl;return;}// 创建用于通知的 eventfd监听要求停止监听管道文件事件方便安全释放资源退出程序eventfd_ eventfd(0, EFD_NONBLOCK);std::cout startListening eventfd_ [ eventfd_ ] std::endl;if (eventfd_ -1) {std::cerr Failed to create eventfd. Error: strerror(errno) std::endl;return;}event.events EPOLLIN | EPOLLET;event.data.fd eventfd_;if (epoll_ctl(epollfd_, EPOLL_CTL_ADD, eventfd_, event) -1) {std::cerr Failed to add eventfd to epoll. Error: strerror(errno) std::endl;return;}listeningThread_ std::thread(PipeListener::listenThread, this);std::cout Listening for data on pipe: pipePath_ std::endl;}void stopListening() {if (stopListening_) {std::cout already stop Listening std::endl;return;}stopListening_ true;// 写入一个字节到 eventfd 唤醒 epoll_wait等待安全退出uint64_t value 1;write(eventfd_, value, sizeof(value));if (listeningThread_.joinable()) {listeningThread_.join();std::cout Stopped listening on pipe: pipePath_ std::endl;}// 从 epoll 实例中删除文件描述符epoll_event event;event.data.fd pipe_fd_;event.events EPOLLIN | EPOLLET;epoll_ctl(epollfd_, EPOLL_CTL_DEL, pipe_fd_, event);event.data.fd eventfd_;event.events EPOLLIN | EPOLLET;epoll_ctl(epollfd_, EPOLL_CTL_DEL, pipe_fd_, event);close(pipe_fd_);close(eventfd_);close(epollfd_);std::cout pipe_fd_ [ pipe_fd_ ] close std::endl;std::cout epollfd_ [ epollfd_ ] close std::endl;std::cout eventfd_ [ eventfd_ ] close std::endl;}private:void listenThread() {std::cout listenThread start pipePath_ std::endl;char buffer[kBufferSize];while (true) {struct epoll_event events[2];int nfds epoll_wait(epollfd_, events, 2, -1);if (stopListening_) {break;}if (nfds -1) {std::cerr epoll_wait failed. Error: strerror(errno) std::endl;}for (int i 0; i nfds; i) {if (events[i].data.fd pipe_fd_ (events[i].events EPOLLIN)) {ssize_t bytesRead ::read(pipe_fd_, buffer, sizeof(buffer));if (bytesRead 0) {std::string data(buffer, bytesRead);if (!data.empty() dataCallback_) {dataCallback_(std::move(data));}}} else if (events[i].data.fd eventfd_ (events[i].events EPOLLIN)) {// 读取 eventfd清空它uint64_t value;read(eventfd_, value, sizeof(value));}}}std::cout listenThread exit pipePath_ std::endl;}private:std::string pipePath_;DataCallback dataCallback_;std::thread listeningThread_;bool stopListening_ true; // 默认状态停止的int epollfd_;int eventfd_;int pipe_fd_;
};int main() {PipeListener pipeListener(/home/woan/tmp/test_pipe);// 测试方式启动程序之后在终端用 echo bt_upgrade /home/woan/tmp/test_pipe 命令就能触发pipeListener.setDataCallback([](std::string data) {std::cout Received size: data.size() std::endl;std::cout Received data: data std::endl;std::cout Received data (hex): ;for (char c : data) {std::cout std::hex (int)(unsigned char)c ;}std::cout std::dec std::endl;});pipeListener.startListening();std::cout main std::endl;std::this_thread::sleep_for(std::chrono::seconds(10));pipeListener.stopListening();std::this_thread::sleep_for(std::chrono::seconds(2));pipeListener.startListening();std::this_thread::sleep_for(std::chrono::seconds(10));pipeListener.stopListening();return 0;
}
