网站开发学习流程图,黑帽seo培训多少钱,网站老提示有风险,alexa排名是什么意思啊文件系统事件和网络IO事件一样#xff0c;也可以通过epoll或者IOCP 事件管理器统一调度#xff0c;当所监控的文件或文件夹发生了增删改的事件时#xff0c;就会触发事件回调#xff0c;进行事件处理。很常见的应用#xff0c;如配置文件立即生效功能#xff0c;就可以通…文件系统事件和网络IO事件一样也可以通过epoll或者IOCP 事件管理器统一调度当所监控的文件或文件夹发生了增删改的事件时就会触发事件回调进行事件处理。很常见的应用如配置文件立即生效功能就可以通过这种方式触发软件内部进行配置更新。也可以用来监控日志文件的更新拉取最新日志(类似notepad打开日志文件如果日志文件更新了就会提示reload)。
下面分别给出了linux和windows系统下文件系统事件监听的示意代码仅供参考。
//file: FileMonitor.h#ifndef INOTIFY_FILEMONITOR_H
#define INOTIFY_FILEMONITOR_H#include string
#include map/*** 文件监视器。* 用于监控文件系统中文件相关的事件如创建、删除等操作。*/
class FileMonitor {public:FileMonitor() default;~FileMonitor() default;void startWatch(const std::string path);void stopWatch();bool addWatch(const std::string path);private:// inotify 句柄int inotify_fd{0};// inotify_add_watch返回值 - 要监控的文件名 的映射std::mapint, std::string watchDesc2Name;// 是否停止监控bool isStopped{false};
};#endif //INOTIFY_FILEMONITOR_H// file: FileMonitor.cpp#include sys/inotify.h
#include sys/epoll.h
#include unistd.h
#include thread
#include chrono
#include cstdio
#include iostream
#include FileMonitor.h#define log(format, ...) { \auto now std::chrono::system_clock::to_time_t(std::chrono::system_clock::now()); \char buf[64]; \strftime(buf, sizeof(buf), %Y-%m-%d %H:%M:%S, std::localtime(now)); \printf(%s | %llu | , buf, std::this_thread::get_id()); \printf(format, ##__VA_ARGS__); \printf(\n); }#define EVENT_SIZE ( sizeof (struct inotify_event) )
#define BUF_LEN ( 1024 * ( EVENT_SIZE 16 ) )void FileMonitor::startWatch(const std::string path) {log(Ready to watch...);// inotify 初始化inotify_fd inotify_init();if (!addWatch(path)) {return;}// 创建一个 epoll 句柄log(epoll_create);int epfd epoll_create(256);struct epoll_event ev;ev.data.fd inotify_fd; // 设置要处理的事件相关的文件描述符ev.events EPOLLIN | EPOLLET; // 设置要处理的事件类型// 注册 epoll 事件log(epoll_ctl);epoll_ctl(epfd, EPOLL_CTL_ADD, inotify_fd, ev);// 循环监听事件char buffer[BUF_LEN];struct epoll_event events[20]; // 存储从内核得到的事件集合while (!isStopped) {log(epoll_wait...);// 等待事件发生。返回需要处理的事件数目int nfds epoll_wait(epfd, events, 20, 500);log(Event count: %d, nfds);for (int i 0; i nfds; i) {/*** epoll_wait 会一直阻塞直到下面2种情况* 1. 一个文件描述符触发了事件。* 2. 被一个信号处理函数打断或者 timeout 超时。* 所以下面需要对 fd 进行过滤判断是否是我们需要的 fd 产生了事件*/if (events[i].data.fd ! inotify_fd) {log(Other event, fd%d, events[i].data.fd);continue;}long length read(inotify_fd, buffer, BUF_LEN);if (length 0) {perror(Read failed);}log(Read length: %ld, length);int pos 0;int count 0;while (pos length) {struct inotify_event *event (struct inotify_event *) buffer[pos];log([%d]event-len%u, event-mask%#X, EVENT_SIZE%lu, count, event-len, event-mask, EVENT_SIZE);if (event-len) {if (event-mask IN_CREATE) {log(CREATE: %s, event-name);} else if (event-mask IN_DELETE) {log(DELETE: %s, event-name);} else if (event-mask IN_MODIFY) {log(MODIFY: %s, event-name);} else if (event-mask IN_OPEN) {log(OPEN: %s, event-name);} else if (event-mask IN_CLOSE) {log(CLOSE: %s, event-name);} else {log(Unknown event, mask%u, event-mask);}}pos EVENT_SIZE event-len;}}}log(Stop inotify);for (auto ele: watchDesc2Name) {inotify_rm_watch(inotify_fd, ele.first);}close(epfd);close(inotify_fd);
}void FileMonitor::stopWatch() {isStopped true;
}bool FileMonitor::addWatch(const std::string path) {// TODO 需要对文件夹是否存在进行判断// 监听指定目录下的修改、创建、删除事件int wd inotify_add_watch(inotify_fd, path.c_str(), IN_MODIFY | IN_CREATE | IN_DELETE);
// int wd inotify_add_watch(inotify_fd, path.c_str(), IN_ALL_EVENTS);if (wd 0) {log(inotify_add_watch failed: %s, path.c_str());return false;}log(Add watch: %s, path.c_str());watchDesc2Name[wd] path;return true;
}// main: main.cpp
#include iostream
#include FileMonitor.hint main() {std::string dirPath /home/nvidia/logs;FileMonitor fileMonitor;fileMonitor.startWatch(dirPath);return 0;
}// https://github.com/BornToDeath/cpp/blob/main/test/case11_inotify/main.cpp
#include iostream
#include map
#include windows.h
#define DIRECTORY_PATH LC://TestFolder#define CONTAINING_RECORD(address, type, field) ((type *)( \(PCHAR)(address) - \(ULONG_PTR)(((type *)0)-field)))typedef struct directory_info
{HANDLE hDir;CHAR szDirName[MAX_PATH];CHAR szBuffer[4096];DWORD dwBufLength;OVERLAPPED Overlapped; // 此处需要定义overlapp结构
}DIRECTORY_INFO, * LPDIRECTORY_INFO;class cFileUpdateChecker
{
public:cFileUpdateChecker(const wchar_t* root) :hThread(NULL), dwThread(0), hComp(NULL), pdir(NULL) { wsprintf(dirPath,L%s,root); }~cFileUpdateChecker(){if (hComp) {PostQueuedCompletionStatus(hComp, 0, NULL, NULL);CloseHandle(hComp);}if (hThread) CloseHandle(hThread);if (pdir){CloseHandle(pdir-hDir);HeapFree(GetProcessHeap(), 0, pdir);}for(auto it opened_files.begin();it!opened_files.end();it){if(it-second ! NULL)CloseHandle(it-second);}}// 定义IOCP的工作线程static DWORD WINAPI ThreadFunc(void* p){cFileUpdateChecker* pHost (cFileUpdateChecker*)p;LPDIRECTORY_INFO lpdir NULL;DWORD nbytes, errCode;LPOVERLAPPED lpOverlapped NULL;PFILE_NOTIFY_INFORMATION fni NULL;ULONG_PTR completion_key;DWORD wait 1000;while (true){BOOL bRet GetQueuedCompletionStatus(pHost-hComp, nbytes, completion_key, lpOverlapped, wait);if (FALSE bRet ){ errCode GetLastError();if (errCode WAIT_TIMEOUT){wait INFINITE;continue;}elsebreak;}if (lpOverlapped NULL){break;}else{lpdir CONTAINING_RECORD(lpOverlapped, DIRECTORY_INFO, Overlapped);if (lpdir){fni (PFILE_NOTIFY_INFORMATION)lpdir-szBuffer;int filename_length fni-FileNameLength;wchar_t* root_dir (wchar_t*)lpdir-szDirName;wchar_t* filename fni-FileName[0];switch (fni-Action){case FILE_ACTION_ADDED:wprintf(LThe file %s/%s was added to the directory.\r\n, root_dir, filename);break;case FILE_ACTION_REMOVED:wprintf(LThe file %s/%s was removed from the directory.\r\n, root_dir, filename);break;case FILE_ACTION_MODIFIED:{wchar_t file_path_buffer[MAX_PATH]{};wsprintf(file_path_buffer,L%s\\%s,root_dir, filename);wprintf(LThe file %s was modified. This can be a change in the time stamp or attributes.\r\n, file_path_buffer);auto it pHost-opened_files.find(file_path_buffer);if(it pHost-opened_files.end()){HANDLE hFile CreateFile(file_path_buffer,GENERIC_READ,FILE_SHARE_READ|FILE_SHARE_WRITE,NULL,OPEN_EXISTING,FILE_ATTRIBUTE_NORMAL,NULL);if(hFile ! NULL){DWORD dwFilePointer SetFilePointer(hFile,0,NULL,FILE_END);if(dwFilePointer ! INVALID_SET_FILE_POINTER)pHost-opened_files[file_path_buffer]hFile;elseCloseHandle(hFile);}}else{CHAR szReadText[50] {};DWORD dwRead 0;//需要注意的是,FILE_ACTION_MODIFIED信号仅表示文件系统中的该文件节点对象的写状态更新了,至于是否完成落盘,还需要看修改文件的进程是否完成了刷盘。由于实时性问题刷盘动作可能存在一定的滞后,如果每次进入Modify事件都要增量读取更新的文件内容。可以增加30~50ms的延时bRet ReadFile(it-second,szReadText,32,dwRead,NULL);if(bRet FALSE){CloseHandle(it-second);pHost-opened_files.erase(it);}else{printf(Additional file content: %s.\r\n,szReadText);SetFilePointer(it-second,0,NULL,FILE_END);}}}break;case FILE_ACTION_RENAMED_OLD_NAME:{const wchar_t* new_filename L;int new_filename_length 0;if (fni-NextEntryOffset);{PFILE_NOTIFY_INFORMATION new_fni (PFILE_NOTIFY_INFORMATION)(lpdir-szBuffer fni-NextEntryOffset);new_filename new_fni-FileName[0];new_filename_length new_fni-FileNameLength;}wprintf(LThe file %s/%s was renamed, and this is the new name %s.\r\n, root_dir, filename, new_filename);}break;case FILE_ACTION_RENAMED_NEW_NAME:wprintf(LThe file %s/%s was renamed and this is the new name.\r\n, root_dir, filename);break;default:break;}// re post eventZeroMemory((pHost-pdir-Overlapped), sizeof(OVERLAPPED));ZeroMemory(pHost-pdir-szBuffer, 4096);ReadDirectoryChangesW(pHost-pdir-hDir,pHost-pdir-szBuffer,sizeof(pHost-pdir-szBuffer),TRUE,FILE_NOTIFY_CHANGE_FILE_NAME |FILE_NOTIFY_CHANGE_DIR_NAME |FILE_NOTIFY_CHANGE_ATTRIBUTES |FILE_NOTIFY_CHANGE_SIZE |FILE_NOTIFY_CHANGE_LAST_ACCESS |FILE_NOTIFY_CHANGE_CREATION |FILE_NOTIFY_CHANGE_SECURITY |FILE_NOTIFY_CHANGE_LAST_WRITE,(pHost-pdir-dwBufLength),(OVERLAPPED*)((pHost-pdir-Overlapped)),NULL);}}}return 0;}bool StartChecker(){hComp CreateIoCompletionPort(INVALID_HANDLE_VALUE, NULL, 0, 0);pdir (LPDIRECTORY_INFO)HeapAlloc(GetProcessHeap(), HEAP_ZERO_MEMORY, sizeof(DIRECTORY_INFO));if (NULL pdir){return false;}pdir-hDir CreateFile(dirPath,FILE_LIST_DIRECTORY,FILE_SHARE_READ | FILE_SHARE_WRITE | FILE_SHARE_DELETE,NULL,OPEN_EXISTING,FILE_FLAG_BACKUP_SEMANTICS | FILE_FLAG_OVERLAPPED,NULL);if (pdir-hDir INVALID_HANDLE_VALUE){return false;}// 启动工作线程hThread CreateThread(NULL, 0, ThreadFunc, this, 0, dwThread);if (NULL hThread){return false;}ZeroMemory((pdir-Overlapped), sizeof(OVERLAPPED));ZeroMemory(pdir-szBuffer, 4096);ZeroMemory(pdir-szDirName, MAX_PATH);wsprintf((wchar_t*)pdir-szDirName,L%s, dirPath);// 投递I/O请求到完成端口HANDLE hRet CreateIoCompletionPort(pdir-hDir, hComp,NULL, 0);if (NULL hComp){return false;}BOOL bRet ReadDirectoryChangesW(pdir-hDir,pdir-szBuffer,4096,TRUE,FILE_NOTIFY_CHANGE_FILE_NAME |FILE_NOTIFY_CHANGE_DIR_NAME |FILE_NOTIFY_CHANGE_ATTRIBUTES |FILE_NOTIFY_CHANGE_SIZE |FILE_NOTIFY_CHANGE_LAST_ACCESS |FILE_NOTIFY_CHANGE_CREATION |FILE_NOTIFY_CHANGE_SECURITY |FILE_NOTIFY_CHANGE_LAST_WRITE,pdir-dwBufLength,(pdir-Overlapped),NULL);if (FALSE bRet){return false;}return true;}
private:HANDLE hThread;DWORD dwThread;HANDLE hComp;LPDIRECTORY_INFO pdir;WCHAR dirPath[MAX_PATH];std::mapstd::wstring,HANDLE opened_files;
};int main()
{cFileUpdateChecker* ckr new cFileUpdateChecker(DIRECTORY_PATH);std::cout Supervise ; std::wcout DIRECTORY_PATH Begin... std::endl;ckr-StartChecker();getchar();delete ckr;getchar();
}// https://blog.csdn.net/nhn_devlab/article/details/6034055
