c++实现写日志功能

编程实例：

#include "Mutex.h"#include "CTime.h"#include <fcntl.h>#include <iostream>#include <stdarg.h>#include <fstream>#define LOGPATH "./common.log"#define BUFSIZE 2048class CLog{public:static CLog* getInstance();void Init(const char* path, int level);void Error(char *pFmt, ...);    void Info(char  *pFmt, ...);    void Debug(char *pFmt, ...);    void Warn(char  *pFmt, ...);         void Log(int level, const char * loginfo);private:CLog(){}static CLog *m_log;CLog(const CLog& clog);CLog& operator=(const CLog& clog);Mutex m_mutex;int m_logLevel;const char* m_logPath;enum { LOG_ERROR = 0, LOG_INFO, LOG_WARN, LOG_DEBUG};};CLog* CLog::m_log = NULL;CLog* CLog::getInstance(){if(m_log == NULL){m_log = new CLog();}return m_log;}void CLog::Init(const char* path, int level){m_logPath = path;m_logLevel = level;}void CLog::Log(int level, const char * loginfo){const char *infos[4] = {"ERROR: ", "INFO: ", "WARN : ", "DEBUG: "};m_mutex.Lock();CTime time;std::ofstream fout(m_logPath, std::ios::app|std::ios::ate);if(fout){fout<<"["<<time<<"]"<<infos[level]<<loginfo<<std::endl;if(fout.tellp() > 2*1024*1024){fout.close();std::string logname = m_logPath + time.getTime(); //back the log filerename(m_logPath, logname.c_str());}}else{std::cout << time << infos[0] <<"open file failed \n"<<strerror(errno) << std::endl;}if(fout) fout.close();m_mutex.UnLock();}void CLog::Error(char *pFmt, ...){va_list valist;char Buf[BUFSIZE]={'\0'};va_start(valist, pFmt);vsnprintf(Buf, sizeof(Buf)-1, pFmt, valist);        va_end(valist);       Log(LOG_ERROR, Buf);}void CLog::Info(char  *pFmt, ...){va_list valist;char Buf[BUFSIZE]={'\0'};va_start(valist, pFmt);vsnprintf(Buf, sizeof(Buf)-1, pFmt, valist);        va_end(valist);       Log(LOG_INFO, Buf);}void CLog::Debug(char *pFmt, ...){va_list valist;char Buf[BUFSIZE]={'\0'};va_start(valist, pFmt);vsnprintf(Buf, sizeof(Buf)-1, pFmt, valist);        va_end(valist);       Log(LOG_DEBUG, Buf);}void CLog::Warn(char  *pFmt, ...){va_list valist;char Buf[BUFSIZE]={'\0'};va_start(valist, pFmt);vsnprintf(Buf, sizeof(Buf)-1, pFmt, valist);        va_end(valist);      Log(LOG_WARN, Buf);}

Mutext.h

#include <cstdlib>  #include <pthread.h>  #include <errno.h>#include <unistd.h>#include <cstdio>#include <string.h>class Mutex  {  public:      Mutex();      virtual ~Mutex();        void Lock();      void UnLock();  private:  friend class CondVar;      pthread_mutex_t m_mutex;      Mutex(const Mutex&);      void operator=(const Mutex&);  };    class CondVar  {  public:      explicit CondVar(Mutex* mu);      virtual ~CondVar();            void Wait();      void Signal();      void SignalAll();  private:      pthread_cond_t m_cond;      Mutex *m_mu;  };  class CASLock{public:    CASLock(void* lock);    virtual ~CASLock();    void Lock();void UnLock();bool TryLock();private:void* m_lock;};static void MutexErr(const char* err, int res)  {      if(res != 0)      {          fprintf(stderr, "pthread %s: %s\n", err, strerror(res));          return;      }  }    Mutex::Mutex()  {      MutexErr("init mutex", pthread_mutex_init(&m_mutex, NULL));  }    Mutex::~Mutex()  {      MutexErr("destroy mutex", pthread_mutex_destroy(&m_mutex));  }    void Mutex::Lock()  {      MutexErr("lock mutex", pthread_mutex_lock(&m_mutex));  }    void Mutex::UnLock()  {      MutexErr("unlock mutex", pthread_mutex_unlock(&m_mutex));  }    CondVar::CondVar(Mutex* mu):m_mu(mu)  {      MutexErr("init cond", pthread_cond_init(&m_cond, NULL));  }    CondVar::~CondVar()  {      MutexErr("destroy cond", pthread_cond_destroy(&m_cond));  }    void CondVar::Wait()  {      MutexErr("wait cond", pthread_cond_wait(&m_cond, &m_mu->m_mutex));  }    void CondVar::Signal()  {      MutexErr("signal cond", pthread_cond_signal(&m_cond));  }    void CondVar::SignalAll()  {      MutexErr("broadcast cond", pthread_cond_broadcast(&m_cond));  }CASLock::CASLock(void* lock):m_lock(lock){}CASLock::~CASLock(){}void CASLock::Lock(){while(!__sync_bool_compare_and_swap((int*)m_lock, 0, 1)){sched_yield();}}void CASLock::UnLock(){*((int*)m_lock) = 0;}bool CASLock::TryLock(){if(__sync_bool_compare_and_swap((int*)m_lock, 0, 1))return 0;elsereturn -1;}

CTime.h

#include <iostream>#include <cstring>#include <ctime>#include <sys/time.h>#include <cstdio>class CTime{public:    CTime();CTime(std::string tim);    virtual ~CTime();std::string getTime();std::string getShortTime();friend std::ostream& operator<<(std::ostream& os, CTime& tim);void Start();void Stop();void Reset();void costTime();private:std::string m_time; //reserve the time    void timeToStr(char* buf);struct timeval t1, t2;bool b;};void CTime::timeToStr(char *buf){time_t ti = time(NULL);strftime(buf, 30, "%Y-%m-%d %H:%M:%S", localtime(&ti));}CTime::CTime(){char buf[30]={'\0'};timeToStr(buf);m_time = std::string(buf);}CTime::CTime(std::string tim){if(tim.size() == 0){char buf[30];        timeToStr(buf);m_time = buf;}else{m_time = tim;}}CTime::~CTime(){}std::string CTime::getTime(){return m_time;}std::string CTime::getShortTime(){if(m_time.size()){return m_time.substr(0, m_time.find_first_of(' '));}else{char buf[30];        timeToStr(buf);return std::string(buf);}}void CTime::Start(){b = false;gettimeofday(&t1, NULL);}void CTime::Stop(){gettimeofday(&t2, NULL);}void CTime::Reset(){}void CTime::costTime(){int usec = 0, sec =0;if(t2.tv_usec > t1.tv_usec){usec = t2.tv_usec - t1.tv_usec;}else{b = true;usec = t2.tv_usec + 1000000 - t1.tv_usec;}if(b){sec = t2.tv_sec -1 -t1.tv_sec;}else{sec = t2.tv_sec - t1.tv_sec;}printf("cost the time:%.05fms\n", (double)(sec*1000000+usec)/1000);}std::ostream& operator<<(std::ostream& os, CTime& tim){os <<tim.m_time;return os;}

TestLog.cpp

#include "CLog.h"CLog *cLog = CLog::getInstance();int main(int argc, char *argv[]){cLog->Init("./common.log", 0);cLog->Info("test the program");cLog->Error("err\n");    return 0;}

编译：

g++ -o testLog TestLog.cpp CLog.h Mutex.h CTime.h