Logger

Aim

In cpp project, we may need a way to handle log message. This class is an example to show how to do that. This logger is aimed running on Linux and Windows. This is a singleton class.

Source

github

#include <iostream>
#include "Logger.h"

// usage: ./Logger
class Foo
{
public:
    Foo() { LOGMSG_CLASS_NAME("Foo"); }
    ~Foo() {}

    void PrintLog()
    {
        LOGMSG_MSG("Multi thread function--------------\n");
        LOGMSG_DBG("Log inside class\n");
        LOGMSG_WRN("Log inside class\n");
        LOGMSG_MSG("Log inside class\n");
        LOGMSG_ERR("Log inside class\n");
        LOGMSG_MSG("\n");

        LOGMSG_MSG_S() << "Single thread function-----------------\n";
        LOGMSG_MSG_S() << "Log inside class\n";
        LOGMSG_DBG_S() << "Log inside class\n";
        LOGMSG_WRN_S() << "Log inside class\n";
        LOGMSG_ERR_S() << "Log inside class\n";
    }
};
int main (int argc, char *argv[])
{
    Logger::LoggerConfig config;
    config.logLevel = Logger::LogLevel::DEBUG;
    config.logPath = "./tempLog";
    config.fileSize = 0;
    config.fileSizeLimit = 4 * 1024 * 1024; // 4 MByte
    config.isToConsole = true;
    config.isToFile = true;

    LOGMSG_INIT(config);
    LOGMSG_MSG_C("Multi thread function--------------\n");
    LOGMSG_DBG_C("Log outside class\n");
    LOGMSG_WRN_C("Log outside class\n");
    LOGMSG_MSG_C("Log outside class\n");
    LOGMSG_ERR_C("Log outside class\n");
    LOGMSG_MSG_C("\n");

    LOGMSG_MSG_S_C() << "Single thread function-----------------\n";
    LOGMSG_MSG_S_C() << "Log outside class\n";
    LOGMSG_DBG_S_C() << "Log outside class\n";
    LOGMSG_WRN_S_C() << "Log outside class\n";
    LOGMSG_ERR_S_C() << "Log outside class\n";

    Foo xx;
    xx.PrintLog();
    return 0;
}

Output

This logger can output to console and files. Following is the example of the output. The file size and the location can be controlled by a config class.

20200430_152749_293 [MSG]                      main:    38, 13163,Multi thread function--------------
20200430_152749_293 [DBG]                      main:    39, 13163,Log outside class
20200430_152749_293 [WRN]                      main:    40, 13163,Log outside class
20200430_152749_293 [MSG]                      main:    41, 13163,Log outside class
20200430_152749_293 [ERR]                      main:    42, 13163,Log outside class
20200430_152749_293 [MSG]                      main:    43, 13163,
20200430_152749_293 [MSG]                      main:    45, 13163,Single thread function-----------------
20200430_152749_293 [MSG]                      main:    46, 13163,Log outside class
20200430_152749_293 [DBG]                      main:    47, 13163,Log outside class
20200430_152749_293 [WRN]                      main:    48, 13163,Log outside class
20200430_152749_293 [ERR]                      main:    49, 13163,Log outside class
20200430_152749_293 [MSG]                       Foo::                 PrintLog:    13, 13163,Multi thread function--------------
20200430_152749_293 [DBG]                       Foo::                 PrintLog:    14, 13163,Log inside class
20200430_152749_293 [WRN]                       Foo::                 PrintLog:    15, 13163,Log inside class
20200430_152749_293 [MSG]                       Foo::                 PrintLog:    16, 13163,Log inside class
20200430_152749_293 [ERR]                       Foo::                 PrintLog:    17, 13163,Log inside class
20200430_152749_293 [MSG]                       Foo::                 PrintLog:    18, 13163,
20200430_152749_293 [MSG]                       Foo::                 PrintLog:    20, 13163,Single thread function-----------------
20200430_152749_293 [MSG]                       Foo::                 PrintLog:    21, 13163,Log inside class
20200430_152749_293 [DBG]                       Foo::                 PrintLog:    22, 13163,Log inside class
20200430_152749_293 [WRN]                       Foo::                 PrintLog:    23, 13163,Log inside class
20200430_152749_293 [ERR]                       Foo::                 PrintLog:    24, 13163,Log inside class

CMakeLists.txt

if (UNIX)
else ()
  list(REMOVE_ITEM ${folderName}_inc ${CMAKE_CURRENT_SOURCE_DIR}/DefaultMutex.h)
  list(REMOVE_ITEM ${folderName}_inc ${CMAKE_CURRENT_SOURCE_DIR}/NLFileSys.h)
  list(REMOVE_ITEM ${folderName}_src ${CMAKE_CURRENT_SOURCE_DIR}/DefaultMutex.cpp)
  list(REMOVE_ITEM ${folderName}_src ${CMAKE_CURRENT_SOURCE_DIR}/NLFileSys.cpp)
endif ()

We remove some files during building binary if we are not using linux.

# Handle extra Flags
if (Use_Linux_Lock)
  set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -DUse_Linux_Lock")
  message(STATUS "Use linux lock")
elseif (Use_Windows_Lock)
  set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -DUse_Windows_Lock")
  message(STATUS "Use window lock")
else ()
  set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -DUse_Std_Lock")
  message(STATUS "Use std lock")
endif ()

We can select which mutex lock to use while using cmake.

Example:

cmake -G Ninja ../Logger/ -DCMAKE_BUILD_TYPE=Debug -DUse_Linux_Lock=True

Logger.h

#ifdef Use_Linux_Lock
#include "DefaultMutex.h"
#elif Use_Windows_Lock
#elif Use_Std_Lock
#include <mutex>
#endif

Here shows how to select library files in cpp.