[Documentation] [TitleIndex] [WordIndex] 

Package Proposal

Rosconsole is a drop-in replacement for simple console/terminal output that would normally go through printf. All output from ROS packages would be required to go through this package, allowing it to be routed however we want (logs, rosout, etc.).

Requirements

Implementation/API

I looked at a number of different open-source logging packages to determine if any of them meet our needs. In the end, RLog (http://www.arg0.net/rlog) and log4cxx (http://logging.apache.org/log4cxx/index.html) were the only ones I considered worth a more detailed look. RLog is notable for its speed when turned off, log4cxx for its feature set. Without looking at speed, log4cxx is the hands-down winner (mostly because of its configuration support). After some speed tests (detailed below), I have concluded that log4cxx is fast enough. The other logging packages I looked at, along with the reason for not seriously considering them, are also detailed below.

I propose we implement a light wrapper on top of log4cxx. Log4cxx is a very powerful, feature-rich logging library developed by the Apache foundation. Log4cxx natively supports most of our requirements:

There are a few requirements that log4cxx does not support natively, but that we can easily add in our wrapper:

Wrapping log4cxx instead of using it directly allows us to easily customize it to our needs, and replace it if necessary.

Here's an example of what the usage would be: 

#include "rosconsole.h"

int main(int argc, char** argv)
{
  ROS_INFO( "Info %s", "World" );
  ROS_ERROR( "Error %s", "World" );
  ROS_WARNING( "Warning %s", "World" );
  ROS_DEBUG( "Debug %s", "World" );
}

And an example of what the basic public interface could look like: 

namespace ros
{
  namespace console
  {
    extern bool g_initialized;
    extern ros::thread::mutex g_init_mutex;
    extern log4cxx::LoggerPtr g_logger;

    void print( const log4cxx::LevelPtr& level, const char* file, const int line, const char* fmt, ... );
  }
}

#define ROS_INFO(...)     \
  do                      \
  {                       \
    ROSCONSOLE_AUTOINIT;                 \
    if ( ros::console::g_logger->isInfoEnabled() )                      \
    {                                                                   \
      ros::console::print( log4cxx::Level::INFO, __FILE__, __LINE__, __VA_ARGS__); \
    }                                                                   \
  } while(0)


  
#define ROS_WARNING(...)                 \
  do                                     \
    {                                    \
    ROSCONSOLE_AUTOINIT;                 \
    if ( ros::console::g_logger->isWarnEnabled() )\
    {                                                                   \
      ros::console::print( log4cxx::Level::WARN, __FILE__, __LINE__, __VA_ARGS__); \
    }                                                                   \
  } while(0)

#define ROS_ERROR(...)     \
  do                      \
  {                       \
    ROSCONSOLE_AUTOINIT;                 \
    if ( ros::console::g_logger->isErrorEnabled() )                     \
    {                                                                   \
      ros::console::print( log4cxx::Level::ERROR, __FILE__, __LINE__, __VA_ARGS__); \
    }                                                                   \
  } while(0)

#define ROS_DEBUG(...)     \
  do                      \
  {                       \
    ROSCONSOLE_AUTOINIT;                 \
    if ( ros::console::g_logger->isDebugEnabled() )                     \
    {                                                                   \
      ros::console::print( log4cxx::Level::DEBUG, __FILE__, __LINE__, __VA_ARGS__); \
    }                                                                   \
  } while(0)

#define ROS_FATAL(...)     \
  do                      \
  {                       \
    ROSCONSOLE_AUTOINIT;                 \
    if ( ros::console::g_logger->isFatalEnabled() )                     \
    {                                                                   \
      ros::console::print( log4cxx::Level::FATAL, __FILE__, __LINE__, __VA_ARGS__); \
    }                                                                   \
  } while(0)

Speed comparison, RLog vs. log4cxx

For the speed test I implemented two versions of "rosconsole", one which used rlog, and one which used log4cxx. I then wrote a python script that would generate code calling into rosconsole: 

import sys

f = open('rosconsole_test_generated.cpp', 'w')

for i in range(0,int(sys.argv[1])):
    f.write('void info%s(int i) { ROS_INFO("Info%s: %%d", i); }\n' %(i,i))
    f.write('void warn%s(int i) { ROS_WARNING("Warn%s: %%d", i); }\n' %(i,i))
    f.write('void error%s(int i) { ROS_ERROR("Error%s: %%d", i); }\n' %(i,i))
    f.write('void debug%s(int i) { ROS_DEBUG("Debug%s: %%d", i); }\n' %(i,i))
    f.write('void fatal%s(int i) { ROS_FATAL("Fatal%s: %%d", i); }\n' %(i,i))

f.write('int main(int argc, char** argv)\n{\n')
f.write('for (int i = 0;i < %s; ++i)\n{\n' %(sys.argv[2]))

for i in range(0,int(sys.argv[1])):
    f.write('info%s(i);\n' %(i))
    f.write('warn%s(i);\n' %(i))
    f.write('error%s(i);\n' %(i))
    f.write('debug%s(i);\n' %(i))
    f.write('fatal%s(i);\n' %(i))

f.write('}\n')
f.write('}\n')

The script takes two arguments. The first argument is the number of calls to make inside the for loop (a value of 1 will actually produce an info, warning, error, debug and fatal call). The second argument is the number times the for loop will iterate. It does the "funkiness" with functions because without it gcc was running out of memory trying to optimize the code when the first argument was high (1000).

So, for example, with arguments "1 1", the script generates: 

void info0(int i) { ROS_INFO("Info0: %d", i); }
void warn0(int i) { ROS_WARNING("Warn0: %d", i); }
void error0(int i) { ROS_ERROR("Error0: %d", i); }
void debug0(int i) { ROS_DEBUG("Debug0: %d", i); }
void fatal0(int i) { ROS_FATAL("Fatal0: %d", i); }
int main(int argc, char** argv)
{
for (int i = 0;i < 1; ++i)
{
info0(i);
warn0(i);
error0(i);
debug0(i);
fatal0(i);
}
}

Each test was done ten times, and the average computed. The tests are all with logging turned entirely off, since that is the case where rlog touts its speed.

Test 1: 100 100

log4cxx: 0.004s
rlog: 0.005s

Test 2: 1000 1000

log4cxx: 0.124s
rlog: 0.180s

Test 3: 1 1000000

This is the "tight loop" test... rlog should (and does) dominate here. 

log4cxx: 0.066s
rlog: 0.016s

Test 4: 100 1000000

log4cxx: 8.298s
rlog: 5.098s

Test 5: 1000 1

RLog's worst enemy... it does some initialization the first time each logging statement is called. 

log4cxx: 0.004s
rlog: 0.107s

Other logging packages

2022-05-28 12:57