com/foo/config3.cpp

This file is an example of how to use the current module name to select the Log4cxx configuration file.

/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
#include "config.h"
#include <log4cxx/logmanager.h>
#include <log4cxx/logstring.h>
#include <log4cxx/basicconfigurator.h>
#include <log4cxx/defaultconfigurator.h>
#include <log4cxx/helpers/pool.h>
#include <log4cxx/file.h>
#include <log4cxx/helpers/loglog.h>
#include <log4cxx/helpers/transcoder.h>
 
#ifdef _WIN32
#include <windows.h>
#elif __APPLE__
#include <mach-o/dyld.h>
#elif (defined(_XOPEN_SOURCE) && _XOPEN_SOURCE >= 500) || (defined(_POSIX_C_SOURCE) && _POSIX_C_SOURCE >= 200112L)
#include <unistd.h> // getpid
#else
#include <cstring> // strncpy
#endif
 
 
// Local functions
namespace {
using namespace log4cxx;
 
// Get a list of file base names that may contain configuration data
// and put an alternate path into \c altPrefix
auto DefaultConfigurationFileNames(std::string& altPrefix) -> std::vector<std::string> {
    std::vector<std::string> result;
 
    // Find the executable file name
    static const int bufSize = 4096;
    char buf[bufSize+1] = {0}, pathSepar = '/';
    uint32_t bufCount = 0;
#if defined(_WIN32)
    GetModuleFileName(NULL, buf, bufSize);
    pathSepar = '\\';
#elif defined(__APPLE__)
    _NSGetExecutablePath(buf, &bufCount);
#elif (defined(_XOPEN_SOURCE) && _XOPEN_SOURCE >= 500) || (defined(_POSIX_C_SOURCE) && _POSIX_C_SOURCE >= 200112L)
    std::ostringstream exeLink;
    exeLink << "/proc/" << getpid() << "/exe";
    bufCount = readlink(exeLink.str().c_str(), buf, bufSize);
    if (0 < bufCount)
        buf[bufCount] = 0;
#else
    strncpy(buf, "auto-configured", bufSize);
#endif
    std::string programFileName(buf);
    auto slashIndex = programFileName.rfind(pathSepar);
    if (std::string::npos != slashIndex) {
        // Extract the path
        altPrefix = programFileName.substr(0, slashIndex + 1);
        if (helpers::LogLog::isDebugEnabled())
        {
            LogString msg = LOG4CXX_STR("Alternate prefix [");
            helpers::Transcoder::decode(altPrefix, msg);
            msg += LOG4CXX_STR("]");
            helpers::LogLog::debug(msg);
        }
        // Add a local directory relative name
        result.push_back(programFileName.substr(slashIndex + 1));
        if (helpers::LogLog::isDebugEnabled())
        {
            LogString msg(LOG4CXX_STR("Alternate configuration file name ["));
            helpers::Transcoder::decode(result.back(), msg);
            msg += LOG4CXX_STR("]");
            helpers::LogLog::debug(msg);
        }
        // Add a local directory relative name without any extension
        auto dotIndex = result.back().rfind('.');
        if (std::string::npos != dotIndex)
        {
            result.push_back(result.back());
            result.back().erase(dotIndex);
            if (helpers::LogLog::isDebugEnabled())
            {
                LogString msg(LOG4CXX_STR("Alternate configuration file name ["));
                helpers::Transcoder::decode(result.back(), msg);
                msg += LOG4CXX_STR("]");
                helpers::LogLog::debug(msg);
            }
        }
    }
    else if (!programFileName.empty()) {
        auto dotIndex = result.back().rfind('.');
        if (std::string::npos != dotIndex) {
            programFileName.erase(dotIndex);
            result.push_back(programFileName);
            if (helpers::LogLog::isDebugEnabled())
            {
                LogString msg(LOG4CXX_STR("Alternate configuration file name ["));
                helpers::Transcoder::decode(result.back(), msg);
                msg += LOG4CXX_STR("]");
                helpers::LogLog::debug(msg);
            }
        }
    }
    result.push_back("log4cxx");
    result.push_back("log4j");
    return result;
}
 
// Provide the name of the configuration file to [DefaultConfigurator](@ref log4cxx.DefaultConfigurator).
// Set up a background thread that will check for changes every 5 seconds and reload the configuration
void SelectConfigurationFile() {
#if defined(_DEBUG)
    helpers::LogLog::setInternalDebugging(true);
#endif
    const char* extension[] = { ".xml", ".properties", 0 };
    std::string altPrefix;
    helpers::Pool pool;
 
    for (auto baseName : DefaultConfigurationFileNames(altPrefix)) {
        int i = 0;
        for (; extension[i]; ++i) {
            File current_working_dir_candidate(baseName + extension[i]);
            if (current_working_dir_candidate.exists(pool)) {
                DefaultConfigurator::setConfigurationFileName(current_working_dir_candidate.getPath());
                DefaultConfigurator::setConfigurationWatchSeconds(5);
                break;
            }
            if (!altPrefix.empty()) {
                File alt_dir_candidate(altPrefix + baseName + extension[i]);
                if (alt_dir_candidate.exists(pool)) {
                    DefaultConfigurator::setConfigurationFileName(alt_dir_candidate.getPath());
                    DefaultConfigurator::setConfigurationWatchSeconds(5);
                    break;
                }
            }
        }
        if (extension[i]) // Found a configuration file?
            return;
    }
    // Configuration file not found - send events to the console
    BasicConfigurator::configure();
}
 
} // namespace
 
namespace com { namespace foo {
 
// Retrieve the \c name logger pointer.
// Configure Log4cxx on the first call.
auto getLogger(const std::string& name) -> LoggerPtr {
    using namespace log4cxx;
    static struct log4cxx_initializer {
        log4cxx_initializer() {
            SelectConfigurationFile();
        }
        ~log4cxx_initializer() {
            LogManager::shutdown();
        }
    } initialiser;
    return name.empty()
        ? LogManager::getRootLogger()
        : LogManager::getLogger(name);
}
 
} } // namespace com::foo