tools-cpp/Log.cpp at master · leighgarbs/tools-cpp · GitHub

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// General-purpose timestamp-based log utility

#include <ctime>
#include <ostream>
#include <sstream>
#include <string>
#include <sys/time.h>

#include "Log.hpp"

//==============================================================================
// Log constructor; initializes output_stream
//==============================================================================
Log::Log(std::ostream& output_stream,
         bool          flush_after_write) :
    output_stream(&output_stream),
    current_time_format(GMT),
    flush_after_write(flush_after_write)
{
}

//==============================================================================
// Log destructor; does nothing
//==============================================================================
Log::~Log()
{
}

//==============================================================================
// Writes a standard log message
//==============================================================================
void Log::write(const std::string& message)
{
    // Generate a timestamp
    std::string timestamp;
    generateTimestamp(timestamp);

    // Write the log message
    *output_stream << timestamp + " " + message + "\n";

    if (flush_after_write)
    {
        flush();
    }
}

//==============================================================================
// Writes a warning log message
//==============================================================================
void Log::writeWarning(const std::string& message)
{
    // Write a normal log message but with WARNING prepended
    write("WARNING - " + message);
}

//==============================================================================
// Writes an error log message
//==============================================================================
void Log::writeError(const std::string& message)
{
    // Write a normal log message but with ERROR prepended
    write("ERROR - " + message);
}

//==============================================================================
// Flushes the current output stream
//==============================================================================
void Log::flush()
{
    output_stream->flush();
}

//==============================================================================
// Generates a timestamp to prepend to a log message
//==============================================================================
void Log::generateTimestamp(std::string& timestamp) const
{
    // Get numeric timestamp
    timeval ts;
    if (gettimeofday(&ts, 0) == -1)
    {
        // Could not generate timestamp
        timestamp = "[???]";
        return;
    }

    // Convert ts into string timestamp
    tm ts_local;
    if (current_time_format == LOCAL)
    {
        localtime_r(&ts.tv_sec, &ts_local);
    }
    else
    {
        gmtime_r(&ts.tv_sec, &ts_local);
    }

    // Format ts_local
    unsigned int max_ts_len = 30;
    char ts_local_temp[max_ts_len];
    strftime(ts_local_temp, max_ts_len, "%a %b %d %Y %X:", &ts_local);

    // Save into string timestamp
    timestamp = "[";
    timestamp += ts_local_temp;

    // Add microseconds
    std::ostringstream out_stream;
    out_stream.width(6);
    out_stream.fill('0');
    out_stream << ts.tv_usec;
    timestamp += out_stream.str();

    // Add timezone
    strftime(ts_local_temp, max_ts_len, " %Z", &ts_local);
    timestamp += ts_local_temp;
    timestamp += "]";
}