Using emojis to identify threads in log messages

Using emojis to identify threads in log messages 2023-12-18

The other day I saw this toot by Stargirl, and it caught my eye:

Lwan, when built in debug mode, will print the thread id (obtained by gettid(2) on Linux) for every log message, so I decided to give this idea a try, by porting the code to C. Here's what I came up with:

static const char *get_thread_emoji(void)
{
    static const char *emojis[] = {
        "🐶", "🐱", "🐭", "🐹", "🐰", "🦊", "🐻", "🐼", "🐨", "🐯", "🦁", "🐮",
        "🐷", "🐽", "🐸", "🐵", "🐔", "🐧", "🐦", "🐤", "🦆", "🦉", "🦇", "🐺",
        "🐗", "🐴", "🦄", "🐝", "🪱", "🐛", "🦋", "🐌", "🐞", "🐜", "🪰", "🪲",
        "🪳", "🦟", "🦗", "🦂", "🐢", "🐍", "🦎", "🦖", "🦕", "🐙", "🦑", "🦐",
        "🦞", "🦀", "🐡", "🐠", "🐟", "🐬", "🐳", "🐋", "🦈", "🦭", "🐊", "🐅",
        "🐆", "🦓", "🦍", "🦧", "🦣", "🐘", "🦛", "🦏", "🐪", "🐫", "🦒", "🦘",
        "🦬", "🐃", "🐂", "🐄", "🐎", "🐖", "🐏", "🐑", "🦙", "🐐", "🦌", "🐕",
        "🐩", "🐈", "🐓", "🦃", "🦤", "🦚", "🦜", "🦢", "🦩", "🕊", "🐇", "🦝",
        "🦨", "🦡", "🦫", "🦦", "🦥", "🐁", "🐀", "🐿", "🦔", "🐉", "🐲",
    };
    static __thread const char *emoji;
    static unsigned int last_emoji_id;

    if (!emoji) {
        emoji = emojis[ATOMIC_INC(last_emoji_id) % (int)N_ELEMENTS(emojis)];
    }

    return emoji;
}

This, of course, is only called when $LANG ends with the string .utf8, and the terminal is set to use colors, as determined by this function:

static bool can_use_colors(void)
{
    const char *term;
    const char *no_color;

    if (!isatty(fileno(stdout)))
        return false;

    /* From https://no-color.org: "Command-line software which adds ANSI
     * color to its output by default should check for a NO_COLOR
     * environment variable that, when present and not an empty string
     * (regardless of its value), prevents the addition of ANSI color."  */
    no_color = secure_getenv("NO_COLOR");
    if (no_color && no_color[0])
        return false;

    term = secure_getenv("TERM");
    if (term && streq(term, "dumb"))
        return false;

    return true;
}

While not a 1:1 port from the original Python code, the end result is just as good. Don't take my word for it, though; here's how it looks like: