spdlog/example/example.cpp

//
// Copyright(c) 2015 Gabi Melman.
// Distributed under the MIT License (http://opensource.org/licenses/MIT)

// spdlog usage example

#include <chrono>
#include <cstdio>

void stdout_logger_example();
void basic_example();
void rotating_example();
void daily_example();
void callback_example();
void async_example();
void binary_example();
void vector_example();
void stopwatch_example();
void trace_example();
void multi_sink_example();
void user_defined_example();
void err_handler_example();
void syslog_example();
void udp_example();
void custom_flags_example();
void file_events_example();
void replace_global_logger_example();

#include "spdlog/spdlog.h"
#include "spdlog/version.h"

using namespace spdlog::sinks;

int main(int, char *[]) {
    spdlog::info("Welcome to spdlog version {}.{}.{} !", SPDLOG_VER_MAJOR, SPDLOG_VER_MINOR, SPDLOG_VER_PATCH);
    spdlog::warn("Easy padding in numbers like {:08d}", 12);
    spdlog::critical("Support for int: {0:d};  hex: {0:x};  oct: {0:o}; bin: {0:b}", 42);
    spdlog::info("Support for floats {:03.2f}", 1.23456);
    spdlog::info("Positional args are {1} {0}..", "too", "supported");
    spdlog::info("{:>8} aligned, {:<8} aligned", "right", "left");

    // Runtime log levels
    spdlog::set_level(spdlog::level::info);  // Set global log level to info
    spdlog::debug("This message should not be displayed!");
    spdlog::set_level(spdlog::level::trace);  // Set specific logger's log level
    spdlog::debug("This message should be displayed..");

    // Customize msg format for all loggers
    spdlog::set_pattern("[%H:%M:%S %z] [%^%L%$] [thread %t] %v");
    spdlog::info("This an info message with custom format");
    spdlog::set_pattern("%+");  // back to default format
    spdlog::set_level(spdlog::level::info);

    try {
        stdout_logger_example();
        basic_example();
        rotating_example();
        daily_example();
        callback_example();
        async_example();
        binary_example();
        vector_example();
        multi_sink_example();
        user_defined_example();
        err_handler_example();
        trace_example();
        stopwatch_example();
        udp_example();
        custom_flags_example();
        file_events_example();
        replace_global_logger_example();

        // Release all spdlog resources
        // This is optional (only mandatory if using windows + async log).
        spdlog::shutdown();
    }

    // Exceptions will only be thrown upon failed logger or sink construction (not during logging).
    catch (const spdlog::spdlog_ex &ex) {
        std::printf("Log initialization failed: %s\n", ex.what());
        return 1;
    }
}

#include "spdlog/sinks/stdout_color_sinks.h"
// or #include "spdlog/sinks/stdout_sinks.h" if no colors needed.
void stdout_logger_example() {
    // Create color multithreading logger.
    auto console = spdlog::create<stdout_color_sink_mt>("console");
    // or for stderr:
    //auto console = spdlog::create<stderr_color_sink_mt>("console");
}

#include "spdlog/sinks/basic_file_sink.h"
void basic_example() {
    // Create basic file logger (not rotated).
    auto my_logger = spdlog::create<basic_file_sink_mt>("file_logger", "logs/basic-log.txt", true);
}

#include "spdlog/sinks/rotating_file_sink.h"
void rotating_example() {
    // Create a file rotating logger with 5mb size max and 3 rotated files.
    auto rotating_logger = spdlog::create<rotating_file_sink_mt>("some_logger_name", "logs/rotating.txt", 1048576 * 5, 3);
}

#include "spdlog/sinks/daily_file_sink.h"
void daily_example() {
    // Create a daily logger - a new file is created every day on 2:30am.
    auto daily_logger = spdlog::create<daily_file_format_sink_mt>("daily_logger", "logs/daily.txt", 2, 30);
}

#include "spdlog/sinks/callback_sink.h"
void callback_example() {
    // Create the logger
    auto logger = spdlog::create<callback_sink_mt>("custom_callback_logger", [](const spdlog::details::log_msg & /*msg*/) {
        // do what you need to do with msg
    });
}

#include "spdlog/sinks/async_sink.h"
void async_example() {
    using spdlog::sinks::async_sink;
    auto sink = async_sink::with<basic_file_sink_mt>("logs/async_log.txt", true);
    auto logger = std::make_shared<spdlog::logger>("async_logger", sink);
    for (int i = 1; i < 101; ++i) {
        logger->info("Async message #{}", i);
    }
}

// Log binary data as hex.
// Many types of std::container<char> types can be used.
// Iterator ranges are supported too.
// Format flags:
// {:X} - print in uppercase.
// {:s} - don't separate each byte with space.
// {:p} - don't print the position on each line start.
// {:n} - don't split the output to lines.

#include "spdlog/bin_to_hex.h"
void binary_example() {
    std::vector<char> buf;
    for (int i = 0; i < 80; i++) {
        buf.push_back(static_cast<char>(i & 0xff));
    }
    spdlog::info("Binary example: {}", spdlog::to_hex(buf));
    spdlog::info("Another binary example:{:n}", spdlog::to_hex(std::begin(buf), std::begin(buf) + 10));
    // more examples:
    // logger->info("uppercase: {:X}", spdlog::to_hex(buf));
    // logger->info("uppercase, no delimiters: {:Xs}", spdlog::to_hex(buf));
    // logger->info("uppercase, no delimiters, no position info: {:Xsp}", spdlog::to_hex(buf));
    // logger->info("hexdump style: {:a}", spdlog::to_hex(buf));
    // logger->info("hexdump style, 20 chars per line {:a}", spdlog::to_hex(buf, 20));
}

// Log a vector of numbers
#include "fmt/ranges.h"
void vector_example() {
    std::vector<int> vec = {1, 2, 3};
    spdlog::info("Vector example: {}", vec);
}

// Compile time log levels.
// define SPDLOG_ACTIVE_LEVEL to required level (e.g. SPDLOG_LEVEL_TRACE)
void trace_example() {
    // trace from global logger
    SPDLOG_TRACE("Some trace message.. {} ,{}", 1, 3.23);
    // debug from global logger
    SPDLOG_DEBUG("Some debug message.. {} ,{}", 1, 3.23);
}

// stopwatch example
#include <thread>

#include "spdlog/stopwatch.h"
void stopwatch_example() {
    spdlog::stopwatch sw;
    std::this_thread::sleep_for(std::chrono::milliseconds(123));
    spdlog::info("Stopwatch: {} seconds", sw);
}

#include "spdlog/sinks/udp_sink.h"
void udp_example() {
    udp_sink_config cfg("127.0.0.1", 11091);
    auto my_logger = spdlog::create<udp_sink_mt>("udplog", cfg);
    my_logger->set_level(spdlog::level::debug);
    my_logger->info("hello world");
}

// A logger with multiple sinks (stdout and file) - each with a different format and log level.
void multi_sink_example() {
    auto console_sink = std::make_shared<stdout_color_sink_mt>();
    console_sink->set_level(spdlog::level::warn);
    console_sink->set_pattern("[multi_sink_example] [%^%l%$] %v");

    auto file_sink = std::make_shared<basic_file_sink_mt>("logs/multisink.txt", true);
    file_sink->set_level(spdlog::level::trace);

    spdlog::logger logger("multi_sink", {console_sink, file_sink});
    logger.set_level(spdlog::level::debug);
    logger.warn("this should appear in both console and file");
    logger.info("this message should not appear in the console, only in the file");
}

// User defined types logging
struct my_type {
    int i = 0;
    explicit my_type(int i)
        : i(i) {}
};

template <>
struct fmt::formatter<my_type> : fmt::formatter<std::string> {
    auto format(my_type my, format_context &ctx) const -> decltype(ctx.out()) {
        return fmt::format_to(ctx.out(), "[my_type i={}]", my.i);
    }
};

void user_defined_example() { spdlog::info("user defined type: {}", my_type(14)); }

// Custom error handler. Will be triggered on log failure.
void err_handler_example() {
    // can be set globally or per logger(logger->set_error_handler(..))
    spdlog::set_error_handler([](const std::string &msg) { printf("*** Custom log error handler: %s ***\n", msg.c_str()); });
}

// syslog example (linux/osx/freebsd)
#ifndef _WIN32
    #include "spdlog/sinks/syslog_sink.h"
void syslog_example() {
    std::string ident = "spdlog-example";
    auto syslog_logger = spdlog::create<syslog_sink_mt>("syslog", ident, LOG_PID);
    syslog_logger->warn("This is warning that will end up in syslog.");
}
#endif

// Android example.
#if defined(__ANDROID__)
    #include "spdlog/sinks/android_sink.h"
void android_example() {
    std::string tag = "spdlog-android";
    auto android_logger = spdlog::android_logger_mt("android", tag);
    android_logger->critical("Use \"adb shell logcat\" to view this message.");
}
#endif

// Log patterns can contain custom flags.
// this will add custom flag '%*' which will be bound to a <my_formatter_flag> instance
#include "spdlog/pattern_formatter.h"
class my_formatter_flag : public spdlog::custom_flag_formatter {
public:
    void format(const spdlog::details::log_msg &, const std::tm &, spdlog::memory_buf_t &dest) override {
        std::string some_txt = "custom-flag";
        dest.append(some_txt.data(), some_txt.data() + some_txt.size());
    }

    [[nodiscard]]
    std::unique_ptr<custom_flag_formatter> clone() const override {
        return std::make_unique<my_formatter_flag>();
    }
};

void custom_flags_example() {
    auto formatter = std::make_unique<spdlog::pattern_formatter>();
    formatter->add_flag<my_formatter_flag>('*').set_pattern("[%n] [%*] [%^%l%$] %v");
    // set the new formatter using spdlog::set_formatter(formatter) or
    // logger->set_formatter(formatter) spdlog::set_formatter(std::move(formatter));
}

void file_events_example() {
    // pass the spdlog::file_event_handlers to file sinks for open/close log file notifications
    spdlog::file_event_handlers handlers;
    handlers.before_open = [](spdlog::filename_t) { spdlog::trace("Before opening logfile"); };
    handlers.after_open = [](spdlog::filename_t, std::FILE *fstream) {
        spdlog::trace("After opening logfile");
        fputs("After opening\n", fstream);
    };
    handlers.before_close = [](spdlog::filename_t, std::FILE *fstream) {
        spdlog::trace("Before closing logfile");
        fputs("Before closing\n", fstream);
    };
    handlers.after_close = [](spdlog::filename_t) { spdlog::trace("After closing logfile"); };
    auto file_sink = std::make_shared<spdlog::sinks::basic_file_sink_mt>("logs/events-sample.txt", true, handlers);
    spdlog::logger my_logger("some_logger", file_sink);
    my_logger.trace("Some log line");
}

void replace_global_logger_example() {
    // store the old logger so we don't break other examples.
    auto old_logger = spdlog::global_logger();

    auto new_logger = spdlog::create<basic_file_sink_mt>("new_global_logger", "logs/new-default-log.txt", true);
    spdlog::set_global_logger(new_logger);
    spdlog::set_level(spdlog::level::info);
    spdlog::debug("This message should not be displayed!");
    spdlog::set_level(spdlog::level::trace);
    spdlog::debug("This message should be displayed..");
    spdlog::set_global_logger(old_logger);
}