前言
spdlog是一个跨平台c++ 的开源日志库 ，可以head only 使用，包含部分modern c++ 语法，
更是兼容了c++20 format，支持异步和格式化输出，通俗易懂，适合阅读。
源码下载
用法
直接贴上了 example.cpp 的代码
cpp
//
// Copyright(c) 2015 Gabi Melman.
// Distributed under the MIT License (http://opensource.org/licenses/MIT)
// spdlog usage example
#include <cstdio>
#include <chrono>
void load_levels_example();
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_default_logger_example();
#include "spdlog/spdlog.h"
#include "spdlog/cfg/env.h" // support for loading levels from the environment variable
#include "spdlog/fmt/ostr.h" // support for user defined types
int main(int, char *[]) {
// Log levels can be loaded from argv/env using "SPDLOG_LEVEL"
load_levels_example(); //可以从环境变量获取日志等级
//不同日志等级的输出 可以了解一下format的用法
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);
// Backtrace support
// Loggers can store in a ring buffer all messages (including debug/trace) for later inspection.
// When needed, call dump_backtrace() to see what happened:
spdlog::enable_backtrace(10); // create ring buffer with capacity of 10 messages
for (int i = 0; i < 100; i++) {
spdlog::debug("Backtrace message {}", i); // not logged..
}
// e.g. if some error happened:
spdlog::dump_backtrace(); // log them now!
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_default_logger_example();
// Flush all *registered* loggers using a worker thread every 3 seconds.
// note: registered loggers *must* be thread safe for this to work correctly!
spdlog::flush_every(std::chrono::seconds(3));
// Apply some function on all registered loggers
spdlog::apply_all([&](std::shared_ptr<spdlog::logger> l) { l->info("End of example."); });
// Release all spdlog resources, and drop all loggers in the registry.
// 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 multi threaded logger.
auto console = spdlog::stdout_color_mt("console");
// or for stderr:
// auto console = spdlog::stderr_color_mt("error-logger");
}
#include "spdlog/sinks/basic_file_sink.h"
void basic_example() {
// Create basic file logger (not rotated).
auto my_logger = spdlog::basic_logger_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::rotating_logger_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::daily_logger_mt("daily_logger", "logs/daily.txt", 2, 30);
}
#include "spdlog/sinks/callback_sink.h"
void callback_example() {
// Create the logger
auto logger = spdlog::callback_logger_mt("custom_callback_logger",
[](const spdlog::details::log_msg & /*msg*/) {
// do what you need to do with msg
});
}
#include "spdlog/cfg/env.h"
void load_levels_example() {
// Set the log level to "info" and mylogger to "trace":
// SPDLOG_LEVEL=info,mylogger=trace && ./example
spdlog::cfg::load_env_levels();
// or from command line:
// ./example SPDLOG_LEVEL=info,mylogger=trace
// #include "spdlog/cfg/argv.h" // for loading levels from argv
// spdlog::cfg::load_argv_levels(args, argv);
}
#include "spdlog/async.h"
void async_example() {
// Default thread pool settings can be modified *before* creating the async logger:
// spdlog::init_thread_pool(32768, 1); // queue with max 32k items 1 backing thread.
auto async_file =
spdlog::basic_logger_mt<spdlog::async_factory>("async_file_logger", "logs/async_log.txt");
// alternatively:
// auto async_file =
// spdlog::create_async<spdlog::sinks::basic_file_sink_mt>("async_file_logger",
// "logs/async_log.txt");
for (int i = 1; i < 101; ++i) {
async_file->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.
#if !defined SPDLOG_USE_STD_FORMAT || defined(_MSC_VER)
#include "spdlog/fmt/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));
}
#else
void binary_example() {
// not supported with std::format yet
}
#endif
// Log a vector of numbers
#ifndef SPDLOG_USE_STD_FORMAT
#include "spdlog/fmt/ranges.h"
void vector_example() {
std::vector<int> vec = {1, 2, 3};
spdlog::info("Vector example: {}", vec);
}
#else
void vector_example() {}
#endif
// ! DSPDLOG_USE_STD_FORMAT
// Compile time log levels.
// define SPDLOG_ACTIVE_LEVEL to required level (e.g. SPDLOG_LEVEL_TRACE)
void trace_example() {
// trace from default logger
SPDLOG_TRACE("Some trace message.. {} ,{}", 1, 3.23);
// debug from default logger
SPDLOG_DEBUG("Some debug message.. {} ,{}", 1, 3.23);
// trace from logger object
auto logger = spdlog::get("file_logger");
SPDLOG_LOGGER_TRACE(logger, "another trace message");
}
// stopwatch example
#include "spdlog/stopwatch.h"
#include <thread>
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() {
spdlog::sinks::udp_sink_config cfg("127.0.0.1", 11091);
auto my_logger = spdlog::udp_logger_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<spdlog::sinks::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<spdlog::sinks::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){};
};
#ifndef SPDLOG_USE_STD_FORMAT // when using fmtlib
template <>
struct fmt::formatter<my_type> : fmt::formatter<std::string> {
auto format(my_type my, format_context &ctx) -> decltype(ctx.out()) {
return fmt::format_to(ctx.out(), "[my_type i={}]", my.i);
}
};
#else // when using std::format
template <>
struct std::formatter<my_type> : std::formatter<std::string> {
auto format(my_type my, format_context &ctx) const -> decltype(ctx.out()) {
return format_to(ctx.out(), "[my_type i={}]", my.i);
}
};
#endif
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::syslog_logger_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());
}
std::unique_ptr<custom_flag_formatter> clone() const override {
return spdlog::details::make_unique<my_formatter_flag>();
}
};
void custom_flags_example() {
using spdlog::details::make_unique; // for pre c++14
auto formatter = 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 filename) {
spdlog::info("Before opening {}", filename);
};
handlers.after_open = [](spdlog::filename_t filename, std::FILE *fstream) {
spdlog::info("After opening {}", filename);
fputs("After opening\n", fstream);
};
handlers.before_close = [](spdlog::filename_t filename, std::FILE *fstream) {
spdlog::info("Before closing {}", filename);
fputs("Before closing\n", fstream);
};
handlers.after_close = [](spdlog::filename_t filename) {
spdlog::info("After closing {}", filename);
};
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.info("Some log line");
}
void replace_default_logger_example() {
// store the old logger so we don't break other examples.
auto old_logger = spdlog::default_logger();
auto new_logger =
spdlog::basic_logger_mt("new_default_logger", "logs/new-default-log.txt", true);
spdlog::set_default_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_default_logger(old_logger);
}details
· 整体代码也是尽量使用 inline
· 我在想是不是 可以尽量使用constexpr做到 更快的运行使其
·
circular_q.h
最底层是维护了一个用vector实现的队列 class circular_q 仅支持移动
pushback的时候 如果满了的话 对头会向前移动
cpp
void push_back(T &&item) {
if (max_items_ > 0) {
v_[tail_] = std::move(item);
tail_ = (tail_ + 1) % max_items_;
//注意如果满了 可能会导致队头的消息靠后输出
if (tail_ == head_) // overrun last item if full
{
head_ = (head_ + 1) % max_items_;
++overrun_counter_;
}
}
}at接口做了检查 std::vector 也做了
cpp
const T &at(size_t i) const {
assert(i < size());
return v_[(head_ + i) % max_items_];
}注意获取size的时候需要判断一下
cpp
size_t size() const {
if (tail_ >= head_) {
return tail_ - head_;
} else {
return max_items_ - (head_ - tail_);
}
}backtracer-inl.h
大概就是日志追溯 封装了有锁的环形队列
使用原子变量
cpp
std::atomic<bool> enabled_{false};console_globals.h
null_mutex 是一个锁的空实现 主要是为了保证接口统一
cpp
#include <mutex>
#include <spdlog/details/null_mutex.h>
namespace spdlog {
namespace details {
struct console_mutex {
using mutex_t = std::mutex;
static mutex_t &mutex() {
static mutex_t s_mutex;
return s_mutex;
}
};
struct console_nullmutex {
using mutex_t = null_mutex;
static mutex_t &mutex() {
static mutex_t s_mutex;
return s_mutex;
}
};
} // namespace details
} file_helper.h
封装了文件操作
fmt_helper.h
顾名思义
log_msg_buffer-inl.h
都是对视图的操作 保证了高效性 c17引入了 string_view c20 也引入了span 不仅安全通常来时还是还都是高效的
cpp
class SPDLOG_API log_msg_buffer : public log_msg {
memory_buf_t buffer;//使用alloctor 管理内存 大小为250bytes
void update_string_views();
public:
log_msg_buffer() = default;
explicit log_msg_buffer(const log_msg &orig_msg);
log_msg_buffer(const log_msg_buffer &other);
log_msg_buffer(log_msg_buffer &&other) SPDLOG_NOEXCEPT;
log_msg_buffer &operator=(const log_msg_buffer &other);
log_msg_buffer &operator=(log_msg_buffer &&other) SPDLOG_NOEXCEPT;
};log_msg_inl.h
这里主要是是对日志消息的封装 名字 内容 级别 soc 核心内容
c++20 引入了 source_location 会更加方便 这里主要是为了保证兼容性
cpp
struct SPDLOG_API log_msg {
log_msg() = default;
log_msg(log_clock::time_point log_time,
source_loc loc,
string_view_t logger_name,
level::level_enum lvl,
string_view_t msg);
log_msg(source_loc loc, string_view_t logger_name, level::level_enum lvl, string_view_t msg);
log_msg(string_view_t logger_name, level::level_enum lvl, string_view_t msg);
log_msg(const log_msg &other) = default;
log_msg &operator=(const log_msg &other) = default;
string_view_t logger_name; //日志名字
level::level_enum level{level::off};//枚举级别
log_clock::time_point time;
size_t thread_id{0};
// wrapping the formatted text with color (updated by pattern_formatter).
mutable size_t color_range_start{0};
mutable size_t color_range_end{0};
source_loc source;
string_view_t payload; //内容
};mpmc_blocking_q.h
是多生产者多消费者队列 封装了循环队列 支持三种push
1.第一种就是最正常的 只有队列有位置 才push // Block until message can be enqueued
2.第二种 会直接push 可以会直接覆盖旧数据/ Discard oldest message in the queue if full when trying to add new item.
3.如果没有满 push 满了就会丢弃 // Discard new message if the queue is full when trying to add new item.
内部维护了 discard_counter 原子变量 用来统计抛弃了多少日志
cpp
void enqueue(T &&item) {
{
std::unique_lock<std::mutex> lock(queue_mutex_);
pop_cv_.wait(lock, [this] { return !this->q_.full(); });
q_.push_back(std::move(item));
}
push_cv_.notify_one();
}
// enqueue immediately. overrun oldest message in the queue if no room left.
void enqueue_nowait(T &&item) {
{
std::unique_lock<std::mutex> lock(queue_mutex_);
q_.push_back(std::move(item));
}
push_cv_.notify_one();
}
void enqueue_if_have_room(T &&item) {
bool pushed = false;
{
std::unique_lock<std::mutex> lock(queue_mutex_);
if (!q_.full()) {
q_.push_back(std::move(item));
pushed = true;
}
}
if (pushed) {
push_cv_.notify_one();
} else {
++discard_counter_;
}
}一个是有timeout 一个没有
cpp
bool dequeue_for(T &popped_item, std::chrono::milliseconds wait_duration) {
{
std::unique_lock<std::mutex> lock(queue_mutex_);
if (!push_cv_.wait_for(lock, wait_duration, [this] { return !this->q_.empty(); })) {
return false;
}
popped_item = std::move(q_.front());
q_.pop_front();
}
pop_cv_.notify_one();
return true;
}
// blocking dequeue without a timeout.
void dequeue(T &popped_item) {
{
std::unique_lock<std::mutex> lock(queue_mutex_);
push_cv_.wait(lock, [this] { return !this->q_.empty(); });
popped_item = std::move(q_.front());
q_.pop_front();
}
pop_cv_.notify_one();
}null_mutex.h
空实现.
os_inl.h
操作系统接口
registry-inl.h
日志记录器 管理日志的重要单例类
synchronous_factory.h
异步日志工厂
需要 日志名 和 sink信息
cpp
struct synchronous_factory {
template <typename Sink, typename... SinkArgs>
static std::shared_ptr<spdlog::logger> create(std::string logger_name, SinkArgs &&...args) {
auto sink = std::make_shared<Sink>(std::forward<SinkArgs>(args)...);
auto new_logger = std::make_shared<spdlog::logger>(std::move(logger_name), std::move(sink));
details::registry::instance().initialize_logger(new_logger);
return new_logger;
}
};thread_pool-inl.h
封装了整个异步日志的核心操作
cpp
struct async_msg : log_msg_buffer {}异步日志的sp
cpp
using async_logger_ptr = std::shared_ptr<spdlog::async_logger>;msg枚举类
cpp
enum class async_msg_type { log, flush, terminate };携带msg体
cpp
async_msg(async_logger_ptr &&worker, async_msg_type the_type, const details::log_msg &m)用于给日志后端通知的 构造函数 只传入了 msg枚举类型
cpp
async_msg(async_logger_ptr &&worker, async_msg_type the_type)两个日志前端的操作
cpp
void SPDLOG_INLINE thread_pool::post_log(async_logger_ptr &&worker_ptr,
const details::log_msg &msg,
async_overflow_policy overflow_policy) {
async_msg async_m(std::move(worker_ptr), async_msg_type::log, msg);
post_async_msg_(std::move(async_m), overflow_policy);
}
void SPDLOG_INLINE thread_pool::post_flush(async_logger_ptr &&worker_ptr,
async_overflow_policy overflow_policy) {
post_async_msg_(async_msg(std::move(worker_ptr), async_msg_type::flush), overflow_policy);
}根据传入参数的不同进行不同的 生产操作
cpp
void SPDLOG_INLINE thread_pool::post_async_msg_(async_msg &&new_msg,
async_overflow_policy overflow_policy) {
if (overflow_policy == async_overflow_policy::block) {
q_.enqueue(std::move(new_msg));
} else if (overflow_policy == async_overflow_policy::overrun_oldest) {
q_.enqueue_nowait(std::move(new_msg));
} else {
assert(overflow_policy == async_overflow_policy::discard_new);
q_.enqueue_if_have_room(std::move(new_msg));
}
}线程会一直执行 这个操作 根据前端传入的不同类型进行不同的操作
cpp
void SPDLOG_INLINE thread_pool::worker_loop_() {
while (process_next_msg_()) {
}
}
bool SPDLOG_INLINE thread_pool::process_next_msg_() {
async_msg incoming_async_msg;
q_.dequeue(incoming_async_msg);
switch (incoming_async_msg.msg_type) {
case async_msg_type::log: {
incoming_async_msg.worker_ptr->backend_sink_it_(incoming_async_msg);
return true;
}
case async_msg_type::flush: {
incoming_async_msg.worker_ptr->backend_flush_();
return true;
}
case async_msg_type::terminate: {
return false;
}
default: {
assert(false);
}
}
return true;
}析构操作
cpp
SPDLOG_INLINE thread_pool::~thread_pool() {
SPDLOG_TRY {
//向日志前端发送终止信号
for (size_t i = 0; i < threads_.size(); i++) {
post_async_msg_(async_msg(async_msg_type::terminate), async_overflow_policy::block);
}
//等待每一个线程join
for (auto &t : threads_) {
t.join();
}
}
SPDLOG_CATCH_STD
}构造函数 可以在线程开始的时候执行回调函数 即使没有 函数 也会委托构造到该函数
cpp
SPDLOG_INLINE thread_pool::thread_pool(size_t q_max_items,
size_t threads_n,
std::function<void()> on_thread_start,
std::function<void()> on_thread_stop)
: q_(q_max_items) {
// 线程的数量不能大于1000
if (threads_n == 0 || threads_n > 1000) {
throw_spdlog_ex(
"spdlog::thread_pool(): invalid threads_n param (valid "
"range is 1-1000)");
}
for (size_t i = 0; i < threads_n; i++) {
//执行回调函数
threads_.emplace_back([this, on_thread_start, on_thread_stop] {
on_thread_start();
this->thread_pool::worker_loop_();
on_thread_stop();
});
}
}end details
---------------------------------------------------------
sink
end sink
----------------------------------------------------------------
common-inl.h
封装了一些常用的内联函数（inline functions）、宏定义（macros）、通用的数据结构或者辅助性的工具函数等。这些功能可能被项目中的多个文件共同引用，因此将其封装在一个公共的头文件中可以方便地进行集中管理和共享使用
cpp
using log_clock = std::chrono::system_clock;
//sink的sp
using sink_ptr = std::shared_ptr<sinks::sink>;
//sink list的sp
using sinks_init_list = std::initializer_list<sink_ptr>;
// 出现err的回调函数
using err_handler = std::function<void(const std::string &err_msg)>;
using string_view_t = fmt::basic_string_view<char>;
//250字节 日志存储的关键
using memory_buf_t = fmt::basic_memory_buffer<char, 250>;
template <typename... Args>
using format_string_t = fmt::format_string<Args...>;
//移除cv限定
template <class T>
using remove_cvref_t = typename std::remove_cv<typename std::remove_reference<T>::type>::type;
//原子变量的日志级别 因为可能运行时更改
//多种日志等级
using level_t = std::atomic<int>;
#define SPDLOG_LEVEL_TRACE 0
#define SPDLOG_LEVEL_DEBUG 1
#define SPDLOG_LEVEL_INFO 2
#define SPDLOG_LEVEL_WARN 3
#define SPDLOG_LEVEL_ERROR 4
#define SPDLOG_LEVEL_CRITICAL 5
#define SPDLOG_LEVEL_OFF 6
// Log level enum 日志等级枚举
namespace level {
enum level_enum : int {
trace = SPDLOG_LEVEL_TRACE,
debug = SPDLOG_LEVEL_DEBUG,
info = SPDLOG_LEVEL_INFO,
warn = SPDLOG_LEVEL_WARN,
err = SPDLOG_LEVEL_ERROR,
critical = SPDLOG_LEVEL_CRITICAL,
off = SPDLOG_LEVEL_OFF,
n_levels
};
enum class pattern_time_type {
local, // log localtime
utc // log utc
};
//c++ 20已经有 更好的替代了
struct source_loc {
SPDLOG_CONSTEXPR source_loc() = default;
SPDLOG_CONSTEXPR source_loc(const char *filename_in, int line_in, const char *funcname_in)
: filename{filename_in},
line{line_in},
funcname{funcname_in} {}
SPDLOG_CONSTEXPR bool empty() const SPDLOG_NOEXCEPT { return line == 0; }
const char *filename{nullptr};
int line{0};
const char *funcname{nullptr};
};
//对文件进行操作的时候的回调
struct file_event_handlers {
file_event_handlers()
: before_open(nullptr),
after_open(nullptr),
before_close(nullptr),
after_close(nullptr) {}
std::function<void(const filename_t &filename)> before_open;
std::function<void(const filename_t &filename, std::FILE *file_stream)> after_open;
std::function<void(const filename_t &filename, std::FILE *file_stream)> before_close;
std::function<void(const filename_t &filename)> after_close;
};
//小小的优化 就是说 如果相同的类型就不同强制转换了
template <typename T, typename U, enable_if_t<!std::is_same<T, U>::value, int> = 0>
constexpr T conditional_static_cast(U value) {
return static_cast<T>(value);
}
template <typename T, typename U, enable_if_t<std::is_same<T, U>::value, int> = 0>
constexpr T conditional_static_cast(U value) {
return value;
}未完待续...