sinkable_paas容器

sink是将日志写入实际目标的对象。每一个sink只对应一个写入的目标对象（e.g file、console或db）, 并且独立的拥有自己的formatter对象，用于日志格式配置。

spdlog的logger使用一个vector保存多个用智能指针维护的sink(e.g std::shared_ptr<sink>,表示当前logger的多个日志输出目标sink。当使用logger记录一条日志时，将调用每个sink对象的函数sink(log_msg)。

 spdlog的sink具有_mt（多线程）或_st（单线程）后缀，以指示线程安全。虽然单线程sink不能同时被多个线程使用，因为没有使用线程锁，所以单线程的sink速度更快。

// create a thread safe sink which will keep its file size to a maximum of 5MB and a maximum of 3 rotated files.
#include "spdlog/sinks/rotating_file_sink.h"
...
auto file_logger = spdlog::rotating_logger_mt("file_logger", "logs/mylogfile", 1048576 * 5, 3);

#include "spdlog/sinks/rotating_file_sink.h"
...
auto rotating = make_shared<spdlog::sinks::rotating_file_sink_mt> ("log_filename", 1024*1024, 5, false);
auto file_logger = make_shared<spdlog::logger>("my_logger", rotating);

#include "spdlog/sinks/daily_file_sink.h"
..
auto daily_logger = spdlog::daily_logger_mt("daily_logger", "logs/daily", 14, 55);

#include "spdlog/sinks/basic_file_sink.h"
...
auto logger = spdlog::basic_logger_mt("mylogger", "log.txt");

#include "spdlog/sinks/stdout_sinks.h"
...
auto console = spdlog::stdout_logger_mt("console");
auto err_console = spdlog::stderr_logger_st("console");

#include "spdlog/sinks/stdout_color_sinks.h"
...
auto console = spdlog::stdout_color_mt("console");
auto err_console = spdlog::stderr_color_st("console");

auto sink = std::make_shared<spdlog::sinks::stdout_color_sink_mt>();

#include "spdlog/sinks/ostream_sink.h "
...
std::ostringstream oss;
auto ostream_sink = std::make_shared<spdlog::sinks::ostream_sink_mt> (oss);
auto logger = std::make_shared<spdlog::logger>("my_logger", ostream_sink);

#include "spdlog/sinks/null_sink.h"
...
auto logger = spdlog::create<spdlog::sinks::null_sink_st>("null_logger");

#include "spdlog/sinks/syslog_sink.h"
...
spdlog::syslog_logger logger("logger_name", "my_ident");

#include "spdlog/sinks/systemd_sink.h"
...
auto systemd_sink = std::make_shared<spdlog::sinks::systemd_sink_st>();
spdlog::logger logger("logger_name", systemd_sink);

#include "spdlog/sinks/dist_sink.h"

...
auto dist_sink = make_shared<spdlog::sinks::dist_sink_st>();
auto sink1 = make_shared<spdlog::sinks::stdout_sink_st>();
auto sink2 = make_shared<spdlog::sinks::simple_file_sink_st>("mylog.log");

dist_sink->add_sink(sink1);
dist_sink->add_sink(sink2);

#include "spdlog/sinks/msvc_sink.h"
auto sink = std::make_shared<spdlog::sinks::msvc_sink_mt>();
auto logger = std::make_shared<spdlog::logger>("msvc_logger", sink);

#include "spdlog/sinks/dup_filter_sink.h"
auto dup_filter = std::make_shared<dup_filter_sink_st>(std::chrono::seconds(5));
dup_filter->add_sink(std::make_shared<stdout_color_sink_mt>());
spdlog::logger l("logger", dup_filter);
l.info("Hello");
l.info("Hello");
l.info("Hello");
l.info("Different Hello");

[2019-06-25 17:50:56.511] [logger] [info] Hello
[2019-06-25 17:50:56.512] [logger] [info] Skipped 3 duplicate messages..
[2019-06-25 17:50:56.512] [logger] [info] Different Hello

#include "spdlog/sinks/ringbuffer_sink.h"
auto ringbuffer_sink = std::make_shared<spdlog::sinks::ringbuffer_sink_mt>(128);
std::vector<spdlog::sink_ptr> sinks;
sinks.push_back(std::make_shared<spdlog::sinks::basic_file_sink_mt>("path/to/log.txt"));
sinks.push_back(ringbuffer_sink);
auto logger = std::make_shared<spdlog::logger>("logger_name", std::begin(sinks), std::end(sinks));
for (int i = 0; i < 256; ++i) { 

logger->info("Log message {}", i);
}
// Retrieve all log messages. `log_message` contains 128 messages.
std::vector<std::string> log_messages = ringbuffer_sink->last_formatted();
// Retrieve a maximum of 64 log messages.
std::vector<std::string> log_messages = ringbuffer_sink->last_formatted(64);

#include "spdlog/sinks/base_sink.h"
template<typename Mutex>
class my_sink : public spdlog::sinks::base_sink <Mutex>
{ 

...
protected:
void sink_it_(const spdlog::details::log_msg& msg) override
{ 

// log_msg is a struct containing the log entry info like level, timestamp, thread id etc.
// msg.raw contains pre formatted log
// If needed (very likely but not mandatory), the sink formats the message before sending it to its final destination:
spdlog::memory_buf_t formatted;
spdlog::sinks::base_sink<Mutex>::formatter_->format(msg, formatted);
std::cout << fmt::to_string(formatted);
}
void flush_() override 
{ 

std::cout << std::flush;
}
};
#include "spdlog/details/null_mutex.h"
#include <mutex>
using my_sink_mt = my_sink<std::mutex>;
using my_sink_st = my_sink<spdlog::details::null_mutex>;

inline std::vector<spdlog::sink_ptr> &spdlog::logger::sinks()
{ 

return sinks_;
}

spdlog::get("myExistingLogger")->sinks().push_back(myNewSink);