haclog

• readme EN
• readme 中文

haclog(Happy Async C Log) is a plain C asynchronous log library. The main goal of this library is to make the writing time of log front-end(log producer thread) as small as possible.

Build

haclog supports multiple build tools

cmake

mkdir build
cd build
cmake ..

If you want to compile and run unit tests and benchmark, run run_test_and_benchmark.sh (in Windows, run_test_and_benchmark.bat)

meson

meson setup build
meson compile -C build

Usage samples

hello

#include <stdlib.h>
#include "haclog/haclog.h"

void add_console_handler()
{
	static haclog_console_handler_t handler;
	memset(&handler, 0, sizeof(handler));
	if (haclog_console_handler_init(&handler, 1) != 0) {
		fprintf(stderr, "failed init console handler");
		exit(EXIT_FAILURE);
	}

	haclog_handler_set_level((haclog_handler_t *)&handler, HACLOG_LEVEL_INFO);
	haclog_context_add_handler((haclog_handler_t *)&handler);
}

int main()
{
	// add console handler
	add_console_handler();

	// run haclog backend
	haclog_backend_run();

	// initialize thread context
	haclog_thread_context_init();

	HACLOG_INFO("Hello World");

	double pi = 3.14159265359;
	HACLOG_DEBUG("π = %.5f", pi);

	// NOTE: assert false will crash when build type is debug
	int actual = 1;
	int expect = 1;
	HACLOG_ASSERT_MSG(actual == expect,
		"actual: %d, expect: %d", actual, expect);

	// NOTE: fatal level log will crash when build type is debug
	if (actual != expect) {
		HACLOG_FATAL("actual != expect, crash when debug");
	}

	// cleanup thread context
	haclog_thread_context_init();

	return 0;
}

• Use haclog_context_add_handler, you can add different log handler into context, built-in support handler is as follows
  • haclog_console_handler_t: output to console(stdout/stderr)
  • haclog_file_handler_t: output to file
  • haclog_file_rotate_handler_t: output to file and rotate according to file size
  • haclog_file_time_rot_handler_t: output to file and rotate according to time
• After add handler, call haclog_backend_run to run log backend
• In each thread, before write log, call haclog_thread_context_init to initialize haclog thread context
• When thread exit, call haclog_thread_context_init to cleanup haclog thread context

NOTE: in haclog, the format string in each log must be a string literal, When using C++, the compiler will help the user to automatically detect it; when using C, the user needs to gurantee this by self

/* Bad!!! Don't do that, format string must be a string literal */
// char *fmt_str = NULL;
// int v = rand();
// if (v % 2 == 0) {
// 	fmt_str = "%d is even";
// } else {
// 	fmt_str = "%d is odd";
// }
// HACLOG_FATAL(fmt_str, v);

file handler

void add_file_handler()
{
	static haclog_file_handler_t handler;
	memset(&handler, 0, sizeof(handler));
	if (haclog_file_handler_init(&handler, "logs/hello.log", "w") != 0) {
		fprintf(stderr, "failed init file handler");
		exit(EXIT_FAILURE);
	}
	haclog_handler_set_level((haclog_handler_t *)&handler, HACLOG_LEVEL_DEBUG);
	haclog_context_add_handler((haclog_handler_t *)&handler);
}

rotate file handler

void add_file_rotate_handler()
{
	static haclog_file_rotate_handler_t handler;
	memset(&handler, 0, sizeof(handler));
	if (haclog_file_rotate_handler_init(&handler, "logs/hello.rot.log", 128 * 1024 * 1024, 5) != 0) {
		fprintf(stderr, "failed init file handler");
		exit(EXIT_FAILURE);
	}
	haclog_handler_set_level((haclog_handler_t *)&handler, HACLOG_LEVEL_DEBUG);
	haclog_context_add_handler((haclog_handler_t *)&handler);
}

time rotate file handler

void add_file_time_rot_handler()
{
	static haclog_file_time_rot_handler_t handler;
	memset(&handler, 0, sizeof(handler));
	if (haclog_file_time_rotate_handler_init( &handler, "logs/hello.time_rot.log", HACLOG_TIME_ROTATE_UNIT_DAY, 2, 0) != 0) {
		fprintf(stderr, "failed init file time rotate handler");
		exit(EXIT_FAILURE);
	}
	haclog_handler_set_level((haclog_handler_t *)&handler, HACLOG_LEVEL_DEBUG);
	haclog_context_add_handler((haclog_handler_t *)&handler);
}

Customize log format

By default, detailed log information will be printed in the following pattern:
${level}|${UTC+0 datetime}|${file & line number}|${function}|${thread id}

User can Customize log meta format

int my_write_meta(struct haclog_handler *handler, haclog_meta_info_t *meta)
{
	const char *level = haclog_level_to_str(meta->loc->level);
	return handler->writev(handler, "%s|%llu.%lu ", level,
						   (unsigned long long)meta->ts.tv_sec,
						   (unsigned long)meta->ts.tv_nsec);
}

...

haclog_handler_set_fn_write_meta((haclog_handler_t *)&handler, my_write_meta);
haclog_context_add_handler((haclog_handler_t *)&handler);

Set Bytes Buffer size

haclog_context_set_bytes_buf_size(2 * 1024 * 1024);

Set max length of one log line

haclog_context_set_msg_buf_size(2048);