1.简介与安装
简介:
EasyLogging的主要特点包括：
简单易用：EasyLogging的API设计简洁明了，使用起来非常方便。开发者只需包含头文件并初始化库，即可开始记录日志。
高效性：EasyLogging采用异步日志记录方式，将日志信息的写入操作与程序的主线程分离，从而避免了日志记录对程序性能的影响。
线程安全：EasyLogging支持多线程环境下的日志记录，内部采用了锁机制来保证线程安全。
可配置性：EasyLogging提供了丰富的配置选项，允许开发者根据需要自定义日志记录的级别、格式、输出目标等。
跨平台兼容：EasyLogging支持多种操作系统和编译器，具有良好的跨平台兼容性。
安装
sudo apt install libeasyloggingpp-dev
使用
编译依赖
pkg-config --cflags --libs easyloggingpp
没错,你没有看错, ubuntu20.04上默认安装libeasyloggingpp-dev 没有提示任何 ld链接选项.
通过github 下载最新的源代码, 编译安装, 也是一样.
但实际上, ld链接时提示错误:
g++ -o 1_easylogging_日志.out 1_easylogging_日志.o
/bin/ld: 1_easylogging_日志.o: in function `main':
/home/liuj/1_data/3_cpp-practice/21_开源库/17_easylogging日志库/1_easylogging_日志.cc:7: undefined reference to `el::base::Writer::construct(int, char const*, ...)'
/bin/ld: 1_easylogging_日志.o: in function `__static_initialization_and_destruction_0(int, int)':
/home/liuj/1_data/3_cpp-practice/21_开源库/17_easylogging日志库/1_easylogging_日志.cc:4: undefined reference to `el::base::Storage::Storage(std::shared_ptr<el::LogBuilder> const&)'
/bin/ld: 1_easylogging_日志.o: in function `el::LogBuilder::LogBuilder()':
/usr/include/easylogging++.h:2197: undefined reference to `el::base::utils::OS::termSupportsColor()'
/bin/ld: 1_easylogging_日志.o: in function `el::base::Writer::~Writer()':
解决方法1:
将easylogging++.cc 源代码以头文件方式导入
#include <easylogging++.h>
#include <easylogging++.cc>
解决方法2:
将libeasylogging++.cc 编译为动态库 libeasylogging.so, 拷贝到系统lib目录下 /usr/lib
本文使用的是: 解决方法2
1. 在scons中检测库/usr/lib/libeasylogging.so 存在,不存在则拷贝
2. 链接选项: -leasylogging
2.实例
1.代码
1_easylogging_日志.cc
#include <easylogging++.h>
// #include <easylogging++.cc>
INITIALIZE_EASYLOGGINGPP // 初始化宏，有且只能使用一次
int main(int argc, char* argv[]) {
LOG(INFO) << "My first info log using default logger";
return 0;
}
my_log.conf
* GLOBAL:
ENABLED = true
TO_FILE = true
TO_STANDARD_OUTPUT = true
FORMAT = "[%level | %datetime] | %msg"
FILENAME = "log/log_%datetime{%Y%M%d}.log"
MILLISECONDS_WIDTH = 3
PERFORMANCE_TRACKING = false
MAX_LOG_FILE_SIZE = 2097152 ## 2MB
LOG_FLUSH_THRESHOLD = 0
* TRACE:
FILENAME = "log/trace_log_%datetime{%Y%M%d}.log"
* DEBUG:
FILENAME = "log/debug_log_%datetime{%Y%M%d}.log"
* FATAL:
ENABLED = false
* ERROR:
FILENAME = "log/error_log_%datetime{%Y%M%d}.log"
* WARNING:
FILENAME = "log/warning_log_%datetime{%Y%M%d}.log"
* INFO:
FILENAME = "log/info_log_%datetime{%Y%M%d}.log"
* VERBOSE:
ENABLED = false
2_easylogging_读取配置.cc
#include "easylogging++.h"
INITIALIZE_EASYLOGGINGPP
int main(int argc, char** argv)
{
el::Configurations conf("my_log.conf");
el::Loggers::reconfigureAllLoggers(conf);
LOG(TRACE) << "***** trace log *****";
LOG(DEBUG) << "***** debug log *****";
LOG(ERROR) << "***** error log *****";
LOG(WARNING) << "***** warning log *****";
LOG(INFO) << "***** info log *****";
system("pause");
return 0;
}
3_easylogging_条件打印.cc
#include "easylogging++.h"
INITIALIZE_EASYLOGGINGPP
int main(int argc, char **argv)
{
int i = 0;
while (i++ < 100)
{
// 条件日志
LOG_IF((i % 5 == 0), INFO) << " %5 == 0" << i;
// 每n次记录一次
LOG_EVERY_N(20, INFO) << "LOG_EVERY_N i = " << i;
// 当计数达到n次之后，才开始记录日志
LOG_AFTER_N(6, INFO) << "LOG_AFTER_N i = " << i;
// 当记录次数达到n次之后，就不再记录
LOG_N_TIMES(1, INFO) << "LOG_N_TIMES i = " << i;
}
return 0;
}
2.scons编译
SConstruct
import os
env = Environment()
env["PROGSUFFIX"] = ".out" # 可执行文件后缀.out
env["CCFLAGS"] = " -g3 -O0 -Wall" # gdb 调试
def build_share_lib():
SharedLibrary("easylogging","easylogging++.cc")
# Install(target="/usr/lib",source=['easylogging.so']) # --NG
# Command("/usr/lib/libeasylogging.so","libeasylogging.so","sudo cp -rf libeasylogging.so /usr/lib/") # --NG
# Command("./lib/libeasylogging.so","libeasylogging.so","cp -rf libeasylogging.so ./lib/libeasylogging.so") # --OK
if not os.path.exists("/usr/lib/libeasylogging.so"):
os.system("sudo cp -rf libeasylogging.so /usr/lib/libeasylogging.so") # --ok
print("copy libeasylogging.so /usr/lib ---ok")
# os.system("sudo install libeasylogging.so /usr/lib") # --ok
## 模板2
build_share_lib()
env["LIBS"] = ["easylogging"]
env.Program("1_easylogging_日志.cc", LIBS=["easylogging"],LIBPATH='.') # fix:scons无法优先编译 动态库easylogging.so
env.Program("2_easylogging_读取配置.cc")
env.Program("3_easylogging_条件打印.cc")
scons
scons: Reading SConscript files …
scons: done reading SConscript files.
scons: Building targets …
g++ -o 1_easylogging_日志.o -c -g3 -O0 -Wall 1_easylogging_日志.cc
g++ -o easylogging++.os -c -fPIC easylogging++.cc
g++ -o libeasylogging.so -shared easylogging++.os
g++ -o 1_easylogging_日志.out 1_easylogging_日志.o -L. -leasylogging
g++ -o 2_easylogging_读取配置.o -c -g3 -O0 -Wall 2_easylogging_读取配置.cc
g++ -o 2_easylogging_读取配置.out 2_easylogging_读取配置.o -leasylogging
g++ -o 3_easylogging_条件打印.o -c -g3 -O0 -Wall 3_easylogging_条件打印.cc
g++ -o 3_easylogging_条件打印.out 3_easylogging_条件打印.o -leasylogging
scons: done building targets.
3.运行
./1_easylogging_日志.out
2024-04-24 00:45:55,850 INFO [default] My first info log using default logger
./2_easylogging_读取配置.out
[TRACE | 2024-04-24 00:45:58,466] | ***** trace log *****
[DEBUG | 2024-04-24 00:45:58,466] | ***** debug log *****
[ERROR | 2024-04-24 00:45:58,466] | ***** error log *****
[WARNING | 2024-04-24 00:45:58,466] | ***** warning log *****
[INFO | 2024-04-24 00:45:58,466] | ***** info log *****
sh: pause: command not found
./3_easylogging_条件打印.out
2024-04-24 00:46:03,897 INFO [default] LOG_N_TIMES i = 1
2024-04-24 00:46:03,897 INFO [default] %5 == 05
2024-04-24 00:46:03,897 INFO [default] LOG_AFTER_N i = 7
2024-04-24 00:46:03,897 INFO [default] LOG_AFTER_N i = 8
2024-04-24 00:46:03,897 INFO [default] LOG_AFTER_N i = 9
2024-04-24 00:46:03,897 INFO [default] %5 == 010
2024-04-24 00:46:03,897 INFO [default] LOG_AFTER_N i = 10
2024-04-24 00:46:03,897 INFO [default] LOG_AFTER_N i = 11
2024-04-24 00:46:03,898 INFO [default] LOG_AFTER_N i = 12
2024-04-24 00:46:03,898 INFO [default] LOG_AFTER_N i = 13
2024-04-24 00:46:03,898 INFO [default] LOG_AFTER_N i = 14
2024-04-24 00:46:03,898 INFO [default] %5 == 015
2024-04-24 00:46:03,898 INFO [default] LOG_AFTER_N i = 15
2024-04-24 00:46:03,898 INFO [default] LOG_AFTER_N i = 16
2024-04-24 00:46:03,898 INFO [default] LOG_AFTER_N i = 17
2024-04-24 00:46:03,898 INFO [default] LOG_AFTER_N i = 18
2024-04-24 00:46:03,898 INFO [default] LOG_AFTER_N i = 19
2024-04-24 00:46:03,898 INFO [default] %5 == 020
2024-04-24 00:46:03,898 INFO [default] LOG_EVERY_N i = 20