GLog提供了非常简单易用的c++日志解决方案。
Created 2020.08.18 by Cong Yu; Last modified: 2020.08.18-v1.0.2
Contact: windmillyucong@163.com
Copyleft! 2022 Cong Yu. Some rights reserved.
GLog
References
// todo(congyu) 待整理
使用
使用时非常简单：
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#include <glog/logging.h>
int main(int argc, char **argv) {
google::InitGoogleLogging(argv[0]);
google::InstallFailureSignalHandler();
google::ParseCommandLineFlags(&argc, &argv, false);
LOG(ERROR) << "HELLO!!!";
LOG(INFO) << "HELLO!!!";
}
log格式
glog的输出格式为
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Log line format: [IWEF]yyyymmdd hh:mm:ss.uuuuuu threadid file:line] msg
会输出时间，线程号，文件以及行号，非常方便debug！
CMake 中使用glog
################## add_third_party()
#
# CMake function to define a named third party library interface, with included
# headers and linked libraries.
#
# Parameters:
# NAME: name of target
# INCLUDES: list of include directories for the library
# LINKS: list of other libraries to be linked in to the library
# DEFINES: list of compile definitions
# COMPILE_OPTIONS: list of compile options
#
# Examples:
# add_third_party(
# NAME
# foo
# INCLUDES
# "${CMAKE_INSTALL_INCLUDEDIR}/foo"
# LINKS
# another
# DEFINES
# -Dbar
# COMPILE_OPTIONS
# -Wall
# )
function(ADD_THIRD_PARTY)
cmake_parse_arguments(ADD_THIRD_PARTY
""
"NAME"
"INCLUDES;LINKS;DEFINES;COMPILE_OPTIONS"
${ARGN})
unset(${ADD_THIRD_PARTY_NAME}_LIB_DEPENDS CACHE)
add_library(${ADD_THIRD_PARTY_NAME} INTERFACE)
target_include_directories(${ADD_THIRD_PARTY_NAME} INTERFACE
${ADD_THIRD_PARTY_INCLUDES})
target_link_libraries(${ADD_THIRD_PARTY_NAME} INTERFACE
${ADD_THIRD_PARTY_LINKS})
target_compile_definitions(${ADD_THIRD_PARTY_NAME} INTERFACE
${ADD_THIRD_PARTY_DEFINES})
target_compile_options(${ADD_THIRD_PARTY_NAME} INTERFACE
${ADD_THIRD_PARTY_COMPILE_OPTIONS})
endfunction()
# gflags: Google Commandline Flags
find_package(gflags CONFIG HINTS ${CMAKE_INSTALL_PREFIX})
if (gflags_FOUND)
add_third_party(NAME gflag LINKS gflags)
else (gflags_FOUND)
MESSAGE(FATAL_ERROR "gflag not found")
endif ()
## glog: Google Logging Library
find_package(glog CONFIG HINTS ${CMAKE_INSTALL_PREFIX} NO_CMAKE_PACKAGE_REGISTRY)
if (glog_FOUND)
add_third_party( NAME glog
LINKS glog::glog gflag )
else ()
MESSAGE(FATAL_ERROR "glog not found")
endif ()
################ bin ####################
add_executable(hello_glog src/hello_glog.cpp)
target_link_libraries(hello_glog
glog
gflags
)
log 输出到文件
输出到文件
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$ mkdir log
$ GLOG_log_dir=log ./bin/hello_glog
以上命令会将Log 分三个等级（error和warning以及info）输出到log文件夹下面的文件里面。
log文件备份
以上命令，每次运行都是将log写入到同一个文件夹里面，如果经常运行，log全部堆在一起不方便查看。所以可以使用一些log备份的小技巧，将历史log做成一个队列，只保存指定数量的历史log，每次都将历史log的编号加1，抛弃掉最古老的log。下一个shell脚本如下：
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while true;
do
LOG_BACKUP_PATH=log.backup
if [ -d $LOG_BACKUP_PATH ];then
cd $LOG_BACKUP_PATH
MAX_LOG_NUM=100
[ -d log.$MAX_LOG_NUM ] && rm -r log.$MAX_LOG_NUM
LOG_NUM=$(( $MAX_LOG_NUM - 1 ))
while [ $LOG_NUM -gt 0 ];do
if [ -d log.$LOG_NUM ];then
mv log.$LOG_NUM log.$(( $LOG_NUM + 1 ))
fi
LOG_NUM=$(( $LOG_NUM - 1 ))
done
cd ..
else
mkdir $LOG_BACKUP_PATH
fi
if [ -d log ];then
mv log log.backup/log.1
fi
mkdir log/
# run user cmd
LD_LIBRARY_PATH=./lib GLOG_log_dir=log ./hello_glog_test
if [ $? -eq 0 ];then
break;
fi
ps aux| grep ffmpeg|grep -v grep|awk '{print $2}'|xargs kill -2
sleep 30
done
注意
在输出时，会出现需要某些数据类型需要转换的情况，如int8_t uint8_t等类型的数据是无法直接正常输出的。
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int8_t priority;
LOG(ERROR) << priority;
LOG(ERROR) << static_cast<int>(priority);
此时的输出为, 只有第二行是正常输出：
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E20201010 01:10:39.901511 217686 hello_glog.cpp:95]
E20201010 01:10:39.901536 217686 hello_glog.cpp:96] 1
日志分析脚本
项目中经常会有对日志中的数据进行处理分析的需求，可以写一些自动化的脚本，方便快捷得完成这些任务。
时间分析
如：使用re正则表达式分析时间
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# %%
import re
import datetime
import time
def GlogTimestampAnalysis(line):
data_time_pattern = r'\d{8} \d{2}:\d{2}:\d{2}.\d{6}'
data_time_format = '%Y%m%d %H:%M:%S.%f'
time_str = None
time_info = None
try:
time_str = re.findall(data_time_pattern, line)
time_info = datetime.datetime.strptime(time_str[0], data_time_format)
except Exception as e:
print('{!r}'.format(e))
print(time_str, time_info)
pass
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GlogTimestampAnalysis('E20201010 23:13:54.477016 121482 test.cpp:115]')
Q
todo(congyu) 几个小问题：
- glog的多线程输出是如何做到线程安全的？
Contact
Feel free to contact me windmillyucong@163.com anytime for anything.
License
