CMake脚本下载项目依赖
本文介绍一种使用脚本下载并解压项目依赖库的方法。
场景说明
假设你的项目和多个人共同开发，并且使用了众多第三方库。那么，你和其他合作的开发者之间共享或者同步项目中使用的第三方库就变成一个棘手的事情。如果使用Git版本管理工具和Github等代码托管平台进行第三方库的管理，类似OpenCV这种百兆大小的库对托管仓库的大小和代码拉取都极不友好。如果需要开发者到某个指定的文件服务器上进行下载并自己部署又有些麻烦。本文以Vcpkg导出的第三方库为例，介绍一种使用CMake脚本下载并解压项目依赖库的方法，配合vcpkg安装库的导出和使用更加方便哦。
脚本设计
CMake中的file命令提供了诸多对文件的操作能力：读写文件、传输文件、解压和打包文件等等。设计一个脚本使用CMake的file命令下载并解压项目依赖的第三方库，能够有效地解决项目依赖库分发的问题。
该脚本在CMake的配置阶段执行，将会自动下载解压但三方库的压缩包到libraries目录中。脚本的执行流程如下：
流程：检查是否存在libraries目录，如果否则执行以下流程：
1：检查是否存在libraries.zip;
否：从配置文件读取下载地址，使用file命令下载url指定的文件到本地并命名为libraries.zip;
下载成功：输出下载完成提示;
下载失败：输出错误信息并停止配置;
2：解压压缩包到libraries目录。
将上述流程定义为CMake中的函数，内容如下所示：
# 定义一个下载和解压库的函数
function(download_libraries url_filename)
# 下载并解压库文件
if(NOT EXISTS "${CMAKE_SOURCE_DIR}/libraries")
if(NOT EXISTS "${CMAKE_SOURCE_DIR}/libraries.zip")
file(STRINGS ${url_filename} LIBRARIES_URL)
message(STATUS "Downloading libraries.zip from: ${LIBRARIES_URL}")
file(DOWNLOAD
${LIBRARIES_URL} "${CMAKE_SOURCE_DIR}/libraries.zip"
SHOW_PROGRESS
STATUS DOWNLOAD_STATUS)
list(GET DOWNLOAD_STATUS 0 DOWNLOAD_STATUS_CODE)
list(GET DOWNLOAD_STATUS 1 DOWNLOAD_STATUS_MSG)
if(DOWNLOAD_STATUS_CODE)
message(FATAL_ERROR "Failed to download libraries.zip! -- Error: ${DOWNLOAD_STATUS_MSG}")
else()
message(STATUS "Download complete!")
endif()
endif()
message(STATUS "Extracting libraries.zip...")
file(ARCHIVE_EXTRACT
INPUT "${CMAKE_SOURCE_DIR}/libraries.zip"
DESTINATION "${CMAKE_SOURCE_DIR}/libraries")
message(STATUS "Extraction complete!")
endif()
endfunction() 可以根据自己的实际需求，选择使用合适的file(DOWNLOAD)命令和参数。
项目示例
以一个简单的项目为例介绍上述脚本的使用方法。该项目中，我将vcpkg安装的x64-windows版本的spdlog和yaml库导出成压缩包并存放在我自己的服务器上。然后，创建main程序（来自spdlog库的示例代码）连接到spdlog日志库输出日志。
项目的目录结构如下：
.
|-- README.md
|-- CMakeLists.txt
|-- libraries_url.ini
|-- cmake
| `-- download_libraries.cmake
`-- source
`-- main.cpp 其中，cmake/download_libraries.cmake包含了上述脚本；libraries_url.ini包含了库文件压缩包的下载地址。
CMakeLists.txt的内容如下所示：
cmake_minimum_required(VERSION 3.15)
# 下载并解压第三方库
include(cmake/download_libraries.cmake)
download_libraries(libraries_url.ini)
if(EXISTS ${CMAKE_SOURCE_DIR}/libraries/vcpkg)
set(CMAKE_TOOLCHAIN_FILE ${CMAKE_SOURCE_DIR}/libraries/vcpkg/scripts/buildsystems/vcpkg.cmake)
message(STATUS "Using vcpkg toolchain file: ${CMAKE_TOOLCHAIN_FILE}")
endif()
project(cmake_demo)
set(CMAKE_CXX_STANDARD 17)
set(CMAKE_RUNTIME_OUTPUT_DIRECTORY ${CMAKE_SOURCE_DIR}/bin)
find_package(spdlog CONFIG REQUIRED)
add_executable(main source/main.cpp)
target_link_libraries(main PRIVATE spdlog::spdlog_header_only) main.cpp的内容如下：
//
// Copyright(c) 2015 Gabi Melman.
// Distributed under the MIT License (http://opensource.org/licenses/MIT)
// spdlog usage example
#include <cstdio>
#include <chrono>
void load_levels_example();
void stdout_logger_example();
void basic_example();
void rotating_example();
void daily_example();
void callback_example();
void async_example();
void binary_example();
void vector_example();
void stopwatch_example();
void trace_example();
void multi_sink_example();
void user_defined_example();
void err_handler_example();
void syslog_example();
void udp_example();
void custom_flags_example();
void file_events_example();
void replace_default_logger_example();
void mdc_example();
#include "spdlog/spdlog.h"
#include "spdlog/cfg/env.h" // support for loading levels from the environment variable
#include "spdlog/fmt/ostr.h" // support for user defined types
int main(int, char *[]) {
// Log levels can be loaded from argv/env using "SPDLOG_LEVEL"
load_levels_example();
spdlog::info("Welcome to spdlog version {}.{}.{} !", SPDLOG_VER_MAJOR, SPDLOG_VER_MINOR,
SPDLOG_VER_PATCH);
spdlog::warn("Easy padding in numbers like {:08d}", 12);
spdlog::critical("Support for int: {0:d}; hex: {0:x}; oct: {0:o}; bin: {0:b}", 42);
spdlog::info("Support for floats {:03.2f}", 1.23456);
spdlog::info("Positional args are {1} {0}..", "too", "supported");
spdlog::info("{:>8} aligned, {:<8} aligned", "right", "left");
// Runtime log levels
spdlog::set_level(spdlog::level::info); // Set global log level to info
spdlog::debug("This message should not be displayed!");
spdlog::set_level(spdlog::level::trace); // Set specific logger's log level
spdlog::debug("This message should be displayed..");
// Customize msg format for all loggers
spdlog::set_pattern("[%H:%M:%S %z] [%^%L%$] [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();
mdc_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);
}
// Mapped Diagnostic Context (MDC) is a map that stores key-value pairs (string values) in thread local storage.
// Each thread maintains its own MDC, which loggers use to append diagnostic information to log outputs.
// Note: it is not supported in asynchronous mode due to its reliance on thread-local storage.
#include "spdlog/mdc.h"
void mdc_example()
{
spdlog::mdc::put("key1", "value1");
spdlog::mdc::put("key2", "value2");
// if not using the default format, you can use the %& formatter to print mdc data as well
spdlog::set_pattern("[%H:%M:%S %z] [%^%L%$] [%&] %v");
spdlog::info("Some log message with context");
system("pause");
}使用MSVC编译器编译上述CMake工程，配置CMake的过程中，会看到文件下载进度和相应的输出提示，编译后运行可执行程序，便可以看到spdlog库示例程序的输出结果啦！
其他选择
如果你维护的是一个大型项目并且有着复杂的项目依赖库，推荐使用conan。
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