A golang-style C++ coroutine library and more.

co_recv() is taken from co's doc and simplified for system sockets. It requires the socket to be set in non-blocking mode. co_recv_r() is basically co_recv() but with read/wait ordering switched. And it works on both blocking and non-blocking sockets?

// doc's approach
// https://idealvin.github.io/en/co/coroutine/#coroutineization
int co_recv(int socket, void* buf, int n, int ms = 10000)
{
    do
    {
        /* ============ READ FIRST ============ */
        if (const auto r = co::recv(socket, buf, n); r > 0)
            return r;
        else if (r == 0)
            return 0;

        /* ============ WAIT AFTER ============ */
        co::IoEvent ev(socket, co::ev_read);
        if (!ev.wait(ms))
            return -1;
    }
    while (true);
}
// Supports both blocking and non-blocking sockets, but are there pitfalls?
int co_recv_r(int socket, void* buf, int n, int ms = 10000)
{
    do
    {
        /* ============ WAIT FIRST ============ */
        co::IoEvent ev(socket, co::ev_read);
        if (!ev.wait(ms))
            return -1;

        /* ============ READ AFTER ============ */
        if (const auto r = co::recv(socket, buf, n); r > 0)
            return r;
        else if (r == 0)
            return 0;
    }
    while (true);
}

Full code for a simple test:

#include "co/all.h"

// doc's approach
// https://idealvin.github.io/en/co/coroutine/#coroutineization
int co_recv(int socket, void* buf, int n, int ms = 10000)
{
    do
    {
        /* ============ READ FIRST ============ */
        if (const auto r = co::recv(socket, buf, n); r > 0)
            return r;
        else if (r == 0)
            return 0;

        /* ============ WAIT AFTER ============ */
        co::IoEvent ev(socket, co::ev_read);
        if (!ev.wait(ms))
            return -1;
    }
    while (true);
}
// Supports both blocking and non-blocking sockets, but are there pitfalls?
int co_recv_r(int socket, void* buf, int n, int ms = 10000)
{
    do
    {
        /* ============ WAIT FIRST ============ */
        co::IoEvent ev(socket, co::ev_read);
        if (!ev.wait(ms))
            return -1;

        /* ============ READ AFTER ============ */
        if (const auto r = co::recv(socket, buf, n); r > 0)
            return r;
        else if (r == 0)
            return 0;
    }
    while (true);
}
void handle1(tcp::Connection* conn)
{
    std::cout << std::time(nullptr) << ' ' << __PRETTY_FUNCTION__ << " Start " << std::endl;
    uint8_t buffer[256]{};
    // while (const auto bytes = co_recv(conn->socket(), buffer, 256))
    while (const auto bytes = co_recv_r(conn->socket(), buffer, 256))
        conn->send(buffer, bytes);
    delete conn;
    std::cout << std::time(nullptr) << ' ' << __PRETTY_FUNCTION__ << " End " << std::endl;
}
void handle2(tcp::Connection*)
{
    std::cout << std::time(nullptr) << ' ' << __PRETTY_FUNCTION__ << std::endl;
}
void on_connection(tcp::Connection* conn)
{
    fcntl(conn->socket(), F_SETFL, fcntl(conn->socket(), F_GETFL) & ~O_NONBLOCK);
    if (fcntl(conn->socket(), F_GETFL) & O_NONBLOCK)
        throw std::runtime_error(std::string(__PRETTY_FUNCTION__) + ": the socket is still in non-blocking mode. ");
    auto* s = co::next_scheduler();
    s->go(handle1, conn);
    s->go(handle2, conn);
}
void client()
{
    tcp::Client c("127.1", 8899);
    if (!c.connect(3000))
        throw std::runtime_error(std::string(__PRETTY_FUNCTION__) + ": failed to connect. ");
    for (int i = 0; i < 3; ++i)
    {
        c.send("hello", 5);
        char buffer[6]{};
        if (c.recv(buffer, 5))
        {
            //std::cout << __PRETTY_FUNCTION__ << ": " << buffer << std::endl;
        }
        sleep::sec(1);
    }
}
int main(int, char**)
{
    tcp::Server serv;
    serv.on_connection(on_connection);
    serv.start("0.0.0.0", 8899);

    sleep::ms(200);
    go(client);

    while (true)
        sleep::sec(1024);
}

With co_recv_r() handle2() will be executed between handle1()'s beginning and ending, no matter whether the socket's blocking flag is set or not. But with co_recv() it only happens if the socket is set in non-blocking.

I wonder if there is any pitfall in this code? Or is there serious performance penalty using co::IoEvent? Why isn't this the example in documents?

PS: I have zero knowledge about SSL sockets, not clue if we have to do SSL_read() before SSL_get_error(). I only tested with POCO's SecureStreamSocket and it worked as well.

Under co/base/:

$ xmake f -a x86
checking for the Microsoft Visual Studio (x86) version ... 2019

$ xmake
[ 23%]: compiling.release co\impl\epoll.cc
[ 26%]: compiling.release co\impl\co_win.cpp
[ 29%]: compiling.release stack_trace\stack_trace_win.cpp
[ 33%]: compiling.release win\time.cpp
[ 39%]: compiling.release fast.cc
[  6%]: compiling.release fastring.cc
[  9%]: compiling.release hash\base64.cc
[ 16%]: compiling.release co\impl\co_unix.cc
[ 19%]: compiling.release json.cc
[ 42%]: compiling.release co\impl\scheduler.cc
[ 46%]: compiling.release unix\time.cc
[ 49%]: compiling.release win\os.cpp
[ 52%]: compiling.release str.cc
error: time.cpp
C:\Users\fzheng\source\repos\co\base\win/atomic.h(46): error C3861: '_InterlockedIncrement64': identifier not found
C:\Users\fzheng\source\repos\co\base\win/atomic.h(62): error C3861: '_InterlockedDecrement64': identifier not found
C:\Users\fzheng\source\repos\co\base\win/atomic.h(78): error C3861: '_InterlockedExchangeAdd64': identifier not found
C:\Users\fzheng\source\repos\co\base\win/atomic.h(94): error C3861: '_InterlockedExchangeAdd64': identifier not found
C:\Users\fzheng\source\repos\co\base\win/atomic.h(110): error C3861: '_InterlockedExchangeAdd64': identifier not found
C:\Users\fzheng\source\repos\co\base\win/atomic.h(126): error C3861: '_InterlockedExchangeAdd64': identifier not found
C:\Users\fzheng\source\repos\co\base\win/atomic.h(142): error C3861: '_InterlockedExchangeAdd64': identifier not found
C:\Users\fzheng\source\repos\co\base\win/atomic.h(158): error C3861: '_InterlockedExchangeAdd64': identifier not found
C:\Users\fzheng\source\repos\co\base\win/atomic.h(174): error C3861: '_InterlockedOr64': identifier not found
C:\Users\fzheng\source\repos\co\base\win/atomic.h(190): error C3861: '_InterlockedAnd64': identifier not found
C:\Users\fzheng\source\repos\co\base\win/atomic.h(206): error C3861: '_InterlockedXor64': identifier not found
C:\Users\fzheng\source\repos\co\base\win/atomic.h(222): error C3861: '_InterlockedOr64': identifier not found
C:\Users\fzheng\source\repos\co\base\win/atomic.h(238): error C3861: '_InterlockedAnd64': identifier not found
C:\Users\fzheng\source\repos\co\base\win/atomic.h(254): error C3861: '_InterlockedXor64': identifier not found
C:\Users\fzheng\source\repos\co\base\win/atomic.h(270): error C3861: '_InterlockedExchange64': identifier not found

目前执行xmake install后，会将头文件放在base目录下，静态库被命名为libbase.a。base这个名字太普通了，不够将库与程序内部的名字区分开。既然项目名叫co，何不将头文件放在include/co目录下，且库名为libco.a或libco.so？

这个动静有点大，但从长远来看，我觉得有必要来执行这个改动。

目前的http::Client使用curl_easy_perform，这是一个阻塞接口。 使用单个协程调度器时，http请求将阻塞其他协程。

http::Client应该设计成非阻塞协程的，这才能体现协程的优势。推广到其他API，作为协程库里的实现，应当都设计为非阻塞的~

PS:

1. 非阻塞可通过curl_multi_perform+辅助线程/协程(也许)，或者有更好的办法（基于curl）？
2. 很多测试貌似应该用单个协程调度器，比较容易发现阻塞的问题。

如题，我看readme里面写了这几种使用方式

vcpkg search coost
conan search coost -r all

都找不到这个包

另外，xmake.lua 直接引入coost后，

add_requires("fmt", "coost", "conan::pugixml/1.12.1")
add_packages("fmt", "coost", "conan::pugixml/1.12.1")

在 ubuntu 编译示例代码也会报错

#include "co/all.h"

DEF_string(s, "nice", "");

int main(int argc, char** argv) {
    flag::init(argc, argv);
    LOG << FLG_s;
    return 0;
}

会产生下面的错误

[email protected] /m/c/m/c/cpp_practical_util> x
[ 88%]: linking.debug test
error: /usr/bin/ld: /home/cat/.xmake/packages/c/coost/v3.0.0/e7a64508b634445f93e6b7f099ab5e52/lib/libco.a(stack_trace.cc.o): in function `___::log::StackTraceImpl::dump_stack(void*, int)':
stack_trace.cc:(.text+0xb8): undefined reference to `backtrace_create_state'
/usr/bin/ld: stack_trace.cc:(.text+0xcf): undefined reference to `backtrace_full'
collect2: error: ld returned 1 exit status

i have a program like this

server.listen();
while (server.poll())
    go([socket = socket.acceptConnection()]() mutable {
        char bytes[1024];
        while (int size = socket.receive(bytes, 1024))
        {
            // do something and write to socket
        }
    });

this works perfectly for request-response pattern. but in situations where server push is also desired (like in subscribe-publish pattern, but work with request-response at the same time. ), what can i do if i dont wanna open up another connection and do different things? i dont think frequently sending "check" commands to server is a good idea.

ps: im not using so for networking becuz it doesnt have built-in ssl support (yet).

我根据文档上的xmake编译步骤，编译co/unitest时报错 checking for the architecture ... x64 checking for the Microsoft Visual Studio (x64) version ... 2017 error: unknown target(base) for unitest.deps! 该如何解决

    string URL = "http://github.com";
    auto req_lambda3 = [](shared_ptr<LambdaParams2> p)
    {
        http::Client c("http://github.com"); // https client to github.com:443
        std::cout << "1--nothing---------" << std::endl;
        c.get("/");
        std::cout << c.body() << c.strerror() << "2--nothing---------" << std::endl;
        std::cout << "3--nothing---------" << std::endl;
    };
    co::go(&req_lambda3, make_shared<LambdaParams2>(make_shared<http::Client>(URL.c_str()), make_shared<string>("asdk")));
    std::cout << "4--nothing---------" << std::endl;
    std::this_thread::sleep_for(10000ms);

输出 4--nothing--------- │ 1--nothing---------

抓包没有发送请求

预期 应当 get 成功发送请求

环境

ubuntu18 amd64. g++ 5.5. c++14. libcurl 7.73.0.

#include <opencv2/imgproc.hpp>
#include <opencv2/imgcodecs.hpp>
#include <co/co.h>
#include <co/log.h>

DEC_bool(cout);

int main(int argc, char** argv)
{
    co::init();
    log::init();

    FLG_cout = true;

    co::WaitGroup wg;

    auto mat = cv::imread("./bar.jpeg", cv::IMREAD_UNCHANGED);
    cv::Mat tmp;
    cv::resize(mat, tmp, cv::Size(100, 100));

    LOG << "resize " << tmp.cols << " " << tmp.rows;

    go([wg, mat]{
        wg.add();
        cv::Mat tmp;
        cv::resize(mat, tmp, cv::Size(200, 200));

        LOG << "resize2 " << tmp.cols << " " << tmp.rows;

        wg.done();
    });

    wg.wait();

    return 0;
}

堆栈

#0  cv::hal_baseline::v_int16x8::v_int16x8 (this=0x9fafd01c, v=...)
    at /Volumes/Docs/git/cppframe/build-armeabihf-v7a-Debug/_deps/opencv-src/modules/core/include/opencv2/core/hal/intrin_neon.hpp:206
#1  0xa4b53fd8 in cv::hal_baseline::v_load (ptr=0x9fb1e780)
    at /Volumes/Docs/git/cppframe/build-armeabihf-v7a-Debug/_deps/opencv-src/modules/core/include/opencv2/core/hal/intrin_neon.hpp:1277
#2  0xa4e1bcf0 in cv::HResizeLinearVecU8_X4::operator() (this=0x9fafd688, src=0x9fafd78c, 
    dst=0x9fafd74c, count=2, xofs=0x9fb1db00, alpha=0x9fb1e780, dmax=600, cn=3, xmax=600)
    at /Volumes/Docs/git/cppframe/build-armeabihf-v7a-Debug/_deps/opencv-src/modules/imgproc/src/resize.cpp:1744
#3  0xa4e4bd78 in cv::HResizeLinear<unsigned char, int, short, 2048, cv::HResizeLinearVecU8_X4>::operator() (this=0x9fafdbf8, src=0x9fafd78c, dst=0x9fafd74c, count=2, xofs=0x9fb1db00, 
    alpha=0x9fb1e780, swidth=3240, dwidth=600, cn=3, xmin=0, xmax=600)
    at /Volumes/Docs/git/cppframe/build-armeabihf-v7a-Debug/_deps/opencv-src/modules/imgproc/src/resize.cpp:1830
#4  0xa4e4357c in cv::resizeGeneric_Invoker<cv::HResizeLinear<unsigned char, int, short, 2048, cv::HResizeLinearVecU8_X4>, cv::VResizeLinear<unsigned char, int, short, cv::FixedPtCast<int, unsigned char, 22>, cv::VResizeLinearVec_32s8u> >::operator() (this=0x9fafdcfc, range=...)
    at /Volumes/Docs/git/cppframe/build-armeabihf-v7a-Debug/_deps/opencv-src/modules/imgproc/src/resize.cpp:2167
#5  0xa490fc04 in cv::parallel_for_impl (range=..., body=..., nstripes=0.6103515625)
    at /Volumes/Docs/git/cppframe/build-armeabihf-v7a-Debug/_deps/opencv-src/modules/core/src/parallel.cpp:540
#6  0xa490f9a8 in cv::parallel_for_ (range=..., body=..., nstripes=0.6103515625)
    at /Volumes/Docs/git/cppframe/build-armeabihf-v7a-Debug/_deps/opencv-src/modules/core/src/parallel.cpp:506
#7  0xa4e21438 in cv::resizeGeneric_<cv::HResizeLinear<unsigned char, int, short, 2048, cv::HResizeLinearVecU8_X4>, cv::VResizeLinear<unsigned char, int, short, cv::FixedPtCast<int, unsigned char, 22>, cv::VResizeLinearVec_32s8u> > (src=..., dst=..., xofs=0x9fb1db00, _alpha=0x9fb1e780, 
    yofs=0x9fb1e460, _beta=0x9fb1f0e0, xmin=0, xmax=600, ksize=2)
    at /Volumes/Docs/git/cppframe/build-armeabihf-v7a-Debug/_deps/opencv-src/modules/imgproc/src/resize.cpp:2204
#8  0xa4e20268 in cv::hal::resize (src_type=16, 
--Type <RET> for more, q to quit, c to continue without paging--c
    src_data=0x9ff25040 "4MQ-FJ)BF*CG0FK1GL3IN5KP6MO7OO2JJ1JF3NJ5QK5RI:VP9TQ0JJ7NP;RT0FK)?D.DJ2HN4GN5HO5HP2EM.AI.AI4GO9NV1HP+EL+CI.FL-EK)AG(@F,DJ.GK/HL/HL-FJ+DH+DH-FJ0IM/IO3MS5MS4LR6KS1FN0CK4GO0CK(;C/BI5HO,@E,@E2HM2IK3GH/DB,A"..., src_step=3240, src_width=1080, src_height=720, dst_data=0x9fb005c0 "", dst_step=600, dst_width=200, dst_height=200, inv_scale_x=0.18518518518518517, inv_scale_y=0.27777777777777779, interpolation=1) at /Volumes/Docs/git/cppframe/build-armeabihf-v7a-Debug/_deps/opencv-src/modules/imgproc/src/resize.cpp:4036
#9  0xa4e209d8 in cv::resize (_src=..., _dst=..., dsize=..., inv_scale_x=0.18518518518518517, inv_scale_y=0.27777777777777779, interpolation=1) at /Volumes/Docs/git/cppframe/build-armeabihf-v7a-Debug/_deps/opencv-src/modules/imgproc/src/resize.cpp:4089
#10 0x000126c0 in <lambda()>::operator()(void) const (__closure=0x340d4) at /Volumes/Docs/git/cppframe/frameworks/wuyi_core/main.cpp:26
#11 0x00014004 in co::xx::Function0<main(int, char**)::<lambda()> >::run(void) (this=0x340d0) at /Volumes/Docs/git/cppframe/build-armeabihf-v7a-Debug/install/wuyi_util/include/co/closure.h:24
#12 0xa6477230 in co::SchedulerImpl::main_func (from=...) at /Volumes/Docs/git/cppframe/build-armeabihf-v7a-Debug/_deps/libco-src/src/co/scheduler.cc:38
#13 0xa64b5b44 in tb_context_make () at /Volumes/Docs/git/cppframe/build-armeabihf-v7a-Debug/_deps/libco-src/src/co/context/context_arm.S:131

co::close 触发了del_event(ev) 但是co::recvfrom等待的EV_read 消息订阅被删除，但是recvfrom仍然在等待。

解决方法： 1、或许可以加入EV_close/EV_ignore之类的事件。 2、IoEvent加入多事件绑定，同时绑定EV_read和EV_close/EV_ignore。

https://github.com/idealvin/co/blob/110eadde2c89dffa259a161c100cd4161253441f/base/json.cc#L15

正常访问一个object的member时，应该先调用has_member()来进行判断。但看上面函数的代码，如果直接使用[]来访问相关member，这里的逻辑似乎是打算支持这种行为？

如果不支持的话，21&22行的意义何在呢？ 如果支持的话，接下来访问其它member或者调用str()就会出错了。如以下代码：

#include "co/json.h"

int main() {
  auto v = json::parse("{\"name\": \"tiger\"}");
  v["n"];
  printf("%s\n", v["name"].str().c_str());
  return 0;
}

输出结果是null

编译器采用gcc-arm-none-eabi

在编译context_arm.S时，出现如下问题

make all arm-sylixos-eabi-gcc -mcpu=cortex-a9 -mno-unaligned-access -O0 -g3 -gdwarf-2 -Wall -fmessage-length=0 -fsigned-char -fno-short-enums -fno-strict-aliasing -x assembler-with-cpp -DSYLIXOS -D__linux__ -D__ARM_ARCH_7A__ -DSYLIXOS_LIB -I"D:\SylixOS_WS\workspace\coost/include" -I"D:/SylixOS_WS/workspace/ArmLite/libsylixos/SylixOS" -I"D:/SylixOS_WS/workspace/ArmLite/libsylixos/SylixOS/include" -I"D:/SylixOS_WS/workspace/ArmLite/libsylixos/SylixOS/include/network" -MMD -MP -MF ./Debug/dep/libcoost.so/src/co/context/context_arm.d -c src/co/context/context_arm.S -o Debug/obj/libcoost.so/src/co/context/context_arm.o src/co/context/context_arm.S: Assembler messages: src/co/context/context_arm.S:102: Error: bad instructionfunction tb_context_make,export=1' src/co/context/context_arm.S:142: Error: bad instruction endfunc' src/co/context/context_arm.S:152: Error: bad instructionfunction tb_context_jump,export=1' src/co/context/context_arm.S:204: Error: bad instruction endfunc' make: *** [Debug/obj/libcoost.so/src/co/context/context_arm.o] Error 1

无法识别汇编代码中的 function 以及 endfunc

支持格式化字符串，而不再需要用sprintf，例如folly库中的这种用法：

using folly::format;
using folly::sformat;

// Objects produced by format() can be streamed without creating
// an intermediary string; {} yields the next argument using default
// formatting.
std::cout << format("The answers are {} and {}", 23, 42);
// => "The answers are 23 and 42"

// If you just want the string, though, you're covered.
std::string result = sformat("The answers are {} and {}", 23, 42);
// => "The answers are 23 and 42"

// To insert a literal '{' or '}', just double it.
std::cout << format("{} {{}} {{{}}}", 23, 42);
// => "23 {} {42}"

// Arguments can be referenced out of order, even multiple times
std::cout << format("The answers are {1}, {0}, and {1} again", 23, 42);
// => "The answers are 42, 23, and 42 again"

// It's perfectly fine to not reference all arguments
std::cout << format("The only answer is {1}", 23, 42);
// => "The only answer is 42"

// Values can be extracted from indexable containers
// (random-access sequences and integral-keyed maps), and also from
// string-keyed maps
std::vector<int> v {23, 42};
std::map<std::string, std::string> m { {"what", "answer"} };
std::cout << format("The only {1[what]} is {0[1]}", v, m);
// => "The only answer is 42"

// format works with pairs and tuples
std::tuple<int, std::string, int> t {42, "hello", 23};
std::cout << format("{0} {2} {1}", t);
// => "42 23 hello"

// Format supports width, alignment, arbitrary fill, and various
// format specifiers, with meanings similar to printf
// "X<10": fill with 'X', left-align ('<'), width 10
std::cout << format("{:X<10} {}", "hello", "world");
// => "helloXXXXX world"

// Field width may be a runtime value rather than part of the format string
int x = 6;
std::cout << format("{:-^*}", x, "hi");
// => "--hi--"

// Explicit arguments work with dynamic field width, as long as indexes are
// given for both the value and the field width.
std::cout << format("{2:+^*0}",
9, "unused", 456); // => "+++456+++"

// Format supports printf-style format specifiers
std::cout << format("{0:05d} decimal = {0:04x} hex", 42);
// => "00042 decimal = 002a hex"

// Formatter objects may be written to a string using folly::to or
// folly::toAppend (see folly/Conv.h), or by calling their appendTo(),
// and str() methods
std::string s = format("The only answer is {}", 42).str();
std::cout << s;
// => "The only answer is 42"

// Decimal precision usage
std::cout << format("Only 2 decimals is {:.2f}", 23.34134534535);
// => "Only 2 decimals is 23.34"