如何解决使用 boost::future .then() 将延续任务添加到同一个线程池

我是 Boost 的新手。我正在使用 Boost 1.72.0。我正在尝试探索 boost::asio::thread_pool 并根据 documentation 向其发布任务。我尝试按如下方式发布已发布任务的延续：

使用 boost::launch::executor 策略：

fut.then(boost::launch::executor,[](boost::future<void> res) {

        std::thread::id this_id = std::this_thread::get_id();
        std::cout << "\nThread Id:" << this_id;
        std::cout << "\nThen Task: Start";
    });

在上述情况下，代码崩溃如下。

>   ThreadPool_Boost.exe!boost::executors::executor_ref<boost::executors::executor>::submit(boost::detail::nullary_function<void __cdecl(void)> && closure={...}) Line 73   C++ Symbols loaded.
    [Inline Frame] ThreadPool_Boost.exe!boost::executors::executor::submit(boost::detail::run_it<boost::detail::continuation_shared_state<boost::future<void>,void,void <lambda>(boost::future<void>),boost::detail::shared_state<void>>> &&) Line 107  C++ Symbols loaded.
    ThreadPool_Boost.exe!boost::detail::future_executor_continuation_shared_state<boost::future<void>,void <lambda>(boost::future<void>)>::launch_continuation() Line 4711 C++ Symbols loaded.
    ThreadPool_Boost.exe!boost::detail::shared_state<void>::do_continuation(boost::unique_lock<boost::mutex> & lock={...}) Line 853 C++ Symbols loaded.
    [Inline Frame] ThreadPool_Boost.exe!boost::detail::shared_state_base::mark_finished_internal(boost::unique_lock<boost::mutex> &) Line 345   C++ Symbols loaded.
    [Inline Frame] ThreadPool_Boost.exe!boost::detail::shared_state<void>::mark_finished_with_result_internal(boost::unique_lock<boost::mutex> &) Line 857  C++ Symbols loaded.
    ThreadPool_Boost.exe!boost::detail::shared_state<void>::mark_finished_with_result() Line 864    C++ Symbols loaded.
    ThreadPool_Boost.exe!boost::detail::task_shared_state<void <lambda>(void),void __cdecl(void)>::do_run() Line 3423   C++ Symbols loaded.
    [Inline Frame] ThreadPool_Boost.exe!boost::detail::task_base_shared_state<void __cdecl(void)>::run() Line 2995  C++ Symbols loaded.
    [Inline Frame] ThreadPool_Boost.exe!boost::packaged_task<void __cdecl(void)>::operator()() Line 3781    C++ Symbols loaded.
    ThreadPool_Boost.exe!boost::asio::asio_handler_invoke<boost::packaged_task<void __cdecl(void)>>(boost::packaged_task<void __cdecl(void)> & function,...) Line 70   C++ Symbols loaded.
    [Inline Frame] ThreadPool_Boost.exe!boost_asio_handler_invoke_helpers::invoke(boost::packaged_task<void __cdecl(void)> &) Line 37   C++ Symbols loaded.
    [Inline Frame] ThreadPool_Boost.exe!boost::asio::system_executor::dispatch(boost::packaged_task<void __cdecl(void)> &&) Line 39 C++ Symbols loaded.
    [Inline Frame] ThreadPool_Boost.exe!boost::asio::detail::work_dispatcher<boost::packaged_task<void __cdecl(void)>>::operator()() Line 59    C++ Symbols loaded.
    ThreadPool_Boost.exe!boost::asio::asio_handler_invoke<boost::asio::detail::work_dispatcher<boost::packaged_task<void __cdecl(void)>>>(boost::asio::detail::work_dispatcher<boost::packaged_task<void __cdecl(void)>> & function={...},...) Line 69 C++ Symbols loaded.
    [Inline Frame] ThreadPool_Boost.exe!boost_asio_handler_invoke_helpers::invoke(boost::asio::detail::work_dispatcher<boost::packaged_task<void __cdecl(void)>> &) Line 37 C++ Symbols loaded.
    ThreadPool_Boost.exe!boost::asio::detail::executor_op<boost::asio::detail::work_dispatcher<boost::packaged_task<void __cdecl(void)>>,std::allocator<void>,boost::asio::detail::scheduler_operation>::do_complete(void * owner=0x011a61d8,boost::asio::detail::scheduler_operation * base=0x011af1c8,const boost::system::error_code & __formal={...},unsigned int __formal=0x00000000) Line 70   C++ Symbols loaded.
    [Inline Frame] ThreadPool_Boost.exe!boost::asio::detail::scheduler_operation::complete(void *) Line 40  C++ Symbols loaded.
    ThreadPool_Boost.exe!boost::asio::detail::scheduler::do_run_one(boost::asio::detail::conditionally_enabled_mutex::scoped_lock & lock={...},boost::asio::detail::scheduler_thread_info & this_thread={...},const boost::system::error_code & ec={...}) Line 449    C++ Symbols loaded.
    ThreadPool_Boost.exe!boost::asio::detail::scheduler::run(boost::system::error_code & ec={...}) Line 200 C++ Symbols loaded.
    [Inline Frame] ThreadPool_Boost.exe!boost::asio::thread_pool::thread_function::operator()() Line 33 C++ Symbols loaded.
    ThreadPool_Boost.exe!boost::asio::detail::win_thread::func<boost::asio::thread_pool::thread_function>::run() Line 123   C++ Symbols loaded.
    ThreadPool_Boost.exe!boost::asio::detail::win_thread_function(void * arg=0x011a65a0) Line 128   C++ Symbols loaded.
    ucrtbase.dll!767b38df() Unknown Non-user code. Symbol loading disabled by Include/Exclude setting.
    ucrtbase.dll![Frames below may be incorrect and/or missing,no symbols loaded for ucrtbase.dll] Unknown No symbols loaded.
    kernel32.dll!77b36359() Unknown Non-user code. Symbol loading disabled by Include/Exclude setting.
    ntdll.dll!77d88944()    Unknown Non-user code. Symbol loading disabled by Include/Exclude setting.
    ntdll.dll!77d88914()    Unknown Non-user code. Symbol loading disabled by Include/Exclude setting.

使用“then”的变体，我们可以在其中提及执行者：

fut.then(pool.get_executor(),[](boost::future<void> res) {  /* <---- This is line 62 */

        std::thread::id this_id = std::this_thread::get_id();
        std::cout << "\nThread Id:" << this_id;
        std::cout << "\nThen Task: Start";
    });

上面的代码编译失败，说明如下：

1>C:\Users\shtrived\Desktop\AsyncTask\ThreadPool_Boost\Demo.cpp(62,5): error C2664: 'boost::future<void> boost::future<void>::then<boost::asio::thread_pool::executor_type,main::<lambda_c8a45d8f92e13883b6218f06c9a06a8d>>(Ex &,F &&)': cannot convert argument 1 from 'boost::asio::thread_pool::executor_type' to 'boost::launch'
1>        with
1>        [
1>            Ex=boost::asio::thread_pool::executor_type,1>            F=main::<lambda_c8a45d8f92e13883b6218f06c9a06a8d>
1>        ]

问题：

为什么会出现上述运行时和编译时错误？
如何仅将延续正确发布到线程池？

完整示例代码：

#define BOOST_THREAD_PROVIDES_FUTURE
#define BOOST_THREAD_PROVIDES_SIGNATURE_PACKAGED_TASK
#define BOOST_THREAD_PROVIDES_VARIADIC_THREAD
#define BOOST_ERROR_CODE_HEADER_ONLY
#define BOOST_THREAD_PROVIDES_FUTURE_UNWRAP
#define BOOST_THREAD_PROVIDES_FUTURE_CONTINUATION
#define BOOST_RESULT_OF_USE_DECLTYPE
#define BOOST_THREAD_VERSION 4
#define BOOST_THREAD_PROVIDES_EXECUTORS   //on including this we start getting build errors

#include <boost/thread.hpp>
#include <boost/thread/future.hpp>
#include<iostream>
#include<thread>
#include<stdexcept> //only for testing
#include<vector>
//#include<boost/asio/executor.hpp>
#include<boost/asio.hpp>

int main()
{
    boost::asio::thread_pool pool(1);

    //This is the first function that we want to run on the thread pool 
    auto func = []() {
        cout << "\nTask in progress";
        std::thread::id this_id = std::this_thread::get_id();
        cout << "\nThread Id:" << this_id << " Task 1: Just a cout";
    };

    //Make a packaged task with the above function
    boost::packaged_task<void()> task(std::move(func));

    //Get the future from the packaged task
    boost::future<void> fut = task.get_future();

    //Post the task into the thread pool
    boost::asio::post(pool,std::move(task));

    /*
     * We want to run the continuation in the same thread pool
     */
    fut.then(pool.get_executor(),[](boost::future<void> res) {

        std::thread::id this_id = std::this_thread::get_id();
        std::cout << "\nThread Id:" << this_id;
        std::cout << "\nThen Task: Start";
    });

    pool.join();
    cout << "\nJoin Complete";
}

使用 boost::future .then() 将延续任务添加到同一个线程池

如何解决使用 boost::future .then() 将延续任务添加到同一个线程池

问题：

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