async_1.cpp
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#include <asio/associated_executor.hpp>
#include <asio/bind_executor.hpp>
#include <asio/execution.hpp>
#include <asio/static_thread_pool.hpp>
#include <iostream>
#include <string>
using asio::bind_executor;
using asio::get_associated_executor;
using asio::static_thread_pool;
namespace execution = asio::execution;
// A function to asynchronously read a single line from an input stream.
template <class IoExecutor, class Handler>
void async_getline(IoExecutor io_ex, std::istream& is, Handler handler)
{
// Track work for the handler's associated executor.
auto work_ex = asio::prefer(
get_associated_executor(handler, io_ex),
execution::outstanding_work.tracked);
// Post a function object to do the work asynchronously.
execution::execute(
asio::require(io_ex, execution::blocking.never),
[&is, work_ex, handler=std::move(handler)]() mutable
{
std::string line;
std::getline(is, line);
// Pass the result to the handler, via the associated executor.
execution::execute(
asio::prefer(work_ex, execution::blocking.possibly),
[line=std::move(line), handler=std::move(handler)]() mutable
{
handler(std::move(line));
});
});
}
int main()
{
static_thread_pool io_pool(1);
static_thread_pool completion_pool(1);
std::cout << "Enter a line: ";
async_getline(io_pool.executor(), std::cin,
bind_executor(completion_pool.executor(),
[](std::string line)
{
std::cout << "Line: " << line << "\n";
}));
io_pool.wait();
completion_pool.wait();
}