82 lines
2.6 KiB
C++
82 lines
2.6 KiB
C++
#include <boost/asio/associated_executor.hpp>
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#include <boost/asio/bind_executor.hpp>
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#include <boost/asio/execution.hpp>
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#include <boost/asio/static_thread_pool.hpp>
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#include <iostream>
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#include <string>
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using boost::asio::bind_executor;
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using boost::asio::get_associated_executor;
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using boost::asio::static_thread_pool;
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namespace execution = boost::asio::execution;
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// A function to asynchronously read a single line from an input stream.
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template <class IoExecutor, class Handler>
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void async_getline(IoExecutor io_ex, std::istream& is, Handler handler)
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{
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// Track work for the handler's associated executor.
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auto work_ex = boost::asio::prefer(
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get_associated_executor(handler, io_ex),
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execution::outstanding_work.tracked);
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// Post a function object to do the work asynchronously.
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execution::execute(
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boost::asio::require(io_ex, execution::blocking.never),
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[&is, work_ex, handler=std::move(handler)]() mutable
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{
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std::string line;
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std::getline(is, line);
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// Pass the result to the handler, via the associated executor.
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execution::execute(
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boost::asio::prefer(work_ex, execution::blocking.possibly),
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[line=std::move(line), handler=std::move(handler)]() mutable
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{
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handler(std::move(line));
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});
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});
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}
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// A function to asynchronously read multiple lines from an input stream.
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template <class IoExecutor, class Handler>
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void async_getlines(IoExecutor io_ex, std::istream& is, std::string init, Handler handler)
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{
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// Track work for the I/O executor.
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auto io_work_ex = boost::asio::prefer(io_ex,
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execution::outstanding_work.tracked);
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// Track work for the handler's associated executor.
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auto handler_work_ex = boost::asio::prefer(
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get_associated_executor(handler, io_ex),
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execution::outstanding_work.tracked);
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// Use the associated executor for each operation in the composition.
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async_getline(io_work_ex, is,
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bind_executor(handler_work_ex,
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[io_work_ex, &is, lines=std::move(init), handler=std::move(handler)]
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(std::string line) mutable
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{
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if (line.empty())
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handler(lines);
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else
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async_getlines(io_work_ex, is, lines + line + "\n", std::move(handler));
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}));
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}
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int main()
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{
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static_thread_pool io_pool(1);
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static_thread_pool completion_pool(1);
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std::cout << "Enter text, terminating with a blank line:\n";
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async_getlines(io_pool.executor(), std::cin, "",
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bind_executor(completion_pool.executor(), [](std::string lines)
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{
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std::cout << "Lines:\n" << lines << "\n";
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}));
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io_pool.wait();
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completion_pool.wait();
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}
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