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awaitable examples are simplified

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No need for `rebind_executor` as `asio::deferred` is now the default completion token.
This commit is contained in:
Mohammad Nejati
2024-07-07 14:58:49 +03:30
committed by Mohammad Nejati
parent aabd5b51d3
commit ff5672ec07
6 changed files with 695 additions and 1309 deletions
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example/http/client/awaitable-ssl/http_client_awaitable_ssl.cpp
+79 -84
View File
@@ -13,28 +13,27 @@
//
//------------------------------------------------------------------------------
#include <boost/beast/core.hpp>
#include <boost/beast/http.hpp>
#include <boost/beast/version.hpp>
#include <boost/asio/as_tuple.hpp>
#include <boost/asio/awaitable.hpp>
#include <boost/asio/co_spawn.hpp>
#include <boost/asio/detached.hpp>
#include <boost/asio/io_context.hpp>
#include <boost/asio/ssl.hpp>
#include <boost/asio/use_awaitable.hpp>
#include <boost/beast/core.hpp>
#include <boost/beast/http.hpp>
#include <boost/beast/version.hpp>
#if defined(BOOST_ASIO_HAS_CO_AWAIT)
#include "example/common/root_certificates.hpp"
#include <cstdlib>
#include <iostream>
#include <string>
#include "example/common/root_certificates.hpp"
namespace beast = boost::beast; // from <boost/beast.hpp>
namespace http = beast::http; // from <boost/beast/http.hpp>
namespace net = boost::asio; // from <boost/asio.hpp>
namespace ssl = boost::asio::ssl; // from <boost/asio/ssl.hpp>
using tcp = boost::asio::ip::tcp; // from <boost/asio/ip/tcp.hpp>
#if defined(BOOST_ASIO_HAS_CO_AWAIT)
namespace beast = boost::beast;
namespace http = beast::http;
namespace net = boost::asio;
namespace ssl = boost::asio::ssl;
//------------------------------------------------------------------------------
@@ -47,23 +46,17 @@ do_session(
int version,
ssl::context& ctx)
{
// These objects perform our I/O
// They use an executor with a default completion token of use_awaitable
// This makes our code easy, but will use exceptions as the default error handling,
// i.e. if the connection drops, we might see an exception.
// See async_shutdown for error handling with an error_code.
auto resolver = net::use_awaitable.as_default_on(tcp::resolver(co_await net::this_coro::executor));
using executor_with_default = net::use_awaitable_t<>::executor_with_default<net::any_io_executor>;
using tcp_stream = typename beast::tcp_stream::rebind_executor<executor_with_default>::other;
// We construct the ssl stream from the already rebound tcp_stream.
ssl::stream<tcp_stream> stream{
net::use_awaitable.as_default_on(beast::tcp_stream(co_await net::this_coro::executor)),
ctx};
auto executor = co_await net::this_coro::executor;
auto resolver = net::ip::tcp::resolver{ executor };
auto stream = ssl::stream<beast::tcp_stream>{ executor, ctx };
// Set SNI Hostname (many hosts need this to handshake successfully)
if(! SSL_set_tlsext_host_name(stream.native_handle(), host.c_str()))
throw boost::system::system_error(static_cast<int>(::ERR_get_error()), net::error::get_ssl_category());
if(!SSL_set_tlsext_host_name(stream.native_handle(), host.c_str()))
{
throw boost::system::system_error(
static_cast<int>(::ERR_get_error()),
net::error::get_ssl_category());
}
// Look up the domain name
auto const results = co_await resolver.async_resolve(host, port);
@@ -81,7 +74,7 @@ do_session(
co_await stream.async_handshake(ssl::stream_base::client);
// Set up an HTTP GET request message
http::request<http::string_body> req{http::verb::get, target, version};
http::request<http::string_body> req{ http::verb::get, target, version };
req.set(http::field::host, host);
req.set(http::field::user_agent, BOOST_BEAST_VERSION_STRING);
@@ -92,13 +85,13 @@ do_session(
co_await http::async_write(stream, req);
// This buffer is used for reading and must be persisted
beast::flat_buffer b;
beast::flat_buffer buffer;
// Declare a container to hold the response
http::response<http::dynamic_body> res;
// Receive the HTTP response
co_await http::async_read(stream, b, res);
co_await http::async_read(stream, buffer, res);
// Write the message to standard out
std::cout << res << std::endl;
@@ -107,7 +100,7 @@ do_session(
beast::get_lowest_layer(stream).expires_after(std::chrono::seconds(30));
// Gracefully close the stream - do not threat every error as an exception!
auto [ec] = co_await stream.async_shutdown(net::as_tuple(net::use_awaitable));
auto [ec] = co_await stream.async_shutdown(net::as_tuple);
// ssl::error::stream_truncated, also known as an SSL "short read",
// indicates the peer closed the connection without performing the
@@ -126,75 +119,77 @@ do_session(
// Therefore, if we see a short read here, it has occurred
// after the message has been completed, so it is safe to ignore it.
if(ec != net::ssl::error::stream_truncated)
if(ec && ec != net::ssl::error::stream_truncated)
throw boost::system::system_error(ec, "shutdown");
}
//------------------------------------------------------------------------------
int main(int argc, char** argv)
int
main(int argc, char** argv)
{
// Check command line arguments.
if(argc != 4 && argc != 5)
try
{
std::cerr <<
"Usage: http-client-awaitable <host> <port> <target> [<HTTP version: 1.0 or 1.1(default)>]\n" <<
"Example:\n" <<
" http-client-awaitable www.example.com 443 /\n" <<
" http-client-awaitable www.example.com 443 / 1.0\n";
// Check command line arguments.
if(argc != 4 && argc != 5)
{
std::cerr
<< "Usage: http-client-awaitable <host> <port> <target> [<HTTP version: 1.0 or 1.1(default)>]\n"
<< "Example:\n"
<< " http-client-awaitable www.example.com 443 /\n"
<< " http-client-awaitable www.example.com 443 / 1.0\n";
return EXIT_FAILURE;
}
auto const host = argv[1];
auto const port = argv[2];
auto const target = argv[3];
auto const version =
argc == 5 && !std::strcmp("1.0", argv[4]) ? 10 : 11;
// The io_context is required for all I/O
net::io_context ioc;
// The SSL context is required, and holds certificates
ssl::context ctx{ ssl::context::tlsv12_client };
// This holds the root certificate used for verification
load_root_certificates(ctx);
// Verify the remote server's certificate
ctx.set_verify_mode(ssl::verify_peer);
// Launch the asynchronous operation
net::co_spawn(
ioc,
do_session(host, port, target, version, ctx),
// If the awaitable exists with an exception, it gets delivered here
// as `e`. This can happen for regular errors, such as connection
// drops.
[](std::exception_ptr e)
{
if(e)
std::rethrow_exception(e);
});
// Run the I/O service. The call will return when
// the get operation is complete.
ioc.run();
}
catch(std::exception const& e)
{
std::cerr << "Error: " << e.what() << std::endl;
return EXIT_FAILURE;
}
auto const host = argv[1];
auto const port = argv[2];
auto const target = argv[3];
int version = argc == 5 && !std::strcmp("1.0", argv[4]) ? 10 : 11;
// The io_context is required for all I/O
net::io_context ioc;
// The SSL context is required, and holds certificates
ssl::context ctx{ssl::context::tlsv12_client};
// This holds the root certificate used for verification
load_root_certificates(ctx);
// Verify the remote server's certificate
ctx.set_verify_mode(ssl::verify_peer);
// Launch the asynchronous operation
net::co_spawn(
ioc,
do_session(host, port, target, version, ctx),
// If the awaitable exists with an exception, it gets delivered here as `e`.
// This can happen for regular errors, such as connection drops.
[](std::exception_ptr e)
{
if (!e)
return ;
try
{
std::rethrow_exception(e);
}
catch(std::exception & ex)
{
std::cerr << "Error: " << ex.what() << "\n";
}
});
// Run the I/O service. The call will return when
// the get operation is complete.
ioc.run();
return EXIT_SUCCESS;
}
#else
int main(int, char * [])
int
main(int, char*[])
{
std::printf("awaitables require C++20\n");
return 1;
return EXIT_FAILURE;
}
#endif
example/http/client/awaitable/http_client_awaitable.cpp
+59 -70
View File
@@ -13,44 +13,30 @@
//
//------------------------------------------------------------------------------
#include <boost/asio/awaitable.hpp>
#include <boost/asio/co_spawn.hpp>
#include <boost/asio/io_context.hpp>
#include <boost/beast/core.hpp>
#include <boost/beast/http.hpp>
#include <boost/beast/version.hpp>
#include <boost/asio/awaitable.hpp>
#include <boost/asio/co_spawn.hpp>
#include <boost/asio/detached.hpp>
#include <boost/asio/use_awaitable.hpp>
#if defined(BOOST_ASIO_HAS_CO_AWAIT)
#include <cstdlib>
#include <functional>
#include <iostream>
#include <string>
namespace beast = boost::beast; // from <boost/beast.hpp>
namespace http = beast::http; // from <boost/beast/http.hpp>
namespace net = boost::asio; // from <boost/asio.hpp>
using tcp = boost::asio::ip::tcp; // from <boost/asio/ip/tcp.hpp>
#if defined(BOOST_ASIO_HAS_CO_AWAIT)
//------------------------------------------------------------------------------
namespace beast = boost::beast;
namespace http = beast::http;
namespace net = boost::asio;
// Performs an HTTP GET and prints the response
net::awaitable<void>
do_session(
std::string host,
std::string port,
std::string target,
int version)
do_session(std::string host, std::string port, std::string target, int version)
{
// These objects perform our I/O
// They use an executor with a default completion token of use_awaitable
// This makes our code easy, but will use exceptions as the default error handling,
// i.e. if the connection drops, we might see an exception.
auto resolver = net::use_awaitable.as_default_on(tcp::resolver(co_await net::this_coro::executor));
auto stream = net::use_awaitable.as_default_on(beast::tcp_stream(co_await net::this_coro::executor));
auto executor = co_await net::this_coro::executor;
auto resolver = net::ip::tcp::resolver{ executor };
auto stream = beast::tcp_stream{ executor };
// Look up the domain name
auto const results = co_await resolver.async_resolve(host, port);
@@ -62,7 +48,7 @@ do_session(
co_await stream.async_connect(results);
// Set up an HTTP GET request message
http::request<http::string_body> req{http::verb::get, target, version};
http::request<http::string_body> req{ http::verb::get, target, version };
req.set(http::field::host, host);
req.set(http::field::user_agent, BOOST_BEAST_VERSION_STRING);
@@ -73,20 +59,20 @@ do_session(
co_await http::async_write(stream, req);
// This buffer is used for reading and must be persisted
beast::flat_buffer b;
beast::flat_buffer buffer;
// Declare a container to hold the response
http::response<http::dynamic_body> res;
// Receive the HTTP response
co_await http::async_read(stream, b, res);
co_await http::async_read(stream, buffer, res);
// Write the message to standard out
std::cout << res << std::endl;
// Gracefully close the socket
beast::error_code ec;
stream.socket().shutdown(tcp::socket::shutdown_both, ec);
stream.socket().shutdown(net::ip::tcp::socket::shutdown_both, ec);
// not_connected happens sometimes
// so don't bother reporting it.
@@ -99,58 +85,61 @@ do_session(
//------------------------------------------------------------------------------
int main(int argc, char** argv)
int
main(int argc, char** argv)
{
// Check command line arguments.
if(argc != 4 && argc != 5)
try
{
std::cerr <<
"Usage: http-client-awaitable <host> <port> <target> [<HTTP version: 1.0 or 1.1(default)>]\n" <<
"Example:\n" <<
" http-client-awaitable www.example.com 80 /\n" <<
" http-client-awaitable www.example.com 80 / 1.0\n";
// Check command line arguments.
if(argc != 4 && argc != 5)
{
std::cerr << "Usage: http-client-awaitable <host> <port> <target> [<HTTP version: 1.0 or 1.1(default)>]\n"
<< "Example:\n"
<< " http-client-awaitable www.example.com 80 /\n"
<< " http-client-awaitable www.example.com 80 / 1.0\n";
return EXIT_FAILURE;
}
auto const host = argv[1];
auto const port = argv[2];
auto const target = argv[3];
auto const version =
argc == 5 && !std::strcmp("1.0", argv[4]) ? 10 : 11;
// The io_context is required for all I/O
net::io_context ioc;
// Launch the asynchronous operation
net::co_spawn(
ioc,
do_session(host, port, target, version),
// If the awaitable exists with an exception, it gets delivered here
// as `e`. This can happen for regular errors, such as connection
// drops.
[](std::exception_ptr e)
{
if(e)
std::rethrow_exception(e);
});
// Run the I/O service. The call will return when
// the get operation is complete.
ioc.run();
}
catch(std::exception const& e)
{
std::cerr << "Error: " << e.what() << std::endl;
return EXIT_FAILURE;
}
auto const host = argv[1];
auto const port = argv[2];
auto const target = argv[3];
int version = argc == 5 && !std::strcmp("1.0", argv[4]) ? 10 : 11;
// The io_context is required for all I/O
net::io_context ioc;
// Launch the asynchronous operation
net::co_spawn(
ioc,
do_session(host, port, target, version),
// If the awaitable exists with an exception, it gets delivered here as `e`.
// This can happen for regular errors, such as connection drops.
[](std::exception_ptr e)
{
if (e)
try
{
std::rethrow_exception(e);
}
catch(std::exception & ex)
{
std::cerr << "Error: " << ex.what() << "\n";
}
});
// Run the I/O service. The call will return when
// the get operation is complete.
ioc.run();
return EXIT_SUCCESS;
}
#else
int main(int, char * [])
int
main(int, char*[])
{
std::printf("awaitables require C++20\n");
return 1;
return EXIT_FAILURE;
}
#endif
example/http/server/awaitable/http_server_awaitable.cpp
+86 -111
View File
@@ -13,14 +13,15 @@
//
//------------------------------------------------------------------------------
#include <boost/asio/awaitable.hpp>
#include <boost/asio/co_spawn.hpp>
#include <boost/asio/io_context.hpp>
#include <boost/asio/ip/tcp.hpp>
#include <boost/beast/core.hpp>
#include <boost/beast/http.hpp>
#include <boost/beast/version.hpp>
#include <boost/asio/ip/tcp.hpp>
#include <boost/asio/awaitable.hpp>
#include <boost/asio/co_spawn.hpp>
#include <boost/asio/use_awaitable.hpp>
#include <boost/config.hpp>
#include <algorithm>
#include <cstdlib>
#include <iostream>
@@ -31,13 +32,9 @@
#if defined(BOOST_ASIO_HAS_CO_AWAIT)
namespace beast = boost::beast; // from <boost/beast.hpp>
namespace http = beast::http; // from <boost/beast/http.hpp>
namespace net = boost::asio; // from <boost/asio.hpp>
using tcp = boost::asio::ip::tcp; // from <boost/asio/ip/tcp.hpp>
using tcp_stream = typename beast::tcp_stream::rebind_executor<
net::use_awaitable_t<>::executor_with_default<net::any_io_executor>>::other;
namespace beast = boost::beast;
namespace http = beast::http;
namespace net = boost::asio;
// Return a reasonable mime type based on the extension of a file.
beast::string_view
@@ -206,146 +203,123 @@ handle_request(
return res;
}
//------------------------------------------------------------------------------
// Handles an HTTP server connection
net::awaitable<void>
do_session(
tcp_stream stream,
beast::tcp_stream stream,
std::shared_ptr<std::string const> doc_root)
{
// This buffer is required to persist across reads
beast::flat_buffer buffer;
// This lambda is used to send messages
try
for(;;)
{
for(;;)
// Set the timeout.
stream.expires_after(std::chrono::seconds(30));
// Read a request
http::request<http::string_body> req;
co_await http::async_read(stream, buffer, req);
// Handle the request
http::message_generator msg = handle_request(*doc_root, std::move(req));
// Determine if we should close the connection
bool keep_alive = msg.keep_alive();
// Send the response
co_await beast::async_write(stream, std::move(msg));
if(!keep_alive)
{
// Set the timeout.
stream.expires_after(std::chrono::seconds(30));
// Read a request
http::request<http::string_body> req;
co_await http::async_read(stream, buffer, req);
// Handle the request
http::message_generator msg =
handle_request(*doc_root, std::move(req));
// Determine if we should close the connection
bool keep_alive = msg.keep_alive();
// Send the response
co_await beast::async_write(stream, std::move(msg), net::use_awaitable);
if(! keep_alive)
{
// This means we should close the connection, usually because
// the response indicated the "Connection: close" semantic.
break;
}
// This means we should close the connection, usually because
// the response indicated the "Connection: close" semantic.
break;
}
}
catch (boost::system::system_error & se)
{
if (se.code() != http::error::end_of_stream )
throw ;
}
// Send a TCP shutdown
beast::error_code ec;
stream.socket().shutdown(tcp::socket::shutdown_send, ec);
stream.socket().shutdown(net::ip::tcp::socket::shutdown_send);
// At this point the connection is closed gracefully
// we ignore the error because the client might have
// dropped the connection already.
}
//------------------------------------------------------------------------------
// Accepts incoming connections and launches the sessions
net::awaitable<void>
do_listen(
tcp::endpoint endpoint,
std::shared_ptr<std::string const> doc_root)
do_listen(net::ip::tcp::endpoint endpoint, std::shared_ptr<std::string const> doc_root)
{
// Open the acceptor
auto acceptor = net::use_awaitable.as_default_on(tcp::acceptor(co_await net::this_coro::executor));
acceptor.open(endpoint.protocol());
// Allow address reuse
acceptor.set_option(net::socket_base::reuse_address(true));
// Bind to the server address
acceptor.bind(endpoint);
// Start listening for connections
acceptor.listen(net::socket_base::max_listen_connections);
auto executor = co_await net::this_coro::executor;
auto acceptor = net::ip::tcp::acceptor{ executor, endpoint };
for(;;)
boost::asio::co_spawn(
acceptor.get_executor(),
do_session(tcp_stream(co_await acceptor.async_accept()), doc_root),
[](std::exception_ptr e)
{
net::co_spawn(
executor,
do_session(
beast::tcp_stream{ co_await acceptor.async_accept() },
doc_root),
[](std::exception_ptr e)
{
if(e)
{
if (e)
try
{
std::rethrow_exception(e);
}
catch (std::exception &e) {
std::cerr << "Error in session: " << e.what() << "\n";
}
});
try
{
std::rethrow_exception(e);
}
catch(std::exception const& e)
{
std::cerr << "Error in session: " << e.what() << "\n";
}
}
});
}
}
int main(int argc, char* argv[])
int
main(int argc, char* argv[])
{
// Check command line arguments.
if (argc != 5)
if(argc != 5)
{
std::cerr <<
"Usage: http-server-awaitable <address> <port> <doc_root> <threads>\n" <<
"Example:\n" <<
" http-server-awaitable 0.0.0.0 8080 . 1\n";
std::cerr << "Usage: http-server-awaitable <address> <port> <doc_root> <threads>\n"
<< "Example:\n"
<< " http-server-awaitable 0.0.0.0 8080 . 1\n";
return EXIT_FAILURE;
}
auto const address = net::ip::make_address(argv[1]);
auto const port = static_cast<unsigned short>(std::atoi(argv[2]));
auto const address = net::ip::make_address(argv[1]);
auto const port = static_cast<unsigned short>(std::atoi(argv[2]));
auto const doc_root = std::make_shared<std::string>(argv[3]);
auto const threads = std::max<int>(1, std::atoi(argv[4]));
auto const threads = std::max<int>(1, std::atoi(argv[4]));
// The io_context is required for all I/O
net::io_context ioc{threads};
net::io_context ioc{ threads };
// Spawn a listening port
boost::asio::co_spawn(ioc,
do_listen(tcp::endpoint{address, port}, doc_root),
[](std::exception_ptr e)
{
if (e)
try
{
std::rethrow_exception(e);
}
catch(std::exception & e)
{
std::cerr << "Error in acceptor: " << e.what() << "\n";
}
});
net::co_spawn(
ioc,
do_listen(net::ip::tcp::endpoint{ address, port }, doc_root),
[](std::exception_ptr e)
{
if(e)
{
try
{
std::rethrow_exception(e);
}
catch(std::exception const& e)
{
std::cerr << "Error: " << e.what() << std::endl;
}
}
});
// Run the I/O service on the requested number of threads
std::vector<std::thread> v;
v.reserve(threads - 1);
for(auto i = threads - 1; i > 0; --i)
v.emplace_back(
[&ioc]
{
ioc.run();
});
v.emplace_back([&ioc] { ioc.run(); });
ioc.run();
return EXIT_SUCCESS;
@@ -353,10 +327,11 @@ int main(int argc, char* argv[])
#else
int main(int, char * [])
int
main(int, char*[])
{
std::printf("awaitables require C++20\n");
return 1;
return EXIT_FAILURE;
}
#endif
#endif