TCP Socket.cancel doesn't cause scheduled writes to cancel #446
Description
Hi,
I'm trying to cancel any pending writes to a socket once realising the socket on the other end has gone away after not responding to messages. I was hoping to use basic_stream_socket::cancel but after calling it i can still poll the io context and get it to trigger writes i had queued up. I've produced the following unit test demonstrating what i mean.
#define BOOST_TEST_DYN_LINK
#define BOOST_TEST_MAIN
#define BOOST_TEST_MODULE "C++ Unit Tests for Application"
#include <boost/test/unit_test.hpp>
#include <boost/lexical_cast.hpp>
#include <boost/system/detail/errc.hpp>
#include <boost/system/detail/error_code.hpp>
#define BOOST_TEST_DYN_LINK
#include <boost/test/data/test_case.hpp>
#include <boost/test/framework.hpp>
#include <boost/asio.hpp>
using namespace boost::unit_test::framework;
BOOST_AUTO_TEST_SUITE(BoostSocketTest)
BOOST_AUTO_TEST_CASE(OnClearCallsCancelsIOContext) {
// Arrange
// Create a socket and listen on a port
boost::asio::io_context child_io_context;
boost::asio::ip::tcp::socket child_socket(child_io_context);
boost::asio::ip::tcp::endpoint child_endpoint(boost::asio::ip::tcp::v4(), 5001);
boost::asio::ip::tcp::acceptor child_acceptor(child_io_context);
child_acceptor.open(child_endpoint.protocol());
child_acceptor.set_option(boost::asio::ip::tcp::acceptor::reuse_address(true));
child_acceptor.bind(child_endpoint);
child_acceptor.listen();
bool accepted = false;
child_acceptor.async_accept(
child_socket,
[&accepted](boost::system::error_code ec)
{
if (ec) {
BOOST_FAIL("failed to listen on child socket");
} else {
accepted = true;
}
return;
});
// Create another socket and connect it to the other one
boost::asio::io_context parent_io_context;
boost::asio::ip::tcp::socket parent_socket(parent_io_context);
boost::asio::ip::tcp::resolver parent_resolver(parent_io_context);
bool connected = false;
parent_resolver.async_resolve(
"localhost", "5001",
[&connected, &parent_socket](const boost::system::error_code ec, boost::asio::ip::tcp::resolver::results_type results)
{
BOOST_TEST(ec == boost::system::errc::success, "failed to resolve");
boost::asio::async_connect(parent_socket, results,
[&connected](const boost::system::error_code& ec, const boost::asio::ip::tcp::endpoint& )
{
BOOST_TEST(ec == boost::system::errc::success, "failed to connect");
connected = true;
});
});
// Wait for the parent socket to connect to the
// child socket once completed the IO Contexts
// will have no work left to do so will set their
// state to stopped
while (!accepted or !connected) {
child_io_context.poll();
parent_io_context.poll();
}
BOOST_TEST((accepted && connected), "failed to connect or accept as such cannot simulate interrupted write");
// Queue a message to be sent from the parent socket to the child socket
std::string test_data = "test";
bool callback_was_called = false;
boost::asio::async_write(parent_socket, boost::asio::buffer((uint8_t*)(test_data.data()), test_data.size()),
[&callback_was_called](boost::system::error_code ec, size_t) {
callback_was_called = true;
// Check the reccieved error code is a connection aborted one
BOOST_TEST(ec == boost::system::errc::connection_aborted, "callback was not called with boost operation aborted");
return;
});
// Restart the IO context as there is more work to do
// and fail the test case if it fails to restart
parent_io_context.restart();
if(parent_io_context.stopped()){
BOOST_FAIL("failed to restart parent io context");
}
// Act - cancel the message that was queued to be sent
// this should call the callback and mean there is no
// work to do at the next poll
parent_socket.cancel();
// Assert - that if you poll the io context it doesn't
// send and that the callback was called, if it was
// it will already have checked it reccieved a connection
// aborted error
auto executed = parent_io_context.poll();
BOOST_TEST(executed == 0, "Expected the executor to have done no work");
BOOST_TEST(callback_was_called == true);
}
BOOST_AUTO_TEST_SUITE_END()
Compiled with
g++ -o BoostSocket_test -ansi -W -Wall -Wextra -Wno-non-virtual-dtor -std=c++23 -pthread -DNDEBUG -fPIC -D_FILE_OFFSET_BITS=64 -D_LARGEFILE64_SOURCE=1 -ggdb -DBOOST_BIND_GLOBAL_PLACEHOLDERS -lboost_unit_test_framewor k BoostSocket_test.cpp
Fails the test as such
[root@9f0cfab1ff7b asio]# g++ -o BoostSocket_test -ansi -W -Wall -Wextra -Wno-non-virtual-dtor -std=c++23 -pthread -DNDEBUG -fPIC -D_FILE_OFFSET_BITS=64 -D_LARGEFILE64_SOURCE=1 -ggdb -DBOOST_BIND_GLOBAL_PLACEHOLDERS -lboost_unit_test_framework BoostSocket_test.cpp
[root@9f0cfab1ff7b asio]# chmod +x BoostSocket_test
[root@9f0cfab1ff7b asio]# ./BoostSocket_test
Running 1 test case...
BoostSocket_test.cpp(83): error: in "BoostSocketTest/OnClearCallsCancelsIOContext": callback was not called with boost operation aborted
BoostSocket_test.cpp(104): error: in "BoostSocketTest/OnClearCallsCancelsIOContext": Expected the executor to have done no work
*** 2 failures are detected in the test module "C++ Unit Tests for Application"
I've probably just misunderstood what kind of operations get cancelled by a cancel function call, any advice or pointers would be appreciated.
Thanks in advance
George