Commit 2f40ef61 authored by Alberto Miranda's avatar Alberto Miranda ♨️
Browse files

Fix race condition testing/setting m_is_paused 

Two new private member functions pause_accept() and resume_accept() have
been added to urd, which internally use the compare_exchange_weak()
method to atomically test and set m_is_paused.

Fixes #15.
parent 753b05f7

src/urd.cpp

+22 −6
Original line number Diff line number Diff line
@@ -586,19 +586,20 @@ urd::command_handler(const request_ptr base_request) { 
        case command_type::ping:

            break; // nothing special to do here

        case command_type::pause_accept:

            if(!m_is_paused) {

                m_is_paused = true;

            }

            pause_accept();

            break;

        case command_type::resume_accept:

            if(m_is_paused) {

                m_is_paused = false;

            }

            resume_accept();

            break;

        case command_type::shutdown:

        {

            // TODO

            LOGGER_WARN("Shutdown requested!");

            pause_accept();





            break;

        }

        case command_type::unknown:

            resp->set_error_code(urd_error::bad_args);

            break;
@@ -1027,6 +1028,21 @@ void urd::print_farewell() { 
    LOGGER_INFO("{}", fsep);

}



void urd::pause_accept() {

    bool expected = false;

    while(!m_is_paused.compare_exchange_weak(expected, true) && !expected);



    LOGGER_WARN("Daemon locked: incoming requests will be rejected");

}



void urd::resume_accept() {

    bool expected = true;

    while(!m_is_paused.compare_exchange_weak(expected, false) && expected);



    LOGGER_WARN("Daemon unlocked: incoming requests will be processed");

}





int urd::run() {



    // initialize logging facilities

src/urd.hpp

+3 −0
Original line number Diff line number Diff line
@@ -122,6 +122,9 @@ private: 
                               bool track, const bfs::path& mount, 

                               uint32_t quota);



    void pause_accept();

    void resume_accept();



private:

    std::atomic<bool> m_is_paused;

tests/api-send-command.cpp

+17 −0
Original line number Diff line number Diff line
@@ -68,6 +68,15 @@ SCENARIO("send control commands to urd", "[api::nornsctl_send_command]") { 
                        REQUIRE(task.t_id == 1);

                    }

                }



                AND_WHEN("further NORNSCTL_COMMAND_PAUSE_ACCEPT commands are sent") {



                    rv = nornsctl_send_command(NORNSCTL_COMMAND_PAUSE_ACCEPT, NULL);



                    THEN("nornsctl_send_command() returns NORNS_SUCCESS") {

                        REQUIRE(rv == NORNS_SUCCESS);

                    }

                }

            }

        }
@@ -77,6 +86,14 @@ SCENARIO("send control commands to urd", "[api::nornsctl_send_command]") { 


            THEN("nornsctl_send_command() returns NORNS_SUCCESS") {

                REQUIRE(rv == NORNS_SUCCESS);



                AND_WHEN("further NORNSCTL_COMMAND_RESUME_ACCEPT commands are sent") {

                    rv = nornsctl_send_command(NORNSCTL_COMMAND_RESUME_ACCEPT, NULL);



                    THEN("nornsctl_send_command() returns NORNS_SUCCESS") {

                        REQUIRE(rv == NORNS_SUCCESS);

                    }

                }

            }

        }