[19696][20409] Fix data race on PDP (backport #4220)

include/fastdds/rtps/attributes/ServerAttributes.h

@@ -54,15 +54,14 @@ class RemoteServerAttributes
         return guidPrefix == r.guidPrefix
                && metatrafficUnicastLocatorList == r.metatrafficUnicastLocatorList
                && metatrafficMulticastLocatorList == r.metatrafficMulticastLocatorList;
-        //     && proxy == r.proxy;
     }
 
     RTPS_DllAPI void clear()
     {
         guidPrefix = fastrtps::rtps::GuidPrefix_t::unknown();
         metatrafficUnicastLocatorList.clear();
         metatrafficMulticastLocatorList.clear();
-        proxy = nullptr;
+        is_connected = false;
     }
 
     RTPS_DllAPI fastrtps::rtps::GUID_t GetParticipant() const;
@@ -100,8 +99,8 @@ class RemoteServerAttributes
     //!Guid prefix
     fastrtps::rtps::GuidPrefix_t guidPrefix;
 
-    // Live participant proxy reference
-    const fastrtps::rtps::ParticipantProxyData* proxy{};
+    // Whether connection has been established
+    bool is_connected = false;
 
     // Check if there are specific transport locators associated
     // the template parameter is the locator kind (e.g. LOCATOR_KIND_UDPv4)

include/fastdds/rtps/builtin/data/ParticipantProxyData.h

@@ -63,13 +63,13 @@ class ParticipantProxyData
 {
 public:
 
-    ParticipantProxyData(
+    RTPS_DllAPI ParticipantProxyData(
             const RTPSParticipantAllocationAttributes& allocation);
 
-    ParticipantProxyData(
+    RTPS_DllAPI ParticipantProxyData(
             const ParticipantProxyData& pdata);
 
-    virtual ~ParticipantProxyData();
+    RTPS_DllAPI virtual ~ParticipantProxyData();
 
     //!Protocol version
     ProtocolVersion_t m_protocolVersion;

src/cpp/rtps/builtin/discovery/participant/PDPClient.cpp

@@ -472,7 +472,6 @@ bool PDPClient::create_ds_pdp_reliable_endpoints(
     return true;
 }
 
-// the ParticipantProxyData* pdata must be the one kept in PDP database
 void PDPClient::assignRemoteEndpoints(
         ParticipantProxyData* pdata)
 {
@@ -488,8 +487,7 @@ void PDPClient::assignRemoteEndpoints(
             {
                 if (data_matches_with_prefix(svr.guidPrefix, *pdata))
                 {
-                    std::unique_lock<std::recursive_mutex> lock(*getMutex());
-                    svr.proxy = pdata;
+                    svr.is_connected = true;
                 }
             }
         }
@@ -517,11 +515,11 @@ void PDPClient::notifyAboveRemoteEndpoints(
         {
             if (data_matches_with_prefix(svr.guidPrefix, pdata))
             {
-                if (nullptr == svr.proxy)
+                if (!svr.is_connected && nullptr != get_participant_proxy_data(svr.guidPrefix))
                 {
-                    //! try to retrieve the participant proxy data from an unmangled prefix in case
-                    //! we could not fill svr.proxy in assignRemoteEndpoints()
-                    svr.proxy = get_participant_proxy_data(svr.guidPrefix);
+                    //! mark proxy as connected from an unmangled prefix in case
+                    //! it could not be done in assignRemoteEndpoints()
+                    svr.is_connected = true;
                 }
 
                 match_pdp_reader_nts_(svr, pdata.m_guid.guidPrefix);
@@ -596,7 +594,7 @@ void PDPClient::removeRemoteEndpoints(
             if (svr.guidPrefix == pdata->m_guid.guidPrefix)
             {
                 std::unique_lock<std::recursive_mutex> lock(*getMutex());
-                svr.proxy = nullptr; // reasign when we receive again server DATA(p)
+                svr.is_connected = false;
                 is_server = true;
                 mp_sync->restart_timer(); // enable announcement and sync mechanism till this server reappears
             }
@@ -768,11 +766,11 @@ void PDPClient::announceParticipantState(
                     for (auto& svr : mp_builtin->m_DiscoveryServers)
                     {
                         // if we are matched to a server report demise
-                        if (svr.proxy != nullptr)
+                        if (svr.is_connected)
                         {
                             //locators.push_back(svr.metatrafficMulticastLocatorList);
                             locators.push_back(svr.metatrafficUnicastLocatorList);
-                            remote_readers.emplace_back(svr.proxy->m_guid.guidPrefix,
+                            remote_readers.emplace_back(svr.guidPrefix,
                                     endpoints->reader.reader_->getGuid().entityId);
                         }
                     }
@@ -805,7 +803,7 @@ void PDPClient::announceParticipantState(
                     {
                         // non-pinging announcements like lease duration ones must be
                         // broadcast to all servers
-                        if (svr.proxy == nullptr || !_serverPing)
+                        if (!svr.is_connected || !_serverPing)
                         {
                             locators.push_back(svr.metatrafficMulticastLocatorList);
                             locators.push_back(svr.metatrafficUnicastLocatorList);

src/cpp/rtps/builtin/discovery/participant/PDPListener.cpp

@@ -181,11 +181,14 @@ void PDPListener::process_alive_data(
         // Create a new one when not found
         old_data = parent_pdp_->createParticipantProxyData(new_data, writer_guid);
 
-        reader->getMutex().unlock();
-        lock.unlock();
-
         if (old_data != nullptr)
         {
+            // Copy proxy to be passed forward before releasing PDP mutex
+            ParticipantProxyData old_data_copy(*old_data);
+
+            reader->getMutex().unlock();
+            lock.unlock();
+
             // Assigning remote endpoints implies sending a DATA(p) to all matched and fixed readers, since
             // StatelessWriter::matched_reader_add marks the entire history as unsent if the added reader's
             // durability is bigger or equal to TRANSIENT_LOCAL_DURABILITY_QOS (TRANSIENT_LOCAL or TRANSIENT),
@@ -196,13 +199,19 @@ void PDPListener::process_alive_data(
             // participant is discovered in the middle of BuiltinProtocols::initBuiltinProtocols, which will
             // create the first DATA(p) upon finishing, thus triggering the sent to all fixed and matched
             // readers anyways.
-            parent_pdp_->assignRemoteEndpoints(old_data);
+            parent_pdp_->assignRemoteEndpoints(&old_data_copy);
+        }
+        else
+        {
+            reader->getMutex().unlock();
+            lock.unlock();
         }
     }
     else
     {
         old_data->updateData(new_data);
         old_data->isAlive = true;
+
         reader->getMutex().unlock();
 
         EPROSIMA_LOG_INFO(RTPS_PDP_DISCOVERY, "Update participant "
@@ -215,6 +224,9 @@ void PDPListener::process_alive_data(
             parent_pdp_->mp_EDP->assignRemoteEndpoints(*old_data, true);
         }
 
+        // Copy proxy to be passed forward before releasing PDP mutex
+        ParticipantProxyData old_data_copy(*old_data);
+
         lock.unlock();
 
         RTPSParticipantListener* listener = parent_pdp_->getRTPSParticipant()->getListener();
@@ -224,7 +236,7 @@ void PDPListener::process_alive_data(
 
             {
                 std::lock_guard<std::mutex> cb_lock(parent_pdp_->callback_mtx_);
-                ParticipantDiscoveryInfo info(*old_data);
+                ParticipantDiscoveryInfo info(old_data_copy);
                 info.status = ParticipantDiscoveryInfo::CHANGED_QOS_PARTICIPANT;
 
                 listener->onParticipantDiscovery(

test/blackbox/common/DDSBlackboxTestsDiscovery.cpp

@@ -18,6 +18,7 @@
 #include <atomic>
 #include <chrono>
 #include <condition_variable>
+#include <future>
 #include <memory>
 #include <mutex>
 #include <string>
@@ -36,9 +37,11 @@
 #include <fastdds/dds/domain/DomainParticipantFactory.hpp>
 #include <fastdds/dds/domain/DomainParticipantListener.hpp>
 #include <fastdds/dds/domain/qos/DomainParticipantQos.hpp>
+#include <fastdds/rtps/builtin/data/ParticipantProxyData.h>
 #include <fastdds/rtps/common/Locator.h>
 #include <fastdds/rtps/participant/ParticipantDiscoveryInfo.h>
 #include <fastdds/rtps/transport/test_UDPv4TransportDescriptor.h>
+#include <fastrtps/xmlparser/XMLProfileManager.h>
 #include <rtps/transport/test_UDPv4Transport.h>
 #include <utils/SystemInfo.hpp>
 
@@ -438,13 +441,13 @@ TEST(DDSDiscovery, ParticipantProxyPhysicalData)
                 {
                     delete remote_participant_info;
                 }
-                remote_participant_info = new ParticipantDiscoveryInfo(info);
+                remote_participant_info = new ParticipantProxyData(info.info);
                 found_->store(true);
                 cv_->notify_one();
             }
         }
 
-        ParticipantDiscoveryInfo* remote_participant_info;
+        ParticipantProxyData* remote_participant_info;
 
     private:
 
@@ -496,21 +499,21 @@ TEST(DDSDiscovery, ParticipantProxyPhysicalData)
         participant_found.store(false);
 
         // Prevent assertion on spurious discovery of a participant from elsewhere
-        if (part_1->guid() == listener.remote_participant_info->info.m_guid)
+        if (part_1->guid() == listener.remote_participant_info->m_guid)
         {
             // Check that all three properties are present in the ParticipantProxyData, and that their value
             // is that of the property in part_1 (the original property value)
             for (auto physical_property_name : physical_property_names)
             {
                 // Find property in ParticipantProxyData
                 auto received_property = std::find_if(
-                    listener.remote_participant_info->info.m_properties.begin(),
-                    listener.remote_participant_info->info.m_properties.end(),
+                    listener.remote_participant_info->m_properties.begin(),
+                    listener.remote_participant_info->m_properties.end(),
                     [&](const ParameterProperty_t& property)
                     {
                         return property.first() == physical_property_name;
                     });
-                ASSERT_NE(received_property, listener.remote_participant_info->info.m_properties.end());
+                ASSERT_NE(received_property, listener.remote_participant_info->m_properties.end());
 
                 // Find property in first participant
                 auto part_1_property = PropertyPolicyHelper::find_property(
@@ -556,20 +559,20 @@ TEST(DDSDiscovery, ParticipantProxyPhysicalData)
         participant_found.store(false);
 
         // Prevent assertion on spurious discovery of a participant from elsewhere
-        if (part_1->guid() == listener.remote_participant_info->info.m_guid)
+        if (part_1->guid() == listener.remote_participant_info->m_guid)
         {
             // Check that none of the three properties are present in the ParticipantProxyData.
             for (auto physical_property_name : physical_property_names)
             {
                 // Look for property in ParticipantProxyData
                 auto received_property = std::find_if(
-                    listener.remote_participant_info->info.m_properties.begin(),
-                    listener.remote_participant_info->info.m_properties.end(),
+                    listener.remote_participant_info->m_properties.begin(),
+                    listener.remote_participant_info->m_properties.end(),
                     [&](const ParameterProperty_t& property)
                     {
                         return property.first() == physical_property_name;
                     });
-                ASSERT_EQ(received_property, listener.remote_participant_info->info.m_properties.end());
+                ASSERT_EQ(received_property, listener.remote_participant_info->m_properties.end());
             }
             break;
         }
@@ -1638,3 +1641,137 @@ TEST(DDSDiscovery, WaitSetMatchedStatus)
     test_DDSDiscovery_WaitSetMatchedStatus(false);
     test_DDSDiscovery_WaitSetMatchedStatus(true);
 }
+
+// Regression test for redmine issue 20409
+TEST(DDSDiscovery, DataracePDP)
+{
+    using namespace eprosima;
+    using namespace eprosima::fastdds::dds;
+    using namespace eprosima::fastdds::rtps;
+
+    class CustomDomainParticipantListener : public DomainParticipantListener
+    {
+    public:
+
+        CustomDomainParticipantListener()
+            : DomainParticipantListener()
+            , discovery_future(discovery_promise.get_future())
+            , destruction_future(destruction_promise.get_future())
+            , undiscovery_future(undiscovery_promise.get_future())
+        {
+        }
+
+        void on_participant_discovery(
+                DomainParticipant* /*participant*/,
+                eprosima::fastrtps::rtps::ParticipantDiscoveryInfo&& info) override
+        {
+            if (info.status == eprosima::fastrtps::rtps::ParticipantDiscoveryInfo::DISCOVERED_PARTICIPANT)
+            {
+                try
+                {
+                    discovery_promise.set_value();
+                }
+                catch (std::future_error&)
+                {
+                    // do nothing
+                }
+                destruction_future.wait();
+            }
+            else if (info.status == eprosima::fastrtps::rtps::ParticipantDiscoveryInfo::REMOVED_PARTICIPANT ||
+                    info.status == eprosima::fastrtps::rtps::ParticipantDiscoveryInfo::DROPPED_PARTICIPANT)
+            {
+                try
+                {
+                    undiscovery_promise.set_value();
+                }
+                catch (std::future_error&)
+                {
+                    // do nothing
+                }
+            }
+        }
+
+        std::promise<void> discovery_promise;
+        std::future<void> discovery_future;
+
+        std::promise<void> destruction_promise;
+        std::future<void> destruction_future;
+
+        std::promise<void> undiscovery_promise;
+        std::future<void> undiscovery_future;
+    };
+
+    // Disable intraprocess
+    auto settings = fastrtps::xmlparser::XMLProfileManager::library_settings();
+    auto prev_intraprocess_delivery = settings.intraprocess_delivery;
+    settings.intraprocess_delivery = fastrtps::INTRAPROCESS_OFF;
+    fastrtps::xmlparser::XMLProfileManager::library_settings(settings);
+
+    // DDS Domain Id
+    const unsigned int DOMAIN_ID = (uint32_t)GET_PID() % 230;
+
+    // This is a non deterministic test, so we will run it several times to increase probability of data race detection
+    // if it exists.
+    const unsigned int N_ITER = 10;
+    unsigned int iter_idx = 0;
+    while (iter_idx < N_ITER)
+    {
+        iter_idx++;
+
+        DomainParticipantQos qos;
+        qos.transport().use_builtin_transports = false;
+        auto udp_transport = std::make_shared<UDPv4TransportDescriptor>();
+        qos.transport().user_transports.push_back(udp_transport);
+
+        // Create discoverer participant (the one where a data race on PDP might occur)
+        CustomDomainParticipantListener participant_listener;
+        DomainParticipant* participant = DomainParticipantFactory::get_instance()->create_participant(DOMAIN_ID, qos,
+                        &participant_listener);
+
+        DomainParticipantQos aux_qos;
+        aux_qos.transport().use_builtin_transports = false;
+        auto aux_udp_transport = std::make_shared<test_UDPv4TransportDescriptor>();
+        aux_qos.transport().user_transports.push_back(aux_udp_transport);
+
+        // Create auxiliary participant to be discovered
+        aux_qos.wire_protocol().builtin.discovery_config.leaseDuration_announcementperiod = Duration_t(1, 0);
+        aux_qos.wire_protocol().builtin.discovery_config.leaseDuration = Duration_t(1, 10);
+        DomainParticipant* aux_participant = DomainParticipantFactory::get_instance()->create_participant(DOMAIN_ID,
+                        aux_qos);
+
+        // Wait for discovery
+        participant_listener.discovery_future.wait();
+
+        // Shutdown auxiliary participant's network, so it will be removed after lease duration
+        test_UDPv4Transport::test_UDPv4Transport_ShutdownAllNetwork = true;
+        DomainParticipantFactory::get_instance()->delete_participant(aux_participant);
+        std::this_thread::sleep_for(std::chrono::milliseconds(1500)); // Wait for longer than lease duration
+
+        try
+        {
+            // NOTE: at this point, the discoverer participant is stuck in a UDP discovery thread (unicast or multicast).
+            // At the same time, the events thread is stuck at PDP::remove_remote_participant (lease duration expired
+            // and so the discovered participant is removed), trying to acquire the callback mutex taken by the
+            // discovery thread.
+
+            // If we now signal the discovery thread to continue, a data race might occur if the received
+            // ParticipantProxyData, which is further being processed in the discovery thread (assignRemoteEndpoints),
+            // gets deleted/cleared by the events thread at the same time.
+            // Note that a similar situation might arise in other scenarios, such as on the concurrent reception of a
+            // data P and data uP each on a different thread (unicast and multicast), however these are harder to
+            // reproduce in a regression test.
+            participant_listener.destruction_promise.set_value();
+        }
+        catch (std::future_error&)
+        {
+            // do nothing
+        }
+
+        participant_listener.undiscovery_future.wait();
+        DomainParticipantFactory::get_instance()->delete_participant(participant);
+    }
+
+    // Reestablish previous intraprocess configuration
+    settings.intraprocess_delivery = prev_intraprocess_delivery;
+    fastrtps::xmlparser::XMLProfileManager::library_settings(settings);
+}