New environment variable to change easily the publication mode

README.md

@@ -44,6 +44,17 @@ You have two ways of telling you ROS 2 application which XML to use:
 1. Placing your XML file in the running directory under the name `DEFAULT_FASTRTPS_PROFILES.xml`.
 2. Setting environment variable `FASTRTPS_DEFAULT_PROFILES_FILE` to your XML file.
 
+### Change publication mode
+
+Another way to change easily the publication mode is to use the environment variable `ROS_PUBLICATION_MODE`.
+The admissible values are:
+* `ASYNCHRONOUS`: asynchronous publication mode
+* `SYNCHRONOUS`: synchronous publication mode
+* `AUTO`: let the rmw implementation select the publication mode.
+
+By default, `rmw_fastrtps` assumes this variable to be `ASYNCHRONOUS`.
+Also, if you set the variable to `AUTO`, `rmw_fastrtps` will use the publication mode set in the XML file or, failing that, the default value set in Fast DDS (currently set to `SYNCHRONOUS`).
+
 ## Example
 
 The following example configures Fast DDS to publish synchronously, and to have a pre-allocated history that can be expanded whenever it gets filled.

rmw_fastrtps_cpp/src/publisher.cpp

@@ -135,9 +135,13 @@ rmw_fastrtps_cpp::create_publisher(
   }
 
   if (!participant_info->leave_middleware_default_qos) {
-    publisherParam.qos.m_publishMode.kind = eprosima::fastrtps::ASYNCHRONOUS_PUBLISH_MODE;
     publisherParam.historyMemoryPolicy =
       eprosima::fastrtps::rtps::PREALLOCATED_WITH_REALLOC_MEMORY_MODE;
+    if (participant_info->publishing_mode == publishing_mode_t::ASYNCHRONOUS) {
+      publisherParam.qos.m_publishMode.kind = eprosima::fastrtps::ASYNCHRONOUS_PUBLISH_MODE;
+    } else if (participant_info->publishing_mode == publishing_mode_t::SYNCHRONOUS) {
+      publisherParam.qos.m_publishMode.kind = eprosima::fastrtps::SYNCHRONOUS_PUBLISH_MODE;
+    }
   }
 
   publisherParam.topic.topicKind =

rmw_fastrtps_cpp/src/rmw_client.cpp

@@ -165,9 +165,13 @@ rmw_create_client(
     qos_policies, ros_service_response_prefix, service_name, "Reply");
 
   if (!participant_info->leave_middleware_default_qos) {
-    publisherParam.qos.m_publishMode.kind = eprosima::fastrtps::ASYNCHRONOUS_PUBLISH_MODE;
     publisherParam.historyMemoryPolicy =
       eprosima::fastrtps::rtps::PREALLOCATED_WITH_REALLOC_MEMORY_MODE;
+    if (participant_info->publishing_mode == publishing_mode_t::ASYNCHRONOUS) {
+      publisherParam.qos.m_publishMode.kind = eprosima::fastrtps::ASYNCHRONOUS_PUBLISH_MODE;
+    } else if (participant_info->publishing_mode == publishing_mode_t::SYNCHRONOUS) {
+      publisherParam.qos.m_publishMode.kind = eprosima::fastrtps::SYNCHRONOUS_PUBLISH_MODE;
+    }
   }
 
   publisherParam.topic.topicKind = eprosima::fastrtps::rtps::NO_KEY;

rmw_fastrtps_cpp/src/rmw_service.cpp

@@ -174,9 +174,13 @@ rmw_create_service(
     qos_policies, ros_service_requester_prefix, service_name, "Request");
 
   if (!impl->leave_middleware_default_qos) {
-    publisherParam.qos.m_publishMode.kind = eprosima::fastrtps::ASYNCHRONOUS_PUBLISH_MODE;
     publisherParam.historyMemoryPolicy =
       eprosima::fastrtps::rtps::PREALLOCATED_WITH_REALLOC_MEMORY_MODE;
+    if (impl->publishing_mode == publishing_mode_t::ASYNCHRONOUS) {
+      publisherParam.qos.m_publishMode.kind = eprosima::fastrtps::ASYNCHRONOUS_PUBLISH_MODE;
+    } else if (impl->publishing_mode == publishing_mode_t::SYNCHRONOUS) {
+      publisherParam.qos.m_publishMode.kind = eprosima::fastrtps::SYNCHRONOUS_PUBLISH_MODE;
+    }
   }
 
   publisherParam.topic.topicKind = eprosima::fastrtps::rtps::NO_KEY;

rmw_fastrtps_dynamic_cpp/src/publisher.cpp

@@ -145,9 +145,13 @@ rmw_fastrtps_dynamic_cpp::create_publisher(
   }
 
   if (!participant_info->leave_middleware_default_qos) {
-    publisherParam.qos.m_publishMode.kind = eprosima::fastrtps::ASYNCHRONOUS_PUBLISH_MODE;
     publisherParam.historyMemoryPolicy =
       eprosima::fastrtps::rtps::PREALLOCATED_WITH_REALLOC_MEMORY_MODE;
+    if (participant_info->publishing_mode == publishing_mode_t::ASYNCHRONOUS) {
+      publisherParam.qos.m_publishMode.kind = eprosima::fastrtps::ASYNCHRONOUS_PUBLISH_MODE;
+    } else if (participant_info->publishing_mode == publishing_mode_t::SYNCHRONOUS) {
+      publisherParam.qos.m_publishMode.kind = eprosima::fastrtps::SYNCHRONOUS_PUBLISH_MODE;
+    }
   }
 
   publisherParam.topic.topicKind = eprosima::fastrtps::rtps::NO_KEY;

rmw_fastrtps_dynamic_cpp/src/rmw_client.cpp

@@ -183,9 +183,13 @@ rmw_create_client(
     qos_policies, ros_service_response_prefix, service_name, "Reply");
 
   if (!participant_info->leave_middleware_default_qos) {
-    publisherParam.qos.m_publishMode.kind = eprosima::fastrtps::ASYNCHRONOUS_PUBLISH_MODE;
     publisherParam.historyMemoryPolicy =
       eprosima::fastrtps::rtps::PREALLOCATED_WITH_REALLOC_MEMORY_MODE;
+    if (participant_info->publishing_mode == publishing_mode_t::ASYNCHRONOUS) {
+      publisherParam.qos.m_publishMode.kind = eprosima::fastrtps::ASYNCHRONOUS_PUBLISH_MODE;
+    } else if (participant_info->publishing_mode == publishing_mode_t::SYNCHRONOUS) {
+      publisherParam.qos.m_publishMode.kind = eprosima::fastrtps::SYNCHRONOUS_PUBLISH_MODE;
+    }
   }
 
   publisherParam.topic.topicKind = eprosima::fastrtps::rtps::NO_KEY;

rmw_fastrtps_dynamic_cpp/src/rmw_service.cpp

@@ -192,9 +192,13 @@ rmw_create_service(
     qos_policies, ros_service_requester_prefix, service_name, "Request");
 
   if (!impl->leave_middleware_default_qos) {
-    publisherParam.qos.m_publishMode.kind = eprosima::fastrtps::ASYNCHRONOUS_PUBLISH_MODE;
     publisherParam.historyMemoryPolicy =
       eprosima::fastrtps::rtps::PREALLOCATED_WITH_REALLOC_MEMORY_MODE;
+    if (impl->publishing_mode == publishing_mode_t::ASYNCHRONOUS) {
+      publisherParam.qos.m_publishMode.kind = eprosima::fastrtps::ASYNCHRONOUS_PUBLISH_MODE;
+    } else if (impl->publishing_mode == publishing_mode_t::SYNCHRONOUS) {
+      publisherParam.qos.m_publishMode.kind = eprosima::fastrtps::SYNCHRONOUS_PUBLISH_MODE;
+    }
   }
 
   publisherParam.topic.topicKind = eprosima::fastrtps::rtps::NO_KEY;

rmw_fastrtps_shared_cpp/include/rmw_fastrtps_shared_cpp/custom_participant_info.hpp

@@ -42,6 +42,13 @@ using rmw_dds_common::operator<<;
 
 class ParticipantListener;
 
+enum class publishing_mode_t
+{
+  ASYNCHRONOUS,  // Asynchronous publishing mode
+  SYNCHRONOUS,   // Synchronous publishing mode
+  AUTO           // Use publishing mode set in XML file or Fast DDS default
+};
+
 typedef struct CustomParticipantInfo
 {
   eprosima::fastrtps::Participant * participant;
@@ -53,6 +60,7 @@ typedef struct CustomParticipantInfo
   // their settings are going to be overwritten by code
   // with the default configuration.
   bool leave_middleware_default_qos;
+  publishing_mode_t publishing_mode;
 } CustomParticipantInfo;
 
 class ParticipantListener : public eprosima::fastrtps::ParticipantListener

rmw_fastrtps_shared_cpp/src/participant.cpp

@@ -94,6 +94,7 @@ __create_participant(
   const char * identifier,
   ParticipantAttributes participantAttrs,
   bool leave_middleware_default_qos,
+  publishing_mode_t publishing_mode,
   rmw_dds_common::Context * common_context)
 {
   // Declare everything before beginning to create things.
@@ -122,6 +123,7 @@ __create_participant(
     goto fail;
   }
   participant_info->leave_middleware_default_qos = leave_middleware_default_qos;
+  participant_info->publishing_mode = publishing_mode;
 
   participant_info->participant = participant;
   participant_info->listener = listener;
@@ -185,6 +187,7 @@ rmw_fastrtps_shared_cpp::create_participant(
   participantAttrs.rtps.setName(enclave);
 
   bool leave_middleware_default_qos = false;
+  publishing_mode_t publishing_mode = publishing_mode_t::ASYNCHRONOUS;
   const char * env_value;
   const char * error_str;
   error_str = rcutils_get_env("RMW_FASTRTPS_USE_QOS_FROM_XML", &env_value);
@@ -194,6 +197,20 @@ rmw_fastrtps_shared_cpp::create_participant(
   }
   if (env_value != nullptr) {
     leave_middleware_default_qos = strcmp(env_value, "1") == 0;
+  } else if (env_value == nullptr || !leave_middleware_default_qos) {
+    error_str = rcutils_get_env("ROS_PUBLICATION_MODE", &env_value);
+    if (error_str != NULL) {
+      RCUTILS_LOG_DEBUG_NAMED("rmw_fastrtps_shared_cpp", "Error getting env var: %s\n", error_str);
+      return nullptr;
+    }
+    if (env_value != nullptr) {
+      // Synchronous publishing
+      if (strcmp(env_value, "SYNCHRONOUS") == 0) {
+        publishing_mode = publishing_mode_t::SYNCHRONOUS;
+      } else if (strcmp(env_value, "AUTO") == 0) {
+        publishing_mode = publishing_mode_t::AUTO;
+      }
+    }
   }
   // allow reallocation to support discovery messages bigger than 5000 bytes
   if (!leave_middleware_default_qos) {
@@ -257,6 +274,7 @@ rmw_fastrtps_shared_cpp::create_participant(
     identifier,
     participantAttrs,
     leave_middleware_default_qos,
+    publishing_mode,
     common_context);
 }