Add time sync functionality (#117)

* Add time sync functionality

* Uncrustified

* Add time sync test

* Update test assert

* Uncrustified

Co-authored-by: GitHub Actions Bot <>

Author: Acuadros95

rmw_microxrcedds_c/include/rmw_uros/options.h

@@ -57,6 +57,17 @@ typedef struct rmw_uxrce_transport_params_t
     uint32_t client_key;
 } rmw_uxrce_transport_params_t;
 
+/**
+ * \brief Synchronizes the session time using the NTP protocol.
+ * \param[in, out] result Variable to update with micro-ROS Agent POSIX timestamp in nanoseconds.
+ * \param[in] timeout_ms The waiting time in milliseconds.
+ * \return RMW_RET_OK when success.
+ * \return RMW_RET_INVALID_ARGUMENT If no session is running or the synchronization fails.
+ */
+rmw_ret_t rmw_uros_sync_session(
+        int64_t* result,
+        const int timeout_ms);
+
 /**
  * \brief Parses command line args and fills rmw implementation-specific options.
  * `rmw_init_options allocator` is used to allocate the specific rmw options.

rmw_microxrcedds_c/src/rmw_uros_options.c

@@ -26,6 +26,36 @@
 
 #include <uxr/client/client.h>
 #include <uxr/client/util/ping.h>
+#include <uxr/client/util/time.h>
+
+rmw_ret_t rmw_uros_sync_session(
+        int64_t* result,
+        const int timeout_ms)
+{
+    rmw_ret_t ret = RMW_RET_OK;
+
+    // Check session is initialized
+    if (NULL == session_memory.allocateditems)
+    {
+        RMW_SET_ERROR_MSG("Uninitialized session.");
+        return RMW_RET_ERROR;
+    }
+
+    rmw_uxrce_mempool_item_t* item = session_memory.allocateditems;
+    rmw_context_impl_t* context = (rmw_context_impl_t*)item->data;
+
+    if (uxr_sync_session(&context->session, timeout_ms))
+    {
+        *result = uxr_nanos() - context->session.time_offset;
+    }
+    else
+    {
+        RMW_SET_ERROR_MSG("Time synchronization failed.");
+        return RMW_RET_ERROR;
+    }
+
+    return ret;
+}
 
 rmw_ret_t rmw_uros_init_options(
         int argc,

rmw_microxrcedds_c/test/test_rmw.cpp

@@ -13,6 +13,7 @@
 // limitations under the License.
 
 #include <gtest/gtest.h>
+#include <ctime>
 
 #include <rmw/rmw.h>
 #include <rmw/init_options.h>
@@ -64,3 +65,22 @@ TEST(rmw_microxrcedds, agent_ping)
 
     ASSERT_EQ(rmw_uros_ping_agent(100, 1), RMW_RET_OK);
 }
+
+/*
+ * Testing rmw time sync.
+ */
+TEST(rmw_microxrcedds, sync_session)
+{
+    rmw_context_t test_context = rmw_get_zero_initialized_context();
+    rmw_init_options_t test_options = rmw_get_zero_initialized_init_options();
+    int64_t result_ns = 0;
+
+    ASSERT_EQ(rmw_init_options_init(&test_options, rcutils_get_default_allocator()), RMW_RET_OK);
+    ASSERT_EQ(rmw_init(&test_options, &test_context), RMW_RET_OK);
+
+    std::time_t timestamp_seconds = std::time(nullptr);
+    ASSERT_EQ(rmw_uros_sync_session(&result_ns, 500), RMW_RET_OK);
+    ASSERT_EQ(result_ns / 1000000000, timestamp_seconds);
+
+    ASSERT_EQ(rmw_shutdown(&test_context), RMW_RET_OK);
+}