Add function rcl_event_is_valid (#720)

* Add function rcl_event_is_valid
This functions checks if a passed event is a valid
already init instance of a publisher/subscriber
event.
* Move impl header to its own file
* Reset error status
* Fix alpha order
* Add check for bad allocator
* Add tests to check if error set

Signed-off-by: Jorge Perez <jjperez@ekumenlabs.com>

rcl/include/rcl/event.h

@@ -170,6 +170,28 @@ RCL_WARN_UNUSED
 rmw_event_t *
 rcl_event_get_rmw_handle(const rcl_event_t * event);
 
+/// Check that the event is valid.
+/**
+ * The bool returned is `false` if `event` is invalid.
+ * The bool returned is `true` otherwise.
+ * In the case where `false` is to be returned, an error message is set.
+ * This function cannot fail.
+ *
+ * <hr>
+ * Attribute          | Adherence
+ * ------------------ | -------------
+ * Allocates Memory   | No
+ * Thread-Safe        | No
+ * Uses Atomics       | No
+ * Lock-Free          | Yes
+ *
+ * \param[in] event pointer to the rcl event
+ * \return `true` if `event` is valid, otherwise `false`
+ */
+RCL_PUBLIC
+bool
+rcl_event_is_valid(const rcl_event_t * event);
+
 #ifdef __cplusplus
 }
 #endif

rcl/src/rcl/event.c

@@ -24,21 +24,17 @@ extern "C"
 #include "rcl/error_handling.h"
 #include "rcl/expand_topic_name.h"
 #include "rcl/remap.h"
+#include "rcutils/allocator.h"
 #include "rcutils/logging_macros.h"
 #include "rmw/error_handling.h"
 #include "rmw/validate_full_topic_name.h"
 #include "rmw/event.h"
 
 #include "./common.h"
+#include "./event_impl.h"
 #include "./publisher_impl.h"
 #include "./subscription_impl.h"
 
-typedef struct rcl_event_impl_t
-{
-  rmw_event_t rmw_handle;
-  rcl_allocator_t allocator;
-} rcl_event_impl_t;
-
 rcl_event_t
 rcl_get_zero_initialized_event()
 {
@@ -187,6 +183,20 @@ rcl_event_get_rmw_handle(const rcl_event_t * event)
   }
 }
 
+bool
+rcl_event_is_valid(const rcl_event_t * event)
+{
+  RCL_CHECK_FOR_NULL_WITH_MSG(event, "event pointer is invalid", return false);
+  RCL_CHECK_FOR_NULL_WITH_MSG(event->impl, "event's implementation is invalid", return false);
+  if (event->impl->rmw_handle.event_type == RMW_EVENT_INVALID) {
+    RCUTILS_SET_ERROR_MSG("event's implementation not init");
+    return false;
+  }
+  RCUTILS_CHECK_ALLOCATOR_WITH_MSG(
+    &event->impl->allocator, "not valid allocator", return false);
+  return true;
+}
+
 #ifdef __cplusplus
 }
 #endif

rcl/src/rcl/event_impl.h

@@ -0,0 +1,28 @@
+// Copyright 2020 Open Source Robotics Foundation, Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#ifndef RCL__EVENT_IMPL_H_
+#define RCL__EVENT_IMPL_H_
+
+#include "rmw/rmw.h"
+
+#include "rcl/event.h"
+
+typedef struct rcl_event_impl_t
+{
+  rmw_event_t rmw_handle;
+  rcl_allocator_t allocator;
+} rcl_event_impl_t;
+
+#endif  // RCL__EVENT_IMPL_H_

rcl/test/CMakeLists.txt

@@ -255,6 +255,7 @@ function(test_target_function)
     SRCS rcl/test_events.cpp
     ENV ${rmw_implementation_env_var}
     APPEND_LIBRARY_DIRS ${extra_lib_dirs}
+    INCLUDE_DIRS ${CMAKE_CURRENT_SOURCE_DIR}/../src/rcl/
     LIBRARIES ${PROJECT_NAME}
     AMENT_DEPENDENCIES ${rmw_implementation} "osrf_testing_tools_cpp" "test_msgs"
   )

rcl/test/rcl/test_events.cpp

@@ -25,12 +25,15 @@
 #include "rcl/subscription.h"
 #include "rcl/error_handling.h"
 #include "rmw/incompatible_qos_events_statuses.h"
+#include "rmw/event.h"
 
 #include "test_msgs/msg/strings.h"
 #include "rosidl_runtime_c/string_functions.h"
 
 #include "osrf_testing_tools_cpp/scope_exit.hpp"
 
+#include "./event_impl.h"
+
 using namespace std::chrono_literals;
 using std::chrono::seconds;
 using std::chrono::duration_cast;
@@ -730,6 +733,46 @@ TEST_F(TestEventFixture, test_bad_get_handle)
   EXPECT_EQ(NULL, rcl_event_get_rmw_handle(NULL));
 }
 
+/*
+ * Test cases for the event_is_valid function
+ */
+TEST_F(TestEventFixture, test_event_is_valid)
+{
+  EXPECT_FALSE(rcl_event_is_valid(nullptr));
+  EXPECT_TRUE(rcl_error_is_set());
+  rcl_reset_error();
+
+  setup_publisher_subscriber(default_qos_profile, default_qos_profile);
+  rcl_event_t publisher_event_test = rcl_get_zero_initialized_event();
+  EXPECT_FALSE(rcl_event_is_valid(&publisher_event_test));
+  EXPECT_TRUE(rcl_error_is_set());
+  rcl_reset_error();
+
+  rcl_ret_t ret = rcl_publisher_event_init(
+    &publisher_event_test, &publisher, RCL_PUBLISHER_OFFERED_DEADLINE_MISSED);
+  ASSERT_EQ(ret, RCL_RET_OK) << rcl_get_error_string().str;
+  EXPECT_TRUE(rcl_event_is_valid(&publisher_event_test));
+
+  rmw_event_type_t saved_event_type = publisher_event_test.impl->rmw_handle.event_type;
+  publisher_event_test.impl->rmw_handle.event_type = RMW_EVENT_INVALID;
+  EXPECT_FALSE(rcl_event_is_valid(&publisher_event_test));
+  EXPECT_TRUE(rcl_error_is_set());
+  rcl_reset_error();
+  publisher_event_test.impl->rmw_handle.event_type = saved_event_type;
+
+  rcl_allocator_t saved_alloc = publisher_event_test.impl->allocator;
+  rcl_allocator_t bad_alloc = rcutils_get_zero_initialized_allocator();
+  publisher_event_test.impl->allocator = bad_alloc;
+  EXPECT_FALSE(rcl_event_is_valid(&publisher_event_test));
+  EXPECT_TRUE(rcl_error_is_set());
+  rcl_reset_error();
+  publisher_event_test.impl->allocator = saved_alloc;
+
+  ret = rcl_event_fini(&publisher_event_test);
+  EXPECT_EQ(ret, RCL_RET_OK) << rcl_get_error_string().str;
+  tear_down_publisher_subscriber();
+}
+
 static
 std::array<TestIncompatibleQosEventParams, 5>
 get_test_pubsub_incompatible_qos_inputs()