Added a new implementation of the RealtimeBox with added best effort behaviour

CMakeLists.txt

@@ -9,6 +9,7 @@ set(THIS_PACKAGE_INCLUDE_DEPENDS
   rclcpp
   rclcpp_action
   Threads
+  rcpputils
 )
 
 find_package(ament_cmake REQUIRED)

include/realtime_tools/realtime_box_best_effort.h

@@ -1,18 +1,52 @@
-#pragma once
+// Copyright (c) 2024, Lennart Nachtigall
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are met:
+//
+//    * Redistributions of source code must retain the above copyright
+//      notice, this list of conditions and the following disclaimer.
+//
+//    * Redistributions in binary form must reproduce the above copyright
+//      notice, this list of conditions and the following disclaimer in the
+//      documentation and/or other materials provided with the distribution.
+//
+//    * Neither the name of the Willow Garage, Inc. nor the names of its
+//      contributors may be used to endorse or promote products derived from
+//      this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+// AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+// IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+// ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
+// LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+// CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+// SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+// INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+// CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+// ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+// POSSIBILITY OF SUCH DAMAGE.
 
-#include <mutex>
+// Author: Lennart Nachtigall
+
+#pragma once
 
 #include <initializer_list>
+#include <mutex>
 #include <optional>
+#include <rcpputils/pointer_traits.hpp>
 namespace realtime_tools
 {
 
+template <typename T>
+constexpr auto is_ptr_or_smart_ptr = rcpputils::is_pointer<T>::value;
+
 /*!
     A Box that ensures thread safe access to the boxed contents. 
     Access is best effort. If it can not lock it will return.
 
-    Note: Be carefull with pointers as this implementation will actually just copy the pointer
-    See the tests for an example on how to work with pointers
+    NOTE about pointers:
+    You can use pointers with this box but the access will be different. 
+    Only use the get/set methods that take function pointer for accessing the internal value.
 */
 template <class T, typename mutex_type = std::mutex>
 class RealtimeBoxBestEffort
@@ -25,7 +59,6 @@ class RealtimeBoxBestEffort
   using mutex_t = mutex_type;
   using type = T;
   //Provide various constructors
-
   constexpr explicit RealtimeBoxBestEffort(const T & init = T{}) : value_(init) {}
   constexpr explicit RealtimeBoxBestEffort(const T && init) : value_(std::move(init)) {}
 
@@ -41,8 +74,10 @@ class RealtimeBoxBestEffort
   /**
      * @brief set a new content with best effort
      * @return false if mutex could not be locked
+     * @note disabled for pointer types
     */
-  bool set(const T & value)
+  template <typename U = T>
+  typename std::enable_if_t<!is_ptr_or_smart_ptr<U>, bool> trySet(const T & value)
   {
     std::unique_lock<std::mutex> guard(lock_, std::defer_lock);
     if (!guard.try_lock()) {
@@ -51,49 +86,119 @@ class RealtimeBoxBestEffort
     value_ = value;
     return true;
   }
+  /**
+   * @brief access the content readable with best effort
+   * @return false if the mutex could not be locked
+   * @note only safe way to access pointer type content (rw)
+  */
+  bool trySet(const std::function<void(T &)> & func)
+  {
+    std::unique_lock<std::mutex> guard(lock_, std::defer_lock);
+    if (!guard.try_lock()) {
+      return false;
+    }
+
+    func(value_);
+    return true;
+  }
   /**
      * @brief get the content with best effort
      * @return std::nullopt if content could not be access, otherwise the content is returned
     */
-  [[nodiscard]] std::optional<T> get() const
+  template <typename U = T>
+  [[nodiscard]] typename std::enable_if_t<!is_ptr_or_smart_ptr<U>, std::optional<U>> tryGet() const
   {
     std::unique_lock<std::mutex> guard(lock_, std::defer_lock);
     if (!guard.try_lock()) {
       return std::nullopt;
     }
     return value_;
   }
+  /**
+   * @brief access the content (r) with best effort 
+   * @return false if the mutex could not be locked
+   * @note only safe way to access pointer type content (r)
+  */
+  bool tryGet(const std::function<void(const T &)> & func)
+  {
+    std::unique_lock<std::mutex> guard(lock_, std::defer_lock);
+    if (!guard.try_lock()) {
+      return false;
+    }
+
+    func(value_);
+    return true;
+  }
 
   /**
      * @brief set the content and wait until the mutex could be locked (RealtimeBox behaviour)
      * @return true
     */
-  bool setNonRT(const T & value)
+  template <typename U = T>
+  typename std::enable_if_t<!is_ptr_or_smart_ptr<U>, void> set(const T & value)
   {
     std::lock_guard<std::mutex> guard(lock_);
     value_ = value;
-    //Also return a bool in order to mimic the behaviour from 'set'
-    return true;
   }
+  /**
+   * @brief access the content (rw) and wait until the mutex could locked
+  */
+  void set(const std::function<void(T &)> & func)
+  {
+    std::lock_guard<std::mutex> guard(lock_);
+    func(value_);
+  }
+
   /**
      * @brief get the content and wait until the mutex could be locked (RealtimeBox behaviour)
      * @return copy of the value
     */
-  [[nodiscard]] T getNonRT() const
+  template <typename U = T>
+  [[nodiscard]] typename std::enable_if_t<!is_ptr_or_smart_ptr<U>, U> get() const
   {
     std::lock_guard<std::mutex> guard(lock_);
     return value_;
   }
+  /**
+   * @brief get the content and wait until the mutex could be locked
+   * @note same signature as in the existing RealtimeBox<T>
+  */
+  template <typename U = T>
+  typename std::enable_if_t<!is_ptr_or_smart_ptr<U>, void> get(T & in) const
+  {
+    std::lock_guard<std::mutex> guard(lock_);
+    in = value_;
+  }
+  /**
+   * @brief access the content (r) and wait until the mutex could be locked
+   * @note only safe way to access pointer type content (r)
+   * @note same signature as in the existing RealtimeBox<T>
+  */
+  void get(const std::function<void(const T &)> & func)
+  {
+    std::lock_guard<std::mutex> guard(lock_);
+    func(value_);
+  }
+
   //Make the usage easier by providing a custom assignment operator and a custom conversion operator
   //Only to be used from non-RT!
-  void operator=(const T & value) { set(value); }
+  template <typename U = T>
+  typename std::enable_if_t<!is_ptr_or_smart_ptr<U>, void> operator=(const T & value)
+  {
+    set(value);
+  }
 
+  template <typename U = T, typename = typename std::enable_if_t<!is_ptr_or_smart_ptr<U>>>
   [[nodiscard]] operator T() const
   {
     //Only makes sense with the getNonRT method otherwise we would return an std::optional
-    return getNonRT();
+    return get();
+  }
+  template <typename U = T, typename = typename std::enable_if_t<!is_ptr_or_smart_ptr<U>>>
+  [[nodiscard]] operator std::optional<T>() const
+  {
+    return tryGet();
   }
-  [[nodiscard]] operator std::optional<T>() const { return get(); }
 
   //In case one wants to actually use a pointer in this implementation we allow accessing the lock directly.
   //Note: Be carefull with lock.unlock(). It may only be called from the thread that locked the mutext!
@@ -104,4 +209,4 @@ class RealtimeBoxBestEffort
   T value_;
   mutable mutex_t lock_;
 };
-}  // namespace realtime_tools
+}  // namespace realtime_tools

test/realtime_box_best_effort_tests.cpp

@@ -1,3 +1,33 @@
+// Copyright (c) 2024, Lennart Nachtigall
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are met:
+//
+//    * Redistributions of source code must retain the above copyright
+//      notice, this list of conditions and the following disclaimer.
+//
+//    * Redistributions in binary form must reproduce the above copyright
+//      notice, this list of conditions and the following disclaimer in the
+//      documentation and/or other materials provided with the distribution.
+//
+//    * Neither the name of the Willow Garage, Inc. nor the names of its
+//      contributors may be used to endorse or promote products derived from
+//      this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+// AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+// IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+// ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
+// LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+// CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+// SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+// INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+// CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+// ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+// POSSIBILITY OF SUCH DAMAGE.
+
+// Author: Lennart Nachtigall
+
 #include <gmock/gmock.h>
 #include <realtime_tools/realtime_box_best_effort.h>
 
@@ -29,7 +59,7 @@ TEST(RealtimeBoxBestEffort, empty_construct)
 {
   RealtimeBoxBestEffort<DefaultConstructable> box;
 
-  auto value = box.getNonRT();
+  auto value = box.get();
   EXPECT_EQ(value.a, 10);
   EXPECT_EQ(value.str, "hallo");
 }
@@ -41,7 +71,7 @@ TEST(RealtimeBoxBestEffort, default_construct)
 
   RealtimeBoxBestEffort<DefaultConstructable> box(data);
 
-  auto value = box.getNonRT();
+  auto value = box.get();
   EXPECT_EQ(value.a, 100);
   EXPECT_EQ(value.str, "hallo");
 }
@@ -50,16 +80,30 @@ TEST(RealtimeBoxBestEffort, non_default_constructable)
 {
   RealtimeBoxBestEffort<NonDefaultConstructable> box(NonDefaultConstructable(-10, "hello"));
 
-  auto value = box.getNonRT();
+  auto value = box.get();
   EXPECT_EQ(value.a, -10);
   EXPECT_EQ(value.str, "hello");
 }
+TEST(RealtimeBoxBestEffort, standard_get)
+{
+  RealtimeBoxBestEffort<DefaultConstructable> box(DefaultConstructable{.a = 1000});
+
+  DefaultConstructable data;
+  box.get(data);
+  EXPECT_EQ(data.a, 1000);
+  data.a = 10000;
+
+  box.set(data);
+
+  auto value = box.get();
+  EXPECT_EQ(value.a, 10000);
+}
 
 TEST(RealtimeBoxBestEffort, initializer_list)
 {
   RealtimeBoxBestEffort<FromInitializerList> box({1, 2, 3});
 
-  auto value = box.getNonRT();
+  auto value = box.get();
   EXPECT_EQ(value.data[0], 1);
   EXPECT_EQ(value.data[1], 2);
   EXPECT_EQ(value.data[2], 3);
@@ -73,7 +117,7 @@ TEST(RealtimeBoxBestEffort, assignment_operator)
   //Assignement operator is always non RT!
   box = data;
 
-  auto value = box.getNonRT();
+  auto value = box.get();
   EXPECT_EQ(value.a, 1000);
 }
 TEST(RealtimeBoxBestEffort, typecast_operator)
@@ -99,10 +143,31 @@ TEST(RealtimeBoxBestEffort, pointer_type)
   int * ptr = &a;
 
   RealtimeBoxBestEffort box(ptr);
+  //This does not and should not compile!
+  //auto value = box.get();
+
+  //Instead access it via a passed function. This assues that we access the data within the scope of the lock
+  box.get([](const auto & i) { EXPECT_EQ(*i, 100); });
+
+  box.set([](auto & i) { *i = 200; });
+
+  box.get([](const auto & i) { EXPECT_EQ(*i, 200); });
+
+  box.tryGet([](const auto & i) { EXPECT_EQ(*i, 200); });
+}
+
+TEST(RealtimeBoxBestEffort, smart_ptr_type)
+{
+  std::shared_ptr<int> ptr = std::make_shared<int>(100);
+
+  RealtimeBoxBestEffort box(ptr);
+  //This does not and should not compile!
+  //auto value = box.get();
 
-  auto value = box.getNonRT();
+  //Instead access it via a passed function. This assues that we access the data within the scope of the lock
+  box.get([](const auto & i) { EXPECT_EQ(*i, 100); });
 
-  //Correctly working with pointer types is nasty...
-  std::lock_guard<decltype(box)::mutex_t> guard(box.getMutex());
-  EXPECT_EQ(*value, 100);
-}
+  box.set([](auto & i) { *i = 200; });
+
+  box.get([](const auto & i) { EXPECT_EQ(*i, 200); });
+}