From 49eaeb06fb4e979a07eee79531854370ece5ec5f Mon Sep 17 00:00:00 2001
From: Mario Dominguez <mariodominguez@eprosima.com>
Date: Wed, 16 Oct 2024 08:43:55 +0200
Subject: [PATCH] Refs #21293: Make *LocalReaderPointer atomic

Signed-off-by: Mario Dominguez <mariodominguez@eprosima.com>
---
 src/cpp/rtps/reader/LocalReaderPointer.cpp | 52 ++++++++++++++++++++--
 src/cpp/rtps/reader/LocalReaderPointer.hpp |  7 +--
 2 files changed, 52 insertions(+), 7 deletions(-)

diff --git a/src/cpp/rtps/reader/LocalReaderPointer.cpp b/src/cpp/rtps/reader/LocalReaderPointer.cpp
index f94a30127f..8e75fc3553 100644
--- a/src/cpp/rtps/reader/LocalReaderPointer.cpp
+++ b/src/cpp/rtps/reader/LocalReaderPointer.cpp
@@ -36,9 +36,19 @@ WeakLocalReaderPointer::WeakLocalReaderPointer()
 WeakLocalReaderPointer::WeakLocalReaderPointer(
         BaseReader* reader,
         std::shared_ptr<LocalReaderView> view)
-    : local_reader_(reader)
-    , view_(view)
 {
+    std::lock_guard<std::mutex> lock(this->mutex_);
+    local_reader_ = reader;
+    view_ = view;
+}
+
+WeakLocalReaderPointer::WeakLocalReaderPointer(
+        const WeakLocalReaderPointer& other)
+{
+    std::lock_guard<std::mutex> lock_other(other.mutex_);
+    std::lock_guard<std::mutex> lock(this->mutex_);
+    local_reader_ = other.local_reader_;
+    view_ = other.view_;
 }
 
 BaseReader* WeakLocalReaderPointer::operator ->()
@@ -51,16 +61,29 @@ WeakLocalReaderPointer::operator bool() const
 {
     bool ret = false;
 
+    std::lock_guard<std::mutex> lock(mutex_);
     if (nullptr != local_reader_ &&
             nullptr != view_)
     {
         ret = true;
     }
+
     return ret;
 }
 
+WeakLocalReaderPointer& WeakLocalReaderPointer::operator =(
+        const WeakLocalReaderPointer& other)
+{
+    std::lock_guard<std::mutex> lock_other(other.mutex_);
+    std::lock_guard<std::mutex> lock(this->mutex_);
+    local_reader_ = other.local_reader_;
+    view_ = other.view_;
+    return *this;
+}
+
 void WeakLocalReaderPointer::reset()
 {
+    std::lock_guard<std::mutex> lock(mutex_);
     local_reader_ = nullptr;
     view_.reset();
 }
@@ -75,6 +98,7 @@ LocalReaderPointer::LocalReaderPointer(
         std::shared_ptr<LocalReaderView> view)
     : WeakLocalReaderPointer(reader, view)
 {
+    std::lock_guard<std::mutex> lock(mutex_);
     if (nullptr != view_)
     {
         view_->add_reference();
@@ -83,8 +107,14 @@ LocalReaderPointer::LocalReaderPointer(
 
 LocalReaderPointer::LocalReaderPointer(
         const LocalReaderPointer& other)
-    : WeakLocalReaderPointer(other.local_reader_, other.view_)
+    : WeakLocalReaderPointer()
 {
+    std::lock_guard<std::mutex> lock(mutex_);
+    std::lock_guard<std::mutex> lock_other(other.mutex_);
+
+    local_reader_ = other.local_reader_;
+    view_ = other.view_;
+
     if (nullptr != view_)
     {
         view_->add_reference();
@@ -93,8 +123,14 @@ LocalReaderPointer::LocalReaderPointer(
 
 LocalReaderPointer::LocalReaderPointer(
         const WeakLocalReaderPointer& weak_local_reader_ptr)
-    : WeakLocalReaderPointer(weak_local_reader_ptr.local_reader_, weak_local_reader_ptr.view_)
+    : WeakLocalReaderPointer()
 {
+    std::lock_guard<std::mutex> lock(mutex_);
+    std::lock_guard<std::mutex> lock_other(weak_local_reader_ptr.mutex_);
+
+    local_reader_ = weak_local_reader_ptr.local_reader_;
+    view_ = weak_local_reader_ptr.view_;
+
     if (nullptr != view_)
     {
         view_->add_reference();
@@ -103,6 +139,7 @@ LocalReaderPointer::LocalReaderPointer(
 
 LocalReaderPointer::~LocalReaderPointer()
 {
+    std::lock_guard<std::mutex> lock(mutex_);
     if (nullptr != view_)
     {
         view_->dereference();
@@ -118,6 +155,8 @@ BaseReader* LocalReaderPointer::operator ->()
 LocalReaderPointer& LocalReaderPointer::operator =(
         const LocalReaderPointer& other)
 {
+    std::lock_guard<std::mutex> lock_other(other.mutex_);
+    std::lock_guard<std::mutex> lock(this->mutex_);
     local_reader_ = other.local_reader_;
     view_ = other.view_;
 
@@ -132,6 +171,9 @@ LocalReaderPointer& LocalReaderPointer::operator =(
 LocalReaderPointer& LocalReaderPointer::operator =(
         const WeakLocalReaderPointer& other)
 {
+    std::lock_guard<std::mutex> lock_other(other.mutex_);
+    std::lock_guard<std::mutex> lock(this->mutex_);
+
     local_reader_ = other.local_reader_;
     view_ = other.view_;
 
@@ -147,6 +189,8 @@ LocalReaderPointer::operator bool() const
 {
     bool ret = false;
 
+    std::lock_guard<std::mutex> lock(mutex_);
+
     if (nullptr != local_reader_ &&
             nullptr != view_ &&
             view_->get_status() != LocalReaderViewStatus::INACTIVE)
diff --git a/src/cpp/rtps/reader/LocalReaderPointer.hpp b/src/cpp/rtps/reader/LocalReaderPointer.hpp
index 7377aa91d7..b9efb53544 100644
--- a/src/cpp/rtps/reader/LocalReaderPointer.hpp
+++ b/src/cpp/rtps/reader/LocalReaderPointer.hpp
@@ -34,7 +34,7 @@ class WeakLocalReaderPointer;
  * @brief Class representing a pointer to a local reader.
  *
  * This class simply encapsulates a pointer to a BaseReader and a
- * shared pointer to its associated LocalReaderView.
+ * shared pointer to its associated LocalReaderView in a thread-safe manner.
  *
  * @ingroup READER_MODULE
  */
@@ -65,7 +65,7 @@ class WeakLocalReaderPointer
      * @brief WeakLocalpointers cannot be copied.
      */
     WeakLocalReaderPointer(
-            const WeakLocalReaderPointer&) = default;
+            const WeakLocalReaderPointer&);
 
     /**
      * @brief Destructor for WeakLocalReaderPointer.
@@ -88,7 +88,7 @@ class WeakLocalReaderPointer
      * @return Reference to the assigned WeakLocalReaderPointer.
      */
     WeakLocalReaderPointer& operator =(
-            const WeakLocalReaderPointer& other) = default;
+            const WeakLocalReaderPointer& other);
 
     /**
      * @brief Overloaded operator bool to check the status of the reader.
@@ -104,6 +104,7 @@ class WeakLocalReaderPointer
 
 protected:
 
+    mutable std::mutex mutex_;
     BaseReader* local_reader_{nullptr};
     std::shared_ptr<LocalReaderView> view_;
 };