From 46a96ff4cd1a90c83fb1313bd50c63aee315875f Mon Sep 17 00:00:00 2001
From: "mergify[bot]" <37929162+mergify[bot]@users.noreply.github.com>
Date: Thu, 10 Aug 2023 16:51:28 +0200
Subject: [PATCH] Remove mutex from TimedEventImpl (#3745) (#3750)

* [19256] Remove mutex from TimedEventImpl (#3745)

* Removes mutex from TimedEventImpl

Signed-off-by: Vilas Chitrakaran <cvilas@gmail.com>

* Please linters.

Signed-off-by: Miguel Company <MiguelCompany@eprosima.com>

---------

Signed-off-by: Vilas Chitrakaran <cvilas@gmail.com>
Signed-off-by: Miguel Company <MiguelCompany@eprosima.com>
Co-authored-by: Miguel Company <MiguelCompany@eprosima.com>
Co-authored-by: Holger Schulz <holger.schulz@durham.ac.uk>
(cherry picked from commit a7697c7dc9dce5b6aab46c93b21b0020804560ee)

* Added atomic time_point initialization (#3760)

Signed-off-by: Javier Santiago <javiersantiago@eprosima.com>

---------

Signed-off-by: Javier Santiago <javiersantiago@eprosima.com>
Co-authored-by: Vilas Kumar Chitrakaran <cvilas@gmail.com>
Co-authored-by: jsantiago-eProsima <90755661+jsantiago-eProsima@users.noreply.github.com>
---
 src/cpp/rtps/resources/TimedEventImpl.cpp | 15 ++++----------
 src/cpp/rtps/resources/TimedEventImpl.h   | 25 +++++++----------------
 2 files changed, 11 insertions(+), 29 deletions(-)

diff --git a/src/cpp/rtps/resources/TimedEventImpl.cpp b/src/cpp/rtps/resources/TimedEventImpl.cpp
index ece0247dc81..3bcddc6e09f 100644
--- a/src/cpp/rtps/resources/TimedEventImpl.cpp
+++ b/src/cpp/rtps/resources/TimedEventImpl.cpp
@@ -20,11 +20,9 @@
 
 #include "TimedEventImpl.h"
 
+#include <chrono>
 #include <fastrtps/utils/TimeConversion.h>
 
-#include <atomic>
-#include <functional>
-
 namespace eprosima {
 namespace fastrtps {
 namespace rtps {
@@ -33,6 +31,7 @@ TimedEventImpl::TimedEventImpl(
         Callback callback,
         std::chrono::microseconds interval)
     : interval_microsec_(interval)
+    , next_trigger_time_(std::chrono::steady_clock::now())
     , callback_(std::move(callback))
     , state_(StateCode::INACTIVE)
 {
@@ -73,12 +72,10 @@ bool TimedEventImpl::update(
 
     if (set_time)
     {
-        std::lock_guard<std::mutex> lock(mutex_);
-        next_trigger_time_ = current_time + interval_microsec_;
+        next_trigger_time_ = current_time + interval_microsec_.load();
     }
     else if (expected == StateCode::INACTIVE)
     {
-        std::lock_guard<std::mutex> lock(mutex_);
         next_trigger_time_ = cancel_time;
     }
 
@@ -103,14 +100,12 @@ void TimedEventImpl::trigger(
                 expected = StateCode::INACTIVE;
                 if (state_.compare_exchange_strong(expected, StateCode::WAITING))
                 {
-                    std::lock_guard<std::mutex> lock(mutex_);
-                    next_trigger_time_ = current_time + interval_microsec_;
+                    next_trigger_time_ = current_time + interval_microsec_.load();
                     return;
                 }
             }
         }
 
-        std::lock_guard<std::mutex> lock(mutex_);
         next_trigger_time_ = cancel_time;
     }
 }
@@ -118,7 +113,6 @@ void TimedEventImpl::trigger(
 bool TimedEventImpl::update_interval(
         const eprosima::fastrtps::Duration_t& interval)
 {
-    std::lock_guard<std::mutex> lock(mutex_);
     interval_microsec_ = std::chrono::microseconds(TimeConv::Duration_t2MicroSecondsInt64(interval));
     return true;
 }
@@ -126,7 +120,6 @@ bool TimedEventImpl::update_interval(
 bool TimedEventImpl::update_interval_millisec(
         double interval)
 {
-    std::lock_guard<std::mutex> lock(mutex_);
     interval_microsec_ = std::chrono::microseconds(static_cast<int64_t>(interval * 1000));
     return true;
 }
diff --git a/src/cpp/rtps/resources/TimedEventImpl.h b/src/cpp/rtps/resources/TimedEventImpl.h
index 1c7bc1ce3d9..01ab3c8cdbb 100644
--- a/src/cpp/rtps/resources/TimedEventImpl.h
+++ b/src/cpp/rtps/resources/TimedEventImpl.h
@@ -26,11 +26,7 @@
 #include <fastdds/rtps/resources/TimedEvent.h>
 
 #include <atomic>
-#include <thread>
-#include <memory>
 #include <functional>
-#include <mutex>
-#include <condition_variable>
 
 namespace eprosima {
 namespace fastrtps {
@@ -91,9 +87,8 @@ class TimedEventImpl
      */
     double getIntervalMsec()
     {
-        std::unique_lock<std::mutex> lock(mutex_);
-        auto total_milliseconds = std::chrono::duration_cast<std::chrono::milliseconds>(interval_microsec_);
-        return static_cast<double>(total_milliseconds.count());
+        const auto ms = std::chrono::duration_cast<std::chrono::milliseconds>(interval_microsec_.load());
+        return static_cast<double>(ms.count());
     }
 
     /*!
@@ -102,11 +97,9 @@ class TimedEventImpl
      */
     double getRemainingTimeMilliSec()
     {
-        std::unique_lock<std::mutex> lock(mutex_);
-        return static_cast<double>(
-            std::chrono::duration_cast<std::chrono::milliseconds>(
-                next_trigger_time_ - std::chrono::steady_clock::now()).
-            count());
+        const auto ms = std::chrono::duration_cast<std::chrono::milliseconds>(
+            next_trigger_time_.load() - std::chrono::steady_clock::now());
+        return static_cast<double>(ms.count());
     }
 
     /*!
@@ -115,7 +108,6 @@ class TimedEventImpl
      */
     std::chrono::steady_clock::time_point next_trigger_time()
     {
-        std::unique_lock<std::mutex> lock(mutex_);
         return next_trigger_time_;
     }
 
@@ -154,19 +146,16 @@ class TimedEventImpl
 private:
 
     //! Expiration time in microseconds of the event.
-    std::chrono::microseconds interval_microsec_;
+    std::atomic<std::chrono::microseconds> interval_microsec_;
 
     //! Next time this event should be triggered
-    std::chrono::steady_clock::time_point next_trigger_time_;
+    std::atomic<std::chrono::steady_clock::time_point> next_trigger_time_;
 
     //! User function to be called when this event is triggered
     Callback callback_;
 
     //! Current state of this event
     std::atomic<StateCode> state_;
-
-    //! Protects interval_microsec_ and next_trigger_time_
-    std::mutex mutex_;
 };
 
 } // namespace rtps