From d35de2d043c2b73bc7af8af596d2b0ed5f327b4f Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Rub=C3=A9n=20Norte?= <rubennorte@meta.com>
Date: Tue, 9 Apr 2024 07:51:03 -0700
Subject: [PATCH] Small refactor in RuntimeScheduler_Modern to favor references
 over shared_ptr for non-owning function args (#43852)

Summary:
Pull Request resolved: https://github.com/facebook/react-native/pull/43852

Changelog: [internal]

Just a small refactor so we rely less on shared pointers within `RuntimeSCheduler_Modern`.

Reviewed By: javache

Differential Revision: D55646389

fbshipit-source-id: d01dcba7b1551d349d21717ba585828ed7fb3259
---
 .../RuntimeScheduler_Modern.cpp               | 25 ++++++++++---------
 .../RuntimeScheduler_Modern.h                 |  6 ++---
 2 files changed, 16 insertions(+), 15 deletions(-)

diff --git a/packages/react-native/ReactCommon/react/renderer/runtimescheduler/RuntimeScheduler_Modern.cpp b/packages/react-native/ReactCommon/react/renderer/runtimescheduler/RuntimeScheduler_Modern.cpp
index 8cc6a6deebb..a38be770cb1 100644
--- a/packages/react-native/ReactCommon/react/renderer/runtimescheduler/RuntimeScheduler_Modern.cpp
+++ b/packages/react-native/ReactCommon/react/renderer/runtimescheduler/RuntimeScheduler_Modern.cpp
@@ -71,7 +71,7 @@ bool RuntimeScheduler_Modern::getShouldYield() const noexcept {
   std::shared_lock lock(schedulingMutex_);
 
   return syncTaskRequests_ > 0 ||
-      (!taskQueue_.empty() && taskQueue_.top() != currentTask_);
+      (!taskQueue_.empty() && taskQueue_.top().get() != currentTask_);
 }
 
 void RuntimeScheduler_Modern::cancelTask(Task& task) noexcept {
@@ -105,9 +105,8 @@ void RuntimeScheduler_Modern::executeNowOnTheSameThread(
         auto priority = SchedulerPriority::ImmediatePriority;
         auto expirationTime =
             currentTime + timeoutForSchedulerPriority(priority);
-        auto task = std::make_shared<Task>(
-            priority, std::move(callback), expirationTime);
 
+        auto task = Task{priority, std::move(callback), expirationTime};
         executeTask(runtime, task, currentTime);
       });
 
@@ -207,7 +206,7 @@ void RuntimeScheduler_Modern::startWorkLoop(
         break;
       }
 
-      executeTask(runtime, topPriorityTask, currentTime);
+      executeTask(runtime, *topPriorityTask, currentTime);
     }
   } catch (jsi::JSError& error) {
     handleJSError(runtime, error, true);
@@ -245,19 +244,19 @@ std::shared_ptr<Task> RuntimeScheduler_Modern::selectTask(
 
 void RuntimeScheduler_Modern::executeTask(
     jsi::Runtime& runtime,
-    const std::shared_ptr<Task>& task,
+    Task& task,
     RuntimeSchedulerTimePoint currentTime) {
-  auto didUserCallbackTimeout = task->expirationTime <= currentTime;
+  auto didUserCallbackTimeout = task.expirationTime <= currentTime;
 
   SystraceSection s(
       "RuntimeScheduler::executeTask",
       "priority",
-      serialize(task->priority),
+      serialize(task.priority),
       "didUserCallbackTimeout",
       didUserCallbackTimeout);
 
-  currentTask_ = task;
-  currentPriority_ = task->priority;
+  currentTask_ = &task;
+  currentPriority_ = task.priority;
 
   {
     ScopedShadowTreeRevisionLock revisionLock(
@@ -275,6 +274,8 @@ void RuntimeScheduler_Modern::executeTask(
       updateRendering();
     }
   }
+
+  currentTask_ = nullptr;
 }
 
 /**
@@ -296,16 +297,16 @@ void RuntimeScheduler_Modern::updateRendering() {
 
 void RuntimeScheduler_Modern::executeMacrotask(
     jsi::Runtime& runtime,
-    std::shared_ptr<Task> task,
+    Task& task,
     bool didUserCallbackTimeout) const {
   SystraceSection s("RuntimeScheduler::executeMacrotask");
 
-  auto result = task->execute(runtime, didUserCallbackTimeout);
+  auto result = task.execute(runtime, didUserCallbackTimeout);
 
   if (result.isObject() && result.getObject(runtime).isFunction(runtime)) {
     // If the task returned a continuation callback, we re-assign it to the task
     // and keep the task in the queue.
-    task->callback = result.getObject(runtime).getFunction(runtime);
+    task.callback = result.getObject(runtime).getFunction(runtime);
   }
 }
 
diff --git a/packages/react-native/ReactCommon/react/renderer/runtimescheduler/RuntimeScheduler_Modern.h b/packages/react-native/ReactCommon/react/renderer/runtimescheduler/RuntimeScheduler_Modern.h
index f730509928b..fa9b6c8c8e7 100644
--- a/packages/react-native/ReactCommon/react/renderer/runtimescheduler/RuntimeScheduler_Modern.h
+++ b/packages/react-native/ReactCommon/react/renderer/runtimescheduler/RuntimeScheduler_Modern.h
@@ -135,7 +135,7 @@ class RuntimeScheduler_Modern final : public RuntimeSchedulerBase {
       TaskPriorityComparer>
       taskQueue_;
 
-  std::shared_ptr<Task> currentTask_;
+  Task* currentTask_{};
 
   /**
    * This protects the access to `taskQueue_` and `isWorkLoopScheduled_`.
@@ -162,12 +162,12 @@ class RuntimeScheduler_Modern final : public RuntimeSchedulerBase {
    */
   void executeTask(
       jsi::Runtime& runtime,
-      const std::shared_ptr<Task>& task,
+      Task& task,
       RuntimeSchedulerTimePoint currentTime);
 
   void executeMacrotask(
       jsi::Runtime& runtime,
-      std::shared_ptr<Task> task,
+      Task& task,
       bool didUserCallbackTimeout) const;
 
   void updateRendering();