From fa3525dc83b7d4f5ad224af2fa1cca2690c2e804 Mon Sep 17 00:00:00 2001
From: Valentin Shergin <shergin@fb.com>
Date: Mon, 8 Oct 2018 14:34:20 -0700
Subject: [PATCH] Fabric: Introducting EventBeat::setFailCallback

Summary: In some cases we have to have a way to notify a EventBeat consumer that the beat cannot be (and will not be) delivered, so we introducing special API for that.

Reviewed By: mdvacca

Differential Revision: D10081503

fbshipit-source-id: 4c5a392d32572f426e3744bdba797efcd29b8cb4
---
 ReactCommon/fabric/events/EventBeat.cpp |  4 ++++
 ReactCommon/fabric/events/EventBeat.h   | 12 +++++++++++-
 2 files changed, 15 insertions(+), 1 deletion(-)

diff --git a/ReactCommon/fabric/events/EventBeat.cpp b/ReactCommon/fabric/events/EventBeat.cpp
index 8dd62828b..48d175ec5 100644
--- a/ReactCommon/fabric/events/EventBeat.cpp
+++ b/ReactCommon/fabric/events/EventBeat.cpp
@@ -34,5 +34,9 @@ void EventBeat::setBeatCallback(const BeatCallback &beatCallback) {
   beatCallback_ = beatCallback;
 }
 
+void EventBeat::setFailCallback(const FailCallback &failCallback) {
+  failCallback_ = failCallback;
+}
+
 } // namespace react
 } // namespace facebook
diff --git a/ReactCommon/fabric/events/EventBeat.h b/ReactCommon/fabric/events/EventBeat.h
index ef518eba5..14eababdd 100644
--- a/ReactCommon/fabric/events/EventBeat.h
+++ b/ReactCommon/fabric/events/EventBeat.h
@@ -24,6 +24,7 @@ public:
   virtual ~EventBeat() = default;
 
   using BeatCallback = std::function<void()>;
+  using FailCallback = std::function<void()>;
 
   /*
    * Communicates to the Beat that a consumer is waiting for the coming beat.
@@ -44,11 +45,19 @@ public:
   virtual void induce() const;
 
   /*
-   * Sets a callback function.
+   * Sets the beat callback function.
    * The callback is must be called on the proper thread.
    */
   void setBeatCallback(const BeatCallback &beatCallback);
 
+  /*
+   * Sets the fail callback function.
+   * Called in case if the beat cannot be performed anymore because of
+   * some external circumstances (e.g. execution thread is beling destructed).
+   * The callback can be called on any thread.
+   */
+  void setFailCallback(const FailCallback &failCallback);
+
 protected:
   /*
    * Should be used by sublasses to send a beat.
@@ -57,6 +66,7 @@ protected:
   void beat() const;
 
   BeatCallback beatCallback_;
+  FailCallback failCallback_;
   mutable std::atomic<bool> isRequested_ {false};
 };