From 57da24dfdbaf37b54c39afd3e34f6c5d59ceee62 Mon Sep 17 00:00:00 2001
From: Arthur Sonzogni <sonzogniarthur@gmail.com>
Date: Mon, 4 Jul 2022 23:34:37 +0200
Subject: [PATCH] Fix homescreen example thread safety. (#431)
This addresses and fix:
https://github.com/ArthurSonzogni/FTXUI/issues/430
This patchs makes |shift| to be read and written on the same thread. We
request the update to be made via a task posted on the main thread.
This patch has no real consequence, the previous behavior was fine.
I hope it will help users not to have thread safety issue and better
understand they can post tasks this way.
---
examples/component/homescreen.cpp | 12 +++++++++---
1 file changed, 9 insertions(+), 3 deletions(-)
diff --git a/examples/component/homescreen.cpp b/examples/component/homescreen.cpp
index d8af183f..2f5370ac 100644
--- a/examples/component/homescreen.cpp
+++ b/examples/component/homescreen.cpp
@@ -1,5 +1,6 @@
#include <stddef.h> // for size_t
#include <array> // for array
+#include <atomic> // for atomic
#include <chrono> // for operator""s, chrono_literals
#include <cmath> // for sin
#include <functional> // for ref, reference_wrapper, function
@@ -499,13 +500,18 @@ int main(int argc, const char* argv[]) {
});
});
- bool refresh_ui_continue = true;
+ std::atomic<bool> refresh_ui_continue = true;
std::thread refresh_ui([&] {
while (refresh_ui_continue) {
using namespace std::chrono_literals;
std::this_thread::sleep_for(0.05s);
- shift++;
- screen.PostEvent(Event::Custom);
+ // The |shift| variable belong to the main thread. `screen.Post(task)`
+ // will execute the update on the thread where |screen| lives (e.g. the
+ // main thread). Using `screen.Post(task)` is threadsafe.
+ screen.Post([&] { shift++; });
+ // After updating the state, request a new frame to be drawn. This is done
+ // by simulating a new "custom" event to be handled.
+ screen.Post(Event::Custom);
}
});
--
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