git subrepo clone --branch=sono6good https://github.com/essej/JUCE.git deps/juce

subrepo:
  subdir:   "deps/juce"
  merged:   "b13f9084e"
upstream:
  origin:   "https://github.com/essej/JUCE.git"
  branch:   "sono6good"
  commit:   "b13f9084e"
git-subrepo:
  version:  "0.4.3"
  origin:   "https://github.com/ingydotnet/git-subrepo.git"
  commit:   "2f68596"

deps/juce/modules/juce_events/broadcasters/juce_AsyncUpdater.cpp

@@ -0,0 +1,93 @@
+/*
+  ==============================================================================
+
+   This file is part of the JUCE library.
+   Copyright (c) 2020 - Raw Material Software Limited
+
+   JUCE is an open source library subject to commercial or open-source
+   licensing.
+
+   The code included in this file is provided under the terms of the ISC license
+   http://www.isc.org/downloads/software-support-policy/isc-license. Permission
+   To use, copy, modify, and/or distribute this software for any purpose with or
+   without fee is hereby granted provided that the above copyright notice and
+   this permission notice appear in all copies.
+
+   JUCE IS PROVIDED "AS IS" WITHOUT ANY WARRANTY, AND ALL WARRANTIES, WHETHER
+   EXPRESSED OR IMPLIED, INCLUDING MERCHANTABILITY AND FITNESS FOR PURPOSE, ARE
+   DISCLAIMED.
+
+  ==============================================================================
+*/
+
+namespace juce
+{
+
+class AsyncUpdater::AsyncUpdaterMessage  : public CallbackMessage
+{
+public:
+    AsyncUpdaterMessage (AsyncUpdater& au)  : owner (au) {}
+
+    void messageCallback() override
+    {
+        if (shouldDeliver.compareAndSetBool (0, 1))
+            owner.handleAsyncUpdate();
+    }
+
+    AsyncUpdater& owner;
+    Atomic<int> shouldDeliver;
+
+    JUCE_DECLARE_NON_COPYABLE (AsyncUpdaterMessage)
+};
+
+//==============================================================================
+AsyncUpdater::AsyncUpdater()
+{
+    activeMessage = *new AsyncUpdaterMessage (*this);
+}
+
+AsyncUpdater::~AsyncUpdater()
+{
+    // You're deleting this object with a background thread while there's an update
+    // pending on the main event thread - that's pretty dodgy threading, as the callback could
+    // happen after this destructor has finished. You should either use a MessageManagerLock while
+    // deleting this object, or find some other way to avoid such a race condition.
+    jassert ((! isUpdatePending())
+              || MessageManager::getInstanceWithoutCreating() == nullptr
+              || MessageManager::getInstanceWithoutCreating()->currentThreadHasLockedMessageManager());
+
+    activeMessage->shouldDeliver.set (0);
+}
+
+void AsyncUpdater::triggerAsyncUpdate()
+{
+    // If you're calling this before (or after) the MessageManager is
+    // running, then you're not going to get any callbacks!
+    JUCE_ASSERT_MESSAGE_MANAGER_EXISTS
+
+    if (activeMessage->shouldDeliver.compareAndSetBool (1, 0))
+        if (! activeMessage->post())
+            cancelPendingUpdate(); // if the message queue fails, this avoids getting
+                                   // trapped waiting for the message to arrive
+}
+
+void AsyncUpdater::cancelPendingUpdate() noexcept
+{
+    activeMessage->shouldDeliver.set (0);
+}
+
+void AsyncUpdater::handleUpdateNowIfNeeded()
+{
+    // This can only be called by the event thread.
+    JUCE_ASSERT_MESSAGE_MANAGER_IS_LOCKED
+
+    if (activeMessage->shouldDeliver.exchange (0) != 0)
+        handleAsyncUpdate();
+}
+
+bool AsyncUpdater::isUpdatePending() const noexcept
+{
+    return activeMessage->shouldDeliver.value != 0;
+}
+
+} // namespace juce