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86 lines
2.8 KiB
86 lines
2.8 KiB
/*
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==============================================================================
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This file is part of the JUCE library.
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Copyright (c) 2013 - Raw Material Software Ltd.
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Permission is granted to use this software under the terms of either:
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a) the GPL v2 (or any later version)
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b) the Affero GPL v3
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Details of these licenses can be found at: www.gnu.org/licenses
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JUCE is distributed in the hope that it will be useful, but WITHOUT ANY
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WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
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A PARTICULAR PURPOSE. See the GNU General Public License for more details.
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------------------------------------------------------------------------------
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To release a closed-source product which uses JUCE, commercial licenses are
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available: visit www.juce.com for more information.
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==============================================================================
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*/
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class AsyncUpdater::AsyncUpdaterMessage : public CallbackMessage
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{
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public:
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AsyncUpdaterMessage (AsyncUpdater& au) : owner (au) {}
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void messageCallback() override
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{
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if (shouldDeliver.compareAndSetBool (0, 1))
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owner.handleAsyncUpdate();
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}
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Atomic<int> shouldDeliver;
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private:
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AsyncUpdater& owner;
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JUCE_DECLARE_NON_COPYABLE (AsyncUpdaterMessage)
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};
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//==============================================================================
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AsyncUpdater::AsyncUpdater()
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{
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activeMessage = new AsyncUpdaterMessage (*this);
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}
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AsyncUpdater::~AsyncUpdater()
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{
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// You're deleting this object with a background thread while there's an update
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// pending on the main event thread - that's pretty dodgy threading, as the callback could
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// happen after this destructor has finished. You should either use a MessageManagerLock while
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// deleting this object, or find some other way to avoid such a race condition.
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jassert ((! isUpdatePending()) || MessageManager::getInstance()->currentThreadHasLockedMessageManager());
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activeMessage->shouldDeliver.set (0);
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}
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void AsyncUpdater::triggerAsyncUpdate()
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{
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if (activeMessage->shouldDeliver.compareAndSetBool (1, 0))
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if (! activeMessage->post())
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cancelPendingUpdate(); // if the message queue fails, this avoids getting
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// trapped waiting for the message to arrive
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}
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void AsyncUpdater::cancelPendingUpdate() noexcept
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{
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activeMessage->shouldDeliver.set (0);
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}
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void AsyncUpdater::handleUpdateNowIfNeeded()
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{
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// This can only be called by the event thread.
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jassert (MessageManager::getInstance()->currentThreadHasLockedMessageManager());
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if (activeMessage->shouldDeliver.exchange (0) != 0)
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handleAsyncUpdate();
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}
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bool AsyncUpdater::isUpdatePending() const noexcept
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{
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return activeMessage->shouldDeliver.value != 0;
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}
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