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105 lines
3.7 KiB
C++
105 lines
3.7 KiB
C++
/*
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==============================================================================
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This file is part of the JUCE framework.
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Copyright (c) Raw Material Software Limited
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JUCE is an open source framework subject to commercial or open source
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licensing.
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By downloading, installing, or using the JUCE framework, or combining the
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JUCE framework with any other source code, object code, content or any other
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copyrightable work, you agree to the terms of the JUCE End User Licence
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Agreement, and all incorporated terms including the JUCE Privacy Policy and
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the JUCE Website Terms of Service, as applicable, which will bind you. If you
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do not agree to the terms of these agreements, we will not license the JUCE
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framework to you, and you must discontinue the installation or download
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process and cease use of the JUCE framework.
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JUCE End User Licence Agreement: https://juce.com/legal/juce-8-licence/
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JUCE Privacy Policy: https://juce.com/juce-privacy-policy
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JUCE Website Terms of Service: https://juce.com/juce-website-terms-of-service/
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Or:
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You may also use this code under the terms of the AGPLv3:
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https://www.gnu.org/licenses/agpl-3.0.en.html
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THE JUCE FRAMEWORK IS PROVIDED "AS IS" WITHOUT ANY WARRANTY, AND ALL
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WARRANTIES, WHETHER EXPRESSED OR IMPLIED, INCLUDING WARRANTY OF
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MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, ARE DISCLAIMED.
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==============================================================================
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*/
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namespace juce
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{
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class AsyncUpdater::AsyncUpdaterMessage final : 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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AsyncUpdater& owner;
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Atomic<int> shouldDeliver;
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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())
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|| MessageManager::getInstanceWithoutCreating() == nullptr
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|| MessageManager::getInstanceWithoutCreating()->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 you're calling this before (or after) the MessageManager is
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// running, then you're not going to get any callbacks!
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JUCE_ASSERT_MESSAGE_MANAGER_EXISTS
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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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JUCE_ASSERT_MESSAGE_MANAGER_IS_LOCKED
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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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} // namespace juce
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