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/*
* Copyright (C) 2013 Google Inc. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer
* in the documentation and/or other materials provided with the
* distribution.
* 3. Neither the name of Google Inc. nor the names of its contributors
* may be used to endorse or promote products derived from this
* software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
* OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#ifndef CustomElementCallbackDispatcher_h
#define CustomElementCallbackDispatcher_h
#include "wtf/Vector.h"
namespace WebCore {
class CustomElementCallbackQueue;
class CustomElementCallbackScheduler;
class CustomElementCallbackDispatcher {
WTF_MAKE_NONCOPYABLE(CustomElementCallbackDispatcher);
public:
static CustomElementCallbackDispatcher& instance();
// This is stack allocated in many DOM callbacks. Make it cheap.
class CallbackDeliveryScope {
public:
CallbackDeliveryScope()
: m_savedElementQueueStart(s_elementQueueStart)
{
s_elementQueueStart = s_elementQueueEnd;
}
~CallbackDeliveryScope()
{
if (s_elementQueueStart != s_elementQueueEnd)
processElementQueueAndPop();
s_elementQueueStart = m_savedElementQueueStart;
}
private:
size_t m_savedElementQueueStart;
};
// Returns true if more work may have to be performed at the
// checkpoint by this or other workers (for example, this work
// invoked author scripts)
bool dispatch();
protected:
friend class CustomElementCallbackScheduler;
void enqueue(CustomElementCallbackQueue*);
private:
CustomElementCallbackDispatcher()
{
// Add a null element as a sentinel. This makes it possible to
// identify elements queued when there is no
// CallbackDeliveryScope active. Also, if the processing stack
// is popped when empty, this sentinel will cause a null deref
// crash.
CustomElementCallbackQueue* sentinel = 0;
for (size_t i = 0; i < kNumSentinels; i++)
m_flattenedProcessingStack.append(sentinel);
ASSERT(s_elementQueueEnd == m_flattenedProcessingStack.size());
}
// The start of the element queue on the top of the processing
// stack. An offset into instance().m_flattenedProcessingStack.
static size_t s_elementQueueStart;
// The end of the element queue on the top of the processing
// stack. A cache of instance().m_flattenedProcessingStack.size().
static size_t s_elementQueueEnd;
static bool inCallbackDeliveryScope() { return s_elementQueueStart; }
typedef int ElementQueue;
static ElementQueue currentElementQueue() { return ElementQueue(s_elementQueueStart); }
static void processElementQueueAndPop();
void processElementQueueAndPop(size_t start, size_t end);
// The processing stack, flattened. Element queues lower in the
// stack appear toward the head of the vector. The first element
// is a null sentinel value.
static const size_t kNumSentinels = 1;
Vector<CustomElementCallbackQueue*> m_flattenedProcessingStack;
};
}
#endif // CustomElementCallbackDispatcher_h
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