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| 1 /* | |
| 2 * Copyright (C) 2013 Google Inc. All rights reserved. | |
| 3 * | |
| 4 * Redistribution and use in source and binary forms, with or without | |
| 5 * modification, are permitted provided that the following conditions | |
| 6 * are met: | |
| 7 * | |
| 8 * 1. Redistributions of source code must retain the above copyright | |
| 9 * notice, this list of conditions and the following disclaimer. | |
| 10 * 2. Redistributions in binary form must reproduce the above copyright | |
| 11 * notice, this list of conditions and the following disclaimer | |
| 12 * in the documentation and/or other materials provided with the | |
| 13 * distribution. | |
| 14 * 3. Neither the name of Google Inc. nor the names of its contributors | |
| 15 * may be used to endorse or promote products derived from this | |
| 16 * software without specific prior written permission. | |
| 17 * | |
| 18 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS | |
| 19 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT | |
| 20 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR | |
| 21 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT | |
| 22 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, | |
| 23 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT | |
| 24 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, | |
| 25 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY | |
| 26 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT | |
| 27 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE | |
| 28 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. | |
| 29 */ | |
| 30 | |
| 31 #ifndef CustomElementCallbackDispatcher_h | |
| 32 #define CustomElementCallbackDispatcher_h | |
| 33 | |
| 34 #include "wtf/Vector.h" | |
| 35 | |
| 36 namespace WebCore { | |
| 37 | |
| 38 class CustomElementCallbackQueue; | |
| 39 class CustomElementCallbackScheduler; | |
| 40 | |
| 41 class CustomElementCallbackDispatcher { | |
| 42 WTF_MAKE_NONCOPYABLE(CustomElementCallbackDispatcher); | |
| 43 public: | |
| 44 static CustomElementCallbackDispatcher& instance(); | |
| 45 | |
| 46 // This is stack allocated in many DOM callbacks. Make it cheap. | |
| 47 class CallbackDeliveryScope { | |
| 48 public: | |
| 49 CallbackDeliveryScope() | |
| 50 : m_savedElementQueueStart(s_elementQueueStart) | |
| 51 { | |
| 52 s_elementQueueStart = s_elementQueueEnd; | |
| 53 } | |
| 54 | |
| 55 ~CallbackDeliveryScope() | |
| 56 { | |
| 57 if (s_elementQueueStart != s_elementQueueEnd) | |
| 58 processElementQueueAndPop(); | |
| 59 s_elementQueueStart = m_savedElementQueueStart; | |
| 60 } | |
| 61 | |
| 62 private: | |
| 63 size_t m_savedElementQueueStart; | |
| 64 }; | |
| 65 | |
| 66 // Returns true if more work may have to be performed at the | |
| 67 // checkpoint by this or other workers (for example, this work | |
| 68 // invoked author scripts) | |
| 69 bool dispatch(); | |
| 70 | |
| 71 protected: | |
| 72 friend class CustomElementCallbackScheduler; | |
| 73 void enqueue(CustomElementCallbackQueue*); | |
| 74 | |
| 75 private: | |
| 76 CustomElementCallbackDispatcher() | |
| 77 { | |
| 78 // Add a null element as a sentinel. This makes it possible to | |
| 79 // identify elements queued when there is no | |
| 80 // CallbackDeliveryScope active. Also, if the processing stack | |
| 81 // is popped when empty, this sentinel will cause a null deref | |
| 82 // crash. | |
| 83 CustomElementCallbackQueue* sentinel = 0; | |
| 84 for (size_t i = 0; i < kNumSentinels; i++) | |
| 85 m_flattenedProcessingStack.append(sentinel); | |
| 86 ASSERT(s_elementQueueEnd == m_flattenedProcessingStack.size()); | |
| 87 } | |
| 88 | |
| 89 // The start of the element queue on the top of the processing | |
| 90 // stack. An offset into instance().m_flattenedProcessingStack. | |
| 91 static size_t s_elementQueueStart; | |
| 92 | |
| 93 // The end of the element queue on the top of the processing | |
| 94 // stack. A cache of instance().m_flattenedProcessingStack.size(). | |
| 95 static size_t s_elementQueueEnd; | |
| 96 | |
| 97 static bool inCallbackDeliveryScope() { return s_elementQueueStart; } | |
| 98 | |
| 99 typedef int ElementQueue; | |
| 100 static ElementQueue currentElementQueue() { return ElementQueue(s_elementQue
ueStart); } | |
| 101 | |
| 102 static void processElementQueueAndPop(); | |
| 103 void processElementQueueAndPop(size_t start, size_t end); | |
| 104 | |
| 105 // The processing stack, flattened. Element queues lower in the | |
| 106 // stack appear toward the head of the vector. The first element | |
| 107 // is a null sentinel value. | |
| 108 static const size_t kNumSentinels = 1; | |
| 109 Vector<CustomElementCallbackQueue*> m_flattenedProcessingStack; | |
| 110 }; | |
| 111 | |
| 112 } | |
| 113 | |
| 114 #endif // CustomElementCallbackDispatcher_h | |
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