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 "core/dom/CustomElementCallbackQueue.h" 35 #include "core/dom/Element.h" 36 #include "wtf/HashMap.h" 37 #include "wtf/OwnPtr.h" 38 #include "wtf/PassRefPtr.h" 39 #include "wtf/Vector.h" 40 41 namespace WebCore { 42 43 class CustomElementCallbackDispatcher { 44 WTF_MAKE_NONCOPYABLE(CustomElementCallbackDispatcher); 45 public: 46 static CustomElementCallbackDispatcher& instance(); 47 48 // This is stack allocated in many DOM callbacks. Make it cheap. 49 class CallbackDeliveryScope { 50 public: 51 CallbackDeliveryScope() 52 : m_savedElementQueueStart(s_elementQueueStart) 53 { 54 s_elementQueueStart = s_elementQueueEnd; 55 } 56 57 ~CallbackDeliveryScope() 58 { 59 if (s_elementQueueStart != s_elementQueueEnd) 60 processElementQueueAndPop(); 61 s_elementQueueStart = m_savedElementQueueStart; 62 } 63 64 private: 65 size_t m_savedElementQueueStart; 66 }; 67 68 // Returns true if more work may have to be performed at the 69 // checkpoint by this or other workers (for example, this work 70 // invoked author scripts) 71 bool dispatch(); 72 73 protected: 74 friend class CustomElementCallbackScheduler; 75 76 CustomElementCallbackQueue* createAtFrontOfCurrentElementQueue(PassRefPtr<Element>); 77 CustomElementCallbackQueue* ensureInCurrentElementQueue(PassRefPtr<Element>); 78 79 private: 80 CustomElementCallbackDispatcher() 81 { 82 // Add a null element as a sentinel. This makes it possible to 83 // identify elements queued when there is no 84 // CallbackDeliveryScope active. Also, if the processing stack 85 // is popped when empty, this sentinel will cause a null deref 86 // crash. 87 CustomElementCallbackQueue* sentinel = 0; 88 for (size_t i = 0; i < kNumSentinels; i++) 89 m_flattenedProcessingStack.append(sentinel); 90 ASSERT(s_elementQueueEnd == m_flattenedProcessingStack.size()); 91 } 92 93 // The start of the element queue on the top of the processing 94 // stack. An offset into instance().m_flattenedProcessingStack. 95 static size_t s_elementQueueStart; 96 97 // The end of the element queue on the top of the processing 98 // stack. A cache of instance().m_flattenedProcessingStack.size(). 99 static size_t s_elementQueueEnd; 100 101 static bool inCallbackDeliveryScope() { return s_elementQueueStart; } 102 103 typedef int ElementQueue; 104 static ElementQueue currentElementQueue() { return ElementQueue(s_elementQueueStart); } 105 106 static void processElementQueueAndPop(); 107 void processElementQueueAndPop(size_t start, size_t end); 108 109 CustomElementCallbackQueue* createCallbackQueue(PassRefPtr<Element>); 110 CustomElementCallbackQueue* ensureCallbackQueue(PassRefPtr<Element>); 111 112 // The processing stack, flattened. Element queues lower in the 113 // stack appear toward the head of the vector. The first element 114 // is a null sentinel value. 115 static const size_t kNumSentinels = 1; 116 Vector<CustomElementCallbackQueue*> m_flattenedProcessingStack; 117 118 typedef HashMap<Element*, OwnPtr<CustomElementCallbackQueue> > ElementCallbackQueueMap; 119 ElementCallbackQueueMap m_elementCallbackQueueMap; 120 }; 121 122 } 123 124 #endif // CustomElementCallbackDispatcher_h 125