1 | /* |
2 | * Copyright (C) 2008 Apple 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 | * 1. Redistributions of source code must retain the above copyright |
8 | * notice, this list of conditions and the following disclaimer. |
9 | * 2. Redistributions in binary form must reproduce the above copyright |
10 | * notice, this list of conditions and the following disclaimer in the |
11 | * documentation and/or other materials provided with the distribution. |
12 | * |
13 | * THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY |
14 | * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE |
15 | * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR |
16 | * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR |
17 | * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, |
18 | * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, |
19 | * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR |
20 | * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY |
21 | * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT |
22 | * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE |
23 | * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
24 | * |
25 | */ |
26 | |
27 | #pragma once |
28 | |
29 | #include "ContextDestructionObserver.h" |
30 | #include <wtf/Assertions.h> |
31 | #include <wtf/Forward.h> |
32 | #include <wtf/RefCounted.h> |
33 | #include <wtf/Threading.h> |
34 | |
35 | namespace WebCore { |
36 | |
37 | class Document; |
38 | |
39 | enum class ReasonForSuspension { |
40 | JavaScriptDebuggerPaused, |
41 | WillDeferLoading, |
42 | PageCache, |
43 | PageWillBeSuspended, |
44 | }; |
45 | |
46 | class ActiveDOMObject : public ContextDestructionObserver { |
47 | public: |
48 | // The suspendIfNeeded must be called exactly once after object construction to update |
49 | // the suspended state to match that of the ScriptExecutionContext. |
50 | void suspendIfNeeded(); |
51 | void assertSuspendIfNeededWasCalled() const; |
52 | |
53 | virtual bool hasPendingActivity() const; |
54 | |
55 | // The canSuspendForDocumentSuspension() function is used by the caller if there is a choice between suspending |
56 | // and stopping. For example, a page won't be suspended and placed in the back/forward |
57 | // cache if it contains any objects that cannot be suspended. |
58 | |
59 | // However, the suspend function will sometimes be called even if canSuspendForDocumentSuspension() returns false. |
60 | // That happens in step-by-step JS debugging for example - in this case it would be incorrect |
61 | // to stop the object. Exact semantics of suspend is up to the object in cases like that. |
62 | |
63 | virtual const char* activeDOMObjectName() const = 0; |
64 | |
65 | // These three functions must not have a side effect of creating or destroying |
66 | // any ActiveDOMObject. That means they must not result in calls to arbitrary JavaScript. |
67 | virtual bool canSuspendForDocumentSuspension() const = 0; // Returning false in canSuspendForDocumentSuspension() will prevent the page from entering the PageCache. |
68 | virtual void suspend(ReasonForSuspension); |
69 | virtual void resume(); |
70 | |
71 | // This function must not have a side effect of creating an ActiveDOMObject. |
72 | // That means it must not result in calls to arbitrary JavaScript. |
73 | // It can, however, have a side effect of deleting an ActiveDOMObject. |
74 | virtual void stop(); |
75 | |
76 | template<typename T> void setPendingActivity(T& thisObject) |
77 | { |
78 | ASSERT(&thisObject == this); |
79 | thisObject.ref(); |
80 | ++m_pendingActivityCount; |
81 | } |
82 | |
83 | template<typename T> void unsetPendingActivity(T& thisObject) |
84 | { |
85 | ASSERT(m_pendingActivityCount > 0); |
86 | --m_pendingActivityCount; |
87 | thisObject.deref(); |
88 | } |
89 | |
90 | template<class T> |
91 | class PendingActivity : public RefCounted<PendingActivity<T>> { |
92 | public: |
93 | explicit PendingActivity(T& thisObject) |
94 | : m_thisObject(thisObject) |
95 | { |
96 | ++(m_thisObject->m_pendingActivityCount); |
97 | } |
98 | |
99 | ~PendingActivity() |
100 | { |
101 | ASSERT(m_thisObject->m_pendingActivityCount > 0); |
102 | --(m_thisObject->m_pendingActivityCount); |
103 | } |
104 | |
105 | private: |
106 | Ref<T> m_thisObject; |
107 | }; |
108 | |
109 | template<class T> Ref<PendingActivity<T>> makePendingActivity(T& thisObject) |
110 | { |
111 | ASSERT(&thisObject == this); |
112 | return adoptRef(*new PendingActivity<T>(thisObject)); |
113 | } |
114 | |
115 | bool isContextStopped() const; |
116 | |
117 | protected: |
118 | explicit ActiveDOMObject(ScriptExecutionContext*); |
119 | explicit ActiveDOMObject(Document*) = delete; |
120 | explicit ActiveDOMObject(Document&); // Implemented in Document.h |
121 | virtual ~ActiveDOMObject(); |
122 | |
123 | private: |
124 | unsigned m_pendingActivityCount; |
125 | #if !ASSERT_DISABLED |
126 | bool m_suspendIfNeededWasCalled; |
127 | Ref<Thread> m_creationThread { Thread::current() }; |
128 | #endif |
129 | }; |
130 | |
131 | #if ASSERT_DISABLED |
132 | |
133 | inline void ActiveDOMObject::assertSuspendIfNeededWasCalled() const |
134 | { |
135 | } |
136 | |
137 | #endif |
138 | |
139 | } // namespace WebCore |
140 | |