1/*
2 * Copyright (C) 2011 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 are
6 * met:
7 *
8 *     * Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 *     * Redistributions in binary form must reproduce the above
11 * copyright notice, this list of conditions and the following disclaimer
12 * in the documentation and/or other materials provided with the
13 * distribution.
14 *     * Neither the name of Google Inc. nor the names of its
15 * contributors may be used to endorse or promote products derived from
16 * this 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 V8RecursionScope_h
32#define V8RecursionScope_h
33
34#include "bindings/core/v8/V8PerIsolateData.h"
35#include "core/dom/ExecutionContext.h"
36#include "platform/ScriptForbiddenScope.h"
37#include "wtf/Noncopyable.h"
38#include <v8.h>
39
40namespace blink {
41
42// C++ calls into script contexts which are "owned" by WebKit (created in a
43// process where WebKit.cpp initializes v8) must declare their type:
44//
45//   1. Calls into page/author script from a frame
46//   2. Calls into page/author script from a worker
47//   3. Calls into internal script (typically setup/teardown work)
48//
49// Debug-time checking of this is enforced via this class.
50//
51// Calls of type (1) should generally go through ScriptController, as inspector
52// instrumentation is needed. ScriptController allocates V8RecursionScope for you.
53// Calls of type (2) should always stack-allocate a V8RecursionScope in the same
54// block as the call into script. Calls of type (3) should stack allocate a
55// V8RecursionScope::MicrotaskSuppression -- this skips work that is spec'd to
56// happen at the end of the outer-most script stack frame of calls into page script:
57//
58// http://www.whatwg.org/specs/web-apps/current-work/#perform-a-microtask-checkpoint
59class V8RecursionScope {
60    WTF_MAKE_NONCOPYABLE(V8RecursionScope);
61public:
62    explicit V8RecursionScope(v8::Isolate* isolate)
63        : m_isolate(isolate)
64    {
65        V8PerIsolateData::from(m_isolate)->incrementRecursionLevel();
66        RELEASE_ASSERT(!ScriptForbiddenScope::isScriptForbidden());
67        // If you want V8 to autorun microtasks, this class needs to have a
68        // v8::Isolate::SuppressMicrotaskExecutionScope member.
69        ASSERT(!isolate->WillAutorunMicrotasks());
70    }
71
72    ~V8RecursionScope()
73    {
74        if (!V8PerIsolateData::from(m_isolate)->decrementRecursionLevel())
75            didLeaveScriptContext();
76    }
77
78    static int recursionLevel(v8::Isolate* isolate)
79    {
80        return V8PerIsolateData::from(isolate)->recursionLevel();
81    }
82
83#if ENABLE(ASSERT)
84    static bool properlyUsed(v8::Isolate* isolate)
85    {
86        return recursionLevel(isolate) > 0 || V8PerIsolateData::from(isolate)->internalScriptRecursionLevel() > 0;
87    }
88#endif
89
90    class MicrotaskSuppression {
91    public:
92        MicrotaskSuppression(v8::Isolate* isolate)
93#if ENABLE(ASSERT)
94            : m_isolate(isolate)
95#endif
96        {
97            ASSERT(!ScriptForbiddenScope::isScriptForbidden());
98#if ENABLE(ASSERT)
99            V8PerIsolateData::from(m_isolate)->incrementInternalScriptRecursionLevel();
100#endif
101        }
102
103        ~MicrotaskSuppression()
104        {
105#if ENABLE(ASSERT)
106            V8PerIsolateData::from(m_isolate)->decrementInternalScriptRecursionLevel();
107#endif
108        }
109
110    private:
111#if ENABLE(ASSERT)
112        v8::Isolate* m_isolate;
113#endif
114    };
115
116private:
117    void didLeaveScriptContext();
118
119    v8::Isolate* m_isolate;
120};
121
122} // namespace blink
123
124#endif // V8RecursionScope_h
125