1/*
2 * Copyright (C) 2009 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,
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28 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
29 */
30
31#ifndef V8IsolatedContext_h
32#define V8IsolatedContext_h
33
34#include "IsolatedWorld.h"
35#include "ScriptSourceCode.h" // for WebCore::ScriptSourceCode
36#include "V8DOMWindow.h"
37#include "V8Proxy.h"
38#include "V8Utilities.h"
39#include <v8.h>
40
41namespace WebCore {
42
43class V8Proxy;
44
45// V8IsolatedContext
46//
47// V8IsolatedContext represents a isolated execution environment for
48// JavaScript.  Each isolated world executes in parallel with the main
49// JavaScript world.  An isolated world has access to the same DOM data
50// structures as the main world but none of the JavaScript pointers.
51//
52// It is an error to ever share a JavaScript pointer between two isolated
53// worlds or between an isolated world and the main world.  Because
54// isolated worlds have access to the DOM, they need their own DOM wrappers
55// to avoid having pointers to the main world's DOM wrappers (which are
56// JavaScript objects).
57class V8IsolatedContext {
58public:
59    // Creates an isolated world. To destroy it, call destroy().
60    // This will delete the isolated world when the context it owns is GC'd.
61    V8IsolatedContext(V8Proxy* proxy, int extensionGroup);
62    ~V8IsolatedContext();
63
64    // Call this to destroy the isolated world. It will be deleted sometime
65    // after this call, once all script references to the world's context
66    // have been dropped.
67    void destroy();
68
69    // Returns the isolated world associated with
70    // v8::Context::GetEntered().  Because worlds are isolated, the entire
71    // JavaScript call stack should be from the same isolated world.
72    // Returns 0 if the entered context is from the main world.
73    //
74    // FIXME: Consider edge cases with DOM mutation events that might
75    // violate this invariant.
76    //
77    static V8IsolatedContext* getEntered()
78    {
79        // This is a temporary performance optimization.   Essentially,
80        // GetHiddenValue is too slow for this code path.  We need to get the
81        // V8 team to add a real property to v8::Context for isolated worlds.
82        // Until then, we optimize the common case of not having any isolated
83        // worlds at all.
84        if (!IsolatedWorld::count())
85            return 0;
86        if (!v8::Context::InContext())
87            return 0;
88        return reinterpret_cast<V8IsolatedContext*>(getGlobalObject(v8::Context::GetEntered())->GetPointerFromInternalField(V8DOMWindow::enteredIsolatedWorldIndex));
89    }
90
91    v8::Handle<v8::Context> context() { return m_context->get(); }
92    PassRefPtr<SharedPersistent<v8::Context> > sharedContext() { return m_context; }
93
94    IsolatedWorld* world() const { return m_world.get(); }
95
96private:
97    static v8::Handle<v8::Object> getGlobalObject(v8::Handle<v8::Context> context)
98    {
99        return v8::Handle<v8::Object>::Cast(context->Global()->GetPrototype());
100    }
101
102    // Called by the garbage collector when our JavaScript context is about
103    // to be destroyed.
104    static void contextWeakReferenceCallback(v8::Persistent<v8::Value> object, void* isolatedContext);
105
106    // The underlying v8::Context. This object is keep on the heap as
107    // long as |m_context| has not been garbage collected.
108    RefPtr<SharedPersistent<v8::Context> > m_context;
109
110    RefPtr<IsolatedWorld> m_world;
111};
112
113} // namespace WebCore
114
115#endif // V8IsolatedContext_h
116