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      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
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     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/v8/V8PerIsolateData.h"
     35 #include "core/dom/ExecutionContext.h"
     36 #include "core/dom/ScriptForbiddenScope.h"
     37 #include "wtf/Noncopyable.h"
     38 #include <v8.h>
     39 
     40 namespace WebCore {
     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
     59 class V8RecursionScope {
     60     WTF_MAKE_NONCOPYABLE(V8RecursionScope);
     61 public:
     62     V8RecursionScope(v8::Isolate* isolate, ExecutionContext* context)
     63         : m_isolate(isolate)
     64         , m_executionContext(*context)
     65     {
     66         V8PerIsolateData::from(m_isolate)->incrementRecursionLevel();
     67         ASSERT(!ScriptForbiddenScope::isScriptForbidden());
     68         // If you want V8 to autorun microtasks, this class needs to have a
     69         // v8::Isolate::SuppressMicrotaskExecutionScope member.
     70         ASSERT(!isolate->WillAutorunMicrotasks());
     71     }
     72 
     73     ~V8RecursionScope()
     74     {
     75         if (!V8PerIsolateData::from(m_isolate)->decrementRecursionLevel())
     76             didLeaveScriptContext();
     77     }
     78 
     79     static int recursionLevel(v8::Isolate* isolate)
     80     {
     81         return V8PerIsolateData::from(isolate)->recursionLevel();
     82     }
     83 
     84 #ifndef NDEBUG
     85     static bool properlyUsed(v8::Isolate* isolate)
     86     {
     87         return recursionLevel(isolate) > 0 || V8PerIsolateData::from(isolate)->internalScriptRecursionLevel() > 0;
     88     }
     89 #endif
     90 
     91     class MicrotaskSuppression {
     92     public:
     93         MicrotaskSuppression(v8::Isolate* isolate)
     94 #ifndef NDEBUG
     95             : m_isolate(isolate)
     96 #endif
     97         {
     98             ASSERT(!ScriptForbiddenScope::isScriptForbidden());
     99 #ifndef NDEBUG
    100             V8PerIsolateData::from(m_isolate)->incrementInternalScriptRecursionLevel();
    101 #endif
    102         }
    103 
    104         ~MicrotaskSuppression()
    105         {
    106 #ifndef NDEBUG
    107             V8PerIsolateData::from(m_isolate)->decrementInternalScriptRecursionLevel();
    108 #endif
    109         }
    110 
    111     private:
    112 #ifndef NDEBUG
    113         v8::Isolate* m_isolate;
    114 #endif
    115     };
    116 
    117 private:
    118     void didLeaveScriptContext();
    119 
    120     v8::Isolate* m_isolate;
    121     ExecutionContext& m_executionContext;
    122 };
    123 
    124 } // namespace WebCore
    125 
    126 #endif // V8RecursionScope_h
    127