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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
     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/v8/V8PerIsolateData.h"
     35 #include "core/dom/ScriptExecutionContext.h"
     36 #include "wtf/Noncopyable.h"
     37 
     38 namespace WebCore {
     39 
     40 // C++ calls into script contexts which are "owned" by WebKit (created in a
     41 // process where WebKit.cpp initializes v8) must declare their type:
     42 //
     43 //   1. Calls into page/author script from a frame
     44 //   2. Calls into page/author script from a worker
     45 //   3. Calls into internal script (typically setup/teardown work)
     46 //
     47 // Debug-time checking of this is enforced via this class.
     48 //
     49 // Calls of type (1) should generally go through ScriptController, as inspector
     50 // instrumentation is needed. ScriptController allocates V8RecursionScope for you.
     51 // Calls of type (2) should always stack-allocate a V8RecursionScope in the same
     52 // block as the call into script. Calls of type (3) should stack allocate a
     53 // V8RecursionScope::MicrotaskSuppression -- this skips work that is spec'd to
     54 // happen at the end of the outer-most script stack frame of calls into page script:
     55 //
     56 // http://www.whatwg.org/specs/web-apps/current-work/#perform-a-microtask-checkpoint
     57 class V8RecursionScope {
     58     WTF_MAKE_NONCOPYABLE(V8RecursionScope);
     59 public:
     60     explicit V8RecursionScope(ScriptExecutionContext* context)
     61         : m_isDocumentContext(context && context->isDocument())
     62     {
     63         V8PerIsolateData::current()->incrementRecursionLevel();
     64     }
     65 
     66     ~V8RecursionScope()
     67     {
     68         if (!V8PerIsolateData::current()->decrementRecursionLevel())
     69             didLeaveScriptContext();
     70     }
     71 
     72     static int recursionLevel()
     73     {
     74         return V8PerIsolateData::current()->recursionLevel();
     75     }
     76 
     77 #ifndef NDEBUG
     78     static bool properlyUsed()
     79     {
     80         return recursionLevel() > 0 || V8PerIsolateData::current()->internalScriptRecursionLevel() > 0;
     81     }
     82 #endif
     83 
     84     class MicrotaskSuppression {
     85     public:
     86         MicrotaskSuppression()
     87         {
     88 #ifndef NDEBUG
     89             V8PerIsolateData::current()->incrementInternalScriptRecursionLevel();
     90 #endif
     91         }
     92 
     93         ~MicrotaskSuppression()
     94         {
     95 #ifndef NDEBUG
     96             V8PerIsolateData::current()->decrementInternalScriptRecursionLevel();
     97 #endif
     98         }
     99     };
    100 
    101 private:
    102     void didLeaveScriptContext();
    103 
    104     bool m_isDocumentContext;
    105 };
    106 
    107 } // namespace WebCore
    108 
    109 #endif // V8RecursionScope_h
    110