third_party/WebKit/public/web/WebScopedMicrotaskSuppression.h

   1 /*
   2  * Copyright (C) 2012 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 WebScopedMicrotaskSuppression_h
  32 #define WebScopedMicrotaskSuppression_h
  33
  34 #include "../platform/WebPrivateOwnPtr.h"
  35
  36 namespace blink {
  37
  38 // This class wraps V8RecursionScope::BypassMicrotaskCheckpoint. Please
  39 // see V8RecursionScope.h for full usage. Short story: Embedder calls into
  40 // script contexts which also host page script must do one of two things:
  41 //
  42 //   1. If the call may cause any page/author script to run, it must be
  43 //      captured for pre/post work (e.g. inspector instrumentation/microtask
  44 //      delivery) and thus be invoked through WebFrame (e.g. executeScript*,
  45 //      callFunction*).
  46 //   2. If the call will not cause any page/author script to run, the call
  47 //      should be made directly via the v8 context, but the callsite must be
  48 //      accompanied by a stack allocated WebScopedMicrotaskSuppression, e.g.:
  49 //
  50 //        ...
  51 //        {
  52 //            blink::WebScopedMicrotaskSuppression suppression;
  53 //            func->Call(global, argv, args);
  54 //        }
  55 //        ...
  56 //
  57 class WebScopedMicrotaskSuppression {
  58 public:
  59     WebScopedMicrotaskSuppression() { initialize(); }
  60     ~WebScopedMicrotaskSuppression() { reset(); }
  61
  62 private:
  63     BLINK_EXPORT void initialize();
  64     BLINK_EXPORT void reset();
  65
  66     // Always declare this data member. When assertions are on in
  67     // Release builds of Blink, this header may be included from
  68     // Chromium with different preprocessor options than used when
  69     // building Blink itself.
  70     class Impl;
  71     WebPrivateOwnPtr<Impl> m_impl;
  72 };
  73
  74 } // WebKit
  75
  76 #endif