gin/public/isolate_holder.h

   1 // Copyright 2013 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #ifndef GIN_PUBLIC_ISOLATE_HOLDER_H_
   6 #define GIN_PUBLIC_ISOLATE_HOLDER_H_
   7
   8 #include "base/basictypes.h"
   9 #include "base/memory/scoped_ptr.h"
  10 #include "gin/gin_export.h"
  11 #include "v8/include/v8.h"
  12
  13 namespace gin {
  14
  15 class PerIsolateData;
  16 class RunMicrotasksObserver;
  17
  18 // To embed Gin, first initialize gin using IsolateHolder::Initialize and then
  19 // create an instance of IsolateHolder to hold the v8::Isolate in which you
  20 // will execute JavaScript. You might wish to subclass IsolateHolder if you
  21 // want to tie more state to the lifetime of the isolate.
  22 class GIN_EXPORT IsolateHolder {
  23  public:
  24   // Controls whether or not V8 should only accept strict mode scripts.
  25   enum ScriptMode {
  26     kNonStrictMode,
  27     kStrictMode
  28   };
  29
  30   // Stores whether the client uses v8::Locker to access the isolate.
  31   enum AccessMode {
  32     kSingleThread,
  33     kUseLocker
  34   };
  35
  36   IsolateHolder();
  37   explicit IsolateHolder(AccessMode access_mode);
  38   ~IsolateHolder();
  39
  40   // Should be invoked once before creating IsolateHolder instances to
  41   // initialize V8 and Gin. In case V8_USE_EXTERNAL_STARTUP_DATA is
  42   // defined, V8's initial snapshot should be loaded (by calling
  43   // V8Initializer::LoadV8SnapshotFromFD or
  44   // V8Initializer::LoadV8Snapshot) before calling this method.
  45   static void Initialize(ScriptMode mode,
  46                          v8::ArrayBuffer::Allocator* allocator);
  47
  48   v8::Isolate* isolate() { return isolate_; }
  49
  50   // The implementations of Object.observe() and Promise enqueue v8 Microtasks
  51   // that should be executed just before control is returned to the message
  52   // loop. This method adds a MessageLoop TaskObserver which runs any pending
  53   // Microtasks each time a Task is completed. This method should be called
  54   // once, when a MessageLoop is created and it should be called on the
  55   // MessageLoop's thread.
  56   void AddRunMicrotasksObserver();
  57
  58   // This method should also only be called once, and on the MessageLoop's
  59   // thread.
  60   void RemoveRunMicrotasksObserver();
  61
  62   // This method returns if v8::Locker is needed to access isolate.
  63   AccessMode access_mode() const { return access_mode_; }
  64
  65  private:
  66   v8::Isolate* isolate_;
  67   scoped_ptr<PerIsolateData> isolate_data_;
  68   scoped_ptr<RunMicrotasksObserver> task_observer_;
  69   AccessMode access_mode_;
  70
  71   DISALLOW_COPY_AND_ASSIGN(IsolateHolder);
  72 };
  73
  74 }  // namespace gin
  75
  76 #endif  // GIN_PUBLIC_ISOLATE_HOLDER_H_