1 // Copyright 2021 the V8 project 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 INCLUDE_V8_WEAK_CALLBACK_INFO_H_
6 #define INCLUDE_V8_WEAK_CALLBACK_INFO_H_
7
8 #include "v8config.h" // NOLINT(build/include_directory)
9
10 namespace v8 {
11
12 class Isolate;
13
14 namespace api_internal {
15 V8_EXPORT void InternalFieldOutOfBounds(int index);
16 } // namespace api_internal
17
18 static const int kInternalFieldsInWeakCallback = 2;
19 static const int kEmbedderFieldsInWeakCallback = 2;
20
21 template <typename T>
22 class WeakCallbackInfo {
23 public:
24 using Callback = void (*)(const WeakCallbackInfo<T>& data);
25
WeakCallbackInfo(Isolate* isolate, T* parameter, void* embedder_fields[kEmbedderFieldsInWeakCallback], Callback* callback)26 WeakCallbackInfo(Isolate* isolate, T* parameter,
27 void* embedder_fields[kEmbedderFieldsInWeakCallback],
28 Callback* callback)
29 : isolate_(isolate), parameter_(parameter), callback_(callback) {
30 for (int i = 0; i < kEmbedderFieldsInWeakCallback; ++i) {
31 embedder_fields_[i] = embedder_fields[i];
32 }
33 }
34
GetIsolate() const35 V8_INLINE Isolate* GetIsolate() const { return isolate_; }
GetParameter() const36 V8_INLINE T* GetParameter() const { return parameter_; }
37 V8_INLINE void* GetInternalField(int index) const;
38
39 // When first called, the embedder MUST Reset() the Global which triggered the
40 // callback. The Global itself is unusable for anything else. No v8 other api
41 // calls may be called in the first callback. Should additional work be
42 // required, the embedder must set a second pass callback, which will be
43 // called after all the initial callbacks are processed.
44 // Calling SetSecondPassCallback on the second pass will immediately crash.
SetSecondPassCallback(Callback callback) const45 void SetSecondPassCallback(Callback callback) const { *callback_ = callback; }
46
47 private:
48 Isolate* isolate_;
49 T* parameter_;
50 Callback* callback_;
51 void* embedder_fields_[kEmbedderFieldsInWeakCallback];
52 };
53
54 /**
55 * Weakness type for weak handles.
56 */
57 enum class WeakCallbackType {
58 /**
59 * Passes a user-defined void* parameter back to the callback.
60 */
61 kParameter,
62 /**
63 * Passes the first two internal fields of the object back to the callback.
64 */
65 kInternalFields,
66 };
67
68 template <class T>
GetInternalField(int index) const69 void* WeakCallbackInfo<T>::GetInternalField(int index) const {
70 #ifdef V8_ENABLE_CHECKS
71 if (index < 0 || index >= kEmbedderFieldsInWeakCallback) {
72 api_internal::InternalFieldOutOfBounds(index);
73 }
74 #endif
75 return embedder_fields_[index];
76 }
77
78 } // namespace v8
79
80 #endif // INCLUDE_V8_WEAK_CALLBACK_INFO_H_
81