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Side by Side Diff: blimp/common/mandatory_callback.h

Issue 2626423004: Remove all //blimp code. (Closed)
Patch Set: One last(?) `git merge` for good measure. Created 3 years, 11 months ago
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1 // Copyright 2016 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 BLIMP_COMMON_MANDATORY_CALLBACK_H_
6 #define BLIMP_COMMON_MANDATORY_CALLBACK_H_
7
8 #include <utility>
9
10 #include "base/callback.h"
11 #include "base/logging.h"
12
13 namespace blimp {
14
15 // Adds a leak-detection wrapper to base::Callback objects.
16 //
17 // When a wrapped Callback is destroyed without being Run first, the checker
18 // will DCHECK-crash the program with a stack trace, so that developers can
19 // pinpoint the site of the leak.
20 //
21 // The MandatoryCallback may be passed using std::move; leak detection occurs
22 // when the MandatoryCallback is finally destroyed.
23 //
24 // Usage:
25 // void DoStuff(int d) { ... }
26 // ...
27 // base::Closure my_callback = base::Bind(&DoStuff);
28 // MandatoryCallback<void(int)> leak_checked_callback =
29 // CreateMandatoryCallback(my_callback);
30 //
31 // Note that MandatoryCallbacks lack some functionality from
32 // base::CallbackInternal.
33 // * They can only be invoked once.
34 // * They do not support parameter currying with additional Bind() calls.[1]
35 // * They cannot be Reset().
36 //
37 // [1] Mandatory invocation support would need to be plumbed in to
38 // base::CallbackInternal and base::Bind for this to work,
39 // which is feasible but low-priority for the owners of the callback
40 // libraries.
41
42 template <typename SignatureType>
43 class MandatoryCallback;
44
45 // Template specialization for extracting the function signature data types.
46 template <typename ReturnType, typename... ArgTypes>
47 class MandatoryCallback<ReturnType(ArgTypes...)> {
48 public:
49 using CallbackType = base::Callback<ReturnType(ArgTypes...)>;
50
51 explicit MandatoryCallback(const CallbackType& callback) : cb_(callback) {
52 DCHECK(!cb_.is_null());
53 }
54
55 MandatoryCallback(MandatoryCallback&& other) {
56 cb_ = other.cb_;
57 other.cb_.Reset();
58
59 #if DCHECK_IS_ON()
60 was_run_ = other.was_run_;
61 other.was_run_ = false;
62 #endif
63 }
64
65 ~MandatoryCallback() {
66 #if DCHECK_IS_ON()
67 DCHECK(cb_.is_null() || was_run_);
68 #endif
69 }
70
71 // This a overload that handles the case where there are no arguments provided
72 template <typename...>
73 ReturnType Run() {
74 DCHECK(cb_); // Can't be run following std::move.
75
76 #if DCHECK_IS_ON()
77 DCHECK(!was_run_);
78 was_run_ = true;
79 #endif
80
81 cb_.Run();
82 }
83
84 template <typename... RunArgs>
85 ReturnType Run(RunArgs... args) {
86 DCHECK(cb_); // Can't be run following std::move.
87
88 #if DCHECK_IS_ON()
89 DCHECK(!was_run_);
90 was_run_ = true;
91 #endif
92
93 cb_.Run(std::forward<RunArgs...>(args...));
94 }
95
96 private:
97 // Nulled after being moved.
98 CallbackType cb_;
99
100 #if DCHECK_IS_ON()
101 bool was_run_ = false;
102 #endif
103
104 DISALLOW_COPY_AND_ASSIGN(MandatoryCallback);
105 };
106
107 // Creates a leak-checking proxy callback around |callback|.
108 template <typename SignatureType>
109 MandatoryCallback<SignatureType> CreateMandatoryCallback(
110 const base::Callback<SignatureType>& callback) {
111 return MandatoryCallback<SignatureType>(callback);
112 }
113
114 using MandatoryClosure = MandatoryCallback<void()>;
115
116 } // namespace blimp
117
118 #endif // BLIMP_COMMON_MANDATORY_CALLBACK_H_
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