1// Copyright 2013 The Flutter 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// A class for checking that the current thread is/isn't the same as an initial
6// thread.
7
8#ifndef FLUTTER_FML_MEMORY_THREAD_CHECKER_H_
9#define FLUTTER_FML_MEMORY_THREAD_CHECKER_H_
10
11#include "flutter/fml/build_config.h"
12
13#if defined(OS_WIN)
14#include <windows.h>
15#else
16#include <pthread.h>
17#endif
18
19#include "flutter/fml/logging.h"
20#include "flutter/fml/macros.h"
21
22namespace fml {
23
24// A simple class that records the identity of the thread that it was created
25// on, and at later points can tell if the current thread is the same as its
26// creation thread. This class is thread-safe.
27//
28// Note: Unlike Chromium's |base::ThreadChecker|, this is *not* Debug-only (so
29// #ifdef it out if you want something Debug-only). (Rationale: Having a
30// |CalledOnValidThread()| that lies in Release builds seems bad. Moreover,
31// there's a small space cost to having even an empty class. )
32class ThreadChecker final {
33 public:
34#if defined(OS_WIN)
35 ThreadChecker() : self_(GetCurrentThreadId()) {}
36 ~ThreadChecker() {}
37
38 bool IsCreationThreadCurrent() const { return GetCurrentThreadId() == self_; }
39
40 private:
41 DWORD self_;
42
43#else
44 ThreadChecker() : self_(pthread_self()) {}
45 ~ThreadChecker() {}
46
47 // Returns true if the current thread is the thread this object was created
48 // on and false otherwise.
49 bool IsCreationThreadCurrent() const {
50 pthread_t current_thread = pthread_self();
51 bool is_creation_thread_current = !!pthread_equal(current_thread, self_);
52#ifdef __APPLE__
53 // TODO(https://github.com/flutter/flutter/issues/45272): Implement for
54 // other platforms.
55 if (!is_creation_thread_current) {
56 static const int buffer_length = 128;
57 char expected_thread[buffer_length];
58 char actual_thread[buffer_length];
59 if (0 == pthread_getname_np(current_thread, actual_thread,
60 buffer_length) &&
61 0 == pthread_getname_np(self_, actual_thread, buffer_length)) {
62 FML_DLOG(ERROR) << "IsCreationThreadCurrent expected thread: '"
63 << expected_thread << "' actual thread:'"
64 << actual_thread << "'";
65 }
66 }
67#endif // __APPLE__
68 return is_creation_thread_current;
69 }
70
71 private:
72 pthread_t self_;
73#endif
74};
75
76#if !defined(NDEBUG)
77#define FML_DECLARE_THREAD_CHECKER(c) fml::ThreadChecker c
78#define FML_DCHECK_CREATION_THREAD_IS_CURRENT(c) \
79 FML_DCHECK((c).IsCreationThreadCurrent())
80#else
81#define FML_DECLARE_THREAD_CHECKER(c)
82#define FML_DCHECK_CREATION_THREAD_IS_CURRENT(c) ((void)0)
83#endif
84
85} // namespace fml
86
87#endif // FLUTTER_FML_MEMORY_THREAD_CHECKER_H_
88