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// Copyright 2013 The Flutter Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
// A class for checking that the current thread is/isn't the same as an initial
// thread.
#ifndef FLUTTER_FML_MEMORY_THREAD_CHECKER_H_
#define FLUTTER_FML_MEMORY_THREAD_CHECKER_H_
#include "flutter/fml/build_config.h"
#include "flutter/fml/logging.h"
#include "flutter/fml/macros.h"
#if defined(FML_OS_WIN)
#include <windows.h>
#else
#include <pthread.h>
#endif
namespace fml {
// A simple class that records the identity of the thread that it was created
// on, and at later points can tell if the current thread is the same as its
// creation thread. This class is thread-safe.
//
// Note: Unlike Chromium's |base::ThreadChecker|, this is *not* Debug-only (so
// #ifdef it out if you want something Debug-only). (Rationale: Having a
// |CalledOnValidThread()| that lies in Release builds seems bad. Moreover,
// there's a small space cost to having even an empty class. )
class ThreadChecker final {
public:
static void DisableNextThreadCheckFailure() { disable_next_failure_ = true; }
private:
static thread_local bool disable_next_failure_;
public:
#if defined(FML_OS_WIN)
ThreadChecker() : self_(GetCurrentThreadId()) {}
~ThreadChecker() {}
bool IsCreationThreadCurrent() const {
bool result = GetCurrentThreadId() == self_;
if (!result && disable_next_failure_) {
disable_next_failure_ = false;
return true;
}
return result;
}
private:
DWORD self_;
#else
ThreadChecker() : self_(pthread_self()) {}
~ThreadChecker() {}
// Returns true if the current thread is the thread this object was created
// on and false otherwise.
bool IsCreationThreadCurrent() const {
pthread_t current_thread = pthread_self();
bool is_creation_thread_current = !!pthread_equal(current_thread, self_);
if (disable_next_failure_ && !is_creation_thread_current) {
disable_next_failure_ = false;
return true;
}
#ifdef __APPLE__
// TODO(https://github.com/flutter/flutter/issues/45272): Implement for
// other platforms.
if (!is_creation_thread_current) {
static const int buffer_length = 128;
char expected_thread[buffer_length];
char actual_thread[buffer_length];
if (0 == pthread_getname_np(current_thread, actual_thread,
buffer_length) &&
0 == pthread_getname_np(self_, expected_thread, buffer_length)) {
FML_DLOG(ERROR) << "Object referenced on a thread other than the one "
"on which it was created. Expected thread: '"
<< expected_thread << "'. Actual thread: '"
<< actual_thread << "'.";
}
}
#endif // __APPLE__
return is_creation_thread_current;
}
private:
pthread_t self_;
#endif
};
#if !defined(NDEBUG)
#define FML_DECLARE_THREAD_CHECKER(c) fml::ThreadChecker c
#define FML_DCHECK_CREATION_THREAD_IS_CURRENT(c) \
FML_DCHECK((c).IsCreationThreadCurrent())
#else
#define FML_DECLARE_THREAD_CHECKER(c)
#define FML_DCHECK_CREATION_THREAD_IS_CURRENT(c) ((void)0)
#endif
} // namespace fml
#endif // FLUTTER_FML_MEMORY_THREAD_CHECKER_H_