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// Copyright (c) 2012 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "base/sequence_checker_impl.h"
#include <utility>
#include "base/check.h"
#include "base/debug/stack_trace.h"
#include "base/memory/ptr_util.h"
#include "base/sequence_token.h"
#include "base/threading/thread_checker.h"
#include "base/threading/thread_checker_impl.h"
#include "base/threading/thread_local_storage.h"
namespace base {
// static
void SequenceCheckerImpl::EnableStackLogging() {
ThreadChecker::EnableStackLogging();
}
class SequenceCheckerImpl::Core {
public:
Core() : sequence_token_(SequenceToken::GetForCurrentThread()) {}
~Core() = default;
bool CalledOnValidSequence(
std::unique_ptr<debug::StackTrace>* out_bound_at) const {
// SequenceToken::GetForCurrentThread() accesses thread-local storage.
// During destruction the state of thread-local storage is not guaranteed to
// be in a consistent state. Further, task-runner only installs the
// SequenceToken when running a task. For this reason, |sequence_token_| is
// not checked during thread destruction.
if (!SequenceCheckerImpl::HasThreadLocalStorageBeenDestroyed() &&
sequence_token_.IsValid()) {
if (sequence_token_ != SequenceToken::GetForCurrentThread()) {
if (out_bound_at)
*out_bound_at = thread_checker_.GetBoundAt();
return false;
}
return true;
}
// SequenceChecker behaves as a ThreadChecker when it is not bound to a
// valid sequence token.
return thread_checker_.CalledOnValidThread(out_bound_at);
}
private:
SequenceToken sequence_token_{SequenceToken::GetForCurrentThread()};
// Used when |sequence_token_| is invalid, or during thread destruction.
ThreadCheckerImpl thread_checker_;
};
SequenceCheckerImpl::SequenceCheckerImpl() : core_(std::make_unique<Core>()) {}
SequenceCheckerImpl::~SequenceCheckerImpl() = default;
SequenceCheckerImpl::SequenceCheckerImpl(SequenceCheckerImpl&& other) {
// Verify that |other| is called on its associated sequence and bind it now if
// it is currently detached (even if this isn't a DCHECK build).
const bool other_called_on_valid_sequence = other.CalledOnValidSequence();
DCHECK(other_called_on_valid_sequence);
core_ = std::move(other.core_);
}
SequenceCheckerImpl& SequenceCheckerImpl::operator=(
SequenceCheckerImpl&& other) {
// If |this| is not in a detached state it needs to be bound to the current
// sequence.
DCHECK(CalledOnValidSequence());
// Verify that |other| is called on its associated sequence and bind it now if
// it is currently detached (even if this isn't a DCHECK build).
const bool other_called_on_valid_sequence = other.CalledOnValidSequence();
DCHECK(other_called_on_valid_sequence);
// Intentionally not using either |lock_| in this method to let TSAN catch
// racy assign.
TS_UNCHECKED_READ(core_) = std::move(TS_UNCHECKED_READ(other.core_));
return *this;
}
bool SequenceCheckerImpl::CalledOnValidSequence(
std::unique_ptr<debug::StackTrace>* bound_at) const {
AutoLock auto_lock(lock_);
if (!core_)
core_ = std::make_unique<Core>();
return core_->CalledOnValidSequence(bound_at);
}
void SequenceCheckerImpl::DetachFromSequence() {
AutoLock auto_lock(lock_);
core_.reset();
}
// static
bool SequenceCheckerImpl::HasThreadLocalStorageBeenDestroyed() {
return ThreadLocalStorage::HasBeenDestroyed();
}
} // namespace base
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