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base / sequence_checker_impl.h [blame]
// Copyright 2012 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef BASE_SEQUENCE_CHECKER_IMPL_H_
#define BASE_SEQUENCE_CHECKER_IMPL_H_
#include <cstdint>
#include <memory>
#include <vector>
#include "base/base_export.h"
#include "base/sequence_token.h"
#include "base/synchronization/lock.h"
#include "base/thread_annotations.h"
#include "base/threading/platform_thread_ref.h"
namespace base {
namespace debug {
class StackTrace;
}
// Real implementation of SequenceChecker.
//
// In most cases, SEQUENCE_CHECKER should be used instead of this, get the right
// implementation for the build configuration. It's possible to temporarily use
// this directly to get sequence checking in production builds, which can be
// handy to debug issues only seen in the field. However, when used in a
// non-DCHECK build, SequenceCheckerImpl::CalledOnValidSequence() will not
// consider locks as a valid way to guarantee mutual exclusion (returns false if
// not invoked from the bound sequence, even if all calls are made under the
// same lock).
// Marked with "context" capability to support thread_annotations.h.
class THREAD_ANNOTATION_ATTRIBUTE__(capability("context"))
BASE_EXPORT SequenceCheckerImpl {
public:
static void EnableStackLogging();
SequenceCheckerImpl();
// Allow move construct/assign. This must be called on |other|'s associated
// sequence and assignment can only be made into a SequenceCheckerImpl which
// is detached or already associated with the current sequence. This isn't
// thread-safe (|this| and |other| shouldn't be in use while this move is
// performed). If the assignment was legal, the resulting SequenceCheckerImpl
// will be bound to the current sequence and |other| will be detached.
SequenceCheckerImpl(SequenceCheckerImpl&& other);
SequenceCheckerImpl& operator=(SequenceCheckerImpl&& other);
SequenceCheckerImpl(const SequenceCheckerImpl&) = delete;
SequenceCheckerImpl& operator=(const SequenceCheckerImpl&) = delete;
~SequenceCheckerImpl();
// Returns true if called in sequence with previous calls to this method and
// the constructor.
// On returning false, if logging is enabled with EnableStackLogging() and
// `out_bound_at` is not null, this method allocates a StackTrace and returns
// it in the out-parameter, storing inside it the stack from where the failing
// SequenceChecker was bound to its sequence. Otherwise, out_bound_at is left
// untouched.
[[nodiscard]] bool CalledOnValidSequence(
std::unique_ptr<debug::StackTrace>* out_bound_at = nullptr) const;
// Unbinds the checker from the currently associated sequence. The checker
// will be re-bound on the next call to CalledOnValidSequence().
void DetachFromSequence();
private:
void EnsureAssigned() const EXCLUSIVE_LOCKS_REQUIRED(lock_);
// Members are mutable so that `CalledOnValidSequence()` can set them.
mutable Lock lock_;
// Stack from which this was bound (set if `EnableStackLogging()` was called).
mutable std::unique_ptr<debug::StackTrace> bound_at_ GUARDED_BY(lock_);
// Sequence to which this is bound.
mutable internal::SequenceToken sequence_token_ GUARDED_BY(lock_);
#if DCHECK_IS_ON()
// Locks to which this is bound.
mutable std::vector<uintptr_t> locks_ GUARDED_BY(lock_);
#endif // DCHECK_IS_ON()
// Thread to which this is bound. Only used to evaluate
// `CalledOnValidSequence()` after TLS destruction.
mutable PlatformThreadRef thread_ref_ GUARDED_BY(lock_);
};
} // namespace base
#endif // BASE_SEQUENCE_CHECKER_IMPL_H_