| // Copyright 2017 The Chromium OS Authors. All rights reserved. |
| // Use of this source code is governed by a BSD-style license that can be |
| // found in the LICENSE file. |
| #ifndef CRYPTOHOME_DIRCRYPTO_DATA_MIGRATOR_ATOMIC_FLAG_H_ |
| #define CRYPTOHOME_DIRCRYPTO_DATA_MIGRATOR_ATOMIC_FLAG_H_ |
| |
| #include <base/atomicops.h> |
| #include <base/macros.h> |
| #include <base/sequence_checker.h> |
| |
| namespace cryptohome { |
| namespace dircrypto_data_migrator { |
| |
| // A flag that can safely be set from one thread and read from other threads. |
| // |
| // This class IS NOT intended for synchronization between threads. |
| // |
| // NOTE: This is a dead copy of base::AtomicFlag. We need this because the |
| // current version r395517S is too old and it doesn't include crrev.com/409020. |
| // TODO(hashimoto): Remove this once libchrome is upreved. b/37434548 |
| class AtomicFlag { |
| public: |
| AtomicFlag(); |
| ~AtomicFlag() = default; |
| |
| // Set the flag. Must always be called from the same sequence. |
| void Set(); |
| |
| // Returns true iff the flag was set. If this returns true, the current thread |
| // is guaranteed to be synchronized with all memory operations on the sequence |
| // which invoked Set() up until at least the first call to Set() on it. |
| bool IsSet() const; |
| |
| // Resets the flag. Be careful when using this: callers might not expect |
| // IsSet() to return false after returning true once. |
| void UnsafeResetForTesting(); |
| |
| private: |
| base::subtle::Atomic32 flag_ = 0; |
| base::SequenceChecker set_sequence_checker_; |
| |
| DISALLOW_COPY_AND_ASSIGN(AtomicFlag); |
| }; |
| |
| } // namespace dircrypto_data_migrator |
| } // namespace cryptohome |
| |
| #endif // CRYPTOHOME_DIRCRYPTO_DATA_MIGRATOR_ATOMIC_FLAG_H_ |