scoped_locker.h

// Copyright 2025 The Pigweed Authors
//
// Licensed under the Apache License, Version 2.0 (the "License"); you may not
// use this file except in compliance with the License. You may obtain a copy of
// the License at
//
//     https://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
// WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
// License for the specific language governing permissions and limitations under
// the License.
#pragma once
 
#include <mutex>
 
#include "pw_sync/lock_annotations.h"
#include "pw_sync/lock_traits.h"
 
namespace pw {
 
 
template <typename BasicLockable>
class PW_SCOPED_LOCKABLE ScopedLocker {
 public:
  static_assert(pw::sync::is_basic_lockable_v<BasicLockable>,
                "lock type must satisfy BasicLockable");
 
  explicit ScopedLocker(BasicLockable& lock) noexcept
      PW_EXCLUSIVE_LOCK_FUNCTION(lock)
      : lock_(lock) {
    lock_.lock();
    locked_ = true;
  }
 
  ScopedLocker(BasicLockable& lock, std::defer_lock_t) noexcept
      PW_LOCKS_EXCLUDED(lock)
      : lock_(lock), locked_(false) {}
 
  ~ScopedLocker() PW_UNLOCK_FUNCTION() {
    if (locked_) {
      lock_.unlock();
    }
  }
 
  ScopedLocker(const ScopedLocker&) = delete;
  ScopedLocker(ScopedLocker&&) = delete;
  ScopedLocker& operator=(const ScopedLocker&) = delete;
  ScopedLocker& operator=(ScopedLocker&&) = delete;
 
  void lock() PW_EXCLUSIVE_LOCK_FUNCTION() {
    lock_.lock();
    locked_ = true;
  }
 
  void unlock() PW_UNLOCK_FUNCTION() {
    locked_ = false;
    lock_.unlock();
  }
 
 private:
  BasicLockable& lock_;
  bool locked_ PW_GUARDED_BY(lock_);
};
 
// Deduction guide to allow ``ScopedLocker(lock)`` rather than
// ``ScopedLocker<T>(lock)``.
template <typename T>
ScopedLocker(T lock) -> ScopedLocker<T>;
 
// Deduction guide to allow ``ScopedLocker(lock, std::defer_lock)`` rather than
// ``ScopedLocker<T>(lock, std::defer_lock)``.
template <typename T>
ScopedLocker(T lock, std::defer_lock_t) -> ScopedLocker<T>;
 
 
}  // namespace pw