virtual_basic_lockable.h

// Copyright 2021 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 "pw_polyfill/language_feature_macros.h"
#include "pw_sync/lock_annotations.h"
 
namespace pw::sync {
 
class PW_LOCKABLE("pw::sync::VirtualBasicLockable") VirtualBasicLockable {
 public:
  void lock() PW_EXCLUSIVE_LOCK_FUNCTION() {
    DoLockOperation(Operation::kLock);
  }
 
  void unlock() PW_UNLOCK_FUNCTION() { DoLockOperation(Operation::kUnlock); }
 
 protected:
  ~VirtualBasicLockable() = default;
 
  enum class Operation {
    kLock,
    kUnlock,
  };
 
 private:
  virtual void DoLockOperation(Operation operation) = 0;
};
 
class PW_LOCKABLE("pw::sync::NoOpLock") NoOpLock final
    : public VirtualBasicLockable {
 public:
  constexpr NoOpLock() {}
  NoOpLock(const NoOpLock&) = delete;
  NoOpLock(NoOpLock&&) = delete;
  NoOpLock& operator=(const NoOpLock&) = delete;
  NoOpLock& operator=(NoOpLock&&) = delete;
 
  static NoOpLock& Instance() {
    PW_CONSTINIT static NoOpLock lock;
    return lock;
  }
 
 private:
  void DoLockOperation(Operation) override {}
};
 
template <typename LockType>
class GenericBasicLockable : public VirtualBasicLockable {
 public:
  virtual ~GenericBasicLockable() = default;
 
 protected:
  LockType& impl() { return impl_; }
 
 private:
  void DoLockOperation(Operation operation) override
      PW_NO_LOCK_SAFETY_ANALYSIS {
    switch (operation) {
      case Operation::kLock:
        return impl_.lock();
 
      case Operation::kUnlock:
      default:
        return impl_.unlock();
    }
  }
 
  LockType impl_;
};
 
template <typename LockType>
class PW_LOCKABLE("pw::sync::GenericLockable") GenericLockable
    : public GenericBasicLockable<LockType> {
 public:
  [[nodiscard]] bool try_lock() PW_EXCLUSIVE_TRYLOCK_FUNCTION(true) {
    return GenericBasicLockable<LockType>::impl().try_lock();
  }
};
 
}  // namespace pw::sync