timed_borrow.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 <optional>
#include <type_traits>
 
#include "pw_chrono/system_clock.h"
#include "pw_sync/borrow.h"
#include "pw_sync/lock_annotations.h"
#include "pw_sync/lock_traits.h"
#include "pw_sync/virtual_basic_lockable.h"
 
namespace pw::sync {
 
template <typename GuardedType,
          typename LockType = pw::sync::VirtualBasicLockable>
class TimedBorrowable : public Borrowable<GuardedType, LockType> {
 private:
  using Base = Borrowable<GuardedType, LockType>;
 
  static_assert(is_lockable_for_v<LockType, chrono::SystemClock::duration>);
  static_assert(is_lockable_until_v<LockType, chrono::SystemClock::time_point>);
 
 public:
  constexpr TimedBorrowable(GuardedType& object, LockType& lock) noexcept
      : Base(object, lock) {}
 
  template <typename U>
  constexpr TimedBorrowable(const Borrowable<U, LockType>& other)
      : Base(other) {}
 
  std::optional<BorrowedPointer<GuardedType, LockType>> try_acquire_for(
      chrono::SystemClock::duration timeout) const PW_NO_LOCK_SAFETY_ANALYSIS {
    if (!Base::lock_->try_lock_for(timeout)) {
      return std::nullopt;
    }
    return Base::Borrow();
  }
 
  std::optional<BorrowedPointer<GuardedType, LockType>> try_acquire_until(
      chrono::SystemClock::time_point deadline) const
      PW_NO_LOCK_SAFETY_ANALYSIS {
    if (!Base::lock_->try_lock_until(deadline)) {
      return std::nullopt;
    }
    return Base::Borrow();
  }
};
 
}  // namespace pw::sync