| /** |
| * Copyright 2011-2015 Quickstep Technologies LLC. |
| * Copyright 2015 Pivotal Software, Inc. |
| * |
| * 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 |
| * |
| * http://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. |
| **/ |
| |
| #ifndef QUICKSTEP_UTILITY_SHARDED_LOCK_MANAGER_HPP_ |
| #define QUICKSTEP_UTILITY_SHARDED_LOCK_MANAGER_HPP_ |
| |
| #include <array> |
| #include <cstddef> |
| #include <functional> |
| |
| #include "threading/SharedMutex.hpp" |
| #include "utility/Macros.hpp" |
| |
| namespace quickstep { |
| |
| /** \addtogroup Utility |
| * @{ |
| */ |
| |
| /** |
| * @brief Maintains a fixed number of SharedMutex objects and an interface for |
| * mapping instances of the template class T to one of the underlying |
| * SharedMutex's. The mapping is done by calling std::hash<T>::operator() |
| * on the object. |
| * |
| * @param T The class to map to SharedMutex's. |
| * @param N The number of SharedMutex's to use in the underlying array. |
| * @param SharedMutexT The shared mutex class to use for locks. |
| */ |
| template <typename T, std::size_t N, typename SharedMutexT = SharedMutex> |
| class ShardedLockManager { |
| public: |
| /** |
| * @brief Default constructor. |
| */ |
| ShardedLockManager() { } |
| |
| /** |
| * @brief Get the SharedMutex corresponding to the provided key. |
| * @param key The key to map to a SharedMutex. |
| * @return The corresponding SharedMutex. |
| */ |
| SharedMutexT *get(const T key) { |
| return &shards[hash_(key) % N]; |
| } |
| |
| private: |
| std::hash<T> hash_; |
| std::array<SharedMutexT, N> shards; |
| |
| DISALLOW_COPY_AND_ASSIGN(ShardedLockManager); |
| }; |
| |
| /** @} */ |
| |
| } // namespace quickstep |
| |
| #endif // QUICKSTEP_UTILITY_SHARDED_LOCK_MANAGER_HPP_ |