AlpakaInterface/interface/VecArray.h

0001 #ifndef HeterogeneousCore_AlpakaInterface_interface_VecArray_h
0002 #define HeterogeneousCore_AlpakaInterface_interface_VecArray_h
0003
0004 //
0005 // Author: Felice Pantaleo, CERN
0006 //
0007
0008 #include <utility>
0009
0010 #include <alpaka/alpaka.hpp>
0011
0012 namespace cms::alpakatools {
0013
0014   template <class T, int maxSize>
0015   class VecArray {
0016   public:
0017     using self = VecArray<T, maxSize>;
0018     using value_t = T;
0019
0020     inline constexpr int push_back_unsafe(const T &element) {
0021       auto previousSize = m_size;
0022       m_size++;
0023       if (previousSize < maxSize) {
0024         m_data[previousSize] = element;
0025         return previousSize;
0026       } else {
0027         --m_size;
0028         return -1;
0029       }
0030     }
0031
0032     template <class... Ts>
0033     constexpr int emplace_back_unsafe(Ts &&...args) {
0034       auto previousSize = m_size;
0035       m_size++;
0036       if (previousSize < maxSize) {
0037         (new (&m_data[previousSize]) T(std::forward<Ts>(args)...));
0038         return previousSize;
0039       } else {
0040         --m_size;
0041         return -1;
0042       }
0043     }
0044
0045     inline constexpr T const &back() const {
0046       if (m_size > 0) {
0047         return m_data[m_size - 1];
0048       } else
0049         return T();  //undefined behaviour
0050     }
0051
0052     inline constexpr T &back() {
0053       if (m_size > 0) {
0054         return m_data[m_size - 1];
0055       } else
0056         return T();  //undefined behaviour
0057     }
0058
0059     // thread-safe version of the vector, when used in a kernel
0060     template <typename TAcc>
0061     ALPAKA_FN_ACC int push_back(const TAcc &acc, const T &element) {
0062       auto previousSize = alpaka::atomicAdd(acc, &m_size, 1, alpaka::hierarchy::Blocks{});
0063       if (previousSize < maxSize) {
0064         m_data[previousSize] = element;
0065         return previousSize;
0066       } else {
0067         alpaka::atomicSub(acc, &m_size, 1, alpaka::hierarchy::Blocks{});
0068         return -1;
0069       }
0070     }
0071
0072     template <typename TAcc, class... Ts>
0073     ALPAKA_FN_ACC int emplace_back(const TAcc &acc, Ts &&...args) {
0074       auto previousSize = alpaka::atomicAdd(acc, &m_size, 1, alpaka::hierarchy::Blocks{});
0075       if (previousSize < maxSize) {
0076         (new (&m_data[previousSize]) T(std::forward<Ts>(args)...));
0077         return previousSize;
0078       } else {
0079         alpaka::atomicSub(acc, &m_size, 1, alpaka::hierarchy::Blocks{});
0080         return -1;
0081       }
0082     }
0083
0084     inline constexpr T pop_back() {
0085       if (m_size > 0) {
0086         auto previousSize = m_size--;
0087         return m_data[previousSize - 1];
0088       } else
0089         return T();
0090     }
0091
0092     inline constexpr T const *begin() const { return m_data; }
0093     inline constexpr T const *end() const { return m_data + m_size; }
0094     inline constexpr T *begin() { return m_data; }
0095     inline constexpr T *end() { return m_data + m_size; }
0096     inline constexpr int size() const { return m_size; }
0097     inline constexpr T &operator[](int i) { return m_data[i]; }
0098     inline constexpr const T &operator[](int i) const { return m_data[i]; }
0099     inline constexpr void reset() { m_size = 0; }
0100     inline static constexpr int capacity() { return maxSize; }
0101     inline constexpr T const *data() const { return m_data; }
0102     inline constexpr void resize(int size) { m_size = size; }
0103     inline constexpr bool empty() const { return 0 == m_size; }
0104     inline constexpr bool full() const { return maxSize == m_size; }
0105
0106   private:
0107     T m_data[maxSize];
0108
0109     int m_size;
0110   };
0111
0112 }  // namespace cms::alpakatools
0113
0114 #endif  // HeterogeneousCore_AlpakaInterface_interface_VecArray_h