Refactor DeviceUVector.

src/common/device_helpers.cuh

@@ -510,7 +510,7 @@ xgboost::common::Span<T> ToSpan(thrust::device_vector<T>& vec,
 
 template <typename T>
 xgboost::common::Span<T> ToSpan(DeviceUVector<T> &vec) {
-  return {thrust::raw_pointer_cast(vec.data()), vec.size()};
+  return {vec.data(), vec.size()};
 }
 
 // thrust begin, similiar to std::begin

src/common/device_vector.cuh

@@ -284,47 +284,64 @@ class LoggingResource : public rmm::mr::device_memory_resource {
 
 LoggingResource *GlobalLoggingResource();
 
+#endif  // defined(XGBOOST_USE_RMM)
+
 /**
- * @brief Container class that doesn't initialize the data.
+ * @brief Container class that doesn't initialize the data when RMM is used.
  */
 template <typename T>
-class DeviceUVector : public rmm::device_uvector<T> {
-  using Super = rmm::device_uvector<T>;
+class DeviceUVector {
+ private:
+#if defined(XGBOOST_USE_RMM)
+  rmm::device_uvector<T> data_{0, rmm::cuda_stream_per_thread, GlobalLoggingResource()};
+#else
+  ::dh::device_vector<T> data_;
+#endif  // defined(XGBOOST_USE_RMM)
 
  public:
-  DeviceUVector() : Super{0, rmm::cuda_stream_per_thread, GlobalLoggingResource()} {}
+  using value_type = T;                        // NOLINT
+  using pointer = value_type *;                // NOLINT
+  using const_pointer = value_type const *;    // NOLINT
+  using reference = value_type &;              // NOLINT
+  using const_reference = value_type const &;  // NOLINT
 
-  void Resize(std::size_t n) { Super::resize(n, rmm::cuda_stream_per_thread); }
-  void Resize(std::size_t n, T const &v) {
+ public:
+  DeviceUVector() = default;
+  DeviceUVector(DeviceUVector const &that) = delete;
+  DeviceUVector &operator=(DeviceUVector const &that) = delete;
+  DeviceUVector(DeviceUVector &&that) = default;
+  DeviceUVector &operator=(DeviceUVector &&that) = default;
+
+  void resize(std::size_t n) {  // NOLINT
+#if defined(XGBOOST_USE_RMM)
+    data_.resize(n, rmm::cuda_stream_per_thread);
+#else
+    data_.resize(n);
+#endif
+  }
+  void resize(std::size_t n, T const &v) {         // NOLINT
+#if defined(XGBOOST_USE_RMM)
     auto orig = this->size();
-    Super::resize(n, rmm::cuda_stream_per_thread);
+    data_.resize(n, rmm::cuda_stream_per_thread);
     if (orig < n) {
       thrust::fill(rmm::exec_policy_nosync{}, this->begin() + orig, this->end(), v);
     }
+#else
+    data_.resize(n, v);
+#endif
   }
+  [[nodiscard]] std::size_t size() const { return data_.size(); }  // NOLINT
 
- private:
-  // undefined private, cannot be accessed.
-  void resize(std::size_t n, rmm::cuda_stream_view stream);  // NOLINT
-};
-
-#else
+  [[nodiscard]] auto begin() { return data_.begin(); }  // NOLINT
+  [[nodiscard]] auto end() { return data_.end(); }      // NOLINT
 
-/**
- * @brief Without RMM, the initialization will happen.
- */
-template <typename T>
-class DeviceUVector : public thrust::device_vector<T, XGBDeviceAllocator<T>> {
-  using Super = thrust::device_vector<T, XGBDeviceAllocator<T>>;
+  [[nodiscard]] auto begin() const { return this->cbegin(); }  // NOLINT
+  [[nodiscard]] auto end() const { return this->cend(); }      // NOLINT
 
- public:
-  void Resize(std::size_t n) { Super::resize(n); }
-  void Resize(std::size_t n, T const &v) { Super::resize(n, v); }
+  [[nodiscard]] auto cbegin() const { return data_.cbegin(); }  // NOLINT
+  [[nodiscard]] auto cend() const { return data_.cend(); }      // NOLINT
 
- private:
-  // undefined private, cannot be accessed.
-  void resize(std::size_t n, T const &v = T{});  // NOLINT
+  [[nodiscard]] auto data() { return thrust::raw_pointer_cast(data_.data()); }        // NOLINT
+  [[nodiscard]] auto data() const { return thrust::raw_pointer_cast(data_.data()); }  // NOLINT
 };
-
-#endif  // defined(XGBOOST_USE_RMM)
 }  // namespace dh

src/common/host_device_vector.cu

@@ -29,7 +29,7 @@ class HostDeviceVectorImpl {
     if (device.IsCUDA()) {
       gpu_access_ = GPUAccess::kWrite;
       SetDevice();
-      data_d_->Resize(size, v);
+      data_d_->resize(size, v);
     } else {
       data_h_.resize(size, v);
     }
@@ -67,12 +67,12 @@ class HostDeviceVectorImpl {
 
   T* DevicePointer() {
     LazySyncDevice(GPUAccess::kWrite);
-    return thrust::raw_pointer_cast(data_d_->data());
+    return data_d_->data();
   }
 
   const T* ConstDevicePointer() {
     LazySyncDevice(GPUAccess::kRead);
-    return thrust::raw_pointer_cast(data_d_->data());
+    return data_d_->data();
   }
 
   common::Span<T> DeviceSpan() {
@@ -181,7 +181,7 @@ class HostDeviceVectorImpl {
       gpu_access_ = GPUAccess::kWrite;
       SetDevice();
       auto old_size = data_d_->size();
-      data_d_->Resize(new_size, std::forward<U>(args)...);
+      data_d_->resize(new_size, std::forward<U>(args)...);
     } else {
       // resize on host
       LazySyncHost(GPUAccess::kNone);
@@ -200,8 +200,8 @@ class HostDeviceVectorImpl {
     gpu_access_ = access;
     if (data_h_.size() != data_d_->size()) { data_h_.resize(data_d_->size()); }
     SetDevice();
-    dh::safe_cuda(cudaMemcpy(data_h_.data(), thrust::raw_pointer_cast(data_d_->data()),
-                             data_d_->size() * sizeof(T), cudaMemcpyDeviceToHost));
+    dh::safe_cuda(cudaMemcpy(data_h_.data(), data_d_->data(), data_d_->size() * sizeof(T),
+                             cudaMemcpyDeviceToHost));
   }
 
   void LazySyncDevice(GPUAccess access) {
@@ -214,9 +214,8 @@ class HostDeviceVectorImpl {
     // data is on the host
     LazyResizeDevice(data_h_.size());
     SetDevice();
-    dh::safe_cuda(cudaMemcpyAsync(thrust::raw_pointer_cast(data_d_->data()), data_h_.data(),
-                                  data_d_->size() * sizeof(T), cudaMemcpyHostToDevice,
-                                  dh::DefaultStream()));
+    dh::safe_cuda(cudaMemcpyAsync(data_d_->data(), data_h_.data(), data_d_->size() * sizeof(T),
+                                  cudaMemcpyHostToDevice, dh::DefaultStream()));
     gpu_access_ = access;
   }
 
@@ -241,8 +240,7 @@ class HostDeviceVectorImpl {
       LazyResizeDevice(Size());
       gpu_access_ = GPUAccess::kWrite;
       SetDevice();
-      dh::safe_cuda(cudaMemcpyAsync(thrust::raw_pointer_cast(data_d_->data()),
-                                    thrust::raw_pointer_cast(other->data_d_->data()),
+      dh::safe_cuda(cudaMemcpyAsync(data_d_->data(), other->data_d_->data(),
                                     data_d_->size() * sizeof(T), cudaMemcpyDefault,
                                     dh::DefaultStream()));
     }
@@ -252,15 +250,14 @@ class HostDeviceVectorImpl {
     LazyResizeDevice(Size());
     gpu_access_ = GPUAccess::kWrite;
     SetDevice();
-    dh::safe_cuda(cudaMemcpyAsync(thrust::raw_pointer_cast(data_d_->data()), begin,
-                                  data_d_->size() * sizeof(T), cudaMemcpyDefault,
-                                  dh::DefaultStream()));
+    dh::safe_cuda(cudaMemcpyAsync(data_d_->data(), begin, data_d_->size() * sizeof(T),
+                                  cudaMemcpyDefault, dh::DefaultStream()));
   }
 
   void LazyResizeDevice(size_t new_size) {
     if (data_d_ && new_size == data_d_->size()) { return; }
     SetDevice();
-    data_d_->Resize(new_size);
+    data_d_->resize(new_size);
   }
 
   void SetDevice() {

tests/cpp/common/test_device_vector.cu

@@ -12,7 +12,7 @@ TEST(DeviceUVector, Basic) {
   std::int32_t verbosity{3};
   std::swap(verbosity, xgboost::GlobalConfigThreadLocalStore::Get()->verbosity);
   DeviceUVector<float> uvec;
-  uvec.Resize(12);
+  uvec.resize(12);
   auto peak = GlobalMemoryLogger().PeakMemory();
   auto n_bytes = sizeof(decltype(uvec)::value_type) * uvec.size();
   ASSERT_EQ(peak, n_bytes);