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diff --git a/extern/ceres/internal/ceres/cuda_buffer.h b/extern/ceres/internal/ceres/cuda_buffer.h
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+// Ceres Solver - A fast non-linear least squares minimizer
+// Copyright 2022 Google Inc. All rights reserved.
+// http://ceres-solver.org/
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are met:
+//
+// * Redistributions of source code must retain the above copyright notice,
+//   this list of conditions and the following disclaimer.
+// * Redistributions in binary form must reproduce the above copyright notice,
+//   this list of conditions and the following disclaimer in the documentation
+//   and/or other materials provided with the distribution.
+// * Neither the name of Google Inc. nor the names of its contributors may be
+//   used to endorse or promote products derived from this software without
+//   specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+// AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+// IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+// ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
+// LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+// CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+// SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+// INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+// CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+// ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+// POSSIBILITY OF SUCH DAMAGE.
+//
+// Author: joydeepb@cs.utexas.edu (Joydeep Biswas)
+
+#ifndef CERES_INTERNAL_CUDA_BUFFER_H_
+#define CERES_INTERNAL_CUDA_BUFFER_H_
+
+#include "ceres/internal/config.h"
+
+#ifndef CERES_NO_CUDA
+
+#include <vector>
+
+#include "cuda_runtime.h"
+#include "glog/logging.h"
+
+// An encapsulated buffer to maintain GPU memory, and handle transfers between
+// GPU and system memory. It is the responsibility of the user to ensure that
+// the appropriate GPU device is selected before each subroutine is called. This
+// is particularly important when using multiple GPU devices on different CPU
+// threads, since active Cuda devices are determined by the cuda runtime on a
+// per-thread basis. Note that unless otherwise specified, all methods use the
+// default stream, and are synchronous.
+template <typename T>
+class CudaBuffer {
+ public:
+  CudaBuffer() = default;
+  CudaBuffer(const CudaBuffer&) = delete;
+  CudaBuffer& operator=(const CudaBuffer&) = delete;
+
+  ~CudaBuffer() {
+    if (data_ != nullptr) {
+      CHECK_EQ(cudaFree(data_), cudaSuccess);
+    }
+  }
+
+  // Grow the GPU memory buffer if needed to accommodate data of the specified
+  // size
+  void Reserve(const size_t size) {
+    if (size > size_) {
+      if (data_ != nullptr) {
+        CHECK_EQ(cudaFree(data_), cudaSuccess);
+      }
+      CHECK_EQ(cudaMalloc(&data_, size * sizeof(T)), cudaSuccess);
+      size_ = size;
+    }
+  }
+
+  // Perform an asynchronous copy from CPU memory to GPU memory using the stream
+  // provided.
+  void CopyToGpuAsync(const T* data, const size_t size, cudaStream_t stream) {
+    Reserve(size);
+    CHECK_EQ(cudaMemcpyAsync(
+                 data_, data, size * sizeof(T), cudaMemcpyHostToDevice, stream),
+             cudaSuccess);
+  }
+
+  // Copy data from the GPU to CPU memory. This is necessarily synchronous since
+  // any potential GPU kernels that may be writing to the buffer must finish
+  // before the transfer happens.
+  void CopyToHost(T* data, const size_t size) {
+    CHECK(data_ != nullptr);
+    CHECK_EQ(cudaMemcpy(data, data_, size * sizeof(T), cudaMemcpyDeviceToHost),
+             cudaSuccess);
+  }
+
+  void CopyToGpu(const std::vector<T>& data) {
+    CopyToGpu(data.data(), data.size());
+  }
+
+  T* data() { return data_; }
+  size_t size() const { return size_; }
+
+ private:
+  T* data_ = nullptr;
+  size_t size_ = 0;
+};
+
+#endif  // CERES_NO_CUDA
+
+#endif  // CERES_INTERNAL_CUDA_BUFFER_H_
+\ No newline at end of file