chore: import upstream snapshot with attribution

paddle/phi/kernels/cpu/class_center_sample_kernel.cc

@@ -0,0 +1,129 @@
+//   Copyright (c) 2021 PaddlePaddle Authors. All Rights Reserved.
+//
+// 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.
+
+#include <map>
+#include <set>
+#include <vector>
+
+#include "paddle/phi/backends/cpu/cpu_context.h"
+#include "paddle/phi/core/generator.h"
+#include "paddle/phi/core/kernel_registry.h"
+#include "paddle/phi/kernels/class_center_sample_kernel.h"
+
+namespace phi {
+
+template <typename T, typename Context>
+void ClassCenterSampleKernel(const Context& dev_ctx,
+                             const DenseTensor& label,
+                             int num_classes,
+                             int num_samples,
+                             int ring_id,
+                             int rank,
+                             int nranks,
+                             bool fix_seed,
+                             int seed,
+                             DenseTensor* remapped_label,
+                             DenseTensor* sampled_local_class_center) {
+  PADDLE_ENFORCE_GT(num_classes,
+                    0,
+                    errors::InvalidArgument(
+                        "The value 'num_classes' for Op(class_center_sample) "
+                        "must be greater than 0, "
+                        "but the value given is %d.",
+                        num_classes));
+
+  PADDLE_ENFORCE_GT(num_samples,
+                    0,
+                    errors::InvalidArgument(
+                        "The value 'num_samples' for Op(class_center_sample) "
+                        "must be greater than 0, "
+                        "but the value given is %d.",
+                        num_samples));
+
+  PADDLE_ENFORCE_LE(num_samples,
+                    num_classes,
+                    errors::InvalidArgument(
+                        "The value 'num_samples' for Op(class_center_sample) "
+                        "must be less than or equal to %d, "
+                        "but the value given is %d.",
+                        num_classes,
+                        num_samples));
+
+  int64_t numel = label.numel();
+  auto* label_ptr = label.data<T>();
+
+  // get unique positive class center by ascending
+  std::set<T, std::less<T>> unique_label;  // NOLINT
+  for (int64_t i = 0; i < numel; ++i) {
+    unique_label.insert(label_ptr[i]);
+  }
+
+  // construct a lookup table and get sampled_local_class_center
+  std::vector<T> actual_sampled;
+  std::map<T, T> new_class_dict;
+  T idx = 0;
+  for (auto& t : unique_label) {
+    new_class_dict[t] = idx;
+    actual_sampled.push_back(t);
+    idx++;
+  }
+
+  if (!fix_seed) {
+    std::random_device rnd;
+    seed = static_cast<int>(rnd());
+  }
+  std::uniform_int_distribution<T> dist(0, num_classes - 1);
+  std::shared_ptr<std::mt19937_64> engine;
+  if (seed) {
+    engine = std::make_shared<std::mt19937_64>();
+    engine->seed(seed);
+  } else {
+    engine = dev_ctx.GetGenerator()->GetCPUEngine();
+  }
+  // sample negative class center randomly
+  while (unique_label.size() < static_cast<size_t>(num_samples)) {
+    T neg = dist(*engine);
+    if (unique_label.find(neg) == unique_label.end()) {
+      unique_label.insert(neg);
+      // unorder for negative class center
+      actual_sampled.push_back(neg);
+    }
+  }
+
+  int actual_num_samples = unique_label.size();
+  sampled_local_class_center->Resize({actual_num_samples});
+  T* sampled_local_class_center_ptr =
+      dev_ctx.template Alloc<T>(sampled_local_class_center);
+
+  idx = 0;
+  for (auto& t : actual_sampled) {
+    sampled_local_class_center_ptr[idx] = t;
+    idx++;
+  }
+
+  // remap the input label to sampled class
+  auto* remapped_label_ptr = dev_ctx.template Alloc<T>(remapped_label);
+  for (int64_t i = 0; i < numel; ++i) {
+    remapped_label_ptr[i] = new_class_dict[label_ptr[i]];
+  }
+}
+
+}  // namespace phi
+
+PD_REGISTER_KERNEL(class_center_sample,
+                   CPU,
+                   ALL_LAYOUT,
+                   phi::ClassCenterSampleKernel,
+                   int64_t,
+                   int) {}