#ifndef CAFFE2_OPERATORS_INDEX_HASH_OPS_H_
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#define CAFFE2_OPERATORS_INDEX_HASH_OPS_H_
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#include "caffe2/core/asan.h"
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#include "caffe2/core/logging.h"
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#include "caffe2/core/operator.h"
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namespace caffe2 {
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template <class Context>
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class IndexHashOp : public Operator<Context> {
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public:
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USE_OPERATOR_CONTEXT_FUNCTIONS;
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template <class... Args>
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explicit IndexHashOp(Args&&... args)
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: Operator<Context>(std::forward<Args>(args)...),
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seed_(this->template GetSingleArgument<int64_t>("seed", 0)),
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modulo_(this->template GetSingleArgument<int64_t>("modulo", 0)) {
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CAFFE_ENFORCE_GT(modulo_, 0, "MODULO should be > 0");
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}
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bool RunOnDevice() override {
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return DispatchHelper<TensorTypes<int32_t, int64_t>>::call(
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this, Input(INDICES));
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}
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template <typename T>
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bool DoRunWithType() {
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auto& indices = Input(INDICES);
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auto* hashed_indices =
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Output(HASHED_INDICES, indices.sizes(), at::dtype<T>());
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CAFFE_ENFORCE_GE(
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static_cast<int64_t>(std::numeric_limits<T>::max()),
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modulo_,
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"MODULO shouldn't be larger than the numeric limit of the indices");
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auto N = indices.numel();
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auto* indices_data = indices.template data<T>();
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auto* hashed_indices_data = hashed_indices->template mutable_data<T>();
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for (auto i = 0; i < N; i++) {
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hashed_indices_data[i] = hash(indices_data[i]);
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}
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return true;
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}
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protected:
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template <typename T>
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CAFFE2_NO_SANITIZE("signed-integer-overflow") T hash(T id) {
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int8_t* bytes = (int8_t*)&id;
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T hashed = seed_ * 0xDEADBEEF;
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for (int i = 0; i < sizeof(T) / sizeof(int8_t); i++) {
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hashed = hashed * 65537 + bytes[i];
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}
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// We want the result of the modulo to be positive. This works under the
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// assumption that modulo_ > 0 which is enforced in the constructor.
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auto modHashed = hashed % modulo_;
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return modHashed >= 0 ? modHashed : modHashed + modulo_;
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}
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private:
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INPUT_TAGS(INDICES);
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OUTPUT_TAGS(HASHED_INDICES);
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int64_t seed_;
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int64_t modulo_;
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};
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} // namespace caffe2
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#endif // CAFFE2_OPERATORS_INDEX_HASH_OPS_H_
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