Fix IndicesEstimator constructor (#4906)

Summary:
X-link: facebookresearch/FBGEMM#1945

The old behaviour of constructor delegation is invalid, it creates a temporary object.

Pull Request resolved: #4906

Reviewed By: cthi

Differential Revision: D82979114

Pulled By: q10

fbshipit-source-id: 1becc704617b858e453ed1a542f349a9b26fc54e

Author: cyyever

fbgemm_gpu/src/tbe/eeg/indices_estimator.cpp

@@ -7,6 +7,7 @@
  */
 
 #include "indices_estimator.h"
+#include <algorithm>
 #include <cassert>
 #include <chrono>
 #include <fstream>
@@ -45,7 +46,7 @@ void IndicesEstimator::populateLogTable_() {
   }
 }
 
-IndicesEstimator::IndicesEstimator(const torch::Tensor& indices) {
+void IndicesEstimator::init(const torch::Tensor& indices) {
   TORCH_CHECK(
       indices.numel() > 0, "indices numel is ", indices.numel(), "(< 1)");
 
@@ -62,6 +63,10 @@ IndicesEstimator::IndicesEstimator(const torch::Tensor& indices) {
   populateLogTable_();
 }
 
+IndicesEstimator::IndicesEstimator(const torch::Tensor& indices) {
+  init(indices);
+}
+
 IndicesEstimator::IndicesEstimator(const std::filesystem::path& tensors_path) {
   // NOTE: PyTorch API requires us to use a torch::pickle_load on a
   // vector<char> (torch::load doesn't work here)
@@ -79,7 +84,7 @@ IndicesEstimator::IndicesEstimator(const std::filesystem::path& tensors_path) {
   assert((ival.isTensor()) && "Loaded file is not a tensor!");
 
   // Pass it to the tensor-based constructor
-  IndicesEstimator(ival.toTensor());
+  init(ival.toTensor());
 }
 
 std::vector<double> IndicesEstimator::heavyHitters() const {

fbgemm_gpu/src/tbe/eeg/indices_estimator.h

@@ -37,6 +37,8 @@ class IndicesEstimator {
   double estimateQuality(const IndicesDistributionParameters& params) const;
 
  private:
+  void init(const torch::Tensor& indices);
+
   // Hardcoded parameters
   // Heavy hitter threshold: we make sure they account for >=90% of the mass or
   // the top 20 frequencies, whichever comes first. We also ensure that we cover