[L2Space] Adding benchmarks for distance

Author: 2ooom

.gitignore

@@ -2,4 +2,7 @@
 .vscode
 .idea
 # macOS
-.DS_Store
+.DS_Store
+
+benchmark
+build

bench.sh

@@ -0,0 +1,4 @@
+#!/usr/bin/env bash
+rm ./build/bench
+clang++ hnswlib/bench.cpp -lbenchmark -L/usr/local/lib/ -march=x86-64 -m64 -O3 -std=c++11 -Wall -fPIC -undefined dynamic_lookup -o build/bench
+./build/bench --benchmark_repetitions=20 --benchmark_display_aggregates_only=true

hnswlib/bench.cpp

@@ -0,0 +1,90 @@
+#include <assert.h>
+#include "../benchmark/include/benchmark/benchmark.h"
+#include <vector>
+#include <string>
+#include <fstream>
+#include <sstream>
+#include <iostream>
+#include "hnswlib.h"
+
+class L2BaseBench : public benchmark::Fixture {
+    public:
+    size_t dimension;
+    size_t nb_embeddings = 100;
+
+    hnswlib::L2Space* space;
+    void* dist_func_param;
+    hnswlib::DISTFUNC<float> dist_func;
+    std::vector<std::vector<float>> scenario_input;
+    size_t scenario_input_index;
+    size_t scenario_input_size;
+
+    const float RAND_MAX_FLOAT = (float)(RAND_MAX);
+
+    void SetUp(const ::benchmark::State& state) {
+        scenario_input.clear();
+        scenario_input.reserve(nb_embeddings);
+        for(int i = 0; i < nb_embeddings; i++) {
+            std::vector<float> vector(dimension);
+            for (int j = 0; j < dimension; j++) {
+                vector[j] = (float)rand()/RAND_MAX_FLOAT;
+            }
+            scenario_input.push_back(vector);
+        }
+        space = new hnswlib::L2Space(dimension);
+        dist_func_param = space->get_dist_func_param();
+        dist_func = space->get_dist_func();
+
+        scenario_input_size = scenario_input.size();
+        scenario_input_index = 0;
+    }
+
+    void TearDown(const ::benchmark::State& state) {
+        delete space;
+    }
+
+    float* get_vector() {
+        float* vector_data = scenario_input[scenario_input_index].data();
+        scenario_input_index++;
+        if(scenario_input_index == scenario_input_size) {
+            scenario_input_index = 0;
+        }
+        return vector_data;
+    }
+
+    float compute_distance() {
+        auto vector1 = get_vector();
+        auto vector2 = get_vector();
+        return dist_func(vector1, vector2, dist_func_param);
+    }
+};
+
+#define L2DimBench(dim)\
+    class Dim##dim : public L2BaseBench {\
+        public: Dim##dim() {\
+            dimension = dim;\
+        }\
+    };\
+    BENCHMARK_DEFINE_F(Dim##dim, Dist)(benchmark::State& st) { for (auto _ : st) compute_distance(); }\
+    BENCHMARK_REGISTER_F(Dim##dim, Dist);
+
+L2DimBench(3);
+L2DimBench(4);
+L2DimBench(7);
+L2DimBench(8);
+L2DimBench(9);
+L2DimBench(15);
+L2DimBench(16);
+L2DimBench(100);
+L2DimBench(101);
+L2DimBench(128);
+L2DimBench(129);
+
+BENCHMARK_DEFINE_F(Dim3, Prep)(benchmark::State& st) {
+    for (auto _ : st) {
+        get_vector();
+        get_vector();
+    }
+}
+
+BENCHMARK_MAIN();