parse_stream.cpp

#include <iostream>
#include <algorithm>
#include <chrono>
#include <vector>
#include <map>

#include "simdjson.h"

#define NB_ITERATION 5
#define MIN_BATCH_SIZE 200000
#define MAX_BATCH_SIZE 10000000

bool test_baseline = false;
bool test_per_batch = true;
bool test_best_batch = true;

bool compare(std::pair<size_t, double> i, std::pair<size_t, double> j){
    return i.second > j.second;
}

int main (int argc, char *argv[]){

    if (argc <= 1) {
        std::cerr << "Usage: " << argv[0] << " <jsonfile>" << std::endl;
        exit(1);
    }
    const char *filename = argv[1];
    auto [p, err] = simdjson::padded_string::load(filename);
    if (err) {
        std::cerr << "Could not load the file " << filename << std::endl;
        return EXIT_FAILURE;
    }
    if (test_baseline) {
        std::wclog << "Baseline: Getline + normal parse... " << std::endl;
        std::cout << "Gigabytes/second\t" << "Nb of documents parsed" << std::endl;
        for (auto i = 0; i < 3; i++) {
            //Actual test
            simdjson::document::parser parser;
            simdjson::error_code alloc_error = parser.set_capacity(p.size());
            if (alloc_error) {
                std::cerr << alloc_error << std::endl;
                return EXIT_FAILURE;
            }
            std::istringstream ss(std::string(p.data(), p.size()));

            auto start = std::chrono::steady_clock::now();
            int count = 0;
            std::string line;
            int parse_res = simdjson::SUCCESS;
            while (getline(ss, line)) {
                // TODO we're likely triggering simdjson's padding reallocation here. Is that intentional?
                parser.parse(line);
                count++;
            }

            auto end = std::chrono::steady_clock::now();

            std::chrono::duration<double> secs = end - start;
            double speedinGBs = (p.size()) / (secs.count() * 1000000000.0);
            std::cout << speedinGBs << "\t\t\t\t" << count << std::endl;

            if (parse_res != simdjson::SUCCESS) {
                std::cerr << "Parsing failed" << std::endl;
                exit(1);
            }
        }
    }

    std::map<size_t, double> batch_size_res;
    if(test_per_batch) {
        std::wclog << "parse_many: Speed per batch_size... from " << MIN_BATCH_SIZE
                << " bytes to " << MAX_BATCH_SIZE << " bytes..." << std::endl;
        std::cout << "Batch Size\t" << "Gigabytes/second\t" << "Nb of documents parsed" << std::endl;
        for (size_t i = MIN_BATCH_SIZE; i <= MAX_BATCH_SIZE; i += (MAX_BATCH_SIZE - MIN_BATCH_SIZE) / 50) {
            batch_size_res.insert(std::pair<size_t, double>(i, 0));
            int count;
            for (size_t j = 0; j < 5; j++) {
                //Actual test
                simdjson::document::parser parser;
                simdjson::error_code error;

                auto start = std::chrono::steady_clock::now();
                count = 0;
                for (auto result : parser.parse_many(p, 4000000)) {
                    error = result.error();
                    count++;
                }
                auto end = std::chrono::steady_clock::now();

                std::chrono::duration<double> secs = end - start;
                double speedinGBs = (p.size()) / (secs.count() * 1000000000.0);
                if (speedinGBs > batch_size_res.at(i))
                    batch_size_res[i] = speedinGBs;

                if (error != simdjson::SUCCESS) {
                    std::wcerr << "Parsing failed with: " << error << std::endl;
                    exit(1);
                }
            }
            std::cout << i << "\t\t" << std::fixed << std::setprecision(3) << batch_size_res.at(i) << "\t\t\t\t" << count << std::endl;

        }
    }

    if (test_best_batch) {
        size_t optimal_batch_size;
        if (test_per_batch) {
            optimal_batch_size = (*min_element(batch_size_res.begin(), batch_size_res.end(), compare)).first;
        } else {
            optimal_batch_size = MIN_BATCH_SIZE;
        }
        std::wclog << "Starting speed test... Best of " << NB_ITERATION << " iterations..." << std::endl;
        std::wclog << "Seemingly optimal batch_size: " << optimal_batch_size << "..." << std::endl;
        std::vector<double> res;
        for (int i = 0; i < NB_ITERATION; i++) {

            // Actual test
            simdjson::document::parser parser;
            simdjson::error_code error;

            auto start = std::chrono::steady_clock::now();
            // TODO this includes allocation of the parser; is that intentional?
            for (auto result : parser.parse_many(p, 4000000)) {
                error = result.error();
            }
            auto end = std::chrono::steady_clock::now();

            std::chrono::duration<double> secs = end - start;
            res.push_back(secs.count());

            if (error != simdjson::SUCCESS) {
                std::wcerr << "Parsing failed with: " << error << std::endl;
                exit(1);
            }

        }

        std::min(res.begin(), res.end());

        double min_result = *min_element(res.begin(), res.end());
        double speedinGBs = (p.size()) / (min_result * 1000000000.0);


        std::cout << "Min:  " << min_result << " bytes read: " << p.size()
                << " Gigabytes/second: " << speedinGBs << std::endl;
    }

    return 0;
}