79 lines
2.7 KiB
C++
79 lines
2.7 KiB
C++
#include "tape_config.h"
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#include "tapelib/filetape.h"
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#include "tapelib/tape.h"
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#include "tapelib/tape_util.h"
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#include <chrono>
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#include <cstddef>
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#include <fstream>
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#include <iostream>
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#include <memory>
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#include <string>
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using std::string;
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using std::chrono::high_resolution_clock;
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using std::chrono::milliseconds;
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using namespace tape;
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size_t get_mem_peak() {
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const static string mem_info_file = "/proc/self/status";
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const static string mem_field = "VmPeak:";
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std::ifstream status(mem_info_file);
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size_t mem = 0;
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string line;
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while (std::getline(status, line)) {
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if (line.find(mem_field) != string::npos) {
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std::stringstream mem_line(line.substr(mem_field.size()));
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mem_line >> mem;
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return mem;
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}
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}
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return mem;
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}
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// if we assume N as INPUT tape size, we can calucalte the optimal memory-limit
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// by using this formula:
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// X = sqrt(8000*N)
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// where X is the optimal memory-limit value
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int main(int argc, char *argv[]) {
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AppSettings settings = parse_command_line(argc, argv);
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if (settings.version) {
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std::cout << VERSION_MSG << std::endl;
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return 0;
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}
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if (settings.help) {
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std::cerr << HELP_MSG << std::endl;
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return 0;
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}
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if (!settings.config_file_path.empty() &&
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!read_settings_from_file(settings)) {
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return -1;
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}
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FileTape input(settings.input_file_name, settings.ft_settings);
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if (!input.is_open()) {
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std::cerr << "Failed to create INPUT tape - file not found or "
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"insufficient permissions"
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<< std::endl;
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return -1;
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}
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FileTape output(input, settings.output_file_name, settings.ft_settings);
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if (!output.is_open()) {
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std::cerr << "Failed to create OUTPUT tape - insufficient permissions"
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<< std::endl;
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return -1;
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}
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// tmp tape factory that captures settings.ft_settings from local scope
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TempTapeFactory factory = [&](size_t cells) -> std::unique_ptr<Tape> {
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return std::make_unique<FileTape>(
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FileTape(cells, settings.ft_settings));
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};
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auto start = high_resolution_clock::now();
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external_sort(input, output, factory, settings.memory_limit);
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auto end = high_resolution_clock::now();
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auto duration = std::chrono::duration_cast<milliseconds>(end - start);
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std::cout << "Successfully sorted " << settings.input_file_name << " into "
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<< settings.output_file_name << std::endl;
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std::cout << "The operation took " << duration.count()
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<< " ms to complete and peaked at " << get_mem_peak()
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<< " KiB of virtual memory usage" << std::endl;
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return 0;
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}
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