files

src/main.cpp

@@ -0,0 +1,67 @@
+#include "config.hpp"
+#include "record.hpp"
+#include "sort.cpp"
+#include "writer.hpp"
+#include <fstream>
+#include <iostream>
+#include <sys/stat.h>
+#include <sys/types.h>
+
+void generate_file(int N, const std::string& filename)
+{
+    std::filesystem::path dirPath = std::filesystem::path(filename).parent_path();
+    std::filesystem::create_directories(dirPath);
+
+    std::ofstream out_stream(filename);
+    Writer output(out_stream);
+
+    for (int i = 0; i < N; i++) {
+        Record rec = Record::random();
+        output.write(rec);
+    }
+}
+
+void read_and_evaluate(std::string filename, int n)
+{
+    Buffer main_buffer(n);
+    auto buff = main_buffer.divide(1)[0];
+
+    std::ifstream in_stream(filename);
+    Reader input_reader(in_stream);
+
+    while (true) {
+        size_t records_read = read_chunk(input_reader, buff);
+
+        if (records_read == 0) {
+            break;
+        }
+
+        for (size_t i = 0; i < records_read; ++i) {
+            const Record& rec = buff[i];
+            std::cout << "[Evaluate i = " << i << ": " << rec.evaluate() << "] " << rec << "\n";
+        }
+    }
+}
+
+int main(int argc, char** argv)
+{
+    try {
+        Configuration opts = Configuration::parse_args(argc, argv);
+
+        if (opts.generate_data) {
+            generate_file(opts.N, opts.output_file);
+            return 0;
+        }
+
+        if (opts.evaluate_file) {
+            read_and_evaluate(opts.input_file, opts.N);
+            return 0;
+        }
+
+        sort_file(opts);
+
+    } catch (const std::exception& e) {
+        std::cerr << "Error: " << e.what() << '\n';
+        return 1;
+    }
+}

src/sort.cpp

@@ -0,0 +1,188 @@
+#pragma once
+#include "buffer.hpp"
+#include "config.hpp"
+#include "reader.hpp"
+#include "writer.hpp"
+#include <fstream>
+#include <queue>
+#include <string>
+
+// returns amount of records read
+size_t read_chunk(Reader& reader, SubBuffer& buff)
+{
+    for (size_t i = 0; i < buff.size(); i++) {
+        std::optional<Record> in = reader.read();
+        if (!in.has_value()) {
+            return i;
+        }
+        buff[i] = in.value();
+    }
+    return buff.size();
+}
+
+void write_to_file(const std::string& filename, SubBuffer& buff, size_t n)
+{
+    std::filesystem::path dirPath = std::filesystem::path(filename).parent_path();
+    std::filesystem::create_directories(dirPath);
+
+    std::ofstream out_stream(filename);
+    Writer output_writer(out_stream);
+    for (size_t j = 0; j < n; j++) {
+        output_writer.write(buff[j]);
+    }
+}
+
+size_t create_initial_runs(const std::string& input_filename, const std::string& directory, Buffer& main_buffer)
+{
+    auto buff = main_buffer.divide(1)[0];
+
+    std::ifstream in_stream(input_filename);
+    Reader input_reader(in_stream);
+    size_t run_index;
+
+    for (run_index = 0;; run_index++) {
+        size_t size = read_chunk(input_reader, buff);
+        if (size == 0) {
+            break;
+        }
+        std::sort(buff.begin(), buff.begin() + size);
+        write_to_file(directory + "/" + std::to_string(run_index) + ".run", buff, size);
+    }
+
+    return run_index;
+}
+
+void write_block(Writer& w, SubBuffer& buff, size_t n)
+{
+    for (size_t i = 0; i < n; i++) {
+        w.write(buff[i]);
+    }
+}
+
+void k_way_merge_and_write(std::vector<Reader>& input_readers, Writer& output_writer, std::vector<SubBuffer>& buffers)
+{
+    // for debug purposes
+    std::cout << "buffers size: " << buffers.size() << " input_readers: " << input_readers.size() << '\n';
+    for (size_t i = 0; i < input_readers.size(); i++) {
+        std::cout << "reader " << i << ": " << input_readers[i].read().value() << '\n';
+    }
+
+    struct HeapElement {
+        Record record;
+        size_t source_index;
+        // priority queue is a max heap by default, so comparison is backwards
+        bool operator<(const HeapElement& other) const
+        {
+            return !(record < other.record);
+        }
+    };
+    using MinHeap = std::priority_queue<HeapElement>;
+    MinHeap pq;
+
+    struct BufferState {
+        size_t items_total = 0;
+        size_t current_idx = 0;
+    };
+
+    std::vector<BufferState> buffer_states(input_readers.size());
+
+    // initial fill
+    for (size_t i = 0; i < input_readers.size(); i++) {
+        SubBuffer& input_buffer = buffers[i];
+        buffer_states[i].items_total = read_chunk(input_readers[i], input_buffer);
+        buffer_states[i].current_idx = 0;
+
+        if (buffer_states[i].items_total == 0) {
+            continue;
+        }
+
+        pq.push({ input_buffer[0], i });
+        buffer_states[i].current_idx++;
+    }
+
+    size_t output_index = 0;
+    SubBuffer& output_buffer = buffers[buffers.size() - 1];
+
+    while (!pq.empty()) {
+        HeapElement next = pq.top();
+        pq.pop();
+
+        output_buffer[output_index] = next.record;
+        output_index++;
+
+        if (output_index == output_buffer.size()) {
+            write_block(output_writer, output_buffer, output_index);
+            output_index = 0;
+        }
+
+        size_t source_index = next.source_index;
+
+        if (buffer_states[source_index].current_idx >= buffer_states[source_index].items_total) {
+            buffer_states[source_index].items_total = read_chunk(input_readers[source_index], buffers[source_index]);
+            buffer_states[source_index].current_idx = 0;
+            if (buffer_states[source_index].items_total == 0) {
+                continue;
+            }
+        }
+
+        pq.push({ buffers[source_index][buffer_states[source_index].current_idx], source_index });
+        buffer_states[source_index].current_idx++;
+    }
+}
+
+// I think more or less works correctly now
+// creates input readers, and output writer for a merge to be performed by another function
+// if not every file can be processed at once, splits them
+size_t run_merge_pass(std::vector<SubBuffer>& buffers, std::string current_dir, std::string next_dir, size_t file_count)
+{
+    const size_t K = buffers.size() - 1; // Merge factor (e.g., 3)
+
+    size_t new_runs = 0;
+    for (size_t i = 0; i < file_count; i += K) {
+        // std::cout << "pass 0 run " << i << '\n';
+        // create input readers, to turn into a function i would have to some complicated ownership semantics, and i don't want to bother with that
+        std::vector<std::ifstream> in_streams;
+        std::vector<Reader> input_readers;
+        in_streams.reserve(K);
+        input_readers.reserve(K);
+        for (size_t j = 0; j < K; j++) {
+            std::string filename = current_dir + "/" + std::to_string(i + j) + ".run";
+            in_streams.emplace_back(std::ifstream(filename));
+            input_readers.emplace_back(Reader(in_streams[j]));
+        }
+
+        // create the output writer -||-
+        std::string filename = next_dir + "/" + std::to_string(new_runs) + ".run";
+        std::filesystem::path dirPath = std::filesystem::path(filename).parent_path();
+        std::filesystem::create_directories(dirPath);
+        std::ofstream out_stream(filename);
+        Writer output_writer(out_stream);
+
+        k_way_merge_and_write(input_readers, output_writer, buffers);
+        new_runs++;
+    }
+
+    return new_runs;
+}
+
+int sort_file(const Configuration& opts)
+{
+    Buffer main_buffer(opts.n * opts.b);
+    size_t file_count;
+
+    file_count = create_initial_runs(opts.input_file, opts.directory + "/pass0", main_buffer);
+
+    auto buffers = main_buffer.divide(opts.n);
+    for (int i = 0;; i++) {
+        std::string current_dir = opts.directory + "/pass" + std::to_string(i);
+        std::string next_dir = opts.directory + "/pass" + std::to_string(i + 1);
+        file_count = run_merge_pass(buffers, current_dir, next_dir, file_count);
+        if (file_count == 1) {
+            // #todo move the resulting file to the output dir
+            break;
+        }
+    }
+
+    // #todo cleanup tmp files
+    return 0;
+}