378 lines
11 KiB
C++
378 lines
11 KiB
C++
#include <algorithm>
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#include <cerrno>
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#include <chrono>
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#include <cstdint>
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#include <cstdlib>
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#include <cstring>
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#include <iostream>
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#include <random>
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#include <stdexcept>
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#include <string>
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#include <sys/wait.h>
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#include <unistd.h>
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#include <vector>
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constexpr int NIL = -1;
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struct Node {
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int32_t value;
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int next;
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};
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struct Options {
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size_t size = 100000;
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int max_depth = 3;
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size_t min_size = 4096;
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unsigned seed = 1337;
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bool print = false;
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};
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struct SortResult {
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std::vector<int32_t> values;
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};
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static void throw_errno(const std::string& what) {
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throw std::runtime_error(what + ": " + std::strerror(errno));
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}
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static void close_checked(int fd) {
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if (fd >= 0) {
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while (close(fd) < 0 && errno == EINTR) {}
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}
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}
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static void write_all(int fd, const void* data, size_t bytes) {
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const char* p = static_cast<const char*>(data);
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while (bytes > 0) {
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ssize_t n = write(fd, p, bytes);
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if (n < 0) {
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if (errno == EINTR) continue;
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throw_errno("write");
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}
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if (n == 0) throw std::runtime_error("write returned zero");
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p += n;
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bytes -= static_cast<size_t>(n);
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}
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}
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static void read_all(int fd, void* data, size_t bytes) {
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char* p = static_cast<char*>(data);
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while (bytes > 0) {
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ssize_t n = read(fd, p, bytes);
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if (n < 0) {
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if (errno == EINTR) continue;
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throw_errno("read");
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}
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if (n == 0) throw std::runtime_error("unexpected EOF");
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p += n;
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bytes -= static_cast<size_t>(n);
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}
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}
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static void send_values(int fd, const std::vector<int32_t>& values) {
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uint64_t n = static_cast<uint64_t>(values.size());
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write_all(fd, &n, sizeof(n));
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if (!values.empty()) write_all(fd, values.data(), values.size() * sizeof(values[0]));
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}
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static std::vector<int32_t> recv_values(int fd) {
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uint64_t n = 0;
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read_all(fd, &n, sizeof(n));
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if (n > static_cast<uint64_t>(SIZE_MAX / sizeof(int32_t))) {
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throw std::runtime_error("input too large");
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}
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std::vector<int32_t> values(static_cast<size_t>(n));
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if (!values.empty()) read_all(fd, values.data(), values.size() * sizeof(values[0]));
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return values;
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}
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static int merge_lists(std::vector<Node>& nodes, int left, int right) {
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if (left == NIL) return right;
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if (right == NIL) return left;
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int head = NIL;
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int tail = NIL;
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auto append = [&](int idx) {
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if (head == NIL) {
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head = idx;
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tail = idx;
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} else {
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nodes[tail].next = idx;
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tail = idx;
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}
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};
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while (left != NIL && right != NIL) {
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if (nodes[left].value <= nodes[right].value) {
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int next = nodes[left].next;
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append(left);
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left = next;
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} else {
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int next = nodes[right].next;
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append(right);
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right = next;
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}
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}
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if (left != NIL) nodes[tail].next = left;
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if (right != NIL) nodes[tail].next = right;
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return head;
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}
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static void split_list(std::vector<Node>& nodes, int head, int& left, int& right) {
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if (head == NIL || nodes[head].next == NIL) {
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left = head;
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right = NIL;
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return;
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}
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int slow = head;
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int fast = nodes[head].next;
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while (fast != NIL) {
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fast = nodes[fast].next;
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if (fast != NIL) {
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slow = nodes[slow].next;
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fast = nodes[fast].next;
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}
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}
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left = head;
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right = nodes[slow].next;
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nodes[slow].next = NIL;
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}
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static int local_sort(std::vector<Node>& nodes, int head) {
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if (head == NIL || nodes[head].next == NIL) return head;
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int left = NIL;
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int right = NIL;
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split_list(nodes, head, left, right);
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left = local_sort(nodes, left);
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right = local_sort(nodes, right);
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return merge_lists(nodes, left, right);
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}
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static std::vector<Node> make_nodes(const std::vector<int32_t>& values) {
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std::vector<Node> nodes(values.size());
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for (size_t i = 0; i < values.size(); ++i) {
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nodes[i].value = values[i];
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nodes[i].next = (i + 1 == values.size()) ? NIL : static_cast<int>(i + 1);
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}
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return nodes;
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}
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static std::vector<int32_t> collect_values(const std::vector<Node>& nodes, int head) {
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std::vector<int32_t> out;
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out.reserve(nodes.size());
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for (int cur = head; cur != NIL; cur = nodes[cur].next) {
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out.push_back(nodes[cur].value);
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}
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return out;
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}
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static std::vector<int32_t> sort_values_as_list(std::vector<int32_t> values) {
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if (values.size() < 2) return values;
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std::vector<Node> nodes = make_nodes(values);
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int head = local_sort(nodes, 0);
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return collect_values(nodes, head);
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}
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static void split_values_as_list(const std::vector<int32_t>& values,
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std::vector<int32_t>& left_values,
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std::vector<int32_t>& right_values) {
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std::vector<Node> nodes = make_nodes(values);
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int left = NIL;
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int right = NIL;
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split_list(nodes, values.empty() ? NIL : 0, left, right);
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left_values = collect_values(nodes, left);
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right_values = collect_values(nodes, right);
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}
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static std::vector<int32_t> merge_values_as_list(const std::vector<int32_t>& left_values,
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const std::vector<int32_t>& right_values) {
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std::vector<Node> nodes;
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nodes.reserve(left_values.size() + right_values.size());
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int left = NIL;
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int left_tail = NIL;
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for (int32_t value : left_values) {
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int idx = static_cast<int>(nodes.size());
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nodes.push_back({value, NIL});
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if (left == NIL) left = idx;
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else nodes[left_tail].next = idx;
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left_tail = idx;
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}
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int right = NIL;
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int right_tail = NIL;
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for (int32_t value : right_values) {
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int idx = static_cast<int>(nodes.size());
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nodes.push_back({value, NIL});
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if (right == NIL) right = idx;
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else nodes[right_tail].next = idx;
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right_tail = idx;
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}
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int head = merge_lists(nodes, left, right);
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return collect_values(nodes, head);
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}
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static SortResult parallel_sort(std::vector<int32_t> values, int depth, const Options& opt);
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static pid_t spawn_child(const std::vector<int32_t>& part,
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int depth,
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const Options& opt,
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int& result_fd) {
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int to_child[2] = {-1, -1};
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int from_child[2] = {-1, -1};
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if (pipe(to_child) < 0) throw_errno("pipe to_child");
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if (pipe(from_child) < 0) throw_errno("pipe from_child");
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pid_t pid = fork();
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if (pid < 0) throw_errno("fork");
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if (pid == 0) {
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try {
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close_checked(to_child[1]);
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close_checked(from_child[0]);
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std::vector<int32_t> input = recv_values(to_child[0]);
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close_checked(to_child[0]);
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SortResult result = parallel_sort(std::move(input), depth, opt);
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send_values(from_child[1], result.values);
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close_checked(from_child[1]);
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_exit(0);
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} catch (...) {
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_exit(2);
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}
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}
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close_checked(to_child[0]);
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close_checked(from_child[1]);
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send_values(to_child[1], part);
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close_checked(to_child[1]);
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result_fd = from_child[0];
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return pid;
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}
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static SortResult parallel_sort(std::vector<int32_t> values, int depth, const Options& opt) {
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if (values.size() < 2 || depth >= opt.max_depth || values.size() <= opt.min_size) {
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return {sort_values_as_list(std::move(values))};
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}
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std::vector<int32_t> left;
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std::vector<int32_t> right;
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split_values_as_list(values, left, right);
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int left_fd = -1;
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int right_fd = -1;
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pid_t left_pid = spawn_child(left, depth + 1, opt, left_fd);
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pid_t right_pid = spawn_child(right, depth + 1, opt, right_fd);
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std::vector<int32_t> sorted_left = recv_values(left_fd);
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std::vector<int32_t> sorted_right = recv_values(right_fd);
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close_checked(left_fd);
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close_checked(right_fd);
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int left_status = 0;
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int right_status = 0;
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while (waitpid(left_pid, &left_status, 0) < 0 && errno == EINTR) {}
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while (waitpid(right_pid, &right_status, 0) < 0 && errno == EINTR) {}
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if (!WIFEXITED(left_status) || WEXITSTATUS(left_status) != 0) {
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throw std::runtime_error("left child failed");
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}
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if (!WIFEXITED(right_status) || WEXITSTATUS(right_status) != 0) {
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throw std::runtime_error("right child failed");
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}
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return {merge_values_as_list(sorted_left, sorted_right)};
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}
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static Options parse_args(int argc, char** argv) {
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Options opt;
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for (int i = 1; i < argc; ++i) {
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std::string s = argv[i];
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auto value = [&](const std::string& name) -> std::string {
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if (i + 1 >= argc) throw std::runtime_error("missing value for " + name);
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return argv[++i];
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};
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if (s == "--size" || s == "-n") {
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opt.size = std::stoull(value(s));
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} else if (s == "--depth" || s == "-d") {
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opt.max_depth = std::stoi(value(s));
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} else if (s == "--min-size" || s == "-m") {
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opt.min_size = std::stoull(value(s));
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} else if (s == "--seed") {
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opt.seed = static_cast<unsigned>(std::stoul(value(s)));
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} else if (s == "--print") {
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opt.print = true;
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} else if (s == "--help" || s == "-h") {
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std::cout << "Usage: ./pipe_sort [--size N] [--depth D] [--min-size M] "
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<< "[--seed S] [--print]\n";
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std::exit(0);
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} else {
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throw std::runtime_error("unknown argument: " + s);
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}
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}
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if (opt.max_depth < 0) throw std::runtime_error("depth must be non-negative");
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if (opt.size == 0) throw std::runtime_error("size must be positive");
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return opt;
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}
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int main(int argc, char** argv) {
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try {
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Options opt = parse_args(argc, argv);
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std::vector<int32_t> values(opt.size);
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std::mt19937 rng(opt.seed);
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std::uniform_int_distribution<int32_t> dist(-100000000, 100000000);
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for (int32_t& value : values) value = dist(rng);
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const auto t1 = std::chrono::steady_clock::now();
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SortResult result = parallel_sort(std::move(values), 0, opt);
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const auto t2 = std::chrono::steady_clock::now();
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const double elapsed = std::chrono::duration<double>(t2 - t1).count();
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const bool ok = std::is_sorted(result.values.begin(), result.values.end()) &&
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result.values.size() == opt.size;
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if (opt.print) {
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for (int32_t value : result.values) std::cout << value << ' ';
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std::cout << '\n';
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}
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std::cerr << "STAT: program=pipe size=" << opt.size
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<< " depth=" << opt.max_depth
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<< " min_size=" << opt.min_size
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<< " valid=" << (ok ? 1 : 0)
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<< " time=" << elapsed << " sec\n";
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return ok ? 0 : 3;
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} catch (const std::exception& e) {
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std::cerr << "ERROR: " << e.what() << "\n";
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return 1;
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}
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}
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