jenga.cpp

#include "rapidjson/document.h"

#include <stack>
#include <unordered_set>
#include <vector>

using namespace rapidjson;
using namespace std;

#define PATH "/home/andrea/Desktop/dependencies.json"

// TODO: speed up (./jenga jayson should take less than 1s)
// TODO: speed up: analyze using perf
// TODO: speed up: use char* instead of string

unordered_set<string> already_downloaded;
void count_dependents(const Value& rows, string package)
{
    string package_name = package;
    uint total = 0;
    stack<string> S;

    S.push(package_name);

    while (!S.empty()) {
        package_name = S.top();

        if (already_downloaded.find(package_name) != already_downloaded.end()) {
            S.pop();
            continue;
        } else {
            already_downloaded.insert(string(package_name));
        }

        vector<string> deps;
        // Count the dependents packages
        int n = 0;
        for (const auto& row : rows.GetArray()) {
            for (const auto& key : row["key"].GetArray()) {
                if (key == package_name.c_str() && row["id"] != package_name.c_str()) {
                    auto id = row["id"].GetString();
                    deps.push_back(id);
                    n++;
                }
            }
        }

        S.pop();
        if (n == 0) {
            total++;
        } else {
            for (const auto& dep : deps) {
                S.push(dep);
            }
        }
    }

    printf("Total dependents: %d\n", total);
}

int main(int argc, char** argv)
{
    printf("Start\n");
    if (argc != 2) {
        printf("Usage %s package-name\n", argv[0]);
        exit(1);
    }
    string package_name = string(argv[1]);

    // Read the file and load in into the buffer
    FILE* fp = fopen(PATH, "r");
    fseek(fp, 0, SEEK_END);
    auto file_size = (size_t)ftell(fp);
    fseek(fp, 0, SEEK_SET);
    auto * buffer = (char*)malloc(file_size + 1);
    size_t readLength = fread(buffer, 1, file_size, fp);
    buffer[readLength] = '\0';
    fclose(fp);

    // Parse the json inside the buffer
    Document d;
    d.ParseInsitu(buffer);
    printf("Parsed the JSON\n");

    // Start analyzing it

    printf("Starting the analysis\n");
    const Value& rows = d["rows"];
    assert(rows.IsArray());

    printf("Calling count_dependents\n");
    count_dependents(rows, package_name);

    printf("Stop\n");
    free(buffer);
    return 0;
}