Crafter.DB/tests/ShouldKeepViewsStableAcrossGrowth/main.cpp

// SPDX-License-Identifier: LGPL-3.0-only
// SPDX-FileCopyrightText: Copyright (C) 2026 Catcrafts®

// Grows a table through many extents while holding Row views and
// string_views taken before the growth. Guards the fixed-address mapping
// promise: appends never move existing rows or heap bytes.

import Crafter.DB;
import std;

using namespace Crafter;
namespace fs = std::filesystem;
using TimePoint = std::chrono::system_clock::time_point;

namespace {
    int failures = 0;

    void Check(bool condition, std::string_view what) {
        if (!condition) {
            std::println("FAIL: {}", what);
            ++failures;
        }
    }

    template<typename T>
    void CheckEqual(const T& actual, const T& expected, std::string_view what) {
        if (!(actual == expected)) {
            std::println("FAIL: {} — expected '{}', got '{}'", what, expected, actual);
            ++failures;
        }
    }

    struct Event {
        std::string label;
        std::string payload;
        std::uint64_t sequence;

        static constexpr std::uint32_t version = 1;
        static constexpr auto orderedBy = &Event::sequence;
    };
}

int main() {
    const fs::path dir = fs::temp_directory_path() / "crafter-db-growth";
    fs::remove_all(dir);
    const fs::path path = dir / "events.cdb";
    constexpr std::uint64_t count = 300'000;

    {
        DB::Table<Event> table(path);
        table.Emplace(std::string_view("first"), std::string_view("payload of the very first row, long enough for the heap"), std::uint64_t(0));
        const DB::Row<Event> first = table[0];
        const std::string_view firstPayload = first[&Event::payload];
        const std::byte* firstBytes = first.Bytes();
        const char* firstHeapPointer = firstPayload.data();

        std::vector<Event> batch;
        batch.reserve(1000);
        for (std::uint64_t i = 1; i < count; i++) {
            batch.push_back({ std::format("row-{}", i), std::format("payload-{}-{}", i, std::string(i % 40, 'p')), i });
            if (batch.size() == 1000) {
                table.Append(batch);
                batch.clear();
            }
        }
        if (!batch.empty()) table.Append(batch);

        CheckEqual<std::uint64_t>(table.Size(), count, "all rows appended");
        Check(first.Bytes() == firstBytes, "row pointer unchanged after growth");
        Check(firstPayload.data() == firstHeapPointer, "heap pointer unchanged after growth");
        Check(firstPayload == "payload of the very first row, long enough for the heap", "early string_view still reads correctly");
        Check(first[&Event::label] == "first", "early row view still decodes");
        Check(table[count - 1][&Event::label] == std::format("row-{}", count - 1), "last row readable");
        Check(table[123456][&Event::payload] == std::format("payload-{}-{}", 123456, std::string(123456 % 40, 'p')), "middle row readable");

        const DB::TableStats stats = table.Stats();
        Check(stats.fileLength > count * DB::Layout<Event>::rowSize, "file holds the rows");
        table.Flush();
        const DB::Inspection info = DB::TableFile::Inspect(path);
        Check(info.commit.extentCount[0] >= 5, std::format("rows region grew through several extents ({})", info.commit.extentCount[0]));
        Check(info.commit.extentCount[1] >= 5, std::format("heap region grew through several extents ({})", info.commit.extentCount[1]));
        CheckEqual<std::uint64_t>(info.commit.rowCount, count, "committed row count");
        Check(info.commit.fileLength == fs::file_size(path), "committed length equals file size after flush");
    }

    {
        const DB::Table<Event> table(path, { .readOnly = true });
        CheckEqual<std::uint64_t>(table.Size(), count, "rows survive reopen");
        std::uint64_t expected = 0;
        bool ordered = true;
        for (DB::Row<Event> row : table) {
            if (row[&Event::sequence] != expected) ordered = false;
            expected++;
        }
        Check(ordered && expected == count, "sequence intact after reopen");
        CheckEqual<std::uint64_t>(table.LowerBound<&Event::sequence>(150'000), 150'000, "binary search over a multi-extent table");
    }

    fs::remove_all(dir);
    if (failures == 0) std::println("ok");
    return failures == 0 ? 0 : 1;
}