memory_pool.cpp

// Copyright (C) 2015-2023 Jonathan Müller and foonathan/memory contributors
// SPDX-License-Identifier: Zlib

#include "memory_pool.hpp"

#include <algorithm>
#include <doctest/doctest.h>
#include <random>
#include <vector>

#include "allocator_storage.hpp"
#include "test_allocator.hpp"

using namespace foonathan::memory;

// don't test actual node allocationg, but the connection between arena and the implementation
// so only  test for memory_pool<node_pool>
TEST_CASE("memory_pool")
{
    using pool_type = memory_pool<node_pool, allocator_reference<test_allocator>>;
    test_allocator alloc;
    {
        pool_type pool(4, pool_type::min_block_size(4, 25), alloc);
        REQUIRE(pool.node_size() >= 4u);
        REQUIRE(pool.capacity_left() >= 25 * 4u);
        REQUIRE(pool.next_capacity() >= 25 * 4u);
        REQUIRE(alloc.no_allocated() == 1u);

        SUBCASE("normal alloc/dealloc")
        {
            std::vector<void*> ptrs;
            auto               capacity = pool.capacity_left();
            REQUIRE(capacity / 4 >= 25);
            for (std::size_t i = 0u; i != 25; ++i)
                ptrs.push_back(pool.allocate_node());
            REQUIRE(pool.capacity_left() >= 0u);
            REQUIRE(alloc.no_allocated() == 1u);

            std::shuffle(ptrs.begin(), ptrs.end(), std::mt19937{});

            for (auto ptr : ptrs)
                pool.deallocate_node(ptr);
            REQUIRE(pool.capacity_left() == capacity);
        }
        SUBCASE("multiple block alloc/dealloc")
        {
            std::vector<void*> ptrs;
            auto               capacity = pool.capacity_left();
            for (std::size_t i = 0u; i != capacity / pool.node_size(); ++i)
                ptrs.push_back(pool.allocate_node());
            REQUIRE(pool.capacity_left() >= 0u);

            ptrs.push_back(pool.allocate_node());
            REQUIRE(pool.capacity_left() >= capacity - pool.node_size());
            REQUIRE(alloc.no_allocated() == 2u);

            std::shuffle(ptrs.begin(), ptrs.end(), std::mt19937{});

            for (auto ptr : ptrs)
                pool.deallocate_node(ptr);
            REQUIRE(pool.capacity_left() >= capacity);
            REQUIRE(alloc.no_allocated() == 2u);
        }
    }
    {
        pool_type pool(16, pool_type::min_block_size(16, 1), alloc);
        REQUIRE(pool.node_size() == 16u);
        REQUIRE(pool.capacity_left() == 16u);
        REQUIRE(pool.next_capacity() >= 16u);
        REQUIRE(alloc.no_allocated() == 1u);

        auto ptr = pool.allocate_node();
        REQUIRE(ptr);

        pool.deallocate_node(ptr);
    }
    REQUIRE(alloc.no_allocated() == 0u);
}

namespace
{
    template <typename PoolType>
    void use_min_block_size(std::size_t node_size, std::size_t number_of_nodes)
    {
        auto min_size = memory_pool<PoolType>::min_block_size(node_size, number_of_nodes);
        memory_pool<PoolType> pool(node_size, min_size);
        CHECK(pool.capacity_left() >= node_size * number_of_nodes);

        // First allocations should not require realloc.
        for (auto i = 0u; i != number_of_nodes; ++i)
        {
            auto ptr = pool.try_allocate_node();
            CHECK(ptr);
        }

        // Further allocation might require it, but should still succeed then.
        auto ptr = pool.allocate_node();
        CHECK(ptr);
    }
} // namespace

TEST_CASE("memory_pool::min_block_size()")
{
    SUBCASE("node_pool")
    {
        use_min_block_size<node_pool>(1, 1);
        use_min_block_size<node_pool>(16, 1);
        use_min_block_size<node_pool>(1, 1000);
        use_min_block_size<node_pool>(16, 1000);
    }
    SUBCASE("array_pool")
    {
        use_min_block_size<array_pool>(1, 1);
        use_min_block_size<array_pool>(16, 1);
        use_min_block_size<array_pool>(1, 1000);
        use_min_block_size<array_pool>(16, 1000);
    }
    SUBCASE("small_node_pool")
    {
        use_min_block_size<small_node_pool>(1, 1);
        use_min_block_size<small_node_pool>(16, 1);
        use_min_block_size<small_node_pool>(1, 1000);
        use_min_block_size<small_node_pool>(16, 1000);
    }
}