Add DenseHandlePool

4 files changed, 309 insertions, 7 deletions

diff --git a/MODULE.bazel.lock b/MODULE.bazel.lock
index 55c4990..9fb4fd8 100644
--- a/MODULE.bazel.lock
+++ b/MODULE.bazel.lock
@@ -20,7 +20,8 @@
     "https://bcr.bazel.build/modules/bazel_features/1.18.0/MODULE.bazel": "1be0ae2557ab3a72a57aeb31b29be347bcdc5d2b1eb1e70f39e3851a7e97041a",
     "https://bcr.bazel.build/modules/bazel_features/1.19.0/MODULE.bazel": "59adcdf28230d220f0067b1f435b8537dd033bfff8db21335ef9217919c7fb58",
     "https://bcr.bazel.build/modules/bazel_features/1.21.0/MODULE.bazel": "675642261665d8eea09989aa3b8afb5c37627f1be178382c320d1b46afba5e3b",
-    "https://bcr.bazel.build/modules/bazel_features/1.21.0/source.json": "3e8379efaaef53ce35b7b8ba419df829315a880cb0a030e5bb45c96d6d5ecb5f",
+    "https://bcr.bazel.build/modules/bazel_features/1.30.0/MODULE.bazel": "a14b62d05969a293b80257e72e597c2da7f717e1e69fa8b339703ed6731bec87",
+    "https://bcr.bazel.build/modules/bazel_features/1.30.0/source.json": "b07e17f067fe4f69f90b03b36ef1e08fe0d1f3cac254c1241a1818773e3423bc",
     "https://bcr.bazel.build/modules/bazel_features/1.4.1/MODULE.bazel": "e45b6bb2350aff3e442ae1111c555e27eac1d915e77775f6fdc4b351b758b5d7",
     "https://bcr.bazel.build/modules/bazel_features/1.9.1/MODULE.bazel": "8f679097876a9b609ad1f60249c49d68bfab783dd9be012faf9d82547b14815a",
     "https://bcr.bazel.build/modules/bazel_skylib/1.0.3/MODULE.bazel": "bcb0fd896384802d1ad283b4e4eb4d718eebd8cb820b0a2c3a347fb971afd9d8",
@@ -74,7 +75,6 @@
     "https://bcr.bazel.build/modules/rules_cc/0.0.14/MODULE.bazel": "5e343a3aac88b8d7af3b1b6d2093b55c347b8eefc2e7d1442f7a02dc8fea48ac",
     "https://bcr.bazel.build/modules/rules_cc/0.0.15/MODULE.bazel": "6704c35f7b4a72502ee81f61bf88706b54f06b3cbe5558ac17e2e14666cd5dcc",
     "https://bcr.bazel.build/modules/rules_cc/0.0.16/MODULE.bazel": "7661303b8fc1b4d7f532e54e9d6565771fea666fbdf839e0a86affcd02defe87",
-    "https://bcr.bazel.build/modules/rules_cc/0.0.17/MODULE.bazel": "2ae1d8f4238ec67d7185d8861cb0a2cdf4bc608697c331b95bf990e69b62e64a",
     "https://bcr.bazel.build/modules/rules_cc/0.0.2/MODULE.bazel": "6915987c90970493ab97393024c156ea8fb9f3bea953b2f3ec05c34f19b5695c",
     "https://bcr.bazel.build/modules/rules_cc/0.0.6/MODULE.bazel": "abf360251023dfe3efcef65ab9d56beefa8394d4176dd29529750e1c57eaa33f",
     "https://bcr.bazel.build/modules/rules_cc/0.0.8/MODULE.bazel": "964c85c82cfeb6f3855e6a07054fdb159aced38e99a5eecf7bce9d53990afa3e",
@@ -94,8 +94,8 @@
     "https://bcr.bazel.build/modules/rules_java/7.2.0/MODULE.bazel": "06c0334c9be61e6cef2c8c84a7800cef502063269a5af25ceb100b192453d4ab",
     "https://bcr.bazel.build/modules/rules_java/7.3.2/MODULE.bazel": "50dece891cfdf1741ea230d001aa9c14398062f2b7c066470accace78e412bc2",
     "https://bcr.bazel.build/modules/rules_java/7.6.1/MODULE.bazel": "2f14b7e8a1aa2f67ae92bc69d1ec0fa8d9f827c4e17ff5e5f02e91caa3b2d0fe",
-    "https://bcr.bazel.build/modules/rules_java/8.11.0/MODULE.bazel": "c3d280bc5ff1038dcb3bacb95d3f6b83da8dd27bba57820ec89ea4085da767ad",
-    "https://bcr.bazel.build/modules/rules_java/8.11.0/source.json": "302b52a39259a85aa06ca3addb9787864ca3e03b432a5f964ea68244397e7544",
+    "https://bcr.bazel.build/modules/rules_java/8.12.0/MODULE.bazel": "8e6590b961f2defdfc2811c089c75716cb2f06c8a4edeb9a8d85eaa64ee2a761",
+    "https://bcr.bazel.build/modules/rules_java/8.12.0/source.json": "cbd5d55d9d38d4008a7d00bee5b5a5a4b6031fcd4a56515c9accbcd42c7be2ba",
     "https://bcr.bazel.build/modules/rules_java/8.3.2/MODULE.bazel": "7336d5511ad5af0b8615fdc7477535a2e4e723a357b6713af439fe8cf0195017",
     "https://bcr.bazel.build/modules/rules_java/8.5.1/MODULE.bazel": "d8a9e38cc5228881f7055a6079f6f7821a073df3744d441978e7a43e20226939",
     "https://bcr.bazel.build/modules/rules_jvm_external/4.4.2/MODULE.bazel": "a56b85e418c83eb1839819f0b515c431010160383306d13ec21959ac412d2fe7",
@@ -140,15 +140,15 @@
     "https://bcr.bazel.build/modules/stardoc/0.7.2/source.json": "58b029e5e901d6802967754adf0a9056747e8176f017cfe3607c0851f4d42216",
     "https://bcr.bazel.build/modules/upb/0.0.0-20220923-a547704/MODULE.bazel": "7298990c00040a0e2f121f6c32544bab27d4452f80d9ce51349b1a28f3005c43",
     "https://bcr.bazel.build/modules/zlib/1.2.11/MODULE.bazel": "07b389abc85fdbca459b69e2ec656ae5622873af3f845e1c9d80fe179f3effa0",
-    "https://bcr.bazel.build/modules/zlib/1.3.1.bcr.3/MODULE.bazel": "af322bc08976524477c79d1e45e241b6efbeb918c497e8840b8ab116802dda79",
-    "https://bcr.bazel.build/modules/zlib/1.3.1.bcr.3/source.json": "2be409ac3c7601245958cd4fcdff4288be79ed23bd690b4b951f500d54ee6e7d",
+    "https://bcr.bazel.build/modules/zlib/1.3.1.bcr.5/MODULE.bazel": "eec517b5bbe5492629466e11dae908d043364302283de25581e3eb944326c4ca",
+    "https://bcr.bazel.build/modules/zlib/1.3.1.bcr.5/source.json": "22bc55c47af97246cfc093d0acf683a7869377de362b5d1c552c2c2e16b7a806",
     "https://bcr.bazel.build/modules/zlib/1.3.1/MODULE.bazel": "751c9940dcfe869f5f7274e1295422a34623555916eb98c174c1e945594bf198"
   },
   "selectedYankedVersions": {},
   "moduleExtensions": {
     "@@rules_kotlin+//src/main/starlark/core/repositories:bzlmod_setup.bzl%rules_kotlin_extensions": {
       "general": {
-        "bzlTransitiveDigest": "sFhcgPbDQehmbD1EOXzX4H1q/CD5df8zwG4kp4jbvr8=",
+        "bzlTransitiveDigest": "hUTp2w+RUVdL7ma5esCXZJAFnX7vLbVfLd7FwnQI6bU=",
         "usagesDigest": "QI2z8ZUR+mqtbwsf2fLqYdJAkPOHdOV+tF2yVAUgRzw=",
         "recordedFileInputs": {},
         "recordedDirentsInputs": {},
diff --git a/asl/handle_pool/BUILD.bazel b/asl/handle_pool/BUILD.bazel
index bdaa711..08a41a9 100644
--- a/asl/handle_pool/BUILD.bazel
+++ b/asl/handle_pool/BUILD.bazel
@@ -21,6 +21,17 @@ cc_library(
     visibility = ["//visibility:public"],
 )
 
+cc_library(
+    name = "dense_handle_pool",
+    hdrs = [
+        "dense_handle_pool.hpp",
+    ],
+    deps = [
+        ":index_pool",
+    ],
+    visibility = ["//visibility:public"],
+)
+
 cc_test(
     name = "index_pool_tests",
     srcs = [
@@ -33,3 +44,15 @@ cc_test(
         "//asl/testing",
     ],
 )
+
+cc_test(
+    name = "dense_handle_pool_tests",
+    srcs = [
+        "dense_handle_pool_tests.cpp",
+    ],
+    deps = [
+        ":dense_handle_pool",
+        "//asl/tests:utils",
+        "//asl/testing",
+    ],
+)
diff --git a/asl/handle_pool/dense_handle_pool.hpp b/asl/handle_pool/dense_handle_pool.hpp
new file mode 100644
index 0000000..34cd04f
--- /dev/null
+++ b/asl/handle_pool/dense_handle_pool.hpp
@@ -0,0 +1,162 @@
+// Copyright 2025 Steven Le Rouzic
+//
+// SPDX-License-Identifier: BSD-3-Clause
+
+#pragma once
+
+#include "asl/handle_pool/index_pool.hpp"
+#include "asl/memory/allocator.hpp"
+#include "asl/containers/chunked_buffer.hpp"
+
+
+namespace asl
+{
+
+// @Todo If we want the allocator to be non-copyable, we could
+// introduce a reference allocator type that is copyable, and store
+// the "main" allocator in the pool.
+
+template<
+    is_object T,
+    int kIndexBits,
+    int kGenBits,
+    typename UserType = empty,
+    int kUserBits = 0,
+    isize_t kChunkSize = 32,
+    allocator Allocator = DefaultAllocator>
+requires moveable<T> && copyable<Allocator>
+class DenseHandlePool
+{
+    using ThisIndexPool = IndexPool<kIndexBits, kGenBits, UserType, kUserBits, isize_t, Allocator>;
+
+    struct Slot
+    {
+        ThisIndexPool::handle h;
+        T obj;
+
+        template<typename... Args>
+        explicit Slot(ThisIndexPool::handle h, Args&&... args)
+            : h{h}
+            , obj(std::forward<Args>(args)...)
+        {}
+    };
+
+    using Buffer = chunked_buffer<Slot, kChunkSize, Allocator>;
+
+    ThisIndexPool m_index_pool{};
+    Buffer        m_buffer{};
+
+    using config = ThisIndexPool::handle::config;
+
+    template<typename... Args>
+    isize_t push(Args&&... args)
+        requires constructible_from<T, Args&&...>
+    {
+        m_buffer.push(typename ThisIndexPool::handle{}, std::forward<Args>(args)...);
+        return m_buffer.size() - 1;
+    }
+
+public:
+    using handle = ThisIndexPool::handle;
+
+    DenseHandlePool() requires default_constructible<Allocator> = default;
+
+    explicit DenseHandlePool(const Allocator& allocator)
+        : m_index_pool(allocator)
+        , m_buffer(allocator)
+    {}
+
+    ASL_DELETE_COPY(DenseHandlePool);
+    ASL_DEFAULT_MOVE(DenseHandlePool);
+    ~DenseHandlePool() = default;
+
+    [[nodiscard]] bool is_full() const
+    {
+        return m_index_pool.is_full();
+    }
+
+    bool is_valid(handle h) const
+    {
+        return m_index_pool.is_valid(h);
+    }
+
+    template<typename... Args>
+    option<handle> acquire(config::UserType user, Args&&... args)
+        requires config::kHasUser && constructible_from<T, Args&&...>
+    {
+        if (is_full()) { return nullopt; }
+        const isize_t obj_index = push(std::forward<Args>(args)...);
+        const auto handle = m_index_pool.acquire_ensure(user, obj_index);
+        m_buffer[obj_index].h = handle;
+        return handle;
+    }
+
+    template<typename... Args>
+    option<handle> acquire(Args&&... args)
+        requires (!config::kHasUser) && constructible_from<T, Args&&...>
+    {
+        if (is_full()) { return nullopt; }
+        const isize_t obj_index = push(std::forward<Args>(args)...);
+        const auto handle = m_index_pool.acquire_ensure(obj_index);
+        m_buffer[obj_index].h = handle;
+        return handle;
+    }
+
+    template<typename... Args>
+    handle acquire_ensure(config::UserType user, Args&&... args)
+        requires config::kHasUser && constructible_from<T, Args&&...>
+    {
+        ASL_ASSERT_RELEASE(!is_full());
+        const isize_t obj_index = push(std::forward<Args>(args)...);
+        const auto handle = m_index_pool.acquire_ensure(user, obj_index);
+        m_buffer[obj_index].h = handle;
+        return handle;
+    }
+
+    template<typename... Args>
+    handle acquire_ensure(Args&&... args)
+        requires (!config::kHasUser) && constructible_from<T, Args&&...>
+    {
+        ASL_ASSERT_RELEASE(!is_full());
+        const isize_t obj_index = push(std::forward<Args>(args)...);
+        const auto handle = m_index_pool.acquire_ensure(obj_index);
+        m_buffer[obj_index].h = handle;
+        return handle;
+    }
+
+    void release(handle to_release_handle)
+    {
+        if (!is_valid(to_release_handle)) { return; }
+
+        const auto to_release_index = *m_index_pool.get_payload(to_release_handle);
+        if (to_release_index < m_buffer.size() - 1)
+        {
+            const auto to_swap_index = m_buffer.size() - 1;
+            const auto to_swap_handle = m_buffer[to_swap_index].h;
+
+            m_buffer[to_release_index] = std::move(m_buffer[to_swap_index]);
+            m_index_pool.exchange_payload(to_swap_handle, to_release_index);
+        }
+
+        m_buffer.pop();
+        m_index_pool.release(to_release_handle);
+    }
+
+    auto get(this auto&& self, handle h)
+        -> copy_const_t<un_ref_t<decltype(self)>, T>*
+    {
+        if (!self.is_valid(h)) { return nullptr; }
+        const auto index = *self.m_index_pool.get_payload(h);
+        return &self.m_buffer[index].obj;
+    }
+
+    auto get_ensure(this auto&& self, handle h)
+        -> copy_cref_t<decltype(self), T>
+    {
+        ASL_ASSERT_RELEASE(self.is_valid(h));
+        const auto index = *self.m_index_pool.get_payload(h);
+        return std::forward<decltype(self)>(self).m_buffer[index].obj;
+    }
+};
+
+} // namespace asl
diff --git a/asl/handle_pool/dense_handle_pool_tests.cpp b/asl/handle_pool/dense_handle_pool_tests.cpp
new file mode 100644
index 0000000..a98d1d8
--- /dev/null
+++ b/asl/handle_pool/dense_handle_pool_tests.cpp
@@ -0,0 +1,117 @@
+// Copyright 2025 Steven Le Rouzic
+//
+// SPDX-License-Identifier: BSD-3-Clause
+
+#include "asl/testing/testing.hpp"
+#include "asl/tests/types.hpp"
+#include "asl/handle_pool/dense_handle_pool.hpp"
+
+ASL_TEST(acquire_release) // NOLINT
+{
+    asl::DenseHandlePool<int, 1, 1> pool;
+
+    ASL_TEST_EXPECT(!pool.is_full());
+
+    const auto a = pool.acquire_ensure(6);
+    const auto b = pool.acquire_ensure(7);
+
+    ASL_TEST_EXPECT(pool.is_valid(a));
+    ASL_TEST_EXPECT(pool.is_valid(b));
+    ASL_TEST_EXPECT(pool.is_full());
+
+    ASL_TEST_EXPECT(pool.get_ensure(a) == 6);
+    ASL_TEST_EXPECT(pool.get_ensure(b) == 7);
+
+    pool.release(a);
+    ASL_TEST_EXPECT(!pool.is_valid(a));
+    ASL_TEST_EXPECT(pool.is_valid(b));
+    ASL_TEST_EXPECT(!pool.is_full());
+    ASL_TEST_EXPECT(pool.get(a) == nullptr);
+    ASL_TEST_EXPECT(*pool.get(b) == 7);
+
+    const auto c = pool.acquire_ensure(8);
+
+    ASL_TEST_EXPECT(!pool.is_valid(a));
+    ASL_TEST_EXPECT(pool.is_valid(b));
+    ASL_TEST_EXPECT(pool.is_valid(c));
+    ASL_TEST_EXPECT(pool.is_full());
+
+    ASL_TEST_EXPECT(*pool.get(b) == 7);
+    ASL_TEST_EXPECT(*pool.get(c) == 8);
+    ASL_TEST_EXPECT(pool.get(a) == nullptr);
+}
+
+ASL_TEST(element_destructor)
+{
+    asl::DenseHandlePool<DestructorObserver, 8, 8> pool;
+    bool d[3]{};
+
+    const auto d0 = pool.acquire_ensure(&d[0]);
+    const auto d1 = pool.acquire_ensure(&d[1]);
+    const auto d2 = pool.acquire_ensure(&d[2]);
+
+    ASL_TEST_EXPECT(!d[0]);
+    ASL_TEST_EXPECT(!d[1]);
+    ASL_TEST_EXPECT(!d[2]);
+
+    pool.release(d1);
+    ASL_TEST_EXPECT(!d[0]);
+    ASL_TEST_EXPECT(d[1]);
+    ASL_TEST_EXPECT(!d[2]);
+
+    pool.release(d0);
+    ASL_TEST_EXPECT(d[0]);
+    ASL_TEST_EXPECT(d[1]);
+    ASL_TEST_EXPECT(!d[2]);
+
+    pool.release(d2);
+    ASL_TEST_EXPECT(d[0]);
+    ASL_TEST_EXPECT(d[1]);
+    ASL_TEST_EXPECT(d[2]);
+}
+
+ASL_TEST(destructor)
+{
+    bool d[3]{};
+
+    {
+        asl::DenseHandlePool<DestructorObserver, 8, 8> pool;
+
+        pool.acquire_ensure(&d[0]);
+        const auto d1 = pool.acquire_ensure(&d[1]);
+        pool.acquire_ensure(&d[2]);
+
+        ASL_TEST_EXPECT(!d[0]);
+        ASL_TEST_EXPECT(!d[1]);
+        ASL_TEST_EXPECT(!d[2]);
+
+        pool.release(d1);
+        ASL_TEST_EXPECT(!d[0]);
+        ASL_TEST_EXPECT(d[1]);
+        ASL_TEST_EXPECT(!d[2]);
+    }
+
+    ASL_TEST_EXPECT(d[0]);
+    ASL_TEST_EXPECT(d[1]);
+    ASL_TEST_EXPECT(d[2]);
+}
+
+enum Flags : uint8_t
+{
+    kFlag1 = 1,
+    kFlag2 = 2,
+};
+
+ASL_TEST(user_type)
+{
+    asl::DenseHandlePool<int, 8, 8, Flags> pool;
+
+    auto a = pool.acquire_ensure(kFlag2, 22);
+    auto b = pool.acquire_ensure(kFlag1, 11);
+
+    ASL_TEST_EXPECT(pool.get_ensure(a) == 22);
+    ASL_TEST_EXPECT(pool.get_ensure(b) == 11);
+
+    ASL_TEST_EXPECT(a.user() == kFlag2);
+    ASL_TEST_EXPECT(b.user() == kFlag1);
+}