Added custom allocator for subsonic responses

2024-03-19 09:08:43 +01:00
parent 5bfd31ff8a
commit 78384d5d3f
8 changed files with 324 additions and 26 deletions
@@ -0,0 +1,103 @@
+/*
+ * Copyright (C) 2024 Emeric Poupon
+ *
+ * This file is part of LMS.
+ *
+ * LMS is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * LMS is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with LMS.  If not, see <http://www.gnu.org/licenses/>.
+ */
+#pragma once
+
+#include <cassert>
+#include <cstddef>
+#include <cstdint>
+#include <array>
+#include <list>
+
+namespace lms::api::subsonic
+{
+    class TLSMonotonicMemoryResource
+    {
+    public:
+        static TLSMonotonicMemoryResource& getInstance()
+        {
+            static thread_local TLSMonotonicMemoryResource instance;
+            return instance;
+        }
+
+        TLSMonotonicMemoryResource()
+        {
+            allocateNewBlock();
+        }
+
+        [[nodiscard]] std::byte* allocate(std::size_t byteCount, std::size_t alignment)
+        {
+            std::byte* currentAddrAligned{ computeAlignedAddr(_currentAddr, alignment) };
+
+            if (currentAddrAligned + byteCount > &_currentBlock->back() + 1)
+            {
+                allocateNewBlock();
+                currentAddrAligned = computeAlignedAddr(_currentAddr, alignment);
+            }
+
+            // Requested too many bytes for blockSize!
+            if (currentAddrAligned + byteCount > &_currentBlock->back() + 1)
+                throw std::bad_alloc{};
+
+            assert(currentAddrAligned >= &_currentBlock->front());
+            
+            std::byte* res{ currentAddrAligned };
+            _currentAddr = currentAddrAligned + byteCount;
+
+            return res;
+        }
+
+        void deallocate(std::byte*)
+        {
+            // nothing to do!
+        }
+
+        void reset()
+        {
+            // always keep at least one block
+            if (_blocks.size() > 1)
+                _blocks.erase(std::next(std::cbegin(_blocks), 1), std::cend(_blocks));
+
+            _currentBlock = &_blocks.front();
+            _currentAddr = _currentBlock->data();
+        }
+
+    private:
+        void allocateNewBlock()
+        {
+            _currentBlock = &_blocks.emplace_back();
+            _currentAddr = _currentBlock->data();
+        }
+
+        static std::byte* computeAlignedAddr(std::byte* addr, std::size_t alignment) noexcept
+        {
+            const std::uintptr_t addrValue{ reinterpret_cast<std::uintptr_t>(addr) };
+
+            const std::uintptr_t mask{ alignment - 1 };
+            const std::uintptr_t adjustment{ (alignment - (addrValue & mask)) & mask };
+            return reinterpret_cast<std::byte*>(addr + adjustment);
+        }
+
+        static constexpr std::size_t blockSize{ static_cast<std::size_t>(1 * 1024 * 1024) };
+        using BlockType = std::array<std::byte, blockSize>;
+
+        std::list<BlockType> _blocks;
+        BlockType* _currentBlock{};
+        std::byte* _currentAddr{};
+    };
+}