Add FixedSizePoolResource PoC

src/utils/memory.cpp

@@ -2,6 +2,7 @@
 
 #include <algorithm>
 #include <cmath>
+#include <cstddef>
 #include <cstdint>
 #include <limits>
 #include <type_traits>
@@ -150,8 +151,9 @@ void *Pool::Allocate() {
     --chunk->blocks_available;
     return available_block;
   };
-  if (last_alloc_chunk_ && last_alloc_chunk_->blocks_available > 0U)
+  if (last_alloc_chunk_ && last_alloc_chunk_->blocks_available > 0U) {
     return allocate_block_from_chunk(last_alloc_chunk_);
+  }
   // Find a Chunk with available memory.
   for (auto &chunk : chunks_) {
     if (chunk.blocks_available > 0U) {
@@ -333,4 +335,141 @@ void PoolResource::Release() {
 
 // PoolResource END
 
+namespace impl {
+namespace {
+constexpr size_t kInitialChunkSize = 1;
+}  // namespace
+FixedSizePool::FixedSizePool(const size_t block_size, const size_t max_blocks_per_chunk_,
+                             utils::MemoryResource *upstream)
+    : block_size_{block_size},
+      max_blocks_per_chunk_{max_blocks_per_chunk_},
+      chunk_size_{kInitialChunkSize},
+      upstream_{upstream} {
+  internal_block_size_ = RoundUp(block_size, alignof(std::max_align_t));
+}
+
+void *FixedSizePool::Allocate() {
+  if (begin_ == end_) {
+    if (free_list_) {
+      Link *p = free_list_;
+      free_list_ = p->next;
+      return p;
+    }
+
+    Replenish();
+  }
+
+  auto *p = begin_;
+  begin_ += internal_block_size_;
+  return p;
+}
+
+void FixedSizePool::Deallocate(void *p) {
+  static_cast<Link *>(p)->next = free_list_;
+  free_list_ = static_cast<Link *>(p);
+}
+
+void FixedSizePool::Release() {
+  chunk_list_.Release(upstream_);
+
+  chunk_size_ = kInitialChunkSize;
+  begin_ = nullptr;
+  end_ = nullptr;
+  free_list_ = nullptr;
+}
+
+FixedSizePool::~FixedSizePool() { Release(); }
+
+void FixedSizePool::Replenish() {
+  begin_ = static_cast<std::byte *>(chunk_list_.Allocate(chunk_size_ * internal_block_size_, upstream_));
+  end_ = begin_ + chunk_size_ * internal_block_size_;
+
+  // TODO (antonio2368): Add more growth strategies
+  const auto next_chunk_size = chunk_size_ * 2;
+  if (next_chunk_size <= max_blocks_per_chunk_) {
+    chunk_size_ = next_chunk_size;
+  }
+}
+
+}  // namespace impl
+
+namespace {
+inline uint64_t CeilLog2(const uint64_t x) { return utils::Log2(x) + !utils::IsPow2(x); }
+}  // namespace
+
+FixedSizePoolResource::FixedSizePoolResource(const size_t max_blocks_per_chunk, const size_t max_block_size,
+                                             utils::MemoryResource *upstream)
+    : upstream_{upstream} {
+  max_block_size_ = min_block_size_;
+
+  num_pools_ = CeilLog2(max_block_size) - CeilLog2(min_block_size_) + 1;
+  MG_ASSERT(num_pools_ > 0, "Invalid max size of the block.");
+
+  auto allocator = Allocator<impl::FixedSizePool>(upstream_);
+  pools_ = allocator.allocate(num_pools_);
+
+  for (size_t i = 0; i < num_pools_; ++i) {
+    allocator.construct(pools_ + i, max_block_size_, max_blocks_per_chunk, upstream);
+    MG_ASSERT(max_block_size_ <= std::numeric_limits<size_t>::max() / 2);
+    max_block_size_ *= 2;
+  }
+
+  max_block_size_ /= 2;
+}
+
+void *FixedSizePoolResource::DoAllocate(const size_t bytes, const size_t alignment) {
+  MG_ASSERT(bytes > 0);
+  void *ret{nullptr};
+  if (bytes <= max_block_size_) {
+    auto *pool = FindPool(bytes);
+    ret = pool->Allocate();
+  } else {
+    // add to the list of allocated chunks
+    ret = large_blocks_.Allocate(bytes, upstream_);
+  }
+
+  return ret;
+}
+
+void FixedSizePoolResource::DoDeallocate(void *p, const size_t bytes, const size_t alignment) {
+  auto *pool = FindPool(bytes);
+
+  if (pool == nullptr) {
+    large_blocks_.Deallocate(p, upstream_);
+  } else {
+    pool->Deallocate(p);
+  }
+}
+
+impl::FixedSizePool *FixedSizePoolResource::FindPool(const size_t size) const {
+  if (size > max_block_size_) {
+    return nullptr;
+  }
+
+  auto *pool = pools_;
+  while (size > pool->BlockSize()) {
+    ++pool;
+  }
+
+  return pool;
+}
+
+void FixedSizePoolResource::Release() {
+  for (size_t i = 0; i < num_pools_; ++i) {
+    pools_[i].Release();
+  }
+
+  large_blocks_.Release(upstream_);
+}
+
+FixedSizePoolResource::~FixedSizePoolResource() {
+  Release();
+
+  for (size_t i = 0; i < num_pools_; ++i) {
+    pools_[i].~FixedSizePool();
+  }
+
+  upstream_->Deallocate(pools_, sizeof(impl::FixedSizePool) * num_pools_, alignof(impl::FixedSizePool));
+}
+
 }  // namespace utils

src/utils/memory.hpp

@@ -5,6 +5,7 @@
 #pragma once
 
 #include <cstddef>
+#include <list>
 #include <memory>
 #include <mutex>
 #include <new>
@@ -12,6 +13,9 @@
 #include <type_traits>
 #include <utility>
 #include <vector>
+#ifndef NDEBUG
+#include <iostream>
+#endif
 // Although <memory_resource> is in C++17, gcc libstdc++ still needs to
 // implement it fully. It should be available in the next major release
 // version, i.e. gcc 9.x.
@@ -552,4 +556,215 @@ class LimitedMemoryResource final : public utils::MemoryResource {
   bool DoIsEqual(const MemoryResource &other) const noexcept override { return this == &other; }
 };
 
+namespace impl {
+
+// https://stackoverflow.com/a/9194117
+// if y is power 2 we can do (x + y - 1) & ~(y - 1);
+// https://stackoverflow.com/a/14561794
+constexpr size_t RoundUp(const size_t x, const size_t y) {
+  MG_ASSERT(y >= 1);
+  return (x + y - 1) / y * y;
+}
+
+struct LinkedListNode {
+  LinkedListNode *next;
+  LinkedListNode *previous;
+};
+
+struct BlockLinkedListHeaderBase : public LinkedListNode {
+  size_t size;
+
+  using NodeType = LinkedListNode;
+};
+
+struct SingleLinkedListNode {
+  SingleLinkedListNode *next;
+};
+
+struct BlockSingleLinkedListHeaderBase : public SingleLinkedListNode {
+  size_t size;
+
+  using NodeType = SingleLinkedListNode;
+};
+
+template <typename T>
+concept BlockLinkedListHeader = std::is_base_of_v<BlockLinkedListHeaderBase, T>;
+
+template <typename T>
+concept BlockSingleLinkedListHeader = std::is_base_of_v<BlockSingleLinkedListHeaderBase, T>;
+
+template <typename T>
+concept BlockListHeader = BlockLinkedListHeader<T> || BlockSingleLinkedListHeader<T>;
+
+template <BlockListHeader THeader>
+class BlockList {
+  using NodeType = typename THeader::NodeType;
+
+ public:
+  static const size_t header_size = RoundUp(sizeof(THeader), alignof(std::max_align_t));
+
+  explicit BlockList() {
+    // create a circular linked list
+    list_.next = &list_;
+
+    if constexpr (BlockLinkedListHeader<THeader>) {
+      list_.previous = &list_;
+    }
+  }
+
+  void *Allocate(const size_t bytes, utils::MemoryResource *rsrc) {
+    if (bytes > static_cast<size_t>(-1) - header_size) {
+      throw utils::BadAlloc("Requested too many bytes to allocate");
+    }
+
+    void *p = rsrc->Allocate(bytes + header_size);
+    auto *node = new (p) THeader;
+    node->size = bytes + header_size;
+
+    auto *next = list_.next;
+    node->next = next;
+    list_.next = node;
+
+    if constexpr (BlockLinkedListHeader<THeader>) {
+      node->previous = &list_;
+      next->previous = node;
+    }
+
+    return static_cast<std::byte *>(p) + header_size;
+  }
+
+  template <typename T = THeader>
+  requires BlockLinkedListHeader<T> void Deallocate(void *p, utils::MemoryResource *rsrc) {
+    auto *header = static_cast<THeader *>(static_cast<void *>(static_cast<std::byte *>(p) - header_size));
+    auto *next = header->next;
+    auto *previous = header->previous;
+    previous->next = next;
+    next->previous = previous;
+
+    const size_t size = header->size;
+    header->~THeader();
+    rsrc->Deallocate(header, size, alignof(std::max_align_t));
+  }
+
+  void Release(utils::MemoryResource *rsrc) {
+    NodeType *node = list_.next;
+    while (node != &list_) {
+      auto *header = static_cast<THeader *>(node);
+      node = node->next;
+      const size_t size = header->size;
+      header->~THeader();
+      rsrc->Deallocate(header, size, alignof(std::max_align_t));
+    }
+
+    // create a circular linked list
+    list_.next = &list_;
+
+    if constexpr (BlockLinkedListHeader<THeader>) {
+      list_.previous = &list_;
+    }
+  }
+
+ private:
+  NodeType list_;
+};
+
+// https://github.com/bloomberg/bde/blob/master/groups/bdl/bdlma/bdlma_pool.h
+class FixedSizePool final {
+ public:
+  FixedSizePool(size_t block_size, size_t max_blocks_per_chunk, utils::MemoryResource *upstream);
+
+  FixedSizePool(const FixedSizePool &) = delete;
+  FixedSizePool &operator=(const FixedSizePool &) = delete;
+
+  FixedSizePool(FixedSizePool &&) = default;
+  FixedSizePool &operator=(FixedSizePool &&) = default;
+
+  void *Allocate();
+  void Deallocate(void *p);
+
+  void Release();
+
+  auto BlockSize() const { return block_size_; }
+
+  ~FixedSizePool();
+
+ private:
+  struct Link {
+    Link *next;
+  };
+
+  std::byte *begin_{nullptr};
+  std::byte *end_{nullptr};
+
+  Link *free_list_{nullptr};
+
+  size_t internal_block_size_;
+  size_t block_size_;
+  size_t max_blocks_per_chunk_;
+  size_t chunk_size_;
+
+  BlockList<BlockSingleLinkedListHeaderBase> chunk_list_;
+
+  utils::MemoryResource *upstream_;
+
+  void Replenish();
+};
+}  // namespace impl
+
+// https://github.com/bloomberg/bde/blob/master/groups/bdl/bdlma/bdlma_multipool.h
+class FixedSizePoolResource : public MemoryResource {
+ public:
+  explicit FixedSizePoolResource(size_t max_blocks_per_chunk, size_t max_block_size,
+                                 utils::MemoryResource *upstream = utils::NewDeleteResource());
+
+  void Release();
+
+  FixedSizePoolResource(const FixedSizePoolResource &) = delete;
+  FixedSizePoolResource &operator=(const FixedSizePoolResource &) = delete;
+
+  FixedSizePoolResource(FixedSizePoolResource &&) = default;
+  FixedSizePoolResource &operator=(FixedSizePoolResource &&) = default;
+
+  ~FixedSizePoolResource() override;
+
+ private:
+  impl::FixedSizePool *FindPool(size_t size) const;
+
+  void *DoAllocate(size_t bytes, size_t alignment) override;
+  void DoDeallocate(void *p, size_t bytes, size_t alignment) override;
+
+  bool DoIsEqual(const MemoryResource &other) const noexcept override { return this == &other; }
+
+  impl::FixedSizePool *pools_{nullptr};
+  size_t max_block_size_;
+  size_t min_block_size_{8};
+  size_t num_pools_{0};
+
+  impl::BlockList<impl::BlockLinkedListHeaderBase> large_blocks_;
+
+  utils::MemoryResource *upstream_;
+};
+
+#ifndef NDEBUG
+class PrintMemoryResource : public MemoryResource {
+ public:
+  explicit PrintMemoryResource(utils::MemoryResource *memory) : memory_(memory) {}
+
+ private:
+  void *DoAllocate(size_t bytes, size_t alignment) override {
+    std::cout << "Allocating " << bytes << std::endl;
+    return memory_->Allocate(bytes, alignment);
+  }
+
+  void DoDeallocate(void *p, size_t bytes, size_t alignment) override {
+    std::cout << "Deallocating " << bytes << std::endl;
+    return memory_->Deallocate(p, bytes, alignment);
+  }
+
+  bool DoIsEqual(const utils::MemoryResource &other) const noexcept override { return memory_->IsEqual(other); }
+
+  utils::MemoryResource *memory_;
+};
+#endif
+
 }  // namespace utils