Optimize memory_resource & add monotonic_buffer_resource

Author: mutouyun

include/libipc/mem/allocator.h

@@ -15,11 +15,37 @@
 #include "libipc/imp/export.h"
 #include "libipc/imp/uninitialized.h"
 #include "libipc/imp/byte.h"
-#include "libipc/mem/memory_resource.h"
 
 namespace ipc {
 namespace mem {
 
+/// \brief Helper trait for memory resource.
+
+template <typename T, typename = void>
+struct has_allocate : std::false_type {};
+
+template <typename T>
+struct has_allocate<T, 
+  typename std::enable_if<std::is_convertible<
+  decltype(std::declval<T &>().allocate(std::declval<std::size_t>(), 
+                                        std::declval<std::size_t>())), void *
+  >::value>::type> : std::true_type {};
+
+template <typename T, typename = void>
+struct has_deallocate : std::false_type {};
+
+template <typename T>
+struct has_deallocate<T, 
+  decltype(std::declval<T &>().deallocate(std::declval<void *>(), 
+                                          std::declval<std::size_t>(), 
+                                          std::declval<std::size_t>()))
+  > : std::true_type {};
+
+template <typename T>
+using is_memory_resource = 
+  std::enable_if_t<has_allocate  <T>::value && 
+                   has_deallocate<T>::value, bool>;
+
 /**
  * \brief An allocator which exhibits different allocation behavior 
  *        depending upon the memory resource from which it is constructed.
@@ -57,7 +83,7 @@ class LIBIPC_EXPORT allocator {
     holder_mr(MR *p_mr) noexcept
       : res_(p_mr) {}
 
-    // [MSVC] error C2259: 'pmr::allocator::holder_mr<void *,bool>': cannot instantiate abstract class.
+    // [MSVC] error C2259: 'allocator::holder_mr<void *,bool>': cannot instantiate abstract class.
     void *alloc(std::size_t s, std::size_t a) const override { return nullptr; }
     void dealloc(void *p, std::size_t s, std::size_t a) const override {}
   };
@@ -67,7 +93,7 @@ class LIBIPC_EXPORT allocator {
    * \tparam MR memory resource type
    */
   template <typename MR>
-  class holder_mr<MR, verify_memory_resource<MR>> : public holder_mr<MR, void> {
+  class holder_mr<MR, is_memory_resource<MR>> : public holder_mr<MR, void> {
     using base_t = holder_mr<MR, void>;
 
   public:
@@ -89,6 +115,8 @@ class LIBIPC_EXPORT allocator {
   holder_mr_base &      get_holder() noexcept;
   holder_mr_base const &get_holder() const noexcept;
 
+  void init_default_resource() noexcept;
+
 public:
   /// \brief Constructs an `allocator` using the return value of 
   ///       `new_delete_resource::get()` as the underlying memory resource.
@@ -103,13 +131,13 @@ class LIBIPC_EXPORT allocator {
 
   /// \brief Constructs a allocator from a memory resource pointer.
   /// \note The lifetime of the pointer must be longer than that of allocator.
-  template <typename T, verify_memory_resource<T> = true>
+  template <typename T, is_memory_resource<T> = true>
   allocator(T *p_mr) noexcept {
     if (p_mr == nullptr) {
-      ipc::construct<holder_mr<new_delete_resource>>(holder_.data(), new_delete_resource::get());
+      init_default_resource();
       return;
     }
-    ipc::construct<holder_mr<T>>(holder_.data(), p_mr);
+    std::ignore = ipc::construct<holder_mr<T>>(holder_.data(), p_mr);
   }
 
   void swap(allocator &other) noexcept;

include/libipc/mem/memory_resource.h

@@ -1,46 +1,21 @@
 /**
  * \file libipc/memory_resource.h
  * \author mutouyun ([email protected])
- * \brief Implement memory allocation strategies that can be used by pmr::allocator.
+ * \brief Implement memory allocation strategies that can be used by ipc::mem::allocator.
  */
 #pragma once
 
 #include <type_traits>
 #include <cstddef>  // std::size_t, std::max_align_t
 
 #include "libipc/imp/export.h"
-#include "libipc/def.h"
+#include "libipc/imp/span.h"
+#include "libipc/imp/byte.h"
+#include "libipc/mem/allocator.h"
 
 namespace ipc {
 namespace mem {
 
-/// \brief Helper trait for memory resource.
-
-template <typename T, typename = void>
-struct has_allocate : std::false_type {};
-
-template <typename T>
-struct has_allocate<T, 
-  typename std::enable_if<std::is_convertible<
-  decltype(std::declval<T &>().allocate(std::declval<std::size_t>(), 
-                                        std::declval<std::size_t>())), void *
-  >::value>::type> : std::true_type {};
-
-template <typename T, typename = void>
-struct has_deallocate : std::false_type {};
-
-template <typename T>
-struct has_deallocate<T, 
-  decltype(std::declval<T &>().deallocate(std::declval<void *>(), 
-                                          std::declval<std::size_t>(), 
-                                          std::declval<std::size_t>()))
-  > : std::true_type {};
-
-template <typename T>
-using verify_memory_resource = 
-  std::enable_if_t<has_allocate  <T>::value && 
-                   has_deallocate<T>::value, bool>;
-
 /**
  * \class LIBIPC_EXPORT new_delete_resource
  * \brief A memory resource that uses the 
@@ -62,5 +37,47 @@ class LIBIPC_EXPORT new_delete_resource {
   void deallocate(void *p, std::size_t bytes, std::size_t alignment = alignof(std::max_align_t)) noexcept;
 };
 
+/**
+ * \class LIBIPC_EXPORT monotonic_buffer_resource
+ * \brief A special-purpose memory resource class 
+ *        that releases the allocated memory only when the resource is destroyed.
+ * \see https://en.cppreference.com/w/cpp/memory/monotonic_buffer_resource
+ */
+class LIBIPC_EXPORT monotonic_buffer_resource {
+
+  allocator upstream_;
+
+  struct node {
+    node *next;
+    std::size_t size;
+  } *free_list_;
+
+  ipc::byte * head_;
+  ipc::byte * tail_;
+  std::size_t next_size_;
+
+  ipc::byte * const initial_buffer_;
+  std::size_t const initial_size_;
+
+public:
+  monotonic_buffer_resource() noexcept;
+  explicit monotonic_buffer_resource(allocator upstream) noexcept;
+  explicit monotonic_buffer_resource(std::size_t initial_size) noexcept;
+  monotonic_buffer_resource(std::size_t initial_size, allocator upstream) noexcept;
+  monotonic_buffer_resource(ipc::span<ipc::byte> buffer) noexcept;
+  monotonic_buffer_resource(ipc::span<ipc::byte> buffer, allocator upstream) noexcept;
+
+  ~monotonic_buffer_resource() noexcept;
+
+  monotonic_buffer_resource(monotonic_buffer_resource const &) = delete;
+  monotonic_buffer_resource &operator=(monotonic_buffer_resource const &) = delete;
+
+  allocator upstream_resource() const noexcept;
+  void release() noexcept;
+
+  void *allocate(std::size_t bytes, std::size_t alignment = alignof(std::max_align_t)) noexcept;
+  void deallocate(void *p, std::size_t bytes, std::size_t alignment = alignof(std::max_align_t)) noexcept;
+};
+
 } // namespace mem
 } // namespace ipc

src/libipc/mem/allocator.cpp

@@ -3,6 +3,7 @@
 
 #include "libipc/imp/log.h"
 #include "libipc/mem/allocator.h"
+#include "libipc/mem/memory_resource.h"
 
 namespace ipc {
 namespace mem {
@@ -15,6 +16,10 @@ allocator::holder_mr_base const &allocator::get_holder() const noexcept {
   return *reinterpret_cast<holder_mr_base const *>(holder_.data());
 }
 
+void allocator::init_default_resource() noexcept {
+  std::ignore = ipc::construct<holder_mr<new_delete_resource>>(holder_.data(), new_delete_resource::get());
+}
+
 allocator::allocator() noexcept
   : allocator(new_delete_resource::get()) {}
 

src/libipc/mem/monotonic_buffer_resource.cpp

@@ -0,0 +1,140 @@
+
+#include <utility>
+#include <memory>
+#include <algorithm>
+
+#include "libipc/imp/log.h"
+#include "libipc/imp/aligned.h"
+#include "libipc/imp/detect_plat.h"
+#include "libipc/mem/memory_resource.h"
+
+namespace ipc {
+namespace mem {
+namespace {
+
+template <typename Node>
+Node *make_node(allocator const &upstream, std::size_t initial_size, std::size_t alignment) noexcept {
+  LIBIPC_LOG();
+  auto sz = ipc::round_up(sizeof(Node), alignment) + initial_size;
+  LIBIPC_TRY {
+    auto *node = static_cast<Node *>(upstream.allocate(sz));
+    if (node == nullptr) {
+      log.error("failed: allocate memory for `monotonic_buffer_resource`'s node.", 
+                " bytes = ", initial_size, ", alignment = ", alignment);
+      return nullptr;
+    }
+    node->next = nullptr;
+    node->size = sz;
+    return node;
+  } LIBIPC_CATCH(...) {
+    log.error("failed: allocate memory for `monotonic_buffer_resource`'s node.", 
+              " bytes = ", initial_size, ", alignment = ", alignment,
+              "\n\texception: ", ipc::log::exception_string(std::current_exception()));
+    return nullptr;
+  }
+}
+
+std::size_t next_buffer_size(std::size_t size) noexcept {
+  return size * 3 / 2;
+}
+
+} // namespace
+
+monotonic_buffer_resource::monotonic_buffer_resource() noexcept
+  : monotonic_buffer_resource(allocator{}) {}
+
+monotonic_buffer_resource::monotonic_buffer_resource(allocator upstream) noexcept
+  : monotonic_buffer_resource(0, std::move(upstream)) {}
+
+monotonic_buffer_resource::monotonic_buffer_resource(std::size_t initial_size) noexcept
+  : monotonic_buffer_resource(initial_size, allocator{}) {}
+
+monotonic_buffer_resource::monotonic_buffer_resource(std::size_t initial_size, allocator upstream) noexcept
+  : upstream_      (std::move(upstream))
+  , free_list_     (nullptr)
+  , head_          (nullptr)
+  , tail_          (nullptr)
+  , next_size_     (initial_size)
+  , initial_buffer_(nullptr)
+  , initial_size_  (initial_size) {}
+
+monotonic_buffer_resource::monotonic_buffer_resource(ipc::span<ipc::byte> buffer) noexcept
+  : monotonic_buffer_resource(buffer, allocator{}) {}
+
+monotonic_buffer_resource::monotonic_buffer_resource(ipc::span<ipc::byte> buffer, allocator upstream) noexcept
+  : upstream_      (std::move(upstream))
+  , free_list_     (nullptr)
+  , head_          (buffer.begin())
+  , tail_          (buffer.end())
+  , next_size_     (next_buffer_size(buffer.size()))
+  , initial_buffer_(buffer.begin())
+  , initial_size_  (buffer.size()) {}
+
+monotonic_buffer_resource::~monotonic_buffer_resource() noexcept {
+  release();
+}
+
+allocator monotonic_buffer_resource::upstream_resource() const noexcept {
+  return upstream_;
+}
+
+void monotonic_buffer_resource::release() noexcept {
+  LIBIPC_LOG();
+  LIBIPC_TRY {
+    while (free_list_ != nullptr) {
+      auto *next = free_list_->next;
+      upstream_.deallocate(free_list_, free_list_->size);
+      free_list_ = next;
+    }
+  } LIBIPC_CATCH(...) {
+    log.error("failed: deallocate memory for `monotonic_buffer_resource`.",
+              "\n\texception: ", ipc::log::exception_string(std::current_exception()));
+  }
+  // reset to initial state at contruction
+  if ((head_ = initial_buffer_) != nullptr) {
+    tail_ = head_ + initial_size_;
+    next_size_ = next_buffer_size(initial_size_);
+  } else {
+    tail_ = nullptr;
+    next_size_ = initial_size_;
+  }
+}
+
+void *monotonic_buffer_resource::allocate(std::size_t bytes, std::size_t alignment) noexcept {
+  LIBIPC_LOG();
+  if (bytes == 0) {
+    log.error("failed: allocate bytes = 0.");
+    return nullptr;
+  }
+  void *p = head_;
+  auto  s = static_cast<std::size_t>(tail_ - head_);
+  if (std::align(alignment, bytes, p, s) == nullptr) {
+    next_size_ = (std::max)(next_size_, bytes);
+    auto *node = make_node<monotonic_buffer_resource::node>(upstream_, next_size_, alignment);
+    if (node == nullptr) return nullptr;
+    node->next = free_list_;
+    free_list_ = node;
+    next_size_ = next_buffer_size(next_size_);
+    // try again
+    s = node->size - sizeof(monotonic_buffer_resource::node);
+    p = std::align(alignment, bytes, (p = node + 1), s);
+    if (p == nullptr) {
+      log.error("failed: allocate memory for `monotonic_buffer_resource`.", 
+                " bytes = ", bytes, ", alignment = ", alignment);
+      return nullptr;
+    }
+    tail_ = static_cast<ipc::byte *>(p) + s;
+  }
+  head_ = static_cast<ipc::byte *>(p) + bytes;
+  return p;
+}
+
+void monotonic_buffer_resource::deallocate(void *p, std::size_t bytes, std::size_t alignment) noexcept {
+  static_cast<void>(p);
+  static_cast<void>(bytes);
+  static_cast<void>(alignment);
+  // Do nothing.
+}
+
+} // namespace mem
+} // namespace ipc

src/libipc/mem/memory_resource.cpp renamed to src/libipc/mem/new_delete_resource.cpp

@@ -4,7 +4,12 @@
 
 #include "test.h"
 
+#if defined(LIBIPC_CPP_17) && defined(__cpp_lib_memory_resource)
+# include <memory_resource>
+#endif
+
 #include "libipc/mem/allocator.h"
+#include "libipc/mem/memory_resource.h"
 
 TEST(allocator, construct) {
   ipc::mem::allocator alc;
@@ -32,6 +37,26 @@ class dummy_resource {
 
 } // namespace
 
+TEST(allocator, memory_resource_traits) {
+  EXPECT_FALSE(ipc::mem::has_allocate<void>::value);
+  EXPECT_FALSE(ipc::mem::has_allocate<int>::value);
+  EXPECT_FALSE(ipc::mem::has_allocate<std::vector<int>>::value);
+  EXPECT_FALSE(ipc::mem::has_allocate<std::allocator<int>>::value);
+#if defined(LIBIMP_CPP_17) && defined(__cpp_lib_memory_resource)
+  EXPECT_TRUE (ipc::mem::has_allocate<std::ipc::mem::memory_resource>::value);
+  EXPECT_TRUE (ipc::mem::has_allocate<std::ipc::mem::polymorphic_allocator<int>>::value);
+#endif
+
+  EXPECT_FALSE(ipc::mem::has_deallocate<void>::value);
+  EXPECT_FALSE(ipc::mem::has_deallocate<int>::value);
+  EXPECT_FALSE(ipc::mem::has_deallocate<std::vector<int>>::value);
+  EXPECT_FALSE(ipc::mem::has_deallocate<std::allocator<int>>::value);
+#if defined(LIBIMP_CPP_17) && defined(__cpp_lib_memory_resource)
+  EXPECT_TRUE (ipc::mem::has_deallocate<std::ipc::mem::memory_resource>::value);
+  EXPECT_FALSE(ipc::mem::has_deallocate<std::ipc::mem::polymorphic_allocator<int>>::value);
+#endif
+}
+
 TEST(allocator, construct_copy_move) {
   ipc::mem::new_delete_resource mem_res;
   dummy_resource dummy_res;