// Copyright 2021 The gRPC Authors // // Licensed under the Apache License, Version 2.0 (the "License"); // you may not use this file except in compliance with the License. // You may obtain a copy of the License at // // http://www.apache.org/licenses/LICENSE-2.0 // // Unless required by applicable law or agreed to in writing, software // distributed under the License is distributed on an "AS IS" BASIS, // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. // See the License for the specific language governing permissions and // limitations under the License. #ifndef GRPC_EVENT_ENGINE_MEMORY_ALLOCATOR_H #define GRPC_EVENT_ENGINE_MEMORY_ALLOCATOR_H #include <grpc/impl/codegen/port_platform.h> #include <stdlib.h> // for abort() #include <algorithm> #include <memory> #include <type_traits> #include <vector> #include <grpc/event_engine/internal/memory_allocator_impl.h> #include <grpc/slice.h> // forward-declaring an internal struct, not used publicly. struct grpc_slice_buffer; namespace grpc_event_engine { namespace experimental { // TODO(nnoble): needs implementation class SliceBuffer { public: SliceBuffer() { abort(); } explicit SliceBuffer(grpc_slice_buffer*) { abort(); } grpc_slice_buffer* RawSliceBuffer() { return slice_buffer_; } private: grpc_slice_buffer* slice_buffer_; }; // Tracks memory allocated by one system. // Is effectively a thin wrapper/smart pointer for a MemoryAllocatorImpl, // providing a convenient and stable API. class MemoryAllocator { public: /// Construct a MemoryAllocator given an internal::MemoryAllocatorImpl /// implementation. The constructed MemoryAllocator will call /// MemoryAllocatorImpl::Shutdown() upon destruction. explicit MemoryAllocator( std::shared_ptr<internal::MemoryAllocatorImpl> allocator) : allocator_(std::move(allocator)) {} // Construct an invalid MemoryAllocator. MemoryAllocator() : allocator_(nullptr) {} ~MemoryAllocator() { if (allocator_ != nullptr) allocator_->Shutdown(); } MemoryAllocator(const MemoryAllocator&) = delete; MemoryAllocator& operator=(const MemoryAllocator&) = delete; MemoryAllocator(MemoryAllocator&&) = default; MemoryAllocator& operator=(MemoryAllocator&&) = default; /// Drop the underlying allocator and make this an empty object. /// The object will not be usable after this call unless it's a valid /// allocator is moved into it. void Reset() { if (allocator_ != nullptr) allocator_->Shutdown(); allocator_.reset(); } /// Reserve bytes from the quota. /// If we enter overcommit, reclamation will begin concurrently. /// Returns the number of bytes reserved. size_t Reserve(MemoryRequest request) { return allocator_->Reserve(request); } /// Release some bytes that were previously reserved. void Release(size_t n) { return allocator_->Release(n); } // // The remainder of this type are helper functions implemented in terms of // Reserve/Release. // /// An automatic releasing reservation of memory. class Reservation { public: Reservation() = default; Reservation(const Reservation&) = delete; Reservation& operator=(const Reservation&) = delete; Reservation(Reservation&&) = default; Reservation& operator=(Reservation&&) = default; ~Reservation() { if (allocator_ != nullptr) allocator_->Release(size_); } private: friend class MemoryAllocator; Reservation(std::shared_ptr<internal::MemoryAllocatorImpl> allocator, size_t size) : allocator_(std::move(allocator)), size_(size) {} std::shared_ptr<internal::MemoryAllocatorImpl> allocator_; size_t size_ = 0; }; /// Reserve bytes from the quota and automatically release them when /// Reservation is destroyed. Reservation MakeReservation(MemoryRequest request) { return Reservation(allocator_, Reserve(request)); } /// Allocate a new object of type T, with constructor arguments. /// The returned type is wrapped, and upon destruction the reserved memory /// will be released to the allocator automatically. As such, T must have a /// virtual destructor so we can insert the necessary hook. template <typename T, typename... Args> typename std::enable_if<std::has_virtual_destructor<T>::value, T*>::type New( Args&&... args) { // Wrap T such that when it's destroyed, we can release memory back to the // allocator. class Wrapper final : public T { public: explicit Wrapper(std::shared_ptr<internal::MemoryAllocatorImpl> allocator, Args&&... args) : T(std::forward<Args>(args)...), allocator_(std::move(allocator)) {} ~Wrapper() override { allocator_->Release(sizeof(*this)); } private: const std::shared_ptr<internal::MemoryAllocatorImpl> allocator_; }; Reserve(sizeof(Wrapper)); return new Wrapper(allocator_, std::forward<Args>(args)...); } /// Construct a unique_ptr immediately. template <typename T, typename... Args> std::unique_ptr<T> MakeUnique(Args&&... args) { return std::unique_ptr<T>(New<T>(std::forward<Args>(args)...)); } /// Allocate a slice, using MemoryRequest to size the number of returned /// bytes. For a variable length request, check the returned slice length to /// verify how much memory was allocated. Takes care of reserving memory for /// any relevant control structures also. grpc_slice MakeSlice(MemoryRequest request); /// A C++ allocator for containers of T. template <typename T> class Container { public: using value_type = T; /// Construct the allocator: \a underlying_allocator is borrowed, and must /// outlive this object. explicit Container(MemoryAllocator* underlying_allocator) : underlying_allocator_(underlying_allocator) {} template <typename U> explicit Container(const Container<U>& other) : underlying_allocator_(other.underlying_allocator()) {} MemoryAllocator* underlying_allocator() const { return underlying_allocator_; } T* allocate(size_t n) { underlying_allocator_->Reserve(n * sizeof(T)); return static_cast<T*>(::operator new(n * sizeof(T))); } void deallocate(T* p, size_t n) { ::operator delete(p); underlying_allocator_->Release(n * sizeof(T)); } private: MemoryAllocator* underlying_allocator_; }; protected: /// Return a pointer to the underlying implementation. /// Note that the interface of said implementation is unstable and likely to /// change at any time. internal::MemoryAllocatorImpl* get_internal_impl_ptr() { return allocator_.get(); } const internal::MemoryAllocatorImpl* get_internal_impl_ptr() const { return allocator_.get(); } private: std::shared_ptr<internal::MemoryAllocatorImpl> allocator_; }; // Wrapper type around std::vector to make initialization against a // MemoryAllocator based container allocator easy. template <typename T> class Vector : public std::vector<T, MemoryAllocator::Container<T>> { public: explicit Vector(MemoryAllocator* allocator) : std::vector<T, MemoryAllocator::Container<T>>( MemoryAllocator::Container<T>(allocator)) {} }; class MemoryAllocatorFactory { public: virtual ~MemoryAllocatorFactory() = default; /// On Endpoint creation, call \a CreateMemoryAllocator to create a new /// allocator for the endpoint. /// \a name is used to label the memory allocator in debug logs. /// Typically we'll want to: /// auto allocator = factory->CreateMemoryAllocator(peer_address_string); /// auto* endpoint = allocator->New<MyEndpoint>(std::move(allocator), ...); virtual MemoryAllocator CreateMemoryAllocator(absl::string_view name) = 0; }; } // namespace experimental } // namespace grpc_event_engine #endif // GRPC_EVENT_ENGINE_MEMORY_ALLOCATOR_H