components/nvs_flash/src/nvs_memory_management.hpp (ESP-IDF)

/* * SPDX-FileCopyrightText: 2022-2024 Espressif Systems (Shanghai) CO LTD * * SPDX-License-Identifier: Apache-2.0 */ #include <cstdlib> #include "esp_heap_caps.h" #pragma once /** * @brief Type that is only usable with new (std::nothrow) to avoid exceptions. * * This struct shall be inherited by all types in NVS that may be allocated dynamically (with new). * * NVS allocates memory at runtime. Because we use C++, we need to avoid the global ``operator new`` from libstdc++, * since it throws exceptions and we compile NVS with ``-fno-exceptions``. We also need to avoid the global * non-throwing version of that operator from libstdc++, since it is merely a wrapper around the original operator * catching all exceptions. * * This struct removes the normal operator new from this and all types inheriting from it. It furthermore provides * a custom version of operator new (..., const std::nothrow_t&) noexcept that will not use C++ exceptions. * * E.g., if you have a type MyType inheriting from ExceptionlessAllocatable, you want to use it as follows: * @code{c++} * MyType : public ExceptionlessAllocatable { * ExceptionlessAllocatable(); * ExceptionlessAllocatable(int param); * }; * // ... * MyType *m0 = new (std::nothrow) MyType; * MyType *m1 = new (std::nothrow) MyType(47); * // ... * delete m1; * delete m0; * @endcode */ struct ExceptionlessAllocatable { /** * Disallow use of the default new operator, all of NVS is currently tailored to not throw exceptions */ static void *operator new( std::size_t ) = delete; static void *operator new[]( std::size_t ) = delete; /** * Simple implementation with malloc(). No exceptions are thrown if the allocation fails. * To use this operator, your type must inherit from this class and then allocate with: * @code{c} * new (std::nothrow) <YourType>; // default constructor * new (std::nothrow) <YourType>(<constructor parameters>); // non-default constructor * @endcode */ void *operator new (size_t size, const std::nothrow_t&) noexcept { #ifdef CONFIG_NVS_ALLOCATE_CACHE_IN_SPIRAM return heap_caps_malloc_prefer(size, 2, MALLOC_CAP_DEFAULT | MALLOC_CAP_SPIRAM, MALLOC_CAP_DEFAULT | MALLOC_CAP_INTERNAL); #else return std::malloc(size); #endif } void *operator new [](size_t size, const std::nothrow_t&) noexcept { #ifdef CONFIG_NVS_ALLOCATE_CACHE_IN_SPIRAM return heap_caps_malloc_prefer(size, 2, MALLOC_CAP_DEFAULT | MALLOC_CAP_SPIRAM, MALLOC_CAP_DEFAULT | MALLOC_CAP_INTERNAL); #else return std::malloc(size); #endif } /** * Use \c delete as normal. This operator will be called automatically instead of the global one from libstdc++. */ void operator delete (void *obj) noexcept { #ifdef CONFIG_NVS_ALLOCATE_CACHE_IN_SPIRAM return heap_caps_free(obj); #else return std::free(obj); #endif } void operator delete [](void *obj) noexcept { #ifdef CONFIG_NVS_ALLOCATE_CACHE_IN_SPIRAM return heap_caps_free(obj); #else return std::free(obj); #endif } };