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