diff options
author | Jacques Lucke <jacques@blender.org> | 2020-07-06 10:08:53 +0300 |
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committer | Jacques Lucke <jacques@blender.org> | 2020-07-06 10:08:53 +0300 |
commit | 572c48cf98601c66eebec27bb40cfc7e05ea341c (patch) | |
tree | ff2c056d119a6af0fae7c4d5cdef674eb969f0ae /source/blender/blenlib/BLI_memory_utils.hh | |
parent | 703a73fa846531a0888c8f99489c8e213f5c5d81 (diff) |
BLI: improve exception safety of memory utils
Even if we do not use exception in many places in Blender, our core C++ library
should become exception safe. Otherwise, we don't even have the option
to work with exceptions if we decide to do so.
Diffstat (limited to 'source/blender/blenlib/BLI_memory_utils.hh')
-rw-r--r-- | source/blender/blenlib/BLI_memory_utils.hh | 100 |
1 files changed, 79 insertions, 21 deletions
diff --git a/source/blender/blenlib/BLI_memory_utils.hh b/source/blender/blenlib/BLI_memory_utils.hh index 1c0193e2756..4e7234b85fb 100644 --- a/source/blender/blenlib/BLI_memory_utils.hh +++ b/source/blender/blenlib/BLI_memory_utils.hh @@ -19,6 +19,9 @@ /** \file * \ingroup bli + * Some of the functions below have very similar alternatives in the standard library. However, it + * is rather annoying to use those when debugging. Therefore, some more specialized and easier to + * debug functions are provided here. */ #include <memory> @@ -29,52 +32,68 @@ namespace blender { /** - * Call the default constructor on n consecutive elements. For trivially constructible types, this - * does nothing. + * Call the destructor on n consecutive values. For trivially destructible types, this does + * nothing. + * + * Exception Safety: Destructors shouldn't throw exceptions. * * Before: - * ptr: uninitialized - * After: * ptr: initialized + * After: + * ptr: uninitialized */ -template<typename T> void default_construct_n(T *ptr, uint n) +template<typename T> void destruct_n(T *ptr, uint n) { + static_assert(std::is_nothrow_destructible_v<T>, + "This should be true for all types. Destructors are noexcept by default."); + /* This is not strictly necessary, because the loop below will be optimized away anyway. It is * nice to make behavior this explicitly, though. */ - if (std::is_trivially_constructible<T>::value) { + if (std::is_trivially_destructible<T>::value) { return; } for (uint i = 0; i < n; i++) { - new ((void *)(ptr + i)) T; + ptr[i].~T(); } } /** - * Call the destructor on n consecutive values. For trivially destructible types, this does - * nothing. + * Call the default constructor on n consecutive elements. For trivially constructible types, this + * does nothing. + * + * Exception Safety: Strong. * * Before: - * ptr: initialized - * After: * ptr: uninitialized + * After: + * ptr: initialized */ -template<typename T> void destruct_n(T *ptr, uint n) +template<typename T> void default_construct_n(T *ptr, uint n) { /* This is not strictly necessary, because the loop below will be optimized away anyway. It is * nice to make behavior this explicitly, though. */ - if (std::is_trivially_destructible<T>::value) { + if (std::is_trivially_constructible<T>::value) { return; } - for (uint i = 0; i < n; i++) { - ptr[i].~T(); + uint current = 0; + try { + for (; current < n; current++) { + new ((void *)(ptr + current)) T; + } + } + catch (...) { + destruct_n(ptr, current); + throw; } } /** * Copy n values from src to dst. * + * Exception Safety: Basic. + * * Before: * src: initialized * dst: initialized @@ -92,6 +111,8 @@ template<typename T> void initialized_copy_n(const T *src, uint n, T *dst) /** * Copy n values from src to dst. * + * Exception Safety: Strong. + * * Before: * src: initialized * dst: uninitialized @@ -101,14 +122,23 @@ template<typename T> void initialized_copy_n(const T *src, uint n, T *dst) */ template<typename T> void uninitialized_copy_n(const T *src, uint n, T *dst) { - for (uint i = 0; i < n; i++) { - new ((void *)(dst + i)) T(src[i]); + uint current = 0; + try { + for (; current < n; current++) { + new ((void *)(dst + current)) T(src[current]); + } + } + catch (...) { + destruct_n(dst, current); + throw; } } /** * Move n values from src to dst. * + * Exception Safety: Basic. + * * Before: * src: initialized * dst: initialized @@ -126,6 +156,8 @@ template<typename T> void initialized_move_n(T *src, uint n, T *dst) /** * Move n values from src to dst. * + * Exception Safety: Basic. + * * Before: * src: initialized * dst: uninitialized @@ -135,8 +167,19 @@ template<typename T> void initialized_move_n(T *src, uint n, T *dst) */ template<typename T> void uninitialized_move_n(T *src, uint n, T *dst) { - for (uint i = 0; i < n; i++) { - new ((void *)(dst + i)) T(std::move(src[i])); + static_assert(std::is_nothrow_move_constructible_v<T>, + "Ideally, all types should have this property. We might have to remove this " + "limitation of a real reason comes up."); + + uint current = 0; + try { + for (; current < n; current++) { + new ((void *)(dst + current)) T(std::move(src[current])); + } + } + catch (...) { + destruct_n(dst, current); + throw; } } @@ -144,6 +187,8 @@ template<typename T> void uninitialized_move_n(T *src, uint n, T *dst) * Relocate n values from src to dst. Relocation is a move followed by destruction of the src * value. * + * Exception Safety: Basic. + * * Before: * src: initialized * dst: initialized @@ -161,6 +206,8 @@ template<typename T> void initialized_relocate_n(T *src, uint n, T *dst) * Relocate n values from src to dst. Relocation is a move followed by destruction of the src * value. * + * Exception Safety: Basic. + * * Before: * src: initialized * dst: uninitialized @@ -177,6 +224,8 @@ template<typename T> void uninitialized_relocate_n(T *src, uint n, T *dst) /** * Copy the value to n consecutive elements. * + * Exception Safety: Basic. + * * Before: * dst: initialized * After: @@ -192,6 +241,8 @@ template<typename T> void initialized_fill_n(T *dst, uint n, const T &value) /** * Copy the value to n consecutive elements. * + * Exception Safety: Strong. + * * Before: * dst: uninitialized * After: @@ -199,8 +250,15 @@ template<typename T> void initialized_fill_n(T *dst, uint n, const T &value) */ template<typename T> void uninitialized_fill_n(T *dst, uint n, const T &value) { - for (uint i = 0; i < n; i++) { - new ((void *)(dst + i)) T(value); + uint current = 0; + try { + for (; current < n; current++) { + new ((void *)(dst + current)) T(value); + } + } + catch (...) { + destruct_n(dst, current); + throw; } } |