#include <stddef.h>
#include "gromacs/utility/basedefinitions.h"
#include <type_traits>

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Description

C-style memory allocation routines for GROMACS.

This header provides macros snew(), srenew(), smalloc(), and sfree() for C-style memory management. Additionally, snew_aligned() and sfree_aligned() are provided for managing memory with a specified byte alignment.

If an allocation fails, the program is halted by calling gmx_fatal(), which outputs source file and line number and the name of the variable involved. This frees calling code from the trouble of checking the result of the allocations everywhere. It also provides a location for centrally logging memory allocations for diagnosing memory usage (currently can only enabled by changing the source code). Additionally, sfree() works also with a NULL parameter, which standard free() does not.

The macros forward the calls to functions save_malloc(), save_calloc(), save_realloc(), save_free(), save_calloc_aligned(), and save_free_aligned(). There are a few low-level locations in GROMACS that call these directly, but generally the macros should be used. save_malloc_aligned() exists for this purpose, although there is no macro to invoke it.

Macros
#define	snew(ptr, nelem)
	Allocates memory for a given number of elements. More...

#define	srenew(ptr, nelem)
	Reallocates memory for a given number of elements. More...

#define	smalloc(ptr, size)
	Allocates memory for a given number of bytes. More...

#define	snew_aligned(ptr, nelem, alignment)
	Allocates aligned memory for a given number of elements. More...

#define	sfree(ptr)
	Frees memory referenced by `ptr`. More...

#define	sfree_aligned(ptr)
	Frees aligned memory referenced by `ptr`. More...

Functions
void *	save_malloc (const char name, const char file, int line, size_t size)
	GROMACS wrapper for malloc(). More...

void *	save_calloc (const char name, const char file, int line, size_t nelem, size_t elsize)
	GROMACS wrapper for calloc(). More...

void *	save_realloc (const char name, const char file, int line, void *ptr, size_t nelem, size_t elsize)
	GROMACS wrapper for realloc(). More...

void	save_free (const char name, const char file, int line, void *ptr)
	GROMACS wrapper for free(). More...

void *	save_malloc_aligned (const char name, const char file, int line, size_t nelem, size_t elsize, size_t alignment)
	GROMACS wrapper for allocating aligned memory. More...

void *	save_calloc_aligned (const char name, const char file, int line, size_t nelem, size_t elsize, size_t alignment)
	GROMACS wrapper for allocating zero-initialized aligned memory. More...

void	save_free_aligned (const char name, const char file, int line, void *ptr)
	GROMACS wrapper for freeing aligned memory. More...

void	set_over_alloc_dd (gmx_bool set)
	Turns over allocation for variable size atoms/cg/top arrays on or off, default is off. More...

int	over_alloc_dd (int n)
	Returns new allocation count for domain decomposition allocations. More...

template<typename T >
constexpr T	over_alloc_small (T n)
	Over allocation for small data types: int, real etc. More...

template<typename T >
constexpr T	over_alloc_large (T n)
	Over allocation for large data types: complex structs.

Implementation templates for C++ memory allocation macros
These templates are used to implement the snew() etc. macros for C++, where an explicit cast is needed from `void *` (the return value of the allocation wrapper functions) to the type of `ptr`. Having these as `static` avoid some obscure bugs if several files define distinct data structures with identical names and allocate memory for them using snew(). By the C++ standard, such declarations cause undefined behavior, but can be difficult to spot in the existing C code. Without the `static` (and if the compiler does not inline the calls), the linker cannot that data structures with identical names are actually different and links calls to these template functions incorrectly, which can result in allocation of an incorrect amount of memory if the element size is computed within the function. The size cannot be passed as a parameter to the function either, since that provokes warnings from cppcheck for some invocations, where a complex expression is passed as `ptr`.
template<typename T >
static void	gmx_snew_impl (const char name, const char file, int line, T *&ptr, size_t nelem)
	C++ helper for snew(). More...

template<typename T >
static void	gmx_srenew_impl (const char name, const char file, int line, T *&ptr, size_t nelem)
	C++ helper for srenew(). More...

template<typename T >
static void	gmx_smalloc_impl (const char name, const char file, int line, T *&ptr, size_t size)
	C++ helper for smalloc(). More...

template<typename T >
static void	gmx_snew_aligned_impl (const char name, const char file, int line, T *&ptr, size_t nelem, size_t alignment)
	C++ helper for snew_aligned(). More...

template<typename T >
static void	gmx_sfree_impl (const char name, const char file, int line, T *ptr)
	C++ helper for sfree(). More...

template<typename T >
static void	gmx_sfree_aligned_impl (const char name, const char file, int line, T *ptr)
	C++ helper for sfree_aligned(). More...

Variables
constexpr float	OVER_ALLOC_FAC = 1.19F
	Over allocation factor for memory allocations. More...

Macro Definition Documentation

#define sfree ( ptr )

Frees memory referenced by ptr.

ptr is allowed to be NULL, in which case nothing is done.

#define sfree_aligned ( ptr )

Frees aligned memory referenced by ptr.

This must only be called with a pointer obtained through snew_aligned(). ptr is allowed to be NULL, in which case nothing is done.

#define smalloc	(	ptr,
		size
	)

Allocates memory for a given number of bytes.

Parameters

[out]	ptr	Pointer to allocate.
[in]	size	Number of bytes to allocate.

Allocates memory for size bytes and sets this to ptr. The allocated memory is initialized to zero.

#define snew	(	ptr,
		nelem
	)

Allocates memory for a given number of elements.

Parameters

[out]	ptr	Pointer to allocate.
[in]	nelem	Number of elements to allocate.

Allocates memory for nelem elements of type *ptr and sets this to ptr. The allocated memory is initialized to zeros.

#define snew_aligned	(	ptr,
		nelem,
		alignment
	)

Allocates aligned memory for a given number of elements.

Parameters

[out]	ptr	Pointer to allocate.
[in]	nelem	Number of elements to allocate.
[in]	alignment	Requested alignment in bytes.

Allocates memory for nelem elements of type *ptr and sets this to ptr. The returned pointer is alignment-byte aligned. The allocated memory is initialized to zeros.

The returned pointer should only be freed with sfree_aligned().

#define srenew	(	ptr,
		nelem
	)

Reallocates memory for a given number of elements.

Parameters

[in,out]	ptr	Pointer to allocate/reallocate.
[in]	nelem	Number of elements to allocate.

(Re)allocates memory for ptr such that it can hold nelem elements of type *ptr, and sets the new pointer to ptr. If ptr is NULL, memory is allocated as if it was new. If nelem is zero, ptr is freed (if not NULL). Note that the allocated memory is not initialized, unlike with snew().

Function Documentation

template<typename T >

static void gmx_sfree_aligned_impl	(	const char *	name,
		const char *	file,
		int	line,
		T *	ptr
	)

inlinestatic

C++ helper for sfree_aligned().

template<typename T >

static void gmx_sfree_impl	(	const char *	name,
		const char *	file,
		int	line,
		T *	ptr
	)

inlinestatic

C++ helper for sfree().

template<typename T >

static void gmx_smalloc_impl	(	const char *	name,
		const char *	file,
		int	line,
		T *&	ptr,
		size_t	size
	)

inlinestatic

C++ helper for smalloc().

template<typename T >

static void gmx_snew_aligned_impl	(	const char *	name,
		const char *	file,
		int	line,
		T *&	ptr,
		size_t	nelem,
		size_t	alignment
	)

inlinestatic

C++ helper for snew_aligned().

template<typename T >

static void gmx_snew_impl	(	const char *	name,
		const char *	file,
		int	line,
		T *&	ptr,
		size_t	nelem
	)

inlinestatic

C++ helper for snew().

template<typename T >

static void gmx_srenew_impl	(	const char *	name,
		const char *	file,
		int	line,
		T *&	ptr,
		size_t	nelem
	)

inlinestatic

C++ helper for srenew().

int over_alloc_dd ( int n )

Returns new allocation count for domain decomposition allocations.

Returns n when domain decomposition over allocation is off. Returns OVER_ALLOC_FAC*n + 100 when over allocation in on. This is to avoid frequent reallocation during domain decomposition in mdrun.

template<typename T >

constexpr T over_alloc_small ( T n )

Over allocation for small data types: int, real etc.

void* save_calloc	(	const char *	name,
		const char *	file,
		int	line,
		size_t	nelem,
		size_t	elsize
	)

GROMACS wrapper for calloc().

Parameters

[in]	name	Variable name identifying the allocation.
[in]	file	Source code file where the allocation originates from.
[in]	line	Source code line where the allocation originates from.
[in]	nelem	Number of elements to allocate.
[in]	elsize	Number of bytes per element.

Returns: Pointer to the allocated space.

This should generally be called through snew(), not directly.

void* save_calloc_aligned	(	const char *	name,
		const char *	file,
		int	line,
		size_t	nelem,
		size_t	elsize,
		size_t	alignment
	)

GROMACS wrapper for allocating zero-initialized aligned memory.

Parameters

[in]	name	Variable name identifying the allocation.
[in]	file	Source code file where the allocation originates from.
[in]	line	Source code line where the allocation originates from.
[in]	nelem	Number of elements to allocate.
[in]	elsize	Number of bytes per element.
[in]	alignment	Requested alignment in bytes.

Returns: Pointer to the allocated space, aligned at alignment-byte boundary.

This should generally be called through snew_aligned(), not directly.

The returned pointer should only be freed with a call to save_free_aligned().

void save_free	(	const char *	name,
		const char *	file,
		int	line,
		void *	ptr
	)

GROMACS wrapper for free().

Parameters

[in]	name	Variable name identifying the deallocation.
[in]	file	Source code file where the deallocation originates from.
[in]	line	Source code line where the deallocation originates from.
[in]	ptr	Pointer to the allocated memory (can be NULL).

If ptr is NULL, does nothing. This should generally be called through sfree(), not directly. This never fails.

void save_free_aligned	(	const char *	name,
		const char *	file,
		int	line,
		void *	ptr
	)

GROMACS wrapper for freeing aligned memory.

Parameters

[in]	name	Variable name identifying the deallocation.
[in]	file	Source code file where the deallocation originates from.
[in]	line	Source code line where the deallocation originates from.
[in]	ptr	Pointer to the allocated memory (can be NULL).

If ptr is NULL, does nothing. ptr should have been allocated with save_malloc_aligned() or save_calloc_aligned(). This should generally be called through sfree_aligned(), not directly. This never fails.

void* save_malloc	(	const char *	name,
		const char *	file,
		int	line,
		size_t	size
	)

GROMACS wrapper for malloc().

Parameters

[in]	name	Variable name identifying the allocation.
[in]	file	Source code file where the allocation originates from.
[in]	line	Source code line where the allocation originates from.
[in]	size	Number of bytes to allocate.

Returns: Pointer to the allocated space.

This should generally be called through smalloc(), not directly.

void* save_malloc_aligned	(	const char *	name,
		const char *	file,
		int	line,
		size_t	nelem,
		size_t	elsize,
		size_t	alignment
	)

GROMACS wrapper for allocating aligned memory.

Parameters

[in]	name	Variable name identifying the allocation.
[in]	file	Source code file where the allocation originates from.
[in]	line	Source code line where the allocation originates from.
[in]	nelem	Number of elements to allocate.
[in]	elsize	Number of bytes per element.
[in]	alignment	Requested alignment in bytes.

Returns: Pointer to the allocated space, aligned at alignment-byte boundary.

There is no macro that invokes this function.

The returned pointer should only be freed with a call to save_free_aligned().

void* save_realloc	(	const char *	name,
		const char *	file,
		int	line,
		void *	ptr,
		size_t	nelem,
		size_t	elsize
	)

GROMACS wrapper for realloc().

Parameters

[in]	name	Variable name identifying the allocation.
[in]	file	Source code file where the allocation originates from.
[in]	line	Source code line where the allocation originates from.
[in]	ptr	Pointer to the previously allocated memory (can be NULL).
[in]	nelem	Number of elements to allocate.
[in]	elsize	Number of bytes per element.

Returns: Pointer to the allocated space.

As with realloc(), if ptr is NULL, memory is allocated as if malloc() was called. This should generally be called through srenew(), not directly.

Note that the allocated memory is not initialized to zero.

void set_over_alloc_dd ( gmx_bool set )

Turns over allocation for variable size atoms/cg/top arrays on or off, default is off.

Todo:: This is mdrun-specific, so it might be better to put this and over_alloc_dd() much higher up.

Variable Documentation

constexpr float OVER_ALLOC_FAC = 1.19F

Over allocation factor for memory allocations.

Memory (re)allocation can be VERY slow, especially with some MPI libraries that replace the standard malloc and realloc calls. To avoid slow memory allocation we use over_alloc to set the memory allocation size for large data blocks. Since this scales the size with a factor, we use log(n) realloc calls instead of n. This can reduce allocation times from minutes to seconds.

This factor leads to 4 realloc calls to double the array size.

Description

Macros

Functions

Variables

Macro Definition Documentation

Function Documentation

Variable Documentation