Core memory management components for libmemalloc. More...

Files
file	libmemalloc.c
	Core memory management components for libmemalloc.

file	libmemalloc.h

Classes
struct	block_header_t
	Represents the header for a memory block. More...

struct	mem_arena_t
	Represents a memory arena with its own free lists. More...

struct	mmap_t
	Tracks memory-mapped regions for large allocations. More...

struct	gc_thread_t
	Orchestrates the background mark-and-sweep garbage collector. More...

struct	mem_allocator_t
	Manages dynamic memory allocation. More...

Macros
#define	__ALIGN
	Defines structure alignment and enforces the target byte order.

#define	__LIBMEMALLOC_API
	Defines the default visibility attribute for exported symbols.

#define	__LIBMEMALLOC_MALLOC
	Annotates allocator functions that return newly allocated memory.

#define	__LIBMEMALLOC_REALLOC
	Annotates reallocator functions that may return a pointer to resized memory.

#define	PTR_ERR(x) ((void *)((intptr_t)(x)))
	Encodes a negative error code as an error pointer.

#define	ALIGN(x) (((x) + (ARCH_ALIGNMENT - 1U)) & ~(ARCH_ALIGNMENT - 1U))
	Aligns a given value to the nearest memory boundary.

#define	GC_INTERVAL_MS (uint16_t)(100U)
	Default interval in milliseconds between GC cycles.

Enumerations
enum	allocation_strategy_t { FIRST_FIT = (uint8_t)(0u) , NEXT_FIT = (uint8_t)(1u) , BEST_FIT = (uint8_t)(2u) }
	Defines allocation strategies for memory management. More...

Functions
void *	MEM_memset (void *const source, const int value, const size_t size)
	Fills a memory block with a specified byte value using optimized operations.

void *	MEM_memcpy (void const dest, const void src, const size_t size)
	Copies a memory block between buffers using optimized operations.

int	MEM_allocatorInit (mem_allocator_t *const allocator)
	Initializes the memory allocator and its internal structures.

void *	MEM_allocMallocFirstFit (mem_allocator_t const allocator, const size_t size, const char const var)
	Allocates memory using the FIRST_FIT strategy.

void *	MEM_allocMallocBestFit (mem_allocator_t const allocator, const size_t size, const char const var)
	Allocates memory using the BEST_FIT strategy.

void *	MEM_allocMallocNextFit (mem_allocator_t const allocator, const size_t size, const char const var)
	Allocates memory using the NEXT_FIT strategy.

void *	MEM_allocMalloc (mem_allocator_t const allocator, const size_t size, const char const var, const allocation_strategy_t strategy)
	Allocates memory using the specified strategy.

void *	MEM_allocCalloc (mem_allocator_t const allocator, const size_t size, const char const var, const allocation_strategy_t strategy)
	Allocates and zero‐initializes memory using the specified strategy.

void *	MEM_allocRealloc (mem_allocator_t const allocator, void const ptr, const size_t new_size, const char *const var, const allocation_strategy_t strategy)
	Reallocates memory with safety checks using the specified strategy.

int	MEM_allocFree (mem_allocator_t const allocator, void const ptr, const char *const var)
	Releases allocated memory back to the heap.

int	MEM_enableGc (mem_allocator_t *const allocator)
	Start or signal the garbage collector thread.

int	MEM_disableGc (mem_allocator_t *const allocator)
	Stop the garbage collector thread and perform a final collection.

Detailed Description

Core memory management components for libmemalloc.

Macro Definition Documentation

◆ __ALIGN

#define __ALIGN

Defines structure alignment and enforces the target byte order.

When using GCC or Clang, expands to attribute((scalar_storage_order("<host-endian>"), aligned(ARCH_ALIGNMENT))) where <host-endian> fica automaticamente ajustado para "little-endian" ou "big-endian" conforme o compilador. Em compiladores sem suporte a esse atributo, expande para nada.

◆ __LIBMEMALLOC_API

#define __LIBMEMALLOC_API

Defines the default visibility attribute for exported symbols.

When using GCC or compatible compilers, this macro expands to attribute((visibility("default"))) to ensure that symbols are exported (visible) in the resulting shared library (.so). For compilers that do not support this attribute, it expands to nothing.

◆ __LIBMEMALLOC_MALLOC

#define __LIBMEMALLOC_MALLOC

Annotates allocator functions that return newly allocated memory.

When supported by the compiler (GCC/Clang), expands to attribute((malloc, alloc_size(2), warn_unused_result)) which tells the compiler the function behaves like malloc, that the 2nd parameter is the allocation size, and that the return value should not be ignored. Otherwise, expands to nothing.

◆ __LIBMEMALLOC_REALLOC

#define __LIBMEMALLOC_REALLOC

Annotates reallocator functions that may return a pointer to resized memory.

When supported by the compiler (GCC/Clang), expands to attribute((alloc_size(3), warn_unused_result)) which tells the compiler that the 3rd parameter specifies the new size of the allocation and that the return value should not be ignored. Otherwise, expands to nothing.

◆ ALIGN

#define ALIGN ( x ) (((x) + (ARCH_ALIGNMENT - 1U)) & ~(ARCH_ALIGNMENT - 1U))

Aligns a given value to the nearest memory boundary.

Parameters

[in] x Value to be aligned.

Uses bitwise operations to align the value to the nearest multiple of the current architecture's alignment.

◆ GC_INTERVAL_MS

#define GC_INTERVAL_MS (uint16_t)(100U)

Default interval in milliseconds between GC cycles.

Defines the time (in milliseconds) the garbage collector thread sleeps between each mark-and-sweep cycle. Adjusting this value impacts how frequently memory is reclaimed versus the CPU overhead of running the GC.

◆ PTR_ERR

#define PTR_ERR ( x ) ((void *)((intptr_t)(x)))

Encodes a negative error code as an error pointer.

Parameters

[in] x Integer error code (negative errno value).

Returns: A pointer whose value encodes the error code. To test and extract the code, use IS_ERR() and (intptr_t)ptr respectively.

Enumeration Type Documentation

◆ allocation_strategy_t

enum allocation_strategy_t

Defines allocation strategies for memory management.

This enum specifies the available strategies for memory block allocation within the heap.

Fields:

FIRST_FIT – First available block allocation
NEXT_FIT – Continue from last allocation
BEST_FIT – Smallest block fitting the request

Enumerator
FIRST_FIT	Allocate the first available block
NEXT_FIT	Continue searching from the last allocation
BEST_FIT	Use the smallest block that fits the request

Function Documentation

◆ MEM_allocatorInit()

int MEM_allocatorInit ( mem_allocator_t *const allocator )

Initializes the memory allocator and its internal structures.

This function prepares the allocator’s heap by:

Reading and aligning the initial program break to ARCH_ALIGNMENT.
Allocating the arena array and free‐list bins via MEM_growUserHeap().
Zeroing out the free‐list bins.
Initializing the allocator fields (heap_start, heap_end, free_lists).
Setting up the garbage‐collector thread state and its mutex/cond.
Capturing the current thread’s stack bounds via MEM_stackBounds().
(If under Valgrind) creating a mempool for the allocator.

Parameters

[in] allocator Pointer to a mem_allocator_t instance to initialize.

Returns: Integer status code indicating initialization result.

Return values

EXIT_SUCCESS	Allocator initialized successfully.
-EINVAL	Invalid `allocator` pointer.
-ENOMEM	Heap alignment or arena/bin allocation failed.

◆ MEM_allocCalloc()

void * MEM_allocCalloc	(	mem_allocator_t *const	allocator,
		const size_t	size,
		const char *const	var,
		const allocation_strategy_t	strategy
	)

Allocates and zero‐initializes memory using the specified strategy.

This function locks the GC mutex, invokes MEM_allocatorCalloc() with the given strategy, automatically supplying FILE, LINE, and variable name for debugging, then unlocks the mutex.

Parameters

[in]	allocator	Memory allocator context.
[in]	size	Number of bytes requested.
[in]	var	Variable name for debugging.
[in]	strategy	Allocation strategy.

Returns: Pointer to the allocated zeroed memory on success, or an error‐encoded pointer (via PTR_ERR()) on failure.

◆ MEM_allocFree()

int MEM_allocFree	(	mem_allocator_t *const	allocator,
		void *const	ptr,
		const char *const	var
	)

Releases allocated memory back to the heap.

This function locks the GC mutex, invokes MEM_allocatorFree() with automatically supplied FILE, LINE, and variable name for debugging, then unlocks the mutex.

Parameters

[in]	allocator	Memory allocator context.
[in]	ptr	Pointer to memory to free.
[in]	var	Variable name for debugging.

Returns: EXIT_SUCCESS on success, negative error code on failure.

◆ MEM_allocMalloc()

void * MEM_allocMalloc	(	mem_allocator_t *const	allocator,
		const size_t	size,
		const char *const	var,
		const allocation_strategy_t	strategy
	)

Allocates memory using the specified strategy.

This function locks the GC mutex, invokes MEM_allocatorMalloc() with the given strategy, automatically supplying FILE, LINE, and variable name for debugging, then unlocks the mutex.

Parameters

[in]	allocator	Memory allocator context.
[in]	size	Number of bytes requested
[in]	var	Variable name for debugging.
[in]	strategy	Allocation strategy.

Returns: Pointer to the allocated user memory on success, or an error‐encoded pointer (via PTR_ERR()) on failure.

◆ MEM_allocMallocBestFit()

void * MEM_allocMallocBestFit	(	mem_allocator_t *const	allocator,
		const size_t	size,
		const char *const	var
	)

Allocates memory using the BEST_FIT strategy.

This function locks the GC mutex, invokes MEM_allocatorMalloc() with BEST_FIT strategy, automatically supplying FILE, LINE, and variable name for debugging, then unlocks the mutex.

Parameters

[in]	allocator	Memory allocator context.
[in]	size	Number of bytes requested.
[in]	var	Variable name for debugging.

Returns: Pointer to the allocated user memory on success, or an error‐encoded pointer (via PTR_ERR()) on failure.

◆ MEM_allocMallocFirstFit()

void * MEM_allocMallocFirstFit	(	mem_allocator_t *const	allocator,
		const size_t	size,
		const char *const	var
	)

Allocates memory using the FIRST_FIT strategy.

This function locks the GC mutex, invokes MEM_allocatorMalloc() with FIRST_FIT strategy, automatically supplying FILE, LINE, and variable name for debugging, then unlocks the mutex.

Parameters

[in]	allocator	Memory allocator context.
[in]	size	Number of bytes requested.
[in]	var	Variable name for debugging.

Returns: Pointer to the allocated user memory on success, or an error‐encoded pointer (via PTR_ERR()) on failure.

◆ MEM_allocMallocNextFit()

void * MEM_allocMallocNextFit	(	mem_allocator_t *const	allocator,
		const size_t	size,
		const char *const	var
	)

Allocates memory using the NEXT_FIT strategy.

This function locks the GC mutex, invokes MEM_allocatorMalloc() with NEXT_FIT strategy, automatically supplying FILE, LINE, and variable name for debugging, then unlocks the mutex.

Parameters

[in]	allocator	Memory allocator context.
[in]	size	Number of bytes requested.
[in]	var	Variable name for debugging.

Returns: Pointer to the allocated user memory on success, or an error‐encoded pointer (via PTR_ERR()) on failure.

◆ MEM_allocRealloc()

void * MEM_allocRealloc	(	mem_allocator_t *const	allocator,
		void *const	ptr,
		const size_t	new_size,
		const char *const	var,
		const allocation_strategy_t	strategy
	)

Reallocates memory with safety checks using the specified strategy.

This function locks the GC mutex, invokes MEM_allocatorRealloc() with the given strategy, automatically supplying FILE, LINE, and variable name for debugging, then unlocks the mutex.

Parameters

[in]	allocator	Memory allocator context.
[in]	ptr	Pointer to existing memory.
[in]	new_size	New requested size.
[in]	var	Variable name for debugging.
[in]	strategy	Allocation strategy.

Returns: Pointer to the reallocated memory on success (may be same as ptr), or an error‐encoded pointer (via PTR_ERR()) on failure.

◆ MEM_disableGc()

int MEM_disableGc ( mem_allocator_t *const allocator )

Stop the garbage collector thread and perform a final collection.

This function simply wraps MEM_stopGc(), signaling the GC thread to exit, joining it, and running a final mark-and-sweep cycle on the caller thread.

Parameters

[in] allocator Memory allocator context

Returns: EXIT_SUCCESS on success, negative error code on failure.

◆ MEM_enableGc()

int MEM_enableGc ( mem_allocator_t *const allocator )

Start or signal the garbage collector thread.

This function simply wraps MEM_runGc(), starting the GC thread if needed or signaling it to perform a collection cycle.

Parameters

[in] allocator Memory allocator context.

Returns: EXIT_SUCCESS on success, negative error code on failure.

◆ MEM_memcpy()

void * MEM_memcpy	(	void *const	dest,
		const void *	src,
		const size_t	size
	)

Copies a memory block between buffers using optimized operations.

This function copies size bytes from the source buffer to the destination buffer. It first advances the destination pointer to meet the architecture’s alignment requirements, then copies data in ARCH_ALIGNMENT-sized chunks using 64-bit loads and stores, with prefetch hints for both source and destination cache lines. Any remaining bytes at the end are copied.

Parameters

[in]	dest	Destination buffer pointer.
[in]	src	Source buffer pointer.
[in]	size	Number of bytes to copy.

Returns: Original dest pointer on success, an error-encoded pointer (via PTR_ERR()) on failure.

Return values

dest	Original Pointer on successful operation.
-EINVAL	Invalid `src` or `size`.

◆ MEM_memset()

void * MEM_memset	(	void *const	source,
		const int	value,
		const size_t	size
	)

Fills a memory block with a specified byte value using optimized operations.

This function sets each byte in the given memory region to the specified value. It first advances the pointer to meet the architecture’s alignment requirements, then writes data in ARCH_ALIGNMENT-sized chunks using 64-bit stores multiplied by PREFETCH_MULT, with prefetch hints for cache lines. Any remaining bytes at the end are filled one by one.

Parameters

[in]	source	Pointer to the memory block to fill.
[in]	value	Byte value to set (0–255).
[in]	size	Number of bytes to set.

Returns: Original source pointer on success, an error‐encoded pointer (via PTR_ERR()) on failure.

Return values

dest	Original Pointer on successful operation.
-EINVAL	Invalid `src` or `size`.

Files

Classes

Macros

Enumerations

Functions

Detailed Description

Macro Definition Documentation

◆ __ALIGN

◆ __LIBMEMALLOC_API

◆ __LIBMEMALLOC_MALLOC

◆ __LIBMEMALLOC_REALLOC

◆ ALIGN

◆ GC_INTERVAL_MS

◆ PTR_ERR

Enumeration Type Documentation

◆ allocation_strategy_t

Function Documentation

◆ MEM_allocatorInit()

◆ MEM_allocCalloc()

◆ MEM_allocFree()

◆ MEM_allocMalloc()

◆ MEM_allocMallocBestFit()

◆ MEM_allocMallocFirstFit()

◆ MEM_allocMallocNextFit()

◆ MEM_allocRealloc()

◆ MEM_disableGc()

◆ MEM_enableGc()

◆ MEM_memcpy()

◆ MEM_memset()