_PyMem_RawMalloc is calling ‘malloc’ to allocate memory and return pointer
so _PyMem_RawMalloc is equal to ‘malloc’
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| static void *
_PyMem_RawMalloc(void *ctx, size_t size)
{
/* PyMem_RawMalloc(0) means malloc(1). Some systems would return NULL
for malloc(0), which would be treated as an error. Some platforms would
return a pointer with no memory behind it, which would break pymalloc.
To solve these problems, allocate an extra byte. */
if (size == 0)
size = 1;
return malloc(size);
} |
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| typedef struct {
/* user context passed as the first argument to the 4 functions */
void *ctx;
/* allocate a memory block */
void* (*malloc) (void *ctx, size_t size);
/* allocate a memory block initialized by zeros */
void* (*calloc) (void *ctx, size_t nelem, size_t elsize);
/* allocate or resize a memory block */
void* (*realloc) (void *ctx, void *ptr, size_t new_size);
/* release a memory block */
void (*free) (void *ctx, void *ptr);
} PyMemAllocatorEx;
#define PYRAW_FUNCS _PyMem_RawMalloc, _PyMem_RawCalloc, _PyMem_RawRealloc, _PyMem_RawFree // this means
//*ctx = NULL and (*malloc) = _PyMem_RawMalloc = malloc function in c
PyMemAllocatorEx alloc = {NULL, PYRAW_FUNCS};
// alloc will be assigned to _PyMem_Raw, _PyMem, _PyObject
// for PyMem_GetAllocator, it will get alloc by domain name and pick up one of allocator _PyMem_Raw, _PyMem, _PyObject
PyMem_SetAllocator(PYMEM_DOMAIN_RAW, &alloc);
PyMem_SetAllocator(PYMEM_DOMAIN_MEM, &alloc);
PyMem_SetAllocator(PYMEM_DOMAIN_OBJ, &alloc);
void
PyMem_SetAllocator(PyMemAllocatorDomain domain, PyMemAllocatorEx *allocator)
{
switch(domain)
{
case PYMEM_DOMAIN_RAW: _PyMem_Raw = *allocator; break;
case PYMEM_DOMAIN_MEM: _PyMem = *allocator; break;
case PYMEM_DOMAIN_OBJ: _PyObject = *allocator; break;
/* ignore unknown domain */
}
} |
There are 3 Domains that are PYMEM_DOMAIN_RAW, PYMEM_DOMAIN_MEM, PYMEM_DOMAIN_OBJ
alloc will be assigned to _PyMem_Raw, _PyMem, _PyObject based on 3 Domains.
for PyMem_GetAllocator, it will get alloc by domain name and pick up one of allocator _PyMem_Raw, _PyMem, _PyObject
