164 lines
3.7 KiB
C
164 lines
3.7 KiB
C
#include "Python.h"
|
|
#include "pyarena.h"
|
|
|
|
/* A simple arena block structure
|
|
|
|
Measurements with standard library modules suggest the average
|
|
allocation is about 20 bytes and that most compiles use a single
|
|
block.
|
|
*/
|
|
|
|
#define DEFAULT_BLOCK_SIZE 8192
|
|
typedef struct _block {
|
|
size_t ab_size;
|
|
size_t ab_offset;
|
|
struct _block *ab_next;
|
|
void *ab_mem;
|
|
} block;
|
|
|
|
/* The arena manages two kinds of memory, blocks of raw memory
|
|
and a list of PyObject* pointers. PyObjects are decrefed
|
|
when the arena is freed.
|
|
*/
|
|
|
|
struct _arena {
|
|
block *a_head;
|
|
block *a_cur;
|
|
PyObject *a_objects;
|
|
#if defined(Py_DEBUG)
|
|
/* Debug output */
|
|
size_t total_allocs;
|
|
size_t total_size;
|
|
size_t total_blocks;
|
|
size_t total_block_size;
|
|
size_t total_big_blocks;
|
|
#endif
|
|
};
|
|
|
|
static block *
|
|
block_new(size_t size)
|
|
{
|
|
/* Allocate header and block as one unit.
|
|
ab_mem points just past header. */
|
|
block *b = (block *)malloc(sizeof(block) + size);
|
|
if (!b)
|
|
return NULL;
|
|
b->ab_size = size;
|
|
b->ab_mem = (void *)(b + 1);
|
|
b->ab_next = NULL;
|
|
b->ab_offset = 0;
|
|
return b;
|
|
}
|
|
|
|
static void
|
|
block_free(block *b) {
|
|
while (b) {
|
|
block *next = b->ab_next;
|
|
free(b);
|
|
b = next;
|
|
}
|
|
}
|
|
|
|
static void *
|
|
block_alloc(block *b, size_t size)
|
|
{
|
|
void *p;
|
|
assert(b);
|
|
if (b->ab_offset + size > b->ab_size) {
|
|
/* If we need to allocate more memory than will fit in
|
|
the default block, allocate a one-off block that is
|
|
exactly the right size. */
|
|
/* TODO(jhylton): Think about space waste at end of block */
|
|
block *new = block_new(
|
|
size < DEFAULT_BLOCK_SIZE ?
|
|
DEFAULT_BLOCK_SIZE : size);
|
|
if (!new)
|
|
return NULL;
|
|
assert(!b->ab_next);
|
|
b->ab_next = new;
|
|
b = new;
|
|
}
|
|
|
|
assert(b->ab_offset + size <= b->ab_size);
|
|
p = (void *)(((char *)b->ab_mem) + b->ab_offset);
|
|
b->ab_offset += size;
|
|
return p;
|
|
}
|
|
|
|
PyArena *
|
|
PyArena_New()
|
|
{
|
|
PyArena* arena = (PyArena *)malloc(sizeof(PyArena));
|
|
if (!arena)
|
|
return NULL;
|
|
|
|
arena->a_head = block_new(DEFAULT_BLOCK_SIZE);
|
|
arena->a_cur = arena->a_head;
|
|
if (!arena->a_head) {
|
|
free((void *)arena);
|
|
return NULL;
|
|
}
|
|
arena->a_objects = PyList_New(0);
|
|
if (!arena->a_objects) {
|
|
block_free(arena->a_head);
|
|
free((void *)arena);
|
|
return NULL;
|
|
}
|
|
#if defined(Py_DEBUG)
|
|
arena->total_allocs = 0;
|
|
arena->total_size = 0;
|
|
arena->total_blocks = 1;
|
|
arena->total_block_size = DEFAULT_BLOCK_SIZE;
|
|
arena->total_big_blocks = 0;
|
|
#endif
|
|
return arena;
|
|
}
|
|
|
|
void
|
|
PyArena_Free(PyArena *arena)
|
|
{
|
|
assert(arena);
|
|
#if defined(Py_DEBUG)
|
|
/*
|
|
fprintf(stderr,
|
|
"alloc=%d size=%d blocks=%d block_size=%d big=%d objects=%d\n",
|
|
arena->total_allocs, arena->total_size, arena->total_blocks,
|
|
arena->total_block_size, arena->total_big_blocks,
|
|
PyList_Size(arena->a_objects));
|
|
*/
|
|
#endif
|
|
block_free(arena->a_head);
|
|
assert(arena->a_objects->ob_refcnt == 1);
|
|
Py_DECREF(arena->a_objects);
|
|
free(arena);
|
|
}
|
|
|
|
void *
|
|
PyArena_Malloc(PyArena *arena, size_t size)
|
|
{
|
|
void *p = block_alloc(arena->a_cur, size);
|
|
if (!p)
|
|
return NULL;
|
|
#if defined(Py_DEBUG)
|
|
arena->total_allocs++;
|
|
arena->total_size += size;
|
|
#endif
|
|
/* Reset cur if we allocated a new block. */
|
|
if (arena->a_cur->ab_next) {
|
|
arena->a_cur = arena->a_cur->ab_next;
|
|
#if defined(Py_DEBUG)
|
|
arena->total_blocks++;
|
|
arena->total_block_size += arena->a_cur->ab_size;
|
|
if (arena->a_cur->ab_size > DEFAULT_BLOCK_SIZE)
|
|
arena->total_big_blocks++;
|
|
#endif
|
|
}
|
|
return p;
|
|
}
|
|
|
|
int
|
|
PyArena_AddPyObject(PyArena *arena, PyObject *obj)
|
|
{
|
|
return PyList_Append(arena->a_objects, obj) >= 0;
|
|
}
|