mirror of
https://github.com/python/cpython
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129 lines
2.7 KiB
C
129 lines
2.7 KiB
C
#include "Python.h"
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#include "pyarena.h"
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/* An arena list is a linked list that can store either pointers or
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PyObjects. The type is clear from context.
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*/
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typedef struct _arena_list {
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struct _arena_list *al_next;
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void *al_pointer;
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} PyArenaList;
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/* There are two linked lists in an arena, one for malloc pointers and
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one for PyObject. For each list, there is a pointer to the head
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and to the tail. The head is used to free the list. The tail is
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used to add a new element to the list.
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The list always keeps one un-used node at the end of the list.
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*/
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struct _arena {
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PyArenaList *a_malloc_head;
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PyArenaList *a_malloc_tail;
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PyArenaList *a_object_head;
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PyArenaList *a_object_tail;
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};
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static PyArenaList*
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PyArenaList_New(void)
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{
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PyArenaList *alist = (PyArenaList *)malloc(sizeof(PyArenaList));
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if (!alist)
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return NULL;
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alist->al_next = NULL;
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alist->al_pointer = NULL;
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return alist;
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}
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static void
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PyArenaList_FreeObject(PyArenaList *alist)
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{
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while (alist) {
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PyArenaList *prev;
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Py_XDECREF((PyObject *)alist->al_pointer);
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alist->al_pointer = NULL;
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prev = alist;
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alist = alist->al_next;
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free(prev);
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}
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}
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static void
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PyArenaList_FreeMalloc(PyArenaList *alist)
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{
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while (alist) {
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PyArenaList *prev;
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if (alist->al_pointer) {
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free(alist->al_pointer);
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}
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alist->al_pointer = NULL;
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prev = alist;
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alist = alist->al_next;
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free(prev);
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}
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}
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PyArena *
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PyArena_New()
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{
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PyArena* arena = (PyArena *)malloc(sizeof(PyArena));
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if (!arena)
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return NULL;
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arena->a_object_head = PyArenaList_New();
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arena->a_object_tail = arena->a_object_head;
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arena->a_malloc_head = PyArenaList_New();
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arena->a_malloc_tail = arena->a_malloc_head;
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return arena;
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}
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void
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PyArena_Free(PyArena *arena)
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{
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assert(arena);
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PyArenaList_FreeObject(arena->a_object_head);
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PyArenaList_FreeMalloc(arena->a_malloc_head);
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free(arena);
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}
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void *
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PyArena_Malloc(PyArena *arena, size_t size)
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{
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/* A better implementation might actually use an arena. The current
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approach is just a trivial implementation of the API that allows
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it to be tested.
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*/
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void *p;
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assert(size != 0);
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p = malloc(size);
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if (p)
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PyArena_AddMallocPointer(arena, p);
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return p;
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}
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int
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PyArena_AddMallocPointer(PyArena *arena, void *pointer)
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{
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PyArenaList *tail = arena->a_malloc_tail;
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assert(pointer);
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assert(tail->al_pointer != pointer);
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tail->al_next = PyArenaList_New();
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tail->al_pointer = pointer;
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arena->a_malloc_tail = tail->al_next;
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return 1;
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}
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int
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PyArena_AddPyObject(PyArena *arena, PyObject *pointer)
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{
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PyArenaList *tail = arena->a_object_tail;
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assert(pointer);
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tail->al_next = PyArenaList_New();
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tail->al_pointer = pointer;
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arena->a_object_tail = tail->al_next;
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return 1;
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}
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