mirrors/cpython
1
0
Fork 0
mirror of https://github.com/python/cpython.git synced 2025-09-26 18:29:57 +00:00
Code Issues Projects Releases Packages Wiki Activity Actions 10

Just added comments, and cleared some XXX questions, related to int

Browse source 
memory management.
This commit is contained in:
Tim Peters 2002-04-28 16:57:34 +00:00
parent 449b5a8da1
commit 29c0afcfec
1 changed files with 12 additions and 3 deletions
Download patch file Download diff file Expand all files Collapse all files

15
Objects/intobject.c
View file

@ -26,11 +26,18 @@ err_ovf(char *msg)
/* Integers are quite normal objects, to make object handling uniform. /* Integers are quite normal objects, to make object handling uniform.
(Using odd pointers to represent integers would save much space (Using odd pointers to represent integers would save much space
but require extra checks for this special case throughout the code.) but require extra checks for this special case throughout the code.)
Since, a typical Python program spends much of its time allocating Since a typical Python program spends much of its time allocating
and deallocating integers, these operations should be very fast. and deallocating integers, these operations should be very fast.
Therefore we use a dedicated allocation scheme with a much lower Therefore we use a dedicated allocation scheme with a much lower
overhead (in space and time) than straight malloc(): a simple overhead (in space and time) than straight malloc(): a simple
dedicated free list, filled when necessary with memory from malloc(). dedicated free list, filled when necessary with memory from malloc().
block_list is a singly-linked list of all PyIntBlocks ever allocated,
linked via their next members. PyIntBlocks are never returned to the
system before shutdown (PyInt_Fini).
free_list is a singly-linked list of available PyIntObjects, linked
via abuse of their ob_type members.
*/ */
#define BLOCK_SIZE 1000 /* 1K less typical malloc overhead */ #define BLOCK_SIZE 1000 /* 1K less typical malloc overhead */
@ -51,12 +58,14 @@ static PyIntObject *
fill_free_list(void) fill_free_list(void)
{ {
PyIntObject *p, *q; PyIntObject *p, *q;
/* XXX Int blocks escape the object heap. Use PyObject_MALLOC ??? */ /* Python's object allocator isn't appropriate for large blocks. */
p = (PyIntObject *) PyMem_MALLOC(sizeof(PyIntBlock)); p = (PyIntObject *) PyMem_MALLOC(sizeof(PyIntBlock));
if (p == NULL) if (p == NULL)
return (PyIntObject *) PyErr_NoMemory(); return (PyIntObject *) PyErr_NoMemory();
((PyIntBlock *)p)->next = block_list; ((PyIntBlock *)p)->next = block_list;
block_list = (PyIntBlock *)p; block_list = (PyIntBlock *)p;
/* Link the int objects together, from rear to front, then return
the address of the last int object in the block. */
p = &((PyIntBlock *)p)->objects[0]; p = &((PyIntBlock *)p)->objects[0];
q = p + N_INTOBJECTS; q = p + N_INTOBJECTS;
while (--q > p) while (--q > p)
@ -975,7 +984,7 @@ PyInt_Fini(void)
} }
} }
else { else {
PyMem_FREE(list); /* XXX PyObject_FREE ??? */ PyMem_FREE(list);
bf++; bf++;
} }
isum += irem; isum += irem;