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r3366: updates from the junkcode version of talloc.

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The main change is to get rid of talloc_parent_chunk() from all
commonly used code paths, so talloc_free() is now O(1) again. It was
originally O(1), but the last round of changes broke that.

Also some documentation updates
This commit is contained in:
Andrew Tridgell 2004-10-29 11:39:08 +00:00 committed by Gerald (Jerry) Carter
parent 5db5c30ebe
commit d4fe21cdb9
2 changed files with 42 additions and 21 deletions
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12
source/lib/talloc.c
View File

@ -441,7 +441,7 @@ int talloc_free(void *ptr)
if (tc->refs) {
talloc_reference_destructor(tc->refs);
return 0;
return -1;
}
if (tc->destructor) {
@ -469,11 +469,13 @@ int talloc_free(void *ptr)
struct talloc_chunk *p = talloc_parent_chunk(tc->child->refs);
if (p) new_parent = p+1;
}
if (new_parent == null_context) {
struct talloc_chunk *p = talloc_parent_chunk(ptr);
if (p) new_parent = p+1;
if (talloc_free(child) == -1) {
if (new_parent == null_context) {
struct talloc_chunk *p = talloc_parent_chunk(ptr);
if (p) new_parent = p+1;
}
talloc_steal(new_parent, child);
}
talloc_free(talloc_steal(new_parent, child));
}
if (tc->parent) {

51
talloc_guide.txt
View File

@ -101,10 +101,10 @@ condition is if the pointer had a destructor attached to it and the
destructor returned -1. See talloc_set_destructor() for details on
destructors.
If this pointer has an additional reference when talloc_free() is
called then the memory is not actually released, but instead the most
recently established reference is destroyed. See talloc_reference()
for details on establishing additional references.
If this pointer has an additional parent when talloc_free() is called
then the memory is not actually released, but instead the most
recently established parent is destroyed. See talloc_reference() for
details on establishing additional parents.
For more control on which parent is removed, see talloc_unlink()
@ -114,8 +114,8 @@ talloc_free() operates recursively on its children.
=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
void *talloc_reference(const void *context, const void *ptr);
The talloc_reference() function returns an additional reference to
"ptr", and makes this additional reference a child of "context".
The talloc_reference() function makes "context" an additional parent
of "ptr".
The return value of talloc_reference() is always the original pointer
"ptr", unless talloc ran out of memory in creating the reference in
@ -125,19 +125,14 @@ around 48 bytes of memory on intel x86 platforms).
After creating a reference you can free it in one of the following
ways:
- you can talloc_free() a parent of the original pointer. That will
destroy the reference and make the pointer a child of the
"context" argument from the most recently called
talloc_reference() on the pointer.
- you can talloc_free() any parent of the original pointer. That
will reduce the number of parents of this pointer by 1, and will
cause this pointer to be freed if it runs out of parents.
- you can talloc_free() the pointer itself. That will destroy the
most recently established reference to the pointer and leave the
most recently established parent to the pointer and leave the
pointer as a child of its current parent.
- you can talloc_free() the context where you placed the
reference. That will destroy the reference, and leave the pointer
where it is.
For more control on which parent to remove, see talloc_unlink()
@ -205,6 +200,14 @@ The main use for names on pointer is for "talloc reports". See
talloc_report() and talloc_report_full() for details. Also see
talloc_enable_leak_report() and talloc_enable_leak_report_full().
The talloc_set_name() function allocates memory as a child of the
pointer. It is logically equivalent to:
talloc_set_name_const(ptr, talloc_asprintf(ptr, fmt, ...));
Note that multiple calls to talloc_set_name() will allocate more
memory without releasing the name. All of the memory is released when
the ptr is freed using talloc_free().
=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
void talloc_set_name_const(const void *ptr, const char *name);
@ -213,6 +216,11 @@ The function talloc_set_name_const() is just like talloc_set_name(),
but it takes a string constant, and is much faster. It is extensively
used by the "auto naming" macros, such as talloc_p().
This function does not allocate any memory. It just copies the
supplied pointer into the internal representation of the talloc
ptr. This means you must not pass a name pointer to memory that will
disappear before the ptr is freed with talloc_free().
=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
void *talloc_named(const void *context, size_t size, const char *fmt, ...);
@ -263,7 +271,7 @@ is ignored.
talloc_realloc() returns the new pointer, or NULL on failure. The call
will fail either due to a lack of memory, or because the pointer has
an reference (see talloc_reference()).
more than one parent (see talloc_reference()).
=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
@ -408,6 +416,9 @@ The talloc_strdup() function is equivalent to:
ptr = talloc(ctx, strlen(p)+1);
if (ptr) memcpy(ptr, p, strlen(p)+1);
This functions sets the name of the new pointer to the passed
string. This is equivalent to:
talloc_set_name_const(ptr, ptr)
=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
char *talloc_strndup(const void *t, const char *p, size_t n);
@ -415,6 +426,10 @@ char *talloc_strndup(const void *t, const char *p, size_t n);
The talloc_strndup() function is the talloc equivalent of the C
library function strndup()
This functions sets the name of the new pointer to the passed
string. This is equivalent to:
talloc_set_name_const(ptr, ptr)
=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
char *talloc_vasprintf(const void *t, const char *fmt, va_list ap);
@ -429,6 +444,10 @@ char *talloc_asprintf(const void *t, const char *fmt, ...);
The talloc_asprintf() function is the talloc equivalent of the C
library function asprintf()
This functions sets the name of the new pointer to the passed
string. This is equivalent to:
talloc_set_name_const(ptr, ptr)
=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
char *talloc_asprintf_append(char *s, const char *fmt, ...);