Re: [PATCH] bisect: save heap memory. allocate only the required amount

> Arjun Sreedharan <arjun024@gmail.com> writes:
>
>> Find and allocate the required amount instead of allocating extra
>> 100 bytes
>>
>> Signed-off-by: Arjun Sreedharan <arjun024@gmail.com>
>> ---
>
> Interesting.  How much memory do we typically waste (in other words,
> how big did "cnt" grew in your repository where you noticed this)?
>

>>  bisect.c | 7 +++++--
>>  1 file changed, 5 insertions(+), 2 deletions(-)
>>
>> diff --git a/bisect.c b/bisect.c
>> index d6e851d..c96aab0 100644
>> --- a/bisect.c
>> +++ b/bisect.c
>> @@ -215,10 +215,13 @@ static struct commit_list *best_bisection_sorted(struct commit_list *list, int n
>>       }
>>       qsort(array, cnt, sizeof(*array), compare_commit_dist);
>>       for (p = list, i = 0; i < cnt; i++) {
>> -             struct name_decoration *r = xmalloc(sizeof(*r) + 100);
>> +             char name[100];
>> +             sprintf(name, "dist=%d", array[i].distance);
>> +             int name_len = strlen(name);
>
> Decl-after-stmt.
>
> You do not have to run a separate strlen() for this.  The return
> value from sprintf() should tell you how much you need to allocate,
> I think.
>

>> +             struct name_decoration *r = xmalloc(sizeof(*r) + name_len);
>>               struct object *obj = &(array[i].commit->object);
>>
>> -             sprintf(r->name, "dist=%d", array[i].distance);
>> +             memcpy(r->name, name, name_len + 1);
>>               r->next = add_decoration(&name_decoration, obj, r);
>>               p->item = array[i].commit;
>>               p = p->next;