[rrd-developers] [PATCH 1/2] Add utility functions to allocate pointers in variable size chunks.

[Tobias Oetiker]

Hi Kevin,

since 1.4.x is now out, I would like to hold off on adding new
public functions to the 1.4 branche ... these would go into the new
trunk. or is there also a bug-fix component to this change ?

cheers
tobi

Oct 31 kevin brintnall wrote:

> ---
>  doc/librrd.pod  |   18 ++++++++++++++++++
>  src/rrd.h       |    4 ++++
>  src/rrd_utils.c |   53 ++++++++++++++++++++++++++++++++++++++++++-----------
>  3 files changed, 64 insertions(+), 11 deletions(-)
>
> diff --git a/doc/librrd.pod b/doc/librrd.pod
> index 038746c..396e50c 100644
> --- a/doc/librrd.pod
> +++ b/doc/librrd.pod
> @@ -81,6 +81,16 @@ end of the new C<dest>.  Returns 1 on success, 0 on failure.
>      if (!rrd_add_ptr(&arr, &arr_size, elem))
>          handle_failure();
>
> +=item B<rrd_add_ptr_chunk(void ***dest, size_t *dest_size, void *src, size_t *alloc, size_t chunk)>
> +
> +Like C<rrd_add_ptr>, except the destination is allocated in chunks of
> +C<chunk>.  C<alloc> points to the number of entries allocated, whereas
> +C<dest_size> points to the number of valid pointers.  If more pointers are
> +needed, C<chunk> pointers are allocated and C<alloc> is increased
> +accordingly.  C<alloc> must be E<gt>= C<dest_size>.
> +
> +This method improves performance on hosts with expensive C<realloc()>.
> +
>  =item B<rrd_add_strdup(char ***dest, size_t *dest_size, char *src)>
>
>  Like C<rrd_add_ptr>, except adds a C<strdup> of the source string.
> @@ -91,6 +101,14 @@ Like C<rrd_add_ptr>, except adds a C<strdup> of the source string.
>      if (!rrd_add_strdup(&arr, &arr_size, str))
>          handle_failure();
>
> +=item B<rrd_add_strdup_chunk(char ***dest, size_t *dest_size, char *src, size_t *alloc, size_t chunk)>
> +
> +Like C<rrd_add_strdup>, except the destination is allocated in chunks of
> +C<chunk>.  C<alloc> points to the number of entries allocated, whereas
> +C<dest_size> points to the number of valid pointers.  If more pointers are
> +needed, C<chunk> pointers are allocated and C<alloc> is increased
> +accordingly.  C<alloc> must be E<gt>= C<dest_size>.
> +
>  =item B<rrd_free_ptrs(void ***src, size_t *cnt)>
>
>  Free an array of pointers allocated by C<rrd_add_ptr> or
> diff --git a/src/rrd.h b/src/rrd.h
> index ce7e749..6008794 100644
> --- a/src/rrd.h
> +++ b/src/rrd.h
> @@ -333,8 +333,12 @@ int       rrd_proc_start_end(
>
>      long rrd_random(void);
>
> +    int rrd_add_ptr_chunk(void ***dest, size_t *dest_size, void *src,
> +                          size_t *alloc, size_t chunk);
>      int rrd_add_ptr(void ***dest, size_t *dest_size, void *src);
>      int rrd_add_strdup(char ***dest, size_t *dest_size, char *src);
> +    int rrd_add_strdup_chunk(char ***dest, size_t *dest_size, char *src,
> +                             size_t *alloc, size_t chunk);
>      void rrd_free_ptrs(void ***src, size_t *cnt);
>
>      int rrd_mkdir_p(const char *pathname, mode_t mode);
> diff --git a/src/rrd_utils.c b/src/rrd_utils.c
> index 3936cff..6853c66 100644
> --- a/src/rrd_utils.c
> +++ b/src/rrd_utils.c
> @@ -50,29 +50,53 @@ long rrd_random(void)
>      return random();
>  }
>
> -/* rrd_add_ptr: add a pointer to a dynamically sized array of pointers,
> - * realloc as necessary.  returns 1 on success, 0 on failure.
> +/* rrd_add_ptr_chunk: add a pointer to a dynamically sized array of
> + * pointers, realloc as necessary in multiples of "chunk".
> + *
> + * "alloc" is the number of pointers allocated
> + * "dest_size" is the number of valid pointers
> + *
> + * returns 1 on success, 0 on failure.
>   */
>
> -int rrd_add_ptr(void ***dest, size_t *dest_size, void *src)
> +int rrd_add_ptr_chunk(void ***dest, size_t *dest_size, void *src,
> +                      size_t *alloc, size_t chunk)
>  {
>      void **temp;
>
>      assert(dest != NULL);
> +    assert(alloc != NULL);
> +    assert(*alloc >= *dest_size);
>
> -    temp = (void **) rrd_realloc(*dest, (*dest_size+1) * sizeof(*dest));
> -    if (!temp)
> -        return 0;
> +    if (*alloc == *dest_size)
> +    {
> +        temp = (void **) rrd_realloc(*dest, (*alloc+chunk) * sizeof(*dest));
> +        if (!temp)
> +            return 0;
>
> -    *dest = temp;
> -    temp[*dest_size] = src;
> +        *dest = temp;
> +        *alloc += chunk;
> +    }
> +
> +    (*dest)[*dest_size] = src;
>      (*dest_size)++;
>
>      return 1;
>  }
>
> -/* like rrd_add_ptr, but calls strdup() on a string first. */
> -int rrd_add_strdup(char ***dest, size_t *dest_size, char *src)
> +/* rrd_add_ptr: add a pointer to a dynamically sized array of pointers,
> + * realloc as necessary.  returns 1 on success, 0 on failure.
> + */
> +int rrd_add_ptr(void ***dest, size_t *dest_size, void *src)
> +{
> +    size_t alloc = *dest_size;
> +
> +    return rrd_add_ptr_chunk(dest, dest_size, src, &alloc, 1);
> +}
> +
> +/* like rrd_add_ptr_chunk, but calls strdup() on a string first. */
> +int rrd_add_strdup_chunk(char ***dest, size_t *dest_size, char *src,
> +                         size_t *alloc, size_t chunk)
>  {
>      char *dup_src;
>      int add_ok;
> @@ -84,13 +108,20 @@ int rrd_add_strdup(char ***dest, size_t *dest_size, char *src)
>      if (!dup_src)
>          return 0;
>
> -    add_ok = rrd_add_ptr((void ***)dest, dest_size, (void *)dup_src);
> +    add_ok = rrd_add_ptr_chunk((void ***)dest, dest_size, (void *)dup_src, alloc, chunk);
>      if (!add_ok)
>          free(dup_src);
>
>      return add_ok;
>  }
>
> +int rrd_add_strdup(char ***dest, size_t *dest_size, char *src)
> +{
> +    size_t alloc = *dest_size;
> +
> +    return rrd_add_strdup_chunk(dest, dest_size, src, &alloc, 1);
> +}
> +
>  void rrd_free_ptrs(void ***src, size_t *cnt)
>  {
>      void **sp;
>

-- 
Tobi Oetiker, OETIKER+PARTNER AG, Aarweg 15 CH-4600 Olten, Switzerland
http://it.oetiker.ch tobi at oetiker.ch ++41 62 775 9902 / sb: -9900