[HarfBuzz] [Feature Request] Custom allocator support

Jamie Dale jamiedale88+harfbuzz at gmail.com
Mon Oct 5 11:58:19 PDT 2015


Just tested this and it worked fine. Thanks :)

On 3 October 2015 at 13:20, Behdad Esfahbod <behdad.esfahbod at gmail.com>
wrote:

> On 15-10-02 10:00 PM, Jamie Dale wrote:
> > That's similar to what I originally had, so I'm fine with something like
> that.
> > My only question is, what would hb_malloc_impl, hb_calloc_impl,
> > hb_realloc_impl, and hb_free_impl be defined to in your example?
>
> Define it to the name of your external function.  I don't want to fix a
> name
> in HarfBuzz itself.  Updated patch to add externs:
>
> diff --git a/src/hb-private.hh b/src/hb-private.hh
> index 07550cb..826e41a 100644
> --- a/src/hb-private.hh
> +++ b/src/hb-private.hh
> @@ -54,6 +54,23 @@
>  #include <stdarg.h>
>
>
> +/* Compile-time custom allocator support. */
> +
> +#if defined(hb_malloc_impl) \
> + && defined(hb_calloc_impl) \
> + && defined(hb_realloc_impl) \
> + && defined(hb_free_impl)
> +extern void* hb_malloc_impl(size_t size);
> +extern void* hb_calloc_impl(size_t nmemb, size_t size);
> +extern void* hb_realloc_impl(void *, size_t size);
> +extern void  hb_free_impl(void *ptr);
> +#define malloc hb_malloc_impl
> +#define calloc hb_calloc_impl
> +#define realloc hb_realloc_impl
> +#define free hb_free_impl
> +#endif
> +
>
> I'll go ahead and commit this.  Let me know if it doesn't work.
>
> > I went with the extern function approach so I could inject my own
> allocator
> > functions into HarfBuzz at link time, rather than have to include any of
> our
> > code into HarfBuzz at compile time (since any local code changes we make
> have
> > to be re-applied against new versions).
> >
> > For your reference, this was my original implementation:
> >
> > /* Override the allocation functions when
> >  * HAVE_EXTERNAL_ALLOCATOR is defined. */
> > #ifdef HAVE_EXTERNAL_ALLOCATOR
> > extern void* _hb_malloc(size_t);
> > extern void* _hb_calloc(size_t, size_t);
> > extern void* _hb_realloc(void*, size_t);
> > extern void _hb_free(void*);
> > #define malloc _hb_malloc
> > #define calloc _hb_calloc
> > #define realloc _hb_realloc
> > #define free _hb_free
> > #endif
> >
> > Failure to define those functions in something that linked to HarfBuzz
> would
> > produce an unresolved external symbol error at link time.
> >
> > -Jamie.
> >
> > On 2 October 2015 at 08:08, Behdad Esfahbod <behdad.esfahbod at gmail.com
> > <mailto:behdad.esfahbod at gmail.com>> wrote:
> >
> >     Hi Jamie,
> >
> >     I'm opposed to runtime custom allocators, but am fine with something
> like what
> >     you suggest.  However, that has two down sides:
> >
> >       1. It touches a lot of callsites,
> >
> >       2. I have to add macros to make sure stock malloc etc are not used
> by
> >     mistake.
> >
> >     If doing 2., I might as well just define them to their custom
> behavior.  Ie,
> >     would this patch work for you:
> >
> >     diff --git a/src/hb-private.hh b/src/hb-private.hh
> >     index 07550cb..167c067 100644
> >     --- a/src/hb-private.hh
> >     +++ b/src/hb-private.hh
> >     @@ -54,6 +54,19 @@
> >      #include <stdarg.h>
> >
> >
> >     +/* Compile-time custom allocator support. */
> >     +
> >     +#if defined(hb_malloc_impl) \
> >     + && defined(hb_calloc_impl) \
> >     + && defined(hb_realloc_impl) \
> >     + && defined(hb_free_impl)
> >     +#define malloc hb_malloc_impl
> >     +#define calloc hb_calloc_impl
> >     +#define realloc hb_realloc_impl
> >     +#define free hb_free_impl
> >     +#endif
> >     +
> >     +
> >      /* Compiler attributes */
> >
> >
> >
> >
> >     On 15-09-30 03:49 PM, Jamie Dale wrote:
> >     > Since there was no movement here I went ahead and hacked in our
> allocator by
> >     > redefining malloc, calloc, realloc, and free to point to extern'd
> functions
> >     > that I define in our application. This yielded some performance
> benefits for
> >     > us, so I'm hoping that a more standard HarfBuzz solution might
> appear at
> >     some
> >     > point :)
> >     >
> >     > If you're not keen on the idea of allowing the allocator to be
> swapped
> >     out at
> >     > runtime, would you at least allow it to be extern'd at compile
> time? I'm not
> >     > familiar with HarfBuzz coding standards, but I'd propose adding
> >     something like
> >     > a HAVE_EXTERNAL_ALLOCATOR define to control this, and then define
> your own
> >     > allocator functions that you'd use in place of malloc, etc.
> >     >
> >     > Basically, something like this (I currently have this code in
> >     hb-private.hh):
> >     >
> >     > /* Define our allocation functions. These may be provided by an
> >     >  * external source when HAVE_EXTERNAL_ALLOCATOR is defined. */
> >     > #ifdef HAVE_EXTERNAL_ALLOCATOR
> >     > extern void* _hb_malloc(size_t);
> >     > extern void* _hb_calloc(size_t, size_t);
> >     > extern void* _hb_realloc(void*, size_t);
> >     > extern void _hb_free(void*);
> >     > #define hb_malloc _hb_malloc
> >     > #define hb_calloc _hb_calloc
> >     > #define hb_realloc _hb_realloc
> >     > #define hb_free _hb_free
> >     > #else
> >     > #define hb_malloc malloc
> >     > #define hb_calloc calloc
> >     > #define hb_realloc realloc
> >     > #define hb_free free
> >     > #endif
> >     >
> >     > You'd then replace calls to malloc, calloc, realloc, and free from
> within
> >     > HarfBuzz to use hb_malloc, hb_calloc, hb_realloc, and hb_free.
> >     >
> >     > This is basically the code I already have, except I
> >     > redefined malloc, calloc, realloc, and free rather than create the
> >     > hb_*variants, as I didn't want to change too much HarfBuzz code.
> >     >
> >     > Thoughts?
> >     >
> >     > On 31 August 2015 at 22:17, Jamie Dale <
> jamiedale88+harfbuzz at gmail.com <mailto:jamiedale88%2Bharfbuzz at gmail.com>
> >     > <mailto:jamiedale88+harfbuzz at gmail.com <mailto:
> jamiedale88%2Bharfbuzz at gmail.com>>>
> >     wrote:
> >     >
> >     >     Hey,
> >     >
> >     >     I'm not sure if this is correct place to post/discuss feature
> requests...
> >     >     hopefully it is.
> >     >
> >     >     Our project makes use of a custom memory allocator, and we
> like to ensure
> >     >     that our third-party libraries are using this where possible,
> as our
> >     >     allocator can offer significantly better performance, and can
> also allow
> >     >     us better memory profiling and debugging support.
> >     >
> >     >     A look through the HarfBuzz source code would suggest that it
> doesn't
> >     >     currently support custom memory allocators, and instead just
> directly
> >     >     calls the standard malloc/free/etc functions. I was wondering
> if you'd
> >     >     ever considered (or would consider) adding a way to override
> this behaviour?
> >     >
> >     >     In my case, I'd just need a single global override to be set
> before my
> >     >     first call to any other HarfBuzz code... basically something
> like
> >     >     the FT_Memory struct from FreeType:
> >     >
> http://www.freetype.org/freetype2/docs/reference/ft2-system_interface.html#FT_Memory
> >     >
> >     >     Thanks,
> >     >     Jamie.
> >     >
> >     >
> >     >
> >     >
> >     > _______________________________________________
> >     > HarfBuzz mailing list
> >     > HarfBuzz at lists.freedesktop.org <mailto:
> HarfBuzz at lists.freedesktop.org>
> >     > http://lists.freedesktop.org/mailman/listinfo/harfbuzz
> >     >
> >
> >
>
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