FriBidiEnv (was: Re: [FriBidi] fribidi and shaping arabic characters)

[Behdad Esfahbod]

On Fri, 27 Jan 2006, Omer Zak wrote:

> FriBidiEnv (as argument) was introduced to support usage of FriBidi in
> operating systems, which do not support static memory (the operating
> systems in question were GEOS - used in Nokia 9110 cellular phone/FAX;
> and Symbian OS, used in several cellular smartphones by Nokia,
> Sony-Ericsson and others).
>
> In operating systems, which support static memory (such as Linux), the
> FriBidi library sets aside memory for one instance of FriBidiEnv, and it
> is accessed when the argument is set to NULL.
>
> In addition, multithreaded applications need to have a separate
> FriBidiEnv instance for each thread, which needs to use the FriBidi
> library.

Hi Omer,

In the fribidi2 module, I have reimplemented this functionality
by introducing a flags type FriBidiFlags, that is passed to all
the functions that need configurations.

There are still four static variables in the code:

  * fribidi.c (fribidi_debug): Only available if FriBidi is
configured with debugging enabled.

  * fribidi-deprecated.c (flags): Only used to keep the flags for
deprecated functions like fribidi_log2vis that do not take a
flags parameter themselves.

  * fribidi-run.c (free_runs, run_mem_chunk): Used if FriBidi is
not configured to use malloc for each run.


So, to make a thread-safe build of FriBidi with no static memory,
one can build without --disable-debug --enable-malloc, and don't
build the deprecated stuff...  I'm going to add an option
--disable-depreacted for that.  I may even make --enable-malloc
the default, but that's going to slow down FriBidi a bit, and
it's not really used with multi-threaded applications
currently...

behdad



> Due to the need for support for multithreaded applications, I recommend
> to explain to the Debian maintainers about this issue.
>                                                      --- Omer
>
> On Fri, 2006-01-27 at 14:52 -0500, Behdad Esfahbod wrote:
> > On Fri, 27 Jan 2006, kobi zamir wrote:
> >
> > > Hello,
> > >
> > > Fribidi ver. 0.11.0-2 (current cvs) change the log2vis function signiture.
> > > it now has a new argument [ FriBidiEnv *fribidienv ]
> > >
> > > I see that you can call this function with *ribidienv=NULL and get the
> > > same results. what is fribidienv used for ?
> > >
> > > This change in the api may cause linux distributions like debian  not
> > > to upgrade
> > > there fribidi version to 0.11.0 to keep there mlterm, pango ... working.
> > >
> > > Any way around this ?
> >
> > Forget about HEAD.  You should checkout the fribidi2 module.
> > That's documented on the wiki at fribidi.org.  Please test that
> > code base.
>
>

--behdad
http://behdad.org/

"Commandment Three says Do Not Kill, Amendment Two says Blood Will Spill"
	-- Dan Bern, "New American Language"