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Date: Wed, 07 Jan 2015 18:34:00 -0000
From: Eli Zaretskii <eliz@gnu.org>
Subject: Re: [PATCH] Speed up "gdb -tui" output
In-reply-to: <CADPb22QqTE+yq9RSRmvBiu0tdy++8S40D8xzKi6k8nLYmiN48g@mail.gmail.com>
To: Doug Evans <dje@google.com>
Cc: palves@redhat.com, gdb-patches@sourceware.org
Reply-to: Eli Zaretskii <eliz@gnu.org>
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> Date: Wed, 7 Jan 2015 10:09:03 -0800
> From: Doug Evans <dje@google.com>
> Cc: Pedro Alves <palves@redhat.com>, gdb-patches <gdb-patches@sourceware.org>
> 
> >> Should it be calling wrefresh if the file is gdb_stdout?
> >
> > Only if that stream is a real file, not a string or whatever else we
> > support in ui-file.
> 
> tui_file_flush only gets called for tui files

That's not really true, as you yourself point out:

> Though I see tui also has its own ui file strings (tui_sfileopen).
> That can go I think.

I don't see how it could go: it's used.

> >> If we do that, and change tui_puts like:
> >>
> >>  -  /* We could defer the following.  */
> >>  -  wrefresh (w);
> >>  -  fflush (stdout);
> >>  +   if (c == '\n')
> >>  +    gdb_flush (gdb_stdout);
> >>
> >> would it work?
> >
> > No, it's not enough.  There's also gdb_stderr and gdb_stdlog, at
> > least. (tui_puts doesn't get the stream as its argument, so it
> > doesn't really know which stream it is serving.)  I'm trying to make
> > heads or tails out of this, but I'm not there yet.
> 
> Sure, but it does suggest tui_puts is the wrong place to do
> any kind of flushing/refreshing.

How else can you emulate the unbuffered nature of gdb_stderr and the
line-buffered nature of gdb_stdout, for example?  The GDB application
code implicitly expects that.