Re: [Findutils-patches] ./configure-time setting of default arg size

[Eric Blake]

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According to James Youngman on 7/30/2007 10:11 AM:
> On 7/30/07, Eric Blake <address@hidden> wrote:
>> OK, I'll rework the patch along those lines.  Would the macro name
>> DEFAULT_ARG_SIZE be better than ARG_SIZE here?
> 
> Sure.
> 
>> Based on my additional
>> comments to #20594, I think it is still worth tying this patch to 20594; I
>> just have to be careful to not call it a bug fix (because it is not a
>> findutils bug that cygwin's current choice of _SC_ARG_MAX values doesn't
>> work when invoking non-cygwin apps), but instead call it an enhancement.
> 
> That seems sound to me.

With that, here's the revised patch.  OK to commit?

2007-07-31  Eric Blake  <address@hidden>

        Allow choice of default arg size, Savannah bug #20594.
        * configure.ac (DEFAULT_ARG_SIZE): Check environment for a default
        size override.
        * lib/buildcmd.c (bc_use_sensible_arg_max): Use default size from
        configure, if requested.
        * README (DEFAULT_ARG_SIZE): Mention the ability to tune this at
        configure time.
        * NEWS: Document the change.

- --
Don't work too hard, make some time for fun as well!

Eric Blake             address@hidden
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Index: NEWS
===================================================================
RCS file: /sources/findutils/findutils/NEWS,v
retrieving revision 1.198
diff -u -p -r1.198 NEWS
--- NEWS        22 Jul 2007 13:52:51 -0000      1.198
+++ NEWS        31 Jul 2007 12:56:46 -0000
@@ -7,6 +7,7 @@ Findutils version 4.3.9 is released unde
 Public License.
 
 ** Bug Fixes
+
 #20310: configure uses hosts's support status for "sort -z" when
 generating the updatedb script for use on the target.  This is
 inappropriate when cross-compiling, so avoid doing that.
@@ -26,6 +27,11 @@ does not follow the POSIX rules of doing
 updatedb, frcode and code now complies with the GNU Project's coding
 standards.
 
+** Enhancements
+
+#20594: Allow fine-tuning of the default argument size used by xargs
+and find at ./configure time.
+
 ** Documentation Fixes
 
 Point out more explicitly that the subsecond timestamp support
Index: README
===================================================================
RCS file: /sources/findutils/findutils/README,v
retrieving revision 1.6
diff -u -p -r1.6 README
--- README      27 Feb 2005 22:04:44 -0000      1.6
+++ README      31 Jul 2007 12:56:46 -0000
@@ -36,6 +36,13 @@ doing.  This information includes detail
 has been parsed and what files have been stat()ed.  This output is
 normally interesting only to the maintainer, and so is off by default.
 
+DEFAULT_ARG_SIZE=<value>
+  If this environment variable is defined to a numeric expression
+during configure, it determines the default argument size limits used
+by xargs without -s, and by find, when spawning child processes.
+Otherwise, the default is set at 128 kibibytes.  If the system cannot
+support the default limit, the system's limit will be used instead.
+
 
 To gain speed, GNU find avoids statting files whenever possible.
 It does this by:
Index: lib/buildcmd.c
===================================================================
RCS file: /sources/findutils/findutils/lib/buildcmd.c,v
retrieving revision 1.27
diff -u -p -r1.27 buildcmd.c
--- lib/buildcmd.c      2 Jul 2007 08:25:43 -0000       1.27
+++ lib/buildcmd.c      31 Jul 2007 12:56:46 -0000
@@ -500,8 +500,12 @@ bc_init_controlinfo(struct buildcmd_cont
 void
 bc_use_sensible_arg_max(struct buildcmd_control *ctl)
 {
+#ifdef DEFAULT_ARG_SIZE
+  enum { arg_size = DEFAULT_ARG_SIZE };
+#else
   enum { arg_size = (128u * 1024u) };
-  
+#endif
+
   /* Check against the upper and lower limits. */  
   if (arg_size > ctl->posix_arg_size_max)
     ctl->arg_max = ctl->posix_arg_size_max;
@@ -547,4 +551,3 @@ bc_clear_args(const struct buildcmd_cont
   state->todo = 0;
   state->dirfd = -1;
 }
-
Index: configure.ac
===================================================================
RCS file: /sources/findutils/findutils/configure.ac,v
retrieving revision 1.1
diff -u -p -b -r1.1 configure.ac
--- configure.ac        18 Jul 2007 03:40:46 -0000      1.1
+++ configure.ac        31 Jul 2007 12:56:49 -0000
@@ -61,6 +61,13 @@ else
    AC_DEFINE(LEAF_OPTIMISATION, 1, [Define if you want to use the leaf 
optimisation (this can still be turned off with -noleaf)])
 fi
 
+AC_ARG_VAR([DEFAULT_ARG_SIZE], [Default size of arguments to child processes
+of find and xargs, 128k if unspecified])
+if test -n "$DEFAULT_ARG_SIZE"; then
+   AC_DEFINE_UNQUOTED([DEFAULT_ARG_SIZE], [$DEFAULT_ARG_SIZE],
+     [If defined, the default argument size used in child processes])
+fi
+
 
 
 dnl Checks for programs.