src/parsec/disk-image/parsec/parsec-benchmark/pkgs/libs/glib/src/docs/reference/glib/running.sgml - public/gem5-resources - Git at Google

 <?xml version="1.0"?>
 <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.3//EN"
                "http://www.oasis-open.org/docbook/xml/4.3/docbookx.dtd" [
 ]>
 <refentry id="glib-running" revision="17 Jan 2002">
 <refmeta>
 <refentrytitle>Running GLib Applications</refentrytitle>
 <manvolnum>3</manvolnum>
 <refmiscinfo>GLib Library</refmiscinfo>
 </refmeta>

 <refnamediv>
 <refname>Running GLib Applications</refname>
 <refpurpose>
 How to run and debug your GLib application
 </refpurpose>
 </refnamediv>

 <refsect1>
 <title>Running and debugging GLib Applications</title>

 <refsect2>
 <title>Environment variables</title>

 <para>
 GLib inspects a few of environment variables in addition to standard
 variables like <envar>LANG</envar>, <envar>PATH</envar> or <envar>HOME</envar>.
 </para>

 <formalpara id="G_FILENAME_ENCODING">
   <title><envar>G_FILENAME_ENCODING</envar></title>

   <para>
     This environment variable can be set to a comma-separated list of character
     set names. GLib assumes that filenames are encoded in the first character
     set from that list rather than in UTF-8. The special token "@locale" can be
     used to specify the character set for the current locale.
   </para>
 </formalpara>

 <formalpara id="G_BROKEN_FILENAMES">
   <title><envar>G_BROKEN_FILENAMES</envar></title>

   <para>
     If this environment variable is set, GLib assumes that filenames are in
     the locale encoding rather than in UTF-8. G_FILENAME_ENCODING takes
     priority over G_BROKEN_FILENAMES.
   </para>
 </formalpara>

 <formalpara id="G_MESSAGES_PREFIXED">
   <title><envar>G_MESSAGES_PREFIXED</envar></title>

   <para>
     A list of log levels for which messages should be prefixed by the
     program name and PID of the application. The default is to prefix
     everything except <literal>G_LOG_LEVEL_MESSAGE</literal> and <literal>G_LOG_LEVEL_INFO</literal>.
   </para>
 </formalpara>

 <formalpara id="G_DEBUG">
   <title><envar>G_DEBUG</envar></title>
   <para>
     If GLib has been configured with <option>--enable-debug=yes</option>,
     this variable can be set to a list of debug options, which cause GLib
     to print out different types of debugging information.
     <variablelist>
       <varlistentry>
         <term>fatal_warnings</term>
         <listitem><para>Causes GLib to abort the program at the first call
            to <link linkend="g-warning">g_warning</link>() or
 	   <link linkend="g-critical">g_critical</link>(). This option is
            special in that it doesn't require GLib to be configured with
            debugging support.</para>
         </listitem>
       </varlistentry>
       <varlistentry>
         <term>fatal_criticals</term>
         <listitem><para>Causes GLib to abort the program at the first call
            to <link linkend="g-critical">g_critical</link>(). This option is
            special in that it doesn't require GLib to be configured with
            debugging support.</para>
         </listitem>
       </varlistentry>
       <varlistentry>
         <term>gc-friendly</term>
 	<listitem>
 		<para>
 		  Newly allocated memory that isn't directly initialized, as well
 		  as memory being freed will be reset to 0. The point here is to
 		  allow memory checkers and similar programs that use bohem GC alike
 		  algorithms to produce more accurate results.
 		  This option is special in that it doesn't require GLib to be
 		  configured with debugging support.
 		</para>
         </listitem>
       </varlistentry>
       <varlistentry>
         <term>resident-modules</term>
 	<listitem>
 	  <para>
 	    All modules loaded by GModule will be made resident. This can be useful
 	    for tracking memory leaks in modules which are later unloaded; but it can
 	    also hide bugs where code is accessed after the module would have normally
 	    been unloaded.
 	    This option is special in that it doesn't require GLib to be
  	    configured with debugging support.
 	  </para>
         </listitem>
       </varlistentry>
       <varlistentry>
         <term>bind-now-modules</term>
 	<listitem>
 	  <para>
 	    All modules loaded by GModule will bind their symbols at load time, even
 	    when the code uses %G_MODULE_BIND_LAZY.
 	    This option is special in that it doesn't require GLib to be
  	    configured with debugging support.
 	  </para>
         </listitem>
       </varlistentry>
     </variablelist>
     The special value all can be used to turn on all debug options.
     The special value help can be used to print all available options.
   </para>
 </formalpara>

 <formalpara id="G_SLICE">
 	<title><envar>G_SLICE</envar></title>
 	<para>
 	  This environment variable allows reconfiguration of the GSlice
 	  memory allocator.
 	  <variablelist>
 	    <varlistentry>
 	      <term>always-malloc</term>
 	      <listitem>
 		<para>
 		  This will cause all slices allocated through g_slice_alloc() and
 		  released by g_slice_free1() to be actually allocated via direct
 		  calls to g_malloc() and g_free().
 		  This is most useful for memory checkers and similar programs that
 		  use Bohem GC alike algorithms to produce more accurate results.
 		  It can also be in conjunction with debugging features of the system's
 		  malloc implementation such as glibc's MALLOC_CHECK_=2 to debug
 		  erroneous slice allocation code, allthough <literal>debug-blocks</literal>
 		  usually is a better suited debugging tool.
 		</para>
 	      </listitem>
 	    </varlistentry>
 	    <varlistentry>
 	      <term>debug-blocks</term>
 	      <listitem>
 		<para>
 		  Using this option (present since GLib-2.13) engages extra code
 		  which performs sanity checks on the released memory slices.
 		  Invalid slice adresses or slice sizes will be reported and lead to
 		  a program halt.
 		  This option is for debugging scenarios.
 		  In particular, client packages sporting their own test suite should
 		  <emphasis>always enable this option when running tests</emphasis>.
 		  Global slice validation is ensured by storing size and address information
 		  for each allocated chunk, and maintaining a global hash table of that data.
 		  That way, multi-thread scalability is given up, and memory consumption is
 		  increased. However, the resulting code usually performs acceptably well,
 		  possibly better than with comparable memory checking carried out using
 		  external tools. An example of a memory corruption scenario that cannot be
 		  reproduced with <literal>G_SLICE=always-malloc</literal>, but will be caught
 		  by <literal>G_SLICE=debug-blocks</literal> is as follows:
 		  <programlisting>
 		    void *slist = g_slist_alloc(); /* void* gives up type-safety */
 		    g_list_free (slist);           /* corruption: sizeof (GSList) != sizeof (GList) */
 		  </programlisting>
 		</para>
 	      </listitem>
 	    </varlistentry>
 	  </variablelist>
           The special value all can be used to turn on all options.
           The special value help can be used to print all available options.
 	</para>
 </formalpara>

 <formalpara id="G_RANDOM_VERSION">
   <title><envar>G_RANDOM_VERSION</envar></title>

   <para>
     If this environment variable is set to '2.0', the outdated
     pseudo-random number seeding and generation algorithms from
     GLib-2.0 are used instead of the new better ones. Use the GLib-2.0
     algorithms only if you have sequences of numbers generated with
     Glib-2.0 that you need to reproduce exactly.
   </para>
 </formalpara>

 <formalpara id="LIBCHARSET_ALIAS_DIR">
   <title><envar>LIBCHARSET_ALIAS_DIR</envar></title>

   <para>
     Allows to specify a nonstandard location for the
     <filename>charset.aliases</filename> file that is used by the
     character set conversion routines. The default location is the
     <replaceable>libdir</replaceable> specified at compilation time.
   </para>
 </formalpara>

 </refsect2>

 <refsect2 id="setlocale">
 <title>Locale</title>

 <para>
 A number of interfaces in GLib depend on the current locale in which
 an application is running. Therefore, most GLib-using applications should
 call <function>setlocale (LC_ALL, "")</function> to set up the current
 locale.
 </para>

 <para>
 On Windows, in a C program there are several locale concepts
 that not necessarily are synchronized. On one hand, there is the
 system default ANSI code-page, which determines what encoding is used
 for file names handled by the C library's functions and the Win32
 API. (We are talking about the "narrow" functions here that take
 character pointers, not the "wide" ones.)
 </para>

 <para>
 On the other hand, there is the C library's current locale. The
 character set (code-page) used by that is not necessarily the same as
 the system default ANSI code-page. Strings in this character set are
 returned by functions like <function>strftime()</function>.
 </para>

 </refsect2>

 <refsect2>
 <title>Traps and traces</title>

 <para>
 <indexterm><primary>g_trap_free_size</primary></indexterm>
 <indexterm><primary>g_trap_realloc_size</primary></indexterm>
 <indexterm><primary>g_trap_malloc_size</primary></indexterm>
 Some code portions contain trap variables that can be set during debugging
 time if GLib has been configured with <option>--enable-debug=yes</option>.
 Such traps lead to immediate code halts to examine the current program state
 and backtrace.
 </para>

 <para>
 Currently, the following trap variables exist:
 <programlisting>
 static volatile gulong g_trap_free_size;
 static volatile gulong g_trap_realloc_size;
 static volatile gulong g_trap_malloc_size;
 </programlisting>
 If set to a size > 0, <link linkend="g-free">g_free</link>(),
 <link linkend="g-realloc">g_realloc</link>() and
 <link linkend="g-malloc">g_malloc</link>() will be intercepted if the size
 matches the size of the corresponding memory block. This will only work with
 <literal>g_mem_set_vtable (glib_mem_profiler_table)</literal> upon startup
 though, because memory profiling is required to match on the memory block sizes.
 </para>
 <para>
 Note that many modern debuggers support conditional breakpoints, which achieve
 pretty much the same. E.g. in gdb, you can do
 <programlisting>
 break g_malloc
 condition 1 n_bytes == 20
 </programlisting>
 to break only on g_malloc() calls where the size of the allocated memory block
 is 20.
 </para>
 </refsect2>

 <refsect2>
 <title>Gdb debugging macros</title>

 <para>
 glib ships with a set of python macros for the gdb debugger. These includes pretty
 printers for lists, hashtables and gobject types. It also has a backtrace filter
 that makes backtraces with signal emissions easier to read.
 </para>

 <para>
 To use this you need a recent enough gdb that supports python scripting. Gdb 7.0
 should be recent enough, but branches of the "archer" gdb tree as used in Fedora 11
 and Fedora 12 should work too. You then need to install glib in the same prefix as
 gdb so that the python gdb autoloaded files get installed in the right place for
 gdb to pick up.
 </para>

 <para>
 General pretty printing should just happen without having to do anything special.
 To get the signal emission filtered backtrace you must use the "new-backtrace" command
 instead of the standard one.
 </para>

 <para>
 There is also a new command called gforeach that can be used to apply a command
 on each item in a list. E.g. you can do
 <programlisting>
 gforeach i in some_list_variable: print *(GtkWidget *)l
 </programlisting>
 Which would print the contents of each widget in a list of widgets.
 </para>

 </refsect2>

 <refsect2>
 <title>Memory statistics</title>

 <para>
 g_mem_profile() will output a summary g_malloc() memory usage, if memory
 profiling has been enabled by calling
 <literal>g_mem_set_vtable (glib_mem_profiler_table)</literal> upon startup.
 </para>

 <para>
 If GLib has been configured with <option>--enable-debug=yes</option>,
 then g_slice_debug_tree_statistics() can be called in a debugger to
 output details about the memory usage of the slice allocator.
 </para>

 </refsect2>
 </refsect1>
 </refentry>
	<?xml version="1.0"?>
	<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.3//EN"
	"http://www.oasis-open.org/docbook/xml/4.3/docbookx.dtd" [
	]>
	<refentry id="glib-running" revision="17 Jan 2002">
	<refmeta>
	<refentrytitle>Running GLib Applications</refentrytitle>
	<manvolnum>3</manvolnum>
	<refmiscinfo>GLib Library</refmiscinfo>
	</refmeta>

	<refnamediv>
	<refname>Running GLib Applications</refname>
	<refpurpose>
	How to run and debug your GLib application
	</refpurpose>
	</refnamediv>

	<refsect1>
	<title>Running and debugging GLib Applications</title>

	<refsect2>
	<title>Environment variables</title>

	<para>
	GLib inspects a few of environment variables in addition to standard
	variables like <envar>LANG</envar>, <envar>PATH</envar> or <envar>HOME</envar>.
	</para>

	<formalpara id="G_FILENAME_ENCODING">
	<title><envar>G_FILENAME_ENCODING</envar></title>

	<para>
	This environment variable can be set to a comma-separated list of character
	set names. GLib assumes that filenames are encoded in the first character
	set from that list rather than in UTF-8. The special token "@locale" can be
	used to specify the character set for the current locale.
	</para>
	</formalpara>

	<formalpara id="G_BROKEN_FILENAMES">
	<title><envar>G_BROKEN_FILENAMES</envar></title>

	<para>
	If this environment variable is set, GLib assumes that filenames are in
	the locale encoding rather than in UTF-8. G_FILENAME_ENCODING takes
	priority over G_BROKEN_FILENAMES.
	</para>
	</formalpara>

	<formalpara id="G_MESSAGES_PREFIXED">
	<title><envar>G_MESSAGES_PREFIXED</envar></title>

	<para>
	A list of log levels for which messages should be prefixed by the
	program name and PID of the application. The default is to prefix
	everything except <literal>G_LOG_LEVEL_MESSAGE</literal> and <literal>G_LOG_LEVEL_INFO</literal>.
	</para>
	</formalpara>

	<formalpara id="G_DEBUG">
	<title><envar>G_DEBUG</envar></title>
	<para>
	If GLib has been configured with <option>--enable-debug=yes</option>,
	this variable can be set to a list of debug options, which cause GLib
	to print out different types of debugging information.
	<variablelist>
	<varlistentry>
	<term>fatal_warnings</term>
	<listitem><para>Causes GLib to abort the program at the first call
	to <link linkend="g-warning">g_warning</link>() or
	<link linkend="g-critical">g_critical</link>(). This option is
	special in that it doesn't require GLib to be configured with
	debugging support.</para>
	</listitem>
	</varlistentry>
	<varlistentry>
	<term>fatal_criticals</term>
	<listitem><para>Causes GLib to abort the program at the first call
	to <link linkend="g-critical">g_critical</link>(). This option is
	special in that it doesn't require GLib to be configured with
	debugging support.</para>
	</listitem>
	</varlistentry>
	<varlistentry>
	<term>gc-friendly</term>
	<listitem>
	<para>
	Newly allocated memory that isn't directly initialized, as well
	as memory being freed will be reset to 0. The point here is to
	allow memory checkers and similar programs that use bohem GC alike
	algorithms to produce more accurate results.
	This option is special in that it doesn't require GLib to be
	configured with debugging support.
	</para>
	</listitem>
	</varlistentry>
	<varlistentry>
	<term>resident-modules</term>
	<listitem>
	<para>
	All modules loaded by GModule will be made resident. This can be useful
	for tracking memory leaks in modules which are later unloaded; but it can
	also hide bugs where code is accessed after the module would have normally
	been unloaded.
	This option is special in that it doesn't require GLib to be
	configured with debugging support.
	</para>
	</listitem>
	</varlistentry>
	<varlistentry>
	<term>bind-now-modules</term>
	<listitem>
	<para>
	All modules loaded by GModule will bind their symbols at load time, even
	when the code uses %G_MODULE_BIND_LAZY.
	This option is special in that it doesn't require GLib to be
	configured with debugging support.
	</para>
	</listitem>
	</varlistentry>
	</variablelist>
	The special value all can be used to turn on all debug options.
	The special value help can be used to print all available options.
	</para>
	</formalpara>

	<formalpara id="G_SLICE">
	<title><envar>G_SLICE</envar></title>
	<para>
	This environment variable allows reconfiguration of the GSlice
	memory allocator.
	<variablelist>
	<varlistentry>
	<term>always-malloc</term>
	<listitem>
	<para>
	This will cause all slices allocated through g_slice_alloc() and
	released by g_slice_free1() to be actually allocated via direct
	calls to g_malloc() and g_free().
	This is most useful for memory checkers and similar programs that
	use Bohem GC alike algorithms to produce more accurate results.
	It can also be in conjunction with debugging features of the system's
	malloc implementation such as glibc's MALLOC_CHECK_=2 to debug
	erroneous slice allocation code, allthough <literal>debug-blocks</literal>
	usually is a better suited debugging tool.
	</para>
	</listitem>
	</varlistentry>
	<varlistentry>
	<term>debug-blocks</term>
	<listitem>
	<para>
	Using this option (present since GLib-2.13) engages extra code
	which performs sanity checks on the released memory slices.
	Invalid slice adresses or slice sizes will be reported and lead to
	a program halt.
	This option is for debugging scenarios.
	In particular, client packages sporting their own test suite should
	<emphasis>always enable this option when running tests</emphasis>.
	Global slice validation is ensured by storing size and address information
	for each allocated chunk, and maintaining a global hash table of that data.
	That way, multi-thread scalability is given up, and memory consumption is
	increased. However, the resulting code usually performs acceptably well,
	possibly better than with comparable memory checking carried out using
	external tools. An example of a memory corruption scenario that cannot be
	reproduced with <literal>G_SLICE=always-malloc</literal>, but will be caught
	by <literal>G_SLICE=debug-blocks</literal> is as follows:
	<programlisting>
	void slist = g_slist_alloc(); / void* gives up type-safety */
	g_list_free (slist); /* corruption: sizeof (GSList) != sizeof (GList) */
	</programlisting>
	</para>
	</listitem>
	</varlistentry>
	</variablelist>
	The special value all can be used to turn on all options.
	The special value help can be used to print all available options.
	</para>
	</formalpara>

	<formalpara id="G_RANDOM_VERSION">
	<title><envar>G_RANDOM_VERSION</envar></title>

	<para>
	If this environment variable is set to '2.0', the outdated
	pseudo-random number seeding and generation algorithms from
	GLib-2.0 are used instead of the new better ones. Use the GLib-2.0
	algorithms only if you have sequences of numbers generated with
	Glib-2.0 that you need to reproduce exactly.
	</para>
	</formalpara>

	<formalpara id="LIBCHARSET_ALIAS_DIR">
	<title><envar>LIBCHARSET_ALIAS_DIR</envar></title>

	<para>
	Allows to specify a nonstandard location for the
	<filename>charset.aliases</filename> file that is used by the
	character set conversion routines. The default location is the
	<replaceable>libdir</replaceable> specified at compilation time.
	</para>
	</formalpara>

	</refsect2>

	<refsect2 id="setlocale">
	<title>Locale</title>

	<para>
	A number of interfaces in GLib depend on the current locale in which
	an application is running. Therefore, most GLib-using applications should
	call <function>setlocale (LC_ALL, "")</function> to set up the current
	locale.
	</para>

	<para>
	On Windows, in a C program there are several locale concepts
	that not necessarily are synchronized. On one hand, there is the
	system default ANSI code-page, which determines what encoding is used
	for file names handled by the C library's functions and the Win32
	API. (We are talking about the "narrow" functions here that take
	character pointers, not the "wide" ones.)
	</para>

	<para>
	On the other hand, there is the C library's current locale. The
	character set (code-page) used by that is not necessarily the same as
	the system default ANSI code-page. Strings in this character set are
	returned by functions like <function>strftime()</function>.
	</para>

	</refsect2>

	<refsect2>
	<title>Traps and traces</title>

	<para>
	<indexterm><primary>g_trap_free_size</primary></indexterm>
	<indexterm><primary>g_trap_realloc_size</primary></indexterm>
	<indexterm><primary>g_trap_malloc_size</primary></indexterm>
	Some code portions contain trap variables that can be set during debugging
	time if GLib has been configured with <option>--enable-debug=yes</option>.
	Such traps lead to immediate code halts to examine the current program state
	and backtrace.
	</para>

	<para>
	Currently, the following trap variables exist:
	<programlisting>
	static volatile gulong g_trap_free_size;
	static volatile gulong g_trap_realloc_size;
	static volatile gulong g_trap_malloc_size;
	</programlisting>
	If set to a size > 0, <link linkend="g-free">g_free</link>(),
	<link linkend="g-realloc">g_realloc</link>() and
	<link linkend="g-malloc">g_malloc</link>() will be intercepted if the size
	matches the size of the corresponding memory block. This will only work with
	<literal>g_mem_set_vtable (glib_mem_profiler_table)</literal> upon startup
	though, because memory profiling is required to match on the memory block sizes.
	</para>
	<para>
	Note that many modern debuggers support conditional breakpoints, which achieve
	pretty much the same. E.g. in gdb, you can do
	<programlisting>
	break g_malloc
	condition 1 n_bytes == 20
	</programlisting>
	to break only on g_malloc() calls where the size of the allocated memory block
	is 20.
	</para>
	</refsect2>

	<refsect2>
	<title>Gdb debugging macros</title>

	<para>
	glib ships with a set of python macros for the gdb debugger. These includes pretty
	printers for lists, hashtables and gobject types. It also has a backtrace filter
	that makes backtraces with signal emissions easier to read.
	</para>

	<para>
	To use this you need a recent enough gdb that supports python scripting. Gdb 7.0
	should be recent enough, but branches of the "archer" gdb tree as used in Fedora 11
	and Fedora 12 should work too. You then need to install glib in the same prefix as
	gdb so that the python gdb autoloaded files get installed in the right place for
	gdb to pick up.
	</para>

	<para>
	General pretty printing should just happen without having to do anything special.
	To get the signal emission filtered backtrace you must use the "new-backtrace" command
	instead of the standard one.
	</para>

	<para>
	There is also a new command called gforeach that can be used to apply a command
	on each item in a list. E.g. you can do
	<programlisting>
	gforeach i in some_list_variable: print (GtkWidget )l
	</programlisting>
	Which would print the contents of each widget in a list of widgets.
	</para>

	</refsect2>

	<refsect2>
	<title>Memory statistics</title>

	<para>
	g_mem_profile() will output a summary g_malloc() memory usage, if memory
	profiling has been enabled by calling
	<literal>g_mem_set_vtable (glib_mem_profiler_table)</literal> upon startup.
	</para>

	<para>
	If GLib has been configured with <option>--enable-debug=yes</option>,
	then g_slice_debug_tree_statistics() can be called in a debugger to
	output details about the memory usage of the slice allocator.
	</para>

	</refsect2>
	</refsect1>
	</refentry>