Re: Memory woes

["Gustavo J. A. M. " Carneiro <gjc inescporto pt>]

On Ter, 2003-02-25 at 17:36, Rico wrote:
> Hello All!
> I'm getting my hands dirrty with Pan. I have the following struct:
> ******************************************************************************
> typedef struct _Group
> {
> 	GMutex       * article_mutex;
> 
>         guint          loaded_since_last_fetch  : 1;
>         guint          articles_dirty           : 1;     
> 	char           permission;                       
> 	gint8          flags;                            
> 	gint8          old_sort_style;                   
> 	gint8          new_sort_style;                   
> 	gulong         filter_show;                      
> 	guint32        filter_bits;                      
> 	gint32         article_qty;                      
> 	gint32         article_read_qty;                 
> 	gulong         article_low;                      
> 	gulong	       article_last_low_fetched;
> 	gulong         article_high;                     
> 	gulong         article_high_old;                 
> 
> 	Server       * server;
> 	char         * name;                             
> 	char         * filter_name;                      
> 	char         * identity_name;                    
> 	char         * description;                      /* maybe null */
> 	char         * download_dir;                     
> 	char         * default_charset;                  
> 	GStringChunk * chunk;                            
> 
> 	/* PRIVATE */
> 	int            _articles_refcount;
> 	MemChunk     * _article_chunk;                   /* Article objects */
> 	Newsrc       * _newsrc;                          
> 	Newsrc       * _purged;                          
> 	GHashTable   * _articles;                        
> 	GPtrArray    * _deleted_articles;                
> 	char         * _one_big_chunk;                   
> 	guint          _no_fetch_on_load	: 1;	 
> }
> Group;
> *****************************************************************************
> 
> Something like: Group * g = group_new(server, name);
> 
> returns a properly initialized, complete Group, with all the above members
> as reported by gdb. I add those Group's to a GPtrArray like so:
> 
>                 GPtrArray * groups = g_ptr_array_new ();
>         	g_ptr_array_add (groups, g);
> 
> then            call_some_func((Group **) groups->pdata);
> 
> but inside call_some_func(Group **groups), for all x, on
>   
>                 print *groups[x]  
> 
> gdb does not see the last member, _no_fetch_on_load. However, the compiler does
> not complain about an unknown member. Instead, 
> 
>        if (!groups[x]->_no_fetch_on_load) fetch_headers();
> 
> would _always_ make the call to fetch_headers(), even though I had set 
> _no_fetch_on_load to TRUE before getting to that point. Anyone has any idea,
> could provide any hint about what's going on here? I've tried using a gboolean
> instead of a guint _no_fetch_on_load, but same problem. Also, what does the
> ':1'
> mean in "guint loaded_since_last_fetch : 1" ? Is it a compiler extension or is
> it standard C ?

  That is a bitfield. ':1' means that the structure field
loaded_since_last_fetch occupies only one bit in the structure. In this
case, you have a 1-bit unsigned integer, which obviously can only hold
the values 0 and 1.
  Bitfields are standard C.
  In my opinion, gdb is very buggy, unfortunately.

> 
> Thanks,
> Rico.
>  
> 
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-- 
Gustavo Joćo Alves Marques Carneiro
<gjc@inescporto.pt> <gustavo@users.sourceforge.net>