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Re: [PATCH] Variable objects in multi-threaded programs


 >  > I'm somewhat concerned that this patch makes gdb traverse stacks of all
 >  > threads -- it can take quite some time. Would a better solution be
 >  > to store thread id inside varobj?
 > 
 > Yes I think it would.  As an element of struct varobj_root?
 > 
 > Perhaps this should also included as a field in the output of -var-create,
 > the frontend could organise the display of watch expressions by thread.  If
 > we use the GDB thread id, this would be consistent with infrun.c

Here's a revised patch along those lines.  The diffs for gdbthread.h, thread.c
are as before, that of varobj.c is new and there are now ones for mi-cmd-var.c
and varobj.h.

-- 
Nick                                           http://www.inet.net.nz/~nickrob

2008-01-25  Nick Roberts  <nickrob@snap.net.nz>

	* thread.c (make_cleanup_restore_current_thread)
	(do_restore_current_thread_cleanup): Don't make static
	(struct current_thread_cleanup): Move to gdbthread.h

	* gdbthread.h: Declare above functions as externs here.

	* varobj.c  (struct varobj_root): New component thread_id.
	(varobj_create): Set it to -2 for global variables.
	(varobj_get_thread_id, check_scope): New functions.
	(c_value_of_root): Use it to iterate over threads.

	* varobj.h (varobj_get_thread_id): New extern.

	* mi/mi-cmd-var.c (print_varobj): Add thread-id field.


*** varobj.c.~1.99.~	2008-01-04 10:24:29.000000000 +1300
--- varobj.c	2008-01-25 10:50:06.000000000 +1300
***************
*** 24,30 ****
--- 24,32 ----
  #include "language.h"
  #include "wrapper.h"
  #include "gdbcmd.h"
+ #include "gdbthread.h"
  #include "block.h"
+ #include "inferior.h"
  
  #include "gdb_assert.h"
  #include "gdb_string.h"
*************** struct varobj_root
*** 65,70 ****
--- 67,75 ----
    /* The frame for this expression */
    struct frame_id frame;
  
+   /* GDB thread id.  */
+   int thread_id;
+ 
    /* If 1, "update" always recomputes the frame & valid block
       using the currently selected frame. */
    int use_selected_frame;
*************** varobj_create (char *objname,
*** 492,497 ****
--- 497,507 ----
  
        var->format = variable_default_display (var);
        var->root->valid_block = innermost_block;
+       if (innermost_block)
+ 	var->root->thread_id = pid_to_thread_id (inferior_ptid);
+       else
+ 	/* Give global variables a thread_id of -2.  */
+ 	var->root->thread_id = -2;
        expr_len = strlen (expression);
        var->name = savestring (expression, expr_len);
        /* For a root var, the name and the expr are the same.  */
*************** varobj_get_display_format (struct varobj
*** 686,691 ****
--- 696,707 ----
    return var->format;
  }
  
+ int
+ varobj_get_thread_id (struct varobj *var)
+ {
+   return var->root->thread_id;
+ }
+ 
  void
  varobj_set_frozen (struct varobj *var, int frozen)
  {
*************** c_path_expr_of_child (struct varobj *chi
*** 2153,2189 ****
    return child->path_expr;
  }
  
  static struct value *
  c_value_of_root (struct varobj **var_handle)
  {
    struct value *new_val = NULL;
    struct varobj *var = *var_handle;
!   struct frame_info *fi;
!   int within_scope;
  
    /*  Only root variables can be updated... */
    if (!is_root_p (var))
      /* Not a root var */
      return NULL;
  
- 
    /* Determine whether the variable is still around. */
    if (var->root->valid_block == NULL || var->root->use_selected_frame)
      within_scope = 1;
    else
      {
!       fi = frame_find_by_id (var->root->frame);
!       within_scope = fi != NULL;
!       /* FIXME: select_frame could fail */
!       if (fi)
  	{
! 	  CORE_ADDR pc = get_frame_pc (fi);
! 	  if (pc <  BLOCK_START (var->root->valid_block) ||
! 	      pc >= BLOCK_END (var->root->valid_block))
! 	    within_scope = 0;
! 	  else
! 	    select_frame (fi);
! 	}	  
      }
  
    if (within_scope)
--- 2169,2229 ----
    return child->path_expr;
  }
  
+ static void
+ check_scope (struct varobj *var, int* scope)
+ {
+   struct frame_info *fi;
+ 
+   fi = frame_find_by_id (var->root->frame);
+   *scope = fi != NULL;
+ 
+   /* FIXME: select_frame could fail */
+   if (fi)
+     {
+       CORE_ADDR pc = get_frame_pc (fi);
+       if (pc <  BLOCK_START (var->root->valid_block) ||
+ 	  pc >= BLOCK_END (var->root->valid_block))
+ 	*scope = 0;
+       else
+ 	select_frame (fi);
+     }	  
+ }
+ 
  static struct value *
  c_value_of_root (struct varobj **var_handle)
  {
    struct value *new_val = NULL;
    struct varobj *var = *var_handle;
!   struct frame_id saved_frame_id;
!   struct cleanup *old_cleanups = NULL;
!   int within_scope, thread_id;
!   ptid_t ptid;
  
    /*  Only root variables can be updated... */
    if (!is_root_p (var))
      /* Not a root var */
      return NULL;
  
    /* Determine whether the variable is still around. */
    if (var->root->valid_block == NULL || var->root->use_selected_frame)
      within_scope = 1;
    else
      {
!       thread_id = var->root->thread_id;
!       ptid = thread_id_to_pid (thread_id);
!       if (thread_id == 0)
! 	check_scope (var, &within_scope);
!       else if (thread_id != -1 && target_thread_alive (ptid))
  	{
! 
! 	  saved_frame_id = get_frame_id (get_selected_frame (NULL));
! 	  old_cleanups = make_cleanup_restore_current_thread (inferior_ptid,
! 							      saved_frame_id);
! 	  switch_to_thread (ptid);
! 	  check_scope (var, &within_scope);
! 	}
!       else
! 	var->root->thread_id = -1;
      }
  
    if (within_scope)
*************** c_value_of_root (struct varobj **var_han
*** 2194,2199 ****
--- 2234,2241 ----
        return new_val;
      }
  
+   do_cleanups (old_cleanups);
+ 
    return NULL;
  }
  
*** thread.c.~1.59.~	2008-01-24 09:47:31.000000000 +1300
--- thread.c	2008-01-24 15:38:41.000000000 +1300
*************** static void info_threads_command (char *
*** 60,67 ****
  static void thread_apply_command (char *, int);
  static void restore_current_thread (ptid_t);
  static void prune_threads (void);
- static struct cleanup *make_cleanup_restore_current_thread (ptid_t,
-                                                             struct frame_id);
  
  void
  delete_step_resume_breakpoint (void *arg)
--- 60,65 ----
*************** restore_selected_frame (struct frame_id 
*** 496,508 ****
      }
  }
  
! struct current_thread_cleanup
! {
!   ptid_t inferior_ptid;
!   struct frame_id selected_frame_id;
! };
! 
! static void
  do_restore_current_thread_cleanup (void *arg)
  {
    struct current_thread_cleanup *old = arg;
--- 494,500 ----
      }
  }
  
! void
  do_restore_current_thread_cleanup (void *arg)
  {
    struct current_thread_cleanup *old = arg;
*************** do_restore_current_thread_cleanup (void 
*** 511,517 ****
    xfree (old);
  }
  
! static struct cleanup *
  make_cleanup_restore_current_thread (ptid_t inferior_ptid, 
                                       struct frame_id a_frame_id)
  {
--- 503,509 ----
    xfree (old);
  }
  
! struct cleanup *
  make_cleanup_restore_current_thread (ptid_t inferior_ptid, 
                                       struct frame_id a_frame_id)
  {


*** gdbthread.h.~1.19.~	2008-01-24 09:47:30.000000000 +1300
--- gdbthread.h	2008-01-24 15:37:19.000000000 +1300
*************** extern void load_infrun_state (ptid_t pt
*** 143,148 ****
--- 143,159 ----
  /* Switch from one thread to another.  */
  extern void switch_to_thread (ptid_t ptid);
  
+ struct current_thread_cleanup
+ {
+   ptid_t inferior_ptid;
+   struct frame_id selected_frame_id;
+ };
+ 
+ extern void do_restore_current_thread_cleanup (void *arg);
+ 
+ extern struct cleanup * make_cleanup_restore_current_thread
+                           (ptid_t inferior_ptid, struct frame_id a_frame_id);
+ 
  /* Commands with a prefix of `thread'.  */
  extern struct cmd_list_element *thread_cmd_list;
  

*** varobj.h.~1.14.~	2008-01-04 10:24:30.000000000 +1300
--- varobj.h	2008-01-24 22:09:17.000000000 +1300
*************** extern enum varobj_display_formats varob
*** 85,90 ****
--- 85,92 ----
  extern enum varobj_display_formats varobj_get_display_format (
  							struct varobj *var);
  
+ extern int varobj_get_thread_id (struct varobj *var);
+ 
  extern void varobj_set_frozen (struct varobj *var, int frozen);
  
  extern int varobj_get_frozen (struct varobj *var);


*** mi-cmd-var.c.~1.44.~	2008-01-23 16:19:39.000000000 +1300
--- mi-cmd-var.c	2008-01-25 00:43:22.000000000 +1300
*************** print_varobj (struct varobj *var, enum p
*** 50,55 ****
--- 50,56 ----
  {
    struct type *gdb_type;
    char *type;
+   int thread_id;
  
    ui_out_field_string (uiout, "name", varobj_get_objname (var));
    if (print_expression)
*************** print_varobj (struct varobj *var, enum p
*** 66,71 ****
--- 67,76 ----
        xfree (type);
      }
  
+   thread_id = varobj_get_thread_id (var);
+   if (thread_id != -2)
+     ui_out_field_int (uiout, "thread-id", thread_id);
+ 
    if (varobj_get_frozen (var))
      ui_out_field_int (uiout, "frozen", 1);
  }


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