Re: [PATCH] Delete program spaces directly when removing inferiors

[Simon Marchi <simon dot marchi at ericsson dot com>]

On 15-07-08 08:05 AM, Pedro Alves wrote:
> On 09/29/2014 09:33 PM, Simon Marchi wrote:
> 
>> -void
>> -delete_inferior (int pid)
>> -{
>> -  struct inferior *inf = find_inferior_pid (pid);
>> -
>> -  delete_inferior_1 (inf, 0);
>> -
>> -  if (print_inferior_events)
>> -    printf_unfiltered (_("[Inferior %d exited]\n"), pid);
>> -}
>> +  /* If this program space is rendered useless, remove it. */
>> +  if (program_space_empty_p (inf->pspace))
>> +      delete_program_space (inf->pspace);
> 
> I think there's something odd with indentation here.

Ok.

>> -  struct program_space *ss, **ss_link;
>> -  struct program_space *current = current_program_space;
>> +  gdb_assert(pspace != NULL);
>> +  gdb_assert(pspace != current_program_space);
>>  
>> -  ss = program_spaces;
>> -  ss_link = &program_spaces;
>> -  while (ss)
>> +  if (pspace == program_spaces)
>> +    program_spaces = pspace->next;
>> +  else
>>      {
>> -      if (ss == current || !pspace_empty_p (ss))
>> +      struct program_space *i = program_spaces;
>> +
>> +      for (i = program_spaces; i != NULL; i = i->next)
>>  	{
>> -	  ss_link = &ss->next;
>> -	  ss = *ss_link;
>> -	  continue;
>> +	  if (i->next == pspace)
>> +	    {
>> +	      i->next = i->next->next;
>> +	      break;
>> +	    }
>>  	}
>> -
>> -      *ss_link = ss->next;
>> -      release_program_space (ss);
>> -      ss = *ss_link;
>>      }
> 
> I don't find this conversion from while to if+else+for an
> improvement.  You can instead write:
> 
>   ss = program_spaces;
>   ss_link = &program_spaces;
>   while (ss != NULL)
>     {
>       if (ss == pspace)
>         {
>          *ss_link = ss->next;
>           break;
>         }
> 
>       ss_link = &ss->next;
>       ss = *ss_link;
>     }
>   release_program_space (pspace);
> 
> We use this _link pattern in several places.
> 
> OK with that change.

Ok, pushed with those changes:

>From 0560c645c02eba2828a053039dcfdf676cdd1d00 Mon Sep 17 00:00:00 2001
From: Simon Marchi <simon.marchi@ericsson.com>
Date: Mon, 29 Sep 2014 16:33:10 -0400
Subject: [PATCH] Delete program spaces directly when removing inferiors

When deleting an inferior, delete the associated program space as well
if it becomes unused. This replaces the "pruning" approach, with which
you could forget to call prune_program_spaces (as seen, with the
-remove-inferior command, see [1]).

This allows to remove the prune_program_spaces function. At the same
time, I was able to clean up the delete_inferior* family.
delete_inferior_silent and delete_inferior were unused, which allowed
renaming delete_inferior_1 to delete_inferior. Also, since all calls to
it were with silent=1, I removed that parameter completely.

I renamed pspace_empty_p to program_space_empty_p. I prefer if the
"exported" functions have a more explicit and standard name.

Tested on Ubuntu 14.10.

This obsoletes my previous patch "Add call to prune_program_spaces in
mi_cmd_remove_inferior" [1].

[1] https://sourceware.org/ml/gdb-patches/2014-09/msg00717.html

gdb/Changelog:

	* inferior.c (delete_inferior_1): Rename to ...
	(delete_inferior): ..., remove 'silent' parameter, delete
	program space when unused and remove call to prune_program_spaces.
	Remove the old, unused, delete_inferior.
	(delete_inferior_silent): Remove.
	(prune_inferiors): Change call from delete_inferior_1 to
	delete_inferior and remove 'silent' parameter. Remove call to
	prune_program_spaces.
	(remove_inferior_command): Idem.
	* inferior.h (delete_inferior_1): Rename to...
	(delete_inferior): ..., remove 'silent' parameter and remove the
	original delete_inferior.
	(delete_inferior_silent): Remove.
	* mi/mi-main.c (mi_cmd_remove_inferior): Change call from
	delete_inferior_1 to delete_inferior and remove 'silent'
	parameter.
	* progspace.c (prune_program_spaces): Remove.
	(pspace_empty_p): Rename to...
	(program_space_empty_p): ... and make non-static.
	(delete_program_space): New.
	* progspace.h (prune_program_spaces): Remove declaration.
	(program_space_empty_p): New declaration.
	(delete_program_space): New declaration.
---
 gdb/ChangeLog    | 26 ++++++++++++++++++++++++++
 gdb/inferior.c   | 39 ++++++++-------------------------------
 gdb/inferior.h   |  9 +--------
 gdb/mi/mi-main.c |  2 +-
 gdb/progspace.c  | 27 ++++++++++++++-------------
 gdb/progspace.h  | 11 +++++++----
 6 files changed, 57 insertions(+), 57 deletions(-)

diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index b565dde..0a0d50a 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,3 +1,29 @@
+2015-07-08  Simon Marchi  <simon.marchi@ericsson.com>
+
+	* inferior.c (delete_inferior_1): Rename to ...
+	(delete_inferior): ..., remove 'silent' parameter, delete
+	program space when unused and remove call to prune_program_spaces.
+	Remove the old, unused, delete_inferior.
+	(delete_inferior_silent): Remove.
+	(prune_inferiors): Change call from delete_inferior_1 to
+	delete_inferior and remove 'silent' parameter. Remove call to
+	prune_program_spaces.
+	(remove_inferior_command): Idem.
+	* inferior.h (delete_inferior_1): Rename to...
+	(delete_inferior): ..., remove 'silent' parameter and remove the
+	original delete_inferior.
+	(delete_inferior_silent): Remove.
+	* mi/mi-main.c (mi_cmd_remove_inferior): Change call from
+	delete_inferior_1 to delete_inferior and remove 'silent'
+	parameter.
+	* progspace.c (prune_program_spaces): Remove.
+	(pspace_empty_p): Rename to...
+	(program_space_empty_p): ... and make non-static.
+	(delete_program_space): New.
+	* progspace.h (prune_program_spaces): Remove declaration.
+	(program_space_empty_p): New declaration.
+	(delete_program_space): New declaration.
+
 2015-07-08  Jan Kratochvil  <jan.kratochvil@redhat.com>

 	PR compile/18484
diff --git a/gdb/inferior.c b/gdb/inferior.c
index d0783d3..5e98df5 100644
--- a/gdb/inferior.c
+++ b/gdb/inferior.c
@@ -184,11 +184,8 @@ delete_thread_of_inferior (struct thread_info *tp, void *data)
   return 0;
 }

-/* If SILENT then be quiet -- don't announce a inferior death, or the
-   exit of its threads.  */
-
 void
-delete_inferior_1 (struct inferior *todel, int silent)
+delete_inferior (struct inferior *todel)
 {
   struct inferior *inf, *infprev;
   struct delete_thread_of_inferior_arg arg;
@@ -203,7 +200,7 @@ delete_inferior_1 (struct inferior *todel, int silent)
     return;

   arg.pid = inf->pid;
-  arg.silent = silent;
+  arg.silent = 1;

   iterate_over_threads (delete_thread_of_inferior, &arg);

@@ -214,29 +211,13 @@ delete_inferior_1 (struct inferior *todel, int silent)

   observer_notify_inferior_removed (inf);

-  free_inferior (inf);
-}
-
-void
-delete_inferior (int pid)
-{
-  struct inferior *inf = find_inferior_pid (pid);
-
-  delete_inferior_1 (inf, 0);
-
-  if (print_inferior_events)
-    printf_unfiltered (_("[Inferior %d exited]\n"), pid);
-}
+  /* If this program space is rendered useless, remove it. */
+  if (program_space_empty_p (inf->pspace))
+    delete_program_space (inf->pspace);

-void
-delete_inferior_silent (int pid)
-{
-  struct inferior *inf = find_inferior_pid (pid);
-
-  delete_inferior_1 (inf, 1);
+  free_inferior (inf);
 }

-
 /* If SILENT then be quiet -- don't announce a inferior exit, or the
    exit of its threads.  */

@@ -509,11 +490,9 @@ prune_inferiors (void)
 	}

       *ss_link = ss->next;
-      delete_inferior_1 (ss, 1);
+      delete_inferior (ss);
       ss = *ss_link;
     }
-
-  prune_program_spaces ();
 }

 /* Simply returns the count of inferiors.  */
@@ -797,10 +776,8 @@ remove_inferior_command (char *args, int from_tty)
 	  continue;
 	}

-      delete_inferior_1 (inf, 1);
+      delete_inferior (inf);
     }
-
-  prune_program_spaces ();
 }

 struct inferior *
diff --git a/gdb/inferior.h b/gdb/inferior.h
index 2054a2a..48cba45 100644
--- a/gdb/inferior.h
+++ b/gdb/inferior.h
@@ -418,14 +418,7 @@ extern struct inferior *add_inferior (int pid);
    the CLI.  */
 extern struct inferior *add_inferior_silent (int pid);

-/* Delete an existing inferior list entry, due to inferior exit.  */
-extern void delete_inferior (int pid);
-
-extern void delete_inferior_1 (struct inferior *todel, int silent);
-
-/* Same as delete_inferior, but don't print new inferior notifications
-   to the CLI.  */
-extern void delete_inferior_silent (int pid);
+extern void delete_inferior (struct inferior *todel);

 /* Delete an existing inferior list entry, due to inferior detaching.  */
 extern void detach_inferior (int pid);
diff --git a/gdb/mi/mi-main.c b/gdb/mi/mi-main.c
index ddfc9d9..66bcd88 100644
--- a/gdb/mi/mi-main.c
+++ b/gdb/mi/mi-main.c
@@ -1964,7 +1964,7 @@ mi_cmd_remove_inferior (char *command, char **argv, int argc)
       set_current_program_space (new_inferior->pspace);
     }

-  delete_inferior_1 (inf, 1 /* silent */);
+  delete_inferior (inf);
 }

 
diff --git a/gdb/progspace.c b/gdb/progspace.c
index 1c0a254..a8f5ea0 100644
--- a/gdb/progspace.c
+++ b/gdb/progspace.c
@@ -235,8 +235,8 @@ save_current_program_space (void)

 /* Returns true iff there's no inferior bound to PSPACE.  */

-static int
-pspace_empty_p (struct program_space *pspace)
+int
+program_space_empty_p (struct program_space *pspace)
 {
   if (find_inferior_for_program_space (pspace) != NULL)
       return 0;
@@ -244,30 +244,31 @@ pspace_empty_p (struct program_space *pspace)
   return 1;
 }

-/* Prune away automatically added program spaces that aren't required
-   anymore.  */
+/* Remove a program space from the program spaces list and release it.  It is
+   an error to call this function while PSPACE is the current program space. */

 void
-prune_program_spaces (void)
+delete_program_space (struct program_space *pspace)
 {
   struct program_space *ss, **ss_link;
-  struct program_space *current = current_program_space;
+  gdb_assert(pspace != NULL);
+  gdb_assert(pspace != current_program_space);

   ss = program_spaces;
   ss_link = &program_spaces;
-  while (ss)
+  while (ss != NULL)
     {
-      if (ss == current || !pspace_empty_p (ss))
+      if (ss == pspace)
 	{
-	  ss_link = &ss->next;
-	  ss = *ss_link;
-	  continue;
+	  *ss_link = ss->next;
+	  break;
 	}

-      *ss_link = ss->next;
-      release_program_space (ss);
+      ss_link = &ss->next;
       ss = *ss_link;
     }
+
+  release_program_space (pspace);
 }

 /* Prints the list of program spaces and their details on UIOUT.  If
diff --git a/gdb/progspace.h b/gdb/progspace.h
index f960093..48f206e 100644
--- a/gdb/progspace.h
+++ b/gdb/progspace.h
@@ -236,9 +236,16 @@ extern struct program_space *current_program_space;
    pointer to the new object.  */
 extern struct program_space *add_program_space (struct address_space *aspace);

+/* Remove a program space from the program spaces list and release it.  It is
+   an error to call this function while PSPACE is the current program space. */
+extern void delete_program_space (struct program_space *pspace);
+
 /* Returns the number of program spaces listed.  */
 extern int number_of_program_spaces (void);

+/* Returns true iff there's no inferior bound to PSPACE.  */
+extern int program_space_empty_p (struct program_space *pspace);
+
 /* Copies program space SRC to DEST.  Copies the main executable file,
    and the main symbol file.  Returns DEST.  */
 extern struct program_space *clone_program_space (struct program_space *dest,
@@ -289,10 +296,6 @@ extern int address_space_num (struct address_space *aspace);
    mappings.  */
 extern void update_address_spaces (void);

-/* Prune away automatically added program spaces that aren't required
-   anymore.  */
-extern void prune_program_spaces (void);
-
 /* Reset saved solib data at the start of an solib event.  This lets
    us properly collect the data when calling solib_add, so it can then
    later be printed.  */
-- 
2.1.4