Re: attach& support, and attach "async + sync_execution" support.

[Pedro Alves <pedro@codesourcery.com>]

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A Friday 14 March 2008 19:18:21, Daniel Jacobowitz wrote:
> Could you do some refactoring on this, please?  It duplicates code
> from attach_command.  When I fixed up step last year I moved the
> common code into its own function.  Makes it much easier to see
> the differences between async and sync operation.  And for instance
> it lets me see that you're calling deprecated_attach_hook twice
> in async mode :-)

I don't think I was :-)  There were three different exit points.
sync, async/sync_execution, and true async.  I've reverted the
bits that immediatelly proceed after attaching, and defered it
to the continuation (for the attach& support).  I'll look
into short-circuiting that again when non-stop is in.  The
attach& mode is still supported, but we wait for everything to
be stopped and stable before deciding to proceed or normal_stop.

This is look alright?

Tested on x86_64-unknown-linux-gnu with the linux async
support (new patch follows) enabled and disabled.

-- 
Pedro Alves

(P.S. Am I the only one that thinks that continuation
arguments suck?  IMHO, we should move the continuation_arg data
union into the continuation proper, and force people to use
structs for the compound args.  Oh, and who is responsible for
freeing the continuation args?  Nobody seems to be doing that.)

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2008-03-14  Pedro Alves  <pedro@codesourcery.com>

	* infcmd.c (attach_command_post_wait, attach_command_continuation): New.
	(attach_command): Support background async execution, and async
	execution in synchronous mode.

---
 gdb/infcmd.c |  152 ++++++++++++++++++++++++++++++++++++++++++-----------------
 1 file changed, 110 insertions(+), 42 deletions(-)

Index: src/gdb/infcmd.c
===================================================================
--- src.orig/gdb/infcmd.c	2008-03-17 14:55:00.000000000 +0000
+++ src/gdb/infcmd.c	2008-03-17 15:13:04.000000000 +0000
@@ -1875,11 +1875,83 @@ vector_info (char *args, int from_tty)
    This stops it cold in its tracks and allows us to start debugging it.
    and wait for the trace-trap that results from attaching.  */
 
+static void
+attach_command_post_wait (char *args, int from_tty, int async_exec)
+{
+  char *exec_file;
+  char *full_exec_path = NULL;
+
+  stop_soon = NO_STOP_QUIETLY;
+
+  /* If no exec file is yet known, try to determine it from the
+     process itself.  */
+  exec_file = (char *) get_exec_file (0);
+  if (!exec_file)
+    {
+      exec_file = target_pid_to_exec_file (PIDGET (inferior_ptid));
+      if (exec_file)
+	{
+	  /* It's possible we don't have a full path, but rather just a
+	     filename.  Some targets, such as HP-UX, don't provide the
+	     full path, sigh.
+
+	     Attempt to qualify the filename against the source path.
+	     (If that fails, we'll just fall back on the original
+	     filename.  Not much more we can do...)
+	   */
+	  if (!source_full_path_of (exec_file, &full_exec_path))
+	    full_exec_path = savestring (exec_file, strlen (exec_file));
+
+	  exec_file_attach (full_exec_path, from_tty);
+	  symbol_file_add_main (full_exec_path, from_tty);
+	}
+    }
+  else
+    {
+      reopen_exec_file ();
+      reread_symbols ();
+    }
+
+  /* Take any necessary post-attaching actions for this platform.  */
+  target_post_attach (PIDGET (inferior_ptid));
+
+  post_create_inferior (&current_target, from_tty);
+
+  /* Install inferior's terminal modes.  */
+  target_terminal_inferior ();
+
+  if (async_exec)
+    proceed ((CORE_ADDR) -1, TARGET_SIGNAL_0, 0);
+  else
+    {
+      if (target_can_async_p ())
+	async_enable_stdin ();
+      normal_stop ();
+      if (deprecated_attach_hook)
+	deprecated_attach_hook ();
+    }
+}
+
+static void
+attach_command_continuation (struct continuation_arg * arg)
+{
+  char *args;
+  int from_tty;
+  int async_exec;
+
+  args = (char *) arg->data.pointer;
+  from_tty = arg->next->data.integer;
+  async_exec = arg->next->next->data.integer;
+
+  attach_command_post_wait (args, from_tty, async_exec);
+}
+
 void
 attach_command (char *args, int from_tty)
 {
   char *exec_file;
   char *full_exec_path = NULL;
+  int async_exec = 0;
 
   dont_repeat ();		/* Not for the faint of heart */
 
@@ -1913,6 +1985,24 @@ attach_command (char *args, int from_tty
   */
   clear_solib ();
 
+  if (args)
+    {
+      async_exec = strip_bg_char (&args);
+
+      /* If we get a request for running in the bg but the target
+         doesn't support it, error out. */
+      if (async_exec && !target_can_async_p ())
+	error (_("Asynchronous execution not supported on this target."));
+
+      /* If we don't get a request of running in the bg, then we need
+         to simulate synchronous (fg) execution.  */
+      if (!async_exec && target_can_async_p ())
+	{
+	  /* Simulate synchronous execution */
+	  async_disable_stdin ();
+	}
+    }
+
   target_attach (args, from_tty);
 
   /* Set up the "saved terminal modes" of the inferior
@@ -1932,54 +2022,32 @@ attach_command (char *args, int from_tty
      way for handle_inferior_event to reset the stop_signal variable
      after an attach, and this is what STOP_QUIETLY_NO_SIGSTOP is for.  */
   stop_soon = STOP_QUIETLY_NO_SIGSTOP;
-  wait_for_inferior (0);
-  stop_soon = NO_STOP_QUIETLY;
-#endif
 
-  /*
-   * If no exec file is yet known, try to determine it from the
-   * process itself.
-   */
-  exec_file = (char *) get_exec_file (0);
-  if (!exec_file)
+  if (target_can_async_p ())
     {
-      exec_file = target_pid_to_exec_file (PIDGET (inferior_ptid));
-      if (exec_file)
-	{
-	  /* It's possible we don't have a full path, but rather just a
-	     filename.  Some targets, such as HP-UX, don't provide the
-	     full path, sigh.
-
-	     Attempt to qualify the filename against the source path.
-	     (If that fails, we'll just fall back on the original
-	     filename.  Not much more we can do...)
-	   */
-	  if (!source_full_path_of (exec_file, &full_exec_path))
-	    full_exec_path = savestring (exec_file, strlen (exec_file));
+      /* sync_execution mode.  Wait for stop.  */
+      struct continuation_arg *arg1, *arg2, *arg3;
 
-	  exec_file_attach (full_exec_path, from_tty);
-	  symbol_file_add_main (full_exec_path, from_tty);
-	}
+      arg1 =
+	(struct continuation_arg *) xmalloc (sizeof (struct continuation_arg));
+      arg2 =
+	(struct continuation_arg *) xmalloc (sizeof (struct continuation_arg));
+      arg3 =
+	(struct continuation_arg *) xmalloc (sizeof (struct continuation_arg));
+      arg1->next = arg2;
+      arg2->next = arg3;
+      arg3->next = NULL;
+      arg1->data.pointer = args;
+      arg2->data.integer = from_tty;
+      arg3->data.integer = async_exec;
+      add_continuation (attach_command_continuation, arg1);
+      return;
     }
-  else
-    {
-      reopen_exec_file ();
-      reread_symbols ();
-    }
-
-  /* Take any necessary post-attaching actions for this platform.
-   */
-  target_post_attach (PIDGET (inferior_ptid));
-
-  post_create_inferior (&current_target, from_tty);
 
-  /* Install inferior's terminal modes.  */
-  target_terminal_inferior ();
-
-  normal_stop ();
+  wait_for_inferior (0);
+#endif
 
-  if (deprecated_attach_hook)
-    deprecated_attach_hook ();
+  attach_command_post_wait (args, from_tty, async_exec);
 }
 
 /*