[Qemu-devel] [5431] Allow the monitor to be suspended during non-blocking op

[Qemu-devel] [5431] Allow the monitor to be suspended during non-blocking op

[Anthony Liguori]

Revision: 5431
          http://svn.sv.gnu.org/viewvc/?view=rev&root=qemu&revision=5431
Author:   aliguori
Date:     2008-10-06 13:52:44 +0000 (Mon, 06 Oct 2008)

Log Message:
-----------
Allow the monitor to be suspended during non-blocking op

Live migration happens in the background, but it is useful to make the monitor
command appear as if it's blocking.  This allows a management tool to
immediately know when the live migration has completed without having to poll
the migration status.

This patch allows the monitor to be suspended from a monitor callback which
will prevent new monitor commands from being executed.

Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>

Modified Paths:
--------------
    trunk/console.h
    trunk/monitor.c

Modified: trunk/console.h
===================================================================
--- trunk/console.h	2008-10-05 11:47:55 UTC (rev 5430)
+++ trunk/console.h	2008-10-06 13:52:44 UTC (rev 5431)
@@ -175,6 +175,8 @@
 void term_print_help(void);
 void monitor_readline(const char *prompt, int is_password,
                       char *buf, int buf_size);
+void monitor_suspend(void);
+void monitor_resume(void);
 
 /* readline.c */
 typedef void ReadLineFunc(void *opaque, const char *str);

Modified: trunk/monitor.c
===================================================================
--- trunk/monitor.c	2008-10-05 11:47:55 UTC (rev 5430)
+++ trunk/monitor.c	2008-10-06 13:52:44 UTC (rev 5431)
@@ -2694,12 +2694,29 @@
         readline_handle_byte(buf[i]);
 }
 
+static int monitor_suspended;
+
 static void monitor_handle_command1(void *opaque, const char *cmdline)
 {
     monitor_handle_command(cmdline);
-    monitor_start_input();
+    if (!monitor_suspended)
+        monitor_start_input();
+    else
+        monitor_suspended = 2;
 }
 
+void monitor_suspend(void)
+{
+    monitor_suspended = 1;
+}
+
+void monitor_resume(void)
+{
+    if (monitor_suspended == 2)
+        monitor_start_input();
+    monitor_suspended = 0;
+}
+
 static void monitor_start_input(void)
 {
     readline_start("(qemu) ", 0, monitor_handle_command1, NULL);

[Qemu-devel] Re: [5431] Allow the monitor to be suspended during non-blocking op

[Jan Kiszka]

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Anthony Liguori wrote:
> Revision: 5431
>           http://svn.sv.gnu.org/viewvc/?view=rev&root=qemu&revision=5431
> Author:   aliguori
> Date:     2008-10-06 13:52:44 +0000 (Mon, 06 Oct 2008)
> 
> Log Message:
> -----------
> Allow the monitor to be suspended during non-blocking op
> 
> Live migration happens in the background, but it is useful to make the monitor
> command appear as if it's blocking.  This allows a management tool to
> immediately know when the live migration has completed without having to poll
> the migration status.
> 
> This patch allows the monitor to be suspended from a monitor callback which
> will prevent new monitor commands from being executed.

This is not true. The current code just prevents the command prompt from
being printed. Yeah, this subsystem is hairy. :)

I'm currently reworking the whole monitor infrastructure and could
either include a fix in my series to make this true suspension - or name
the interface after its effect: monitor_enable/disable_prompt().

So, what is the actually desired behavior?

Jan


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