diff mbox

New API for asynchronous monitor commands (V2)

Message ID 4B61D782.1010800@redhat.com
State New
Headers show

Commit Message

Kevin Wolf Jan. 28, 2010, 6:29 p.m. UTC 
Am 25.01.2010 19:18, schrieb Adam Litke:
> Changes since V1:
>  - Miscellaneous code cleanups (Thanks Luiz)
> 
> Qemu has a number of commands that can operate asynchronously (savevm, migrate,
> etc) and it will be getting more.  For these commands, the user monitor needs
> to be suspended, but QMP monitors could continue to to accept other commands.
> This patch introduces a new command API that isolates the details of handling
> different monitor types from the actual command execution.
> 
> A monitor command can use this API by implementing the mhandler.cmd_async
> handler (or info_async if appropriate).  This function is responsible for
> submitting the command and does not return any data although it may raise
> errors.  When the command completes, the QMPCompletion callback should be
> invoked with its opaque data and the command result.
> 
> The process for submitting and completing an asynchronous command is different
> for QMP and user monitors.  A user monitor must be suspended at submit time and
> resumed at completion time.  The user_print() function must be passed to the
> QMPCompletion callback so the result can be displayed properly.  QMP monitors
> are simpler.  No submit time setup is required.  When the command completes,
> monitor_protocol_emitter() writes the result in JSON format.
> 
> This API can also be used to implement synchronous commands.  In this case, the
> cmd_async handler should immediately call the QMPCompletion callback.  It is my
> hope that this new interface will work for all commands, leading to a
> drastically simplified monitor.c once all commands are ported.
> 
> Thanks to Anthony for helping me out with the initial design.
> 
> Signed-off-by: Adam Litke <agl@us.ibm.com>

This commit introduces a segfault on info pci for me. The following
patch seems to make it work again. Is it correct or is rather info pci
doing something wrong?


Kevin
diff mbox

Patch

diff --git a/monitor.c b/monitor.c
index fbae5ce..22690c4 100644
--- a/monitor.c
+++ b/monitor.c
@@ -3700,7 +3700,12 @@  static void monitor_print_error(Monitor *mon)

 static int is_async_return(const QObject *data)
 {
-    return data && qdict_haskey(qobject_to_qdict(data), "__mon_async");
+    const QDict *dict = NULL;
+
+    if (data != NULL) {
+        dict = qobject_to_qdict(data);
+    }
+    return dict && qdict_haskey(dict, "__mon_async");
 }

 static void monitor_call_handler(Monitor *mon, const mon_cmd_t *cmd,