[Qemu-devel] [PATCH v3 29/38] qmp: introduce asynchronous command type

[Marc-André Lureau]

Add a new type of command, QmpCommandFuncAsync: those commands can
return later thanks to QmpReturn. This commit introduces the new type
and register function and teach qmp_dipatch() to call it without
qmp_return().

Signed-off-by: Marc-André Lureau <marcandre.lur...@redhat.com>
---
 include/qapi/qmp/dispatch.h |  9 ++++++++-
 qapi/qmp-dispatch.c         |  4 +++-
 qapi/qmp-registry.c         | 27 ++++++++++++++++++++++++---
 3 files changed, 35 insertions(+), 5 deletions(-)

diff --git a/include/qapi/qmp/dispatch.h b/include/qapi/qmp/dispatch.h
index f6db06c164..e426317346 100644
--- a/include/qapi/qmp/dispatch.h
+++ b/include/qapi/qmp/dispatch.h
@@ -21,18 +21,23 @@
 typedef struct QmpReturn QmpReturn;
 
 typedef void (QmpCommandFunc)(QDict *, QObject **, Error **);
+typedef void (QmpCommandAsyncFunc)(QDict *, QmpReturn *);
 
 typedef enum QmpCommandOptions
 {
     QCO_NO_OPTIONS            =  0x0,
     QCO_NO_SUCCESS_RESP       =  (1U << 0),
     QCO_ALLOW_OOB             =  (1U << 1),
+    QCO_ASYNC                 =  (1U << 2),
 } QmpCommandOptions;
 
 typedef struct QmpCommand
 {
     const char *name;
-    QmpCommandFunc *fn;
+    union {
+        QmpCommandFunc *fn;
+        QmpCommandAsyncFunc *async_fn;
+    };
     QmpCommandOptions options;
     QTAILQ_ENTRY(QmpCommand) node;
     bool enabled;
@@ -88,6 +93,8 @@ void qmp_return_error(QmpReturn *qret, Error *err);
 
 void qmp_register_command(QmpCommandList *cmds, const char *name,
                           QmpCommandFunc *fn, QmpCommandOptions options);
+void qmp_register_async_command(QmpCommandList *cmds, const char *name,
+                          QmpCommandAsyncFunc *fn, QmpCommandOptions options);
 void qmp_unregister_command(QmpCommandList *cmds, const char *name);
 QmpCommand *qmp_find_command(QmpCommandList *cmds, const char *name);
 
diff --git a/qapi/qmp-dispatch.c b/qapi/qmp-dispatch.c
index aa8b71a2c0..f7d9931734 100644
--- a/qapi/qmp-dispatch.c
+++ b/qapi/qmp-dispatch.c
@@ -195,7 +195,9 @@ void qmp_dispatch(QmpSession *session, QDict *req)
         QINCREF(args);
     }
 
-    {
+    if (cmd->options & QCO_ASYNC) {
+        cmd->async_fn(args, qmp_return_new(session, req));
+    } else {
         QObject *ret = NULL;
         cmd->fn(args, &ret, &err);
         if (err || cmd->options & QCO_NO_SUCCESS_RESP) {
diff --git a/qapi/qmp-registry.c b/qapi/qmp-registry.c
index 5af484cd9a..180b1c1e69 100644
--- a/qapi/qmp-registry.c
+++ b/qapi/qmp-registry.c
@@ -15,16 +15,37 @@
 #include "qemu/osdep.h"
 #include "qapi/qmp/dispatch.h"
 
-void qmp_register_command(QmpCommandList *cmds, const char *name,
-                          QmpCommandFunc *fn, QmpCommandOptions options)
+
+static QmpCommand *qmp_command_new(QmpCommandList *cmds, const char *name,
+                                   QmpCommandOptions options)
 {
     QmpCommand *cmd = g_malloc0(sizeof(*cmd));
 
     cmd->name = name;
-    cmd->fn = fn;
     cmd->enabled = true;
     cmd->options = options;
     QTAILQ_INSERT_TAIL(cmds, cmd, node);
+
+    return cmd;
+}
+
+
+void qmp_register_command(QmpCommandList *cmds, const char *name,
+                          QmpCommandFunc *fn, QmpCommandOptions options)
+{
+    QmpCommand *cmd = qmp_command_new(cmds, name, options);
+
+    assert(!(options & QCO_ASYNC));
+    cmd->fn = fn;
+}
+
+void qmp_register_async_command(QmpCommandList *cmds, const char *name,
+                            QmpCommandAsyncFunc *fn, QmpCommandOptions options)
+{
+    QmpCommand *cmd = qmp_command_new(cmds, name, options);
+
+    assert(options & QCO_ASYNC);
+    cmd->async_fn = fn;
 }
 
 void qmp_unregister_command(QmpCommandList *cmds, const char *name)
-- 
2.17.0.rc1.1.g4c4f2b46a3