@@ -556,7 +556,8 @@ following example objects:
Usage: { 'command': STRING, '*data': COMPLEX-TYPE-NAME-OR-DICT,
'*returns': TYPE-NAME, '*boxed': true,
- '*gen': false, '*success-response': false }
+ '*gen': false, '*success-response': false,
+ '*allow-oob': false }
Commands are defined by using a dictionary containing several members,
where three members are most common. The 'command' member is a
@@ -636,6 +637,34 @@ possible, the command expression should include the optional key
'success-response' with boolean value false. So far, only QGA makes
use of this member.
+Most of the QMP commands are handled sequentially in such a order.
+Firstly, the JSON Parser parses the command request into some internal
+message, then it delivers the message to QMP dispatchers; secondly,
+the QMP dispatchers will handle the commands one by one in time order,
+respond when necessary. For some commands that always complete
+"quickly" can instead be executed directly during parsing, at the QMP
+client's request. This kind of commands that allow direct execution
+is called "out-of-band" ("oob" as shortcut) commands. the response can
+overtake prior in-band commands' responses. By default, commands are
+always in-band. We need to explicitly specify "allow-oob" to "True"
+to show that one command can be run out-of-band.
+
+One thing to mention is that, although out-of-band execution of
+commands benefit from quick and asynchronous execution, it need to
+satisfy at least the following:
+
+(1) It is extremely quick and never blocks, so that its execution will
+ not block parsing routine of any other monitors.
+
+(2) It does not need BQL, since the parser can be run without BQL,
+ while the dispatcher is always with BQL held.
+
+If not, the command is not suitable to be allowed to run out-of-band,
+and it should set its "allow-oob" to "False". Whether a command is
+allowed to run out-of-band can also be introspected using
+query-qmp-schema command. Please see the section "Client JSON
+Protocol introspection" for more information.
+
=== Events ===
@@ -739,10 +768,12 @@ references by name.
QAPI schema definitions not reachable that way are omitted.
The SchemaInfo for a command has meta-type "command", and variant
-members "arg-type" and "ret-type". On the wire, the "arguments"
-member of a client's "execute" command must conform to the object type
-named by "arg-type". The "return" member that the server passes in a
-success response conforms to the type named by "ret-type".
+members "arg-type", "ret-type" and "allow-oob". On the wire, the
+"arguments" member of a client's "execute" command must conform to the
+object type named by "arg-type". The "return" member that the server
+passes in a success response conforms to the type named by
+"ret-type". When "allow-oob" is set, it means the command supports
+out-of-band execution.
If the command takes no arguments, "arg-type" names an object type
without members. Likewise, if the command returns nothing, "ret-type"
@@ -23,6 +23,7 @@ typedef enum QmpCommandOptions
{
QCO_NO_OPTIONS = 0x0,
QCO_NO_SUCCESS_RESP = 0x1,
+ QCO_ALLOW_OOB = 0x2,
} QmpCommandOptions;
typedef struct QmpCommand
@@ -259,12 +259,16 @@
#
# @ret-type: the name of the command's result type.
#
+# @allow-oob: whether the command allows out-of-band execution.
+# (Since: 2.11)
+#
# TODO: @success-response (currently irrelevant, because it's QGA, not QMP)
#
# Since: 2.5
##
{ 'struct': 'SchemaInfoCommand',
- 'data': { 'arg-type': 'str', 'ret-type': 'str' } }
+ 'data': { 'arg-type': 'str', 'ret-type': 'str',
+ 'allow-oob': 'bool' } }
##
# @SchemaInfoEvent:
@@ -192,10 +192,18 @@ out:
return ret
-def gen_register_command(name, success_response):
- options = 'QCO_NO_OPTIONS'
+def gen_register_command(name, success_response, allow_oob):
+ options = []
+
if not success_response:
- options = 'QCO_NO_SUCCESS_RESP'
+ options += ['QCO_NO_SUCCESS_RESP']
+ if allow_oob:
+ options += ['QCO_ALLOW_OOB']
+
+ if not options:
+ options = ['QCO_NO_OPTIONS']
+
+ options = " | ".join(options)
ret = mcgen('''
qmp_register_command(cmds, "%(name)s",
@@ -241,7 +249,7 @@ class QAPISchemaGenCommandVisitor(QAPISchemaVisitor):
self._visited_ret_types = None
def visit_command(self, name, info, arg_type, ret_type,
- gen, success_response, boxed):
+ gen, success_response, boxed, allow_oob):
if not gen:
return
self.decl += gen_command_decl(name, arg_type, boxed, ret_type)
@@ -250,7 +258,8 @@ class QAPISchemaGenCommandVisitor(QAPISchemaVisitor):
self.defn += gen_marshal_output(ret_type)
self.decl += gen_marshal_decl(name)
self.defn += gen_marshal(name, arg_type, boxed, ret_type)
- self._regy += gen_register_command(name, success_response)
+ self._regy += gen_register_command(name, success_response,
+ allow_oob)
(input_file, output_dir, do_c, do_h, prefix, opts) = parse_command_line()
@@ -28,6 +28,11 @@ def to_json(obj, level=0):
to_json(obj[key], level + 1))
for key in sorted(obj.keys())]
ret = '{' + ', '.join(elts) + '}'
+ elif isinstance(obj, bool):
+ if obj:
+ ret = 'true'
+ else:
+ ret = 'false'
else:
assert False # not implemented
if level == 1:
@@ -154,12 +159,13 @@ const char %(c_name)s[] = %(c_string)s;
for m in variants.variants]})
def visit_command(self, name, info, arg_type, ret_type,
- gen, success_response, boxed):
+ gen, success_response, boxed, allow_oob):
arg_type = arg_type or self._schema.the_empty_object_type
ret_type = ret_type or self._schema.the_empty_object_type
self._gen_json(name, 'command',
{'arg-type': self._use_type(arg_type),
- 'ret-type': self._use_type(ret_type)})
+ 'ret-type': self._use_type(ret_type),
+ 'allow-oob': allow_oob})
def visit_event(self, name, info, arg_type, boxed):
arg_type = arg_type or self._schema.the_empty_object_type
@@ -920,7 +920,8 @@ def check_exprs(exprs):
elif 'command' in expr:
meta = 'command'
check_keys(expr_elem, 'command', [],
- ['data', 'returns', 'gen', 'success-response', 'boxed'])
+ ['data', 'returns', 'gen', 'success-response',
+ 'boxed', 'allow-oob'])
elif 'event' in expr:
meta = 'event'
check_keys(expr_elem, 'event', [], ['data', 'boxed'])
@@ -1031,7 +1032,7 @@ class QAPISchemaVisitor(object):
pass
def visit_command(self, name, info, arg_type, ret_type,
- gen, success_response, boxed):
+ gen, success_response, boxed, allow_oob):
pass
def visit_event(self, name, info, arg_type, boxed):
@@ -1398,7 +1399,7 @@ class QAPISchemaAlternateType(QAPISchemaType):
class QAPISchemaCommand(QAPISchemaEntity):
def __init__(self, name, info, doc, arg_type, ret_type,
- gen, success_response, boxed):
+ gen, success_response, boxed, allow_oob):
QAPISchemaEntity.__init__(self, name, info, doc)
assert not arg_type or isinstance(arg_type, str)
assert not ret_type or isinstance(ret_type, str)
@@ -1409,6 +1410,7 @@ class QAPISchemaCommand(QAPISchemaEntity):
self.gen = gen
self.success_response = success_response
self.boxed = boxed
+ self.allow_oob = allow_oob
def check(self, schema):
if self._arg_type_name:
@@ -1432,7 +1434,8 @@ class QAPISchemaCommand(QAPISchemaEntity):
def visit(self, visitor):
visitor.visit_command(self.name, self.info,
self.arg_type, self.ret_type,
- self.gen, self.success_response, self.boxed)
+ self.gen, self.success_response,
+ self.boxed, self.allow_oob)
class QAPISchemaEvent(QAPISchemaEntity):
@@ -1640,6 +1643,7 @@ class QAPISchema(object):
gen = expr.get('gen', True)
success_response = expr.get('success-response', True)
boxed = expr.get('boxed', False)
+ allow_oob = expr.get('allow-oob', False)
if isinstance(data, OrderedDict):
data = self._make_implicit_object_type(
name, info, doc, 'arg', self._make_members(data, info))
@@ -1647,7 +1651,8 @@ class QAPISchema(object):
assert len(rets) == 1
rets = self._make_array_type(rets[0], info)
self._def_entity(QAPISchemaCommand(name, info, doc, data, rets,
- gen, success_response, boxed))
+ gen, success_response,
+ boxed, allow_oob))
def _def_event(self, expr, info, doc):
name = expr['event']
@@ -236,7 +236,7 @@ class QAPISchemaGenDocVisitor(qapi.QAPISchemaVisitor):
body=texi_entity(doc, 'Members'))
def visit_command(self, name, info, arg_type, ret_type,
- gen, success_response, boxed):
+ gen, success_response, boxed, allow_oob):
doc = self.cur_doc
if self.out:
self.out += '\n'
@@ -36,7 +36,7 @@ class QAPISchemaTestVisitor(QAPISchemaVisitor):
self._print_variants(variants)
def visit_command(self, name, info, arg_type, ret_type,
- gen, success_response, boxed):
+ gen, success_response, boxed, allow_oob):
print 'command %s %s -> %s' % \
(name, arg_type and arg_type.name, ret_type and ret_type.name)
print ' gen=%s success_response=%s boxed=%s' % \
Here "oob" stands for "Out-Of-Band". When "allow-oob" is set, it means the command allows out-of-band execution. Please see the spec update for more details. The "oob" idea is proposed by Markus Armbruster in following thread: https://lists.gnu.org/archive/html/qemu-devel/2017-09/msg02057.html This new "allow-oob" boolean will be exposed by "query-qmp-schema" as well for command entries, so that QMP clients can know which command can be used as out-of-band calls. For example the command "migrate" originally looks like: {"name": "migrate", "ret-type": "17", "meta-type": "command", "arg-type": "86"} And it'll be changed into: {"name": "migrate", "ret-type": "17", "allow-oob": false, "meta-type": "command", "arg-type": "86"} This patch only provides the QMP interface level changes. It does not contains the real out-of-band execution implementation yet. Suggested-by: Markus Armbruster <armbru@redhat.com> Signed-off-by: Peter Xu <peterx@redhat.com> --- docs/devel/qapi-code-gen.txt | 41 ++++++++++++++++++++++++++++++++++++----- include/qapi/qmp/dispatch.h | 1 + qapi/introspect.json | 6 +++++- scripts/qapi-commands.py | 19 ++++++++++++++----- scripts/qapi-introspect.py | 10 ++++++++-- scripts/qapi.py | 15 ++++++++++----- scripts/qapi2texi.py | 2 +- tests/qapi-schema/test-qapi.py | 2 +- 8 files changed, 76 insertions(+), 20 deletions(-)