[Qemu-devel] [PATCH 0/5] Easier conversion from qapi to qobject

[Qemu-devel] [PATCH 0/5] Easier conversion from qapi to qobject

[Eric Blake]

I'm not sure if I'm posted this before, or if it is a cleanup I've
just been sitting on locally.  In all likelihood, it will miss
tomorrow's freeze due to lack of review time, and thus be 2.11
material, but we'll see...

Eric Blake (5):
  qapi: Add QAPI_TO_QOBJECT() convenience macro
  nbd: Use simpler QAPI_TO_QOBJECT()
  nfs: Use simpler QAPI_TO_QOBJECT()
  qapi: Use simpler QAPI_TO_QOBJECT()
  blockdev: Use simpler QAPI_TO_QOBJECT()

 include/qapi/qobject-output-visitor.h | 19 +++++++++++++++++++
 block/nbd.c                           |  8 +++-----
 block/nfs.c                           |  8 +++-----
 block/qapi.c                          |  7 +++----
 blockdev.c                            | 13 ++++---------
 qapi/qobject-output-visitor.c         | 16 ++++++++++++++++
 6 files changed, 48 insertions(+), 23 deletions(-)

-- 
2.13.3

[Qemu-devel] [PATCH 1/5] qapi: Add QAPI_TO_QOBJECT() convenience macro

[Eric Blake]

We have several callers that want to convert a QAPI C type into
a QObject; right now all of them have to copy the same boilerplate
of creating a visitor. A convenience macro makes this paradigm
easier to type.

Signed-off-by: Eric Blake <eblake@redhat.com>
---
 include/qapi/qobject-output-visitor.h | 19 +++++++++++++++++++
 qapi/qobject-output-visitor.c         | 16 ++++++++++++++++
 2 files changed, 35 insertions(+)

diff --git a/include/qapi/qobject-output-visitor.h b/include/qapi/qobject-output-visitor.h
index e5a3490812..f6066ce537 100644
--- a/include/qapi/qobject-output-visitor.h
+++ b/include/qapi/qobject-output-visitor.h
@@ -16,6 +16,8 @@

 #include "qapi/visitor.h"
 #include "qapi/qmp/qobject.h"
+#include "qapi/error.h"
+#include "qapi-visit.h"

 typedef struct QObjectOutputVisitor QObjectOutputVisitor;

@@ -54,4 +56,21 @@ typedef struct QObjectOutputVisitor QObjectOutputVisitor;
  */
 Visitor *qobject_output_visitor_new(QObject **result);

+QObject *qapi_to_qobject(const void *src,
+                         void (*visit_type)(Visitor *, const char *,
+                                            void **, Error **),
+                         Error **errp);
+
+/*
+ * Create a QObject from a QAPI object @src of the given @type.
+ *
+ * Not usable on QAPI scalars (integers, strings, enums), nor on a
+ * QAPI object that references the 'any' type.  @src must not be NULL.
+ */
+#define QAPI_TO_QOBJECT(type, src, err)                                 \
+    (qapi_to_qobject(1 ? (src) : (type *)NULL,                          \
+                     (void (*)(Visitor *, const char *, void**,         \
+                               Error **))visit_type_ ## type,           \
+                     err))
+
 #endif
diff --git a/qapi/qobject-output-visitor.c b/qapi/qobject-output-visitor.c
index 70be84ccb5..0b1f098fa1 100644
--- a/qapi/qobject-output-visitor.c
+++ b/qapi/qobject-output-visitor.c
@@ -251,3 +251,19 @@ Visitor *qobject_output_visitor_new(QObject **result)

     return &v->visitor;
 }
+
+QObject *qapi_to_qobject(const void *src,
+                         void (*visit_type)(Visitor *, const char *,
+                                            void **, Error **),
+                         Error **errp)
+{
+    Visitor *v;
+    void *s = (void *) src; /* cast away const */
+    QObject *dst = NULL;
+
+    v = qobject_output_visitor_new(&dst);
+    visit_type(v, NULL, &s, &error_abort);
+    visit_complete(v, &dst);
+    visit_free(v);
+    return dst;
+}
-- 
2.13.3

[Qemu-devel] [PATCH 2/5] nbd: Use simpler QAPI_TO_QOBJECT()

[Eric Blake]

Use the new macro to avoid some boilerplate.

Signed-off-by: Eric Blake <eblake@redhat.com>
---
 block/nbd.c | 8 +++-----
 1 file changed, 3 insertions(+), 5 deletions(-)

diff --git a/block/nbd.c b/block/nbd.c
index a50d24b50a..f90ac76d1f 100644
--- a/block/nbd.c
+++ b/block/nbd.c
@@ -519,7 +519,6 @@ static void nbd_refresh_filename(BlockDriverState *bs, QDict *options)
     BDRVNBDState *s = bs->opaque;
     QDict *opts = qdict_new();
     QObject *saddr_qdict;
-    Visitor *ov;
     const char *host = NULL, *port = NULL, *path = NULL;

     if (s->saddr->type == SOCKET_ADDRESS_TYPE_INET) {
@@ -548,10 +547,9 @@ static void nbd_refresh_filename(BlockDriverState *bs, QDict *options)
                  "nbd://%s:%s", host, port);
     }

-    ov = qobject_output_visitor_new(&saddr_qdict);
-    visit_type_SocketAddress(ov, NULL, &s->saddr, &error_abort);
-    visit_complete(ov, &saddr_qdict);
-    visit_free(ov);
+    saddr_qdict = QAPI_TO_QOBJECT(SocketAddress, s->saddr, &error_abort);
+    assert(qobject_type(saddr_qdict) == QTYPE_QDICT);
+
     qdict_put_obj(opts, "server", saddr_qdict);

     if (s->export) {
-- 
2.13.3

[Qemu-devel] [PATCH 3/5] nfs: Use simpler QAPI_TO_QOBJECT()

[Eric Blake]

Use the new macro to avoid some boilerplate.

Signed-off-by: Eric Blake <eblake@redhat.com>
---
 block/nfs.c | 8 +++-----
 1 file changed, 3 insertions(+), 5 deletions(-)

diff --git a/block/nfs.c b/block/nfs.c
index d8db419957..5f3045c1af 100644
--- a/block/nfs.c
+++ b/block/nfs.c
@@ -819,7 +819,6 @@ static void nfs_refresh_filename(BlockDriverState *bs, QDict *options)
     NFSClient *client = bs->opaque;
     QDict *opts = qdict_new();
     QObject *server_qdict;
-    Visitor *ov;

     qdict_put_str(opts, "driver", "nfs");

@@ -840,9 +839,9 @@ static void nfs_refresh_filename(BlockDriverState *bs, QDict *options)
                  "nfs://%s%s", client->server->host, client->path);
     }

-    ov = qobject_output_visitor_new(&server_qdict);
-    visit_type_NFSServer(ov, NULL, &client->server, &error_abort);
-    visit_complete(ov, &server_qdict);
+    server_qdict = QAPI_TO_QOBJECT(NFSServer, client->server, &error_abort);
+    assert(qobject_type(server_qdict) == QTYPE_QDICT);
+
     qdict_put_obj(opts, "server", server_qdict);
     qdict_put_str(opts, "path", client->path);

@@ -865,7 +864,6 @@ static void nfs_refresh_filename(BlockDriverState *bs, QDict *options)
         qdict_put_int(opts, "debug", client->debug);
     }

-    visit_free(ov);
     qdict_flatten(opts);
     bs->full_open_options = opts;
 }
-- 
2.13.3

[Qemu-devel] [PATCH 4/5] qapi: Use simpler QAPI_TO_QOBJECT()

[Eric Blake]

Use the new macro to avoid some boilerplate.

Signed-off-by: Eric Blake <eblake@redhat.com>
---
 block/qapi.c | 7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

diff --git a/block/qapi.c b/block/qapi.c
index 080eb8f115..23e666f108 100644
--- a/block/qapi.c
+++ b/block/qapi.c
@@ -675,14 +675,13 @@ void bdrv_image_info_specific_dump(fprintf_function func_fprintf, void *f,
                                    ImageInfoSpecific *info_spec)
 {
     QObject *obj, *data;
-    Visitor *v = qobject_output_visitor_new(&obj);

-    visit_type_ImageInfoSpecific(v, NULL, &info_spec, &error_abort);
-    visit_complete(v, &obj);
+    obj = QAPI_TO_QOBJECT(ImageInfoSpecific, info_spec, &error_abort);
+
+    assert(qobject_type(obj) == QTYPE_QDICT);
     data = qdict_get(qobject_to_qdict(obj), "data");
     dump_qobject(func_fprintf, f, 1, data);
     qobject_decref(obj);
-    visit_free(v);
 }

 void bdrv_image_info_dump(fprintf_function func_fprintf, void *f,
-- 
2.13.3

[Qemu-devel] [PATCH 5/5] blockdev: Use simpler QAPI_TO_QOBJECT()

[Eric Blake]

Use the new macro to avoid some boilerplate.

Signed-off-by: Eric Blake <eblake@redhat.com>
---
 blockdev.c | 13 ++++---------
 1 file changed, 4 insertions(+), 9 deletions(-)

diff --git a/blockdev.c b/blockdev.c
index 7f53cc8bb3..bf26c38195 100644
--- a/blockdev.c
+++ b/blockdev.c
@@ -3884,35 +3884,30 @@ void qmp_blockdev_add(BlockdevOptions *options, Error **errp)
 {
     BlockDriverState *bs;
     QObject *obj;
-    Visitor *v = qobject_output_visitor_new(&obj);
     QDict *qdict;
     Error *local_err = NULL;

-    visit_type_BlockdevOptions(v, NULL, &options, &local_err);
+    obj = QAPI_TO_QOBJECT(BlockdevOptions, options, &local_err);
     if (local_err) {
         error_propagate(errp, local_err);
-        goto fail;
+        return;
     }

-    visit_complete(v, &obj);
     qdict = qobject_to_qdict(obj);

     qdict_flatten(qdict);

     if (!qdict_get_try_str(qdict, "node-name")) {
         error_setg(errp, "'node-name' must be specified for the root node");
-        goto fail;
+        return;
     }

     bs = bds_tree_init(qdict, errp);
     if (!bs) {
-        goto fail;
+        return;
     }

     QTAILQ_INSERT_TAIL(&monitor_bdrv_states, bs, monitor_list);
-
-fail:
-    visit_free(v);
 }

 void qmp_blockdev_del(const char *node_name, Error **errp)
-- 
2.13.3

Re: [Qemu-devel] [PATCH 0/5] Easier conversion from qapi to qobject

[Eric Blake]

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On 07/17/2017 10:56 AM, Eric Blake wrote:
> I'm not sure if I'm posted this before, or if it is a cleanup I've
> just been sitting on locally.  In all likelihood, it will miss
> tomorrow's freeze due to lack of review time, and thus be 2.11
> material, but we'll see...

Answering myself, it was part of my larger (mostly-unreviewed) attempt
to rip out dynamic JSON parsing [1]. But it is independent enough that
it warrants its own thread for separate review.

[1] https://lists.gnu.org/archive/html/qemu-devel/2016-11/msg05425.html

> 
> Eric Blake (5):
>   qapi: Add QAPI_TO_QOBJECT() convenience macro
>   nbd: Use simpler QAPI_TO_QOBJECT()
>   nfs: Use simpler QAPI_TO_QOBJECT()
>   qapi: Use simpler QAPI_TO_QOBJECT()
>   blockdev: Use simpler QAPI_TO_QOBJECT()
> 
>  include/qapi/qobject-output-visitor.h | 19 +++++++++++++++++++
>  block/nbd.c                           |  8 +++-----
>  block/nfs.c                           |  8 +++-----
>  block/qapi.c                          |  7 +++----
>  blockdev.c                            | 13 ++++---------
>  qapi/qobject-output-visitor.c         | 16 ++++++++++++++++
>  6 files changed, 48 insertions(+), 23 deletions(-)

The diffstat is misleading because of the size of the additional
interface and comments.

-- 
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3266
Virtualization:  qemu.org | libvirt.org


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Re: [Qemu-devel] [PATCH 0/5] Easier conversion from qapi to qobject

[Markus Armbruster]

Eric Blake <eblake@redhat.com> writes:

> On 07/17/2017 10:56 AM, Eric Blake wrote:
>> I'm not sure if I'm posted this before, or if it is a cleanup I've
>> just been sitting on locally.  In all likelihood, it will miss
>> tomorrow's freeze due to lack of review time, and thus be 2.11
>> material, but we'll see...

I had a quick glance.  Looks like a small improvement to me.  No need to
rush it into 2.10.  I suspect some (all?) of the remaining qobject
output visitor uses could also be converted.

> Answering myself, it was part of my larger (mostly-unreviewed) attempt
> to rip out dynamic JSON parsing [1]. But it is independent enough that
> it warrants its own thread for separate review.

Yes, splitting it out makes sense.  Thanks!

> [1] https://lists.gnu.org/archive/html/qemu-devel/2016-11/msg05425.html

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