* [Qemu-trivial] [PATCH] Add object_property_get_child().
@ 2012-02-16 17:39 Alexander Barabash
2012-02-16 18:16 ` [Qemu-trivial] [Qemu-devel] " Peter Maydell
2012-02-17 10:17 ` [Qemu-trivial] " Paolo Bonzini
0 siblings, 2 replies; 3+ messages in thread
From: Alexander Barabash @ 2012-02-16 17:39 UTC (permalink / raw)
To: qemu-devel; +Cc: qemu-trivial
Add object_property_get_child().
Adding a direct accessor to a child property.
In the existing implementation, object_property_get() must be used,
with with a visitor, implementing the 'type_str' callback,
receiving the child's canonical path.
In the new implementation, the child is returned directly.
Link properties are resolved in the same way, as they are
when an absolute path is resolved.
Errors relevant to the operation, QERR_OBJECT_PROPERTY_NOT_FOUND
and QERR_OBJECT_PROPERTY_INVALID_TYPE were added.
Also, in the new implementation, some common sense refactoring was done
in the file 'qom/object.c' in the code extracting child and link
properties.
Signed-off-by: Alexander Barabash <alexander_barabash@mentor.com>
diff --git a/include/qemu/object.h b/include/qemu/object.h
index e7e32fe..190f422 100644
--- a/include/qemu/object.h
+++ b/include/qemu/object.h
@@ -711,6 +711,21 @@ int64_t object_property_get_int(Object *obj, const
char *name,
struct Error **errp);
/**
+ * object_property_get_child:
+ * @obj: the object
+ * @name: the name of the property
+ * @errp: returns an error if this function fails
+ *
+ * Returns: if this a child property, the value of the property, or NULL if
+ * an error occurs (including when the property value is not a child
property).
+ *
+ * Result's reference count does not change.
+ * Therefore, he caller is responsible for referencing the result.
+ */
+Object *object_property_get_child(Object *obj, const char *name,
+ struct Error **errp);
+
+/**
* object_property_set:
* @obj: the object
* @v: the visitor that will be used to write the property value.
This should
diff --git a/qerror.h b/qerror.h
index e26c635..45e4468 100644
--- a/qerror.h
+++ b/qerror.h
@@ -178,6 +178,12 @@ QError *qobject_to_qerror(const QObject *obj);
#define QERR_NOT_SUPPORTED \
"{ 'class': 'NotSupported', 'data': {} }"
+#define QERR_OBJECT_PROPERTY_NOT_FOUND \
+ "{ 'class': 'ObjectPropertyNotFound', 'data': { 'object': %s,
'property': %s } }"
+
+#define QERR_OBJECT_PROPERTY_INVALID_TYPE \
+ "{ 'class': 'ObjectPropertyInvalidType', 'data': { 'object': %s,
'property': %s, 'expected_type': %s } }"
+
#define QERR_OPEN_FILE_FAILED \
"{ 'class': 'OpenFileFailed', 'data': { 'filename': %s } }"
diff --git a/qom/object.c b/qom/object.c
index 2de6eaf..61e775b 100644
--- a/qom/object.c
+++ b/qom/object.c
@@ -297,12 +297,86 @@ static void object_property_del_all(Object *obj)
}
}
+/*
+ * To ensure correct format checking,
+ * this function should be used only via REPORT_OBJECT_ERROR() macro.
+ *
+ * The first argument after 'obj' should be of type 'const char *'.
+ * It is ignored, and replaced by the canonical path of 'obj'.
+ */
+static void report_object_error(Error **errp, const char *fmt, Object
*obj, ...)
+ GCC_FMT_ATTR(2, 4);
+static void report_object_error(Error **errp, const char *fmt, Object
*obj, ...)
+{
+ gchar *path;
+ va_list ap;
+
+ if (errp != NULL) {
+ path = object_get_canonical_path(obj);
+ va_start(ap, obj);
+ va_arg(ap, const char *); /* Ignore the dummy string. */
+ error_set(errp, fmt, path, &ap);
+ va_end(ap);
+ g_free(path);
+ }
+}
+#define REPORT_OBJECT_ERROR(errp, fmt, obj, ...) \
+ do { \
+ report_object_error(errp, fmt, obj, "", ## __VA_ARGS__); \
+ } while (0)
+
+#define CHILD_PROPERTY_TYPE_PREFIX "child<"
+#define CHILD_PROPERTY_TYPE_SUFFIX ">"
+#define LINK_PROPERTY_TYPE_PREFIX "link<"
+#define LINK_PROPERTY_TYPE_SUFFIX ">"
+
+static bool object_property_is_child(ObjectProperty *prop)
+{
+ return (strstart(prop->type, CHILD_PROPERTY_TYPE_PREFIX, NULL) != 0);
+}
+
+static bool object_property_is_link(ObjectProperty *prop)
+{
+ return (strstart(prop->type, LINK_PROPERTY_TYPE_PREFIX, NULL) != 0);
+}
+
+/* Go from LINK_PROPERTY_TYPE_PREFIX FOO LINK_PROPERTY_TYPE_SUFFIX to
FOO. */
+static gchar *link_type_to_type(const gchar *type)
+{
+ return g_strndup(&type[sizeof(LINK_PROPERTY_TYPE_PREFIX) - 1],
+ strlen(type)
+ - (sizeof(LINK_PROPERTY_TYPE_PREFIX) - 1)
+ - (sizeof(LINK_PROPERTY_TYPE_SUFFIX) - 1));
+}
+
+static Object *object_property_extract_child(ObjectProperty *prop,
+ bool *p_is_invalid_type)
+{
+ if (p_is_invalid_type != NULL) {
+ *p_is_invalid_type = false;
+ }
+ if (object_property_is_child(prop)) {
+ return (Object *)prop->opaque;
+ } else if (object_property_is_link(prop)) {
+ if (prop->opaque != NULL) {
+ return *(Object **)prop->opaque;
+ } else {
+ return NULL;
+ }
+ } else {
+ if (p_is_invalid_type != NULL) {
+ *p_is_invalid_type = true;
+ }
+ return NULL;
+ }
+}
+
static void object_property_del_child(Object *obj, Object *child,
Error **errp)
{
ObjectProperty *prop;
QTAILQ_FOREACH(prop, &obj->properties, node) {
- if (!strstart(prop->type, "child<", NULL)) {
+ if (!object_property_is_child(prop)) {
continue;
}
@@ -799,6 +873,27 @@ Object *object_get_root(void)
return root;
}
+Object *object_property_get_child(Object *obj, const char *name,
+ struct Error **errp) {
+ Object *result = NULL;
+ ObjectProperty *prop = object_property_find(obj, name);
+ bool is_invalid_type;
+
+ if (prop == NULL) {
+ REPORT_OBJECT_ERROR(errp, QERR_OBJECT_PROPERTY_NOT_FOUND, obj,
name);
+ return NULL;
+ }
+
+ result = object_property_extract_child(prop, &is_invalid_type);
+ if (is_invalid_type) {
+ REPORT_OBJECT_ERROR(errp, QERR_OBJECT_PROPERTY_INVALID_TYPE,
+ obj, name, "child");
+ return NULL;
+ }
+
+ return result;
+}
+
static void object_get_child_property(Object *obj, Visitor *v, void
*opaque,
const char *name, Error **errp)
{
@@ -829,7 +924,10 @@ void object_property_add_child(Object *obj, const
char *name,
*/
assert(!object_is_type(obj, type_interface));
- type = g_strdup_printf("child<%s>",
object_get_typename(OBJECT(child)));
+ type = g_strdup_printf(CHILD_PROPERTY_TYPE_PREFIX
+ "%s"
+ CHILD_PROPERTY_TYPE_SUFFIX,
+ object_get_typename(OBJECT(child)));
object_property_add(obj, name, type, object_get_child_property,
NULL, object_finalize_child_property, child,
errp);
@@ -878,8 +976,7 @@ static void object_set_link_property(Object *obj,
Visitor *v, void *opaque,
if (strcmp(path, "") != 0) {
Object *target;
- /* Go from link<FOO> to FOO. */
- target_type = g_strndup(&type[5], strlen(type) - 6);
+ target_type = link_type_to_type(type);
target = object_resolve_path_type(path, target_type, &ambiguous);
if (ambiguous) {
@@ -907,7 +1004,9 @@ void object_property_add_link(Object *obj, const
char *name,
{
gchar *full_type;
- full_type = g_strdup_printf("link<%s>", type);
+ full_type = g_strdup_printf(LINK_PROPERTY_TYPE_PREFIX
+ "%s"
+ LINK_PROPERTY_TYPE_SUFFIX, type);
object_property_add(obj, name, full_type,
object_get_link_property,
@@ -932,7 +1031,7 @@ gchar *object_get_canonical_path(Object *obj)
g_assert(obj->parent != NULL);
QTAILQ_FOREACH(prop, &obj->parent->properties, node) {
- if (!strstart(prop->type, "child<", NULL)) {
+ if (!object_property_is_child(prop)) {
continue;
}
@@ -980,15 +1079,7 @@ static Object *object_resolve_abs_path(Object *parent,
return NULL;
}
- child = NULL;
- if (strstart(prop->type, "link<", NULL)) {
- Object **pchild = prop->opaque;
- if (*pchild) {
- child = *pchild;
- }
- } else if (strstart(prop->type, "child<", NULL)) {
- child = prop->opaque;
- }
+ child = object_property_extract_child(prop, NULL);
if (!child) {
return NULL;
@@ -1010,7 +1101,7 @@ static Object *object_resolve_partial_path(Object
*parent,
QTAILQ_FOREACH(prop, &parent->properties, node) {
Object *found;
- if (!strstart(prop->type, "child<", NULL)) {
+ if (!object_property_is_child(prop)) {
continue;
}
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [Qemu-trivial] [Qemu-devel] [PATCH] Add object_property_get_child().
2012-02-16 17:39 [Qemu-trivial] [PATCH] Add object_property_get_child() Alexander Barabash
@ 2012-02-16 18:16 ` Peter Maydell
2012-02-17 10:17 ` [Qemu-trivial] " Paolo Bonzini
1 sibling, 0 replies; 3+ messages in thread
From: Peter Maydell @ 2012-02-16 18:16 UTC (permalink / raw)
To: Alexander Barabash; +Cc: qemu-trivial, qemu-devel
On 16 February 2012 17:39, Alexander Barabash
<alexander_barabash@mentor.com> wrote:
>
> Add object_property_get_child().
>
> Adding a direct accessor to a child property.
>
> In the existing implementation, object_property_get() must be used,
> with with a visitor, implementing the 'type_str' callback,
> receiving the child's canonical path.
>
> In the new implementation, the child is returned directly.
> Link properties are resolved in the same way, as they are
> when an absolute path is resolved.
>
> Errors relevant to the operation, QERR_OBJECT_PROPERTY_NOT_FOUND
> and QERR_OBJECT_PROPERTY_INVALID_TYPE were added.
Not trivial (look at the length of it!).
> Also, in the new implementation, some common sense refactoring was done
> in the file 'qom/object.c' in the code extracting child and link
> properties.
If you find yourself writing a commit message with a paragraph
starting "Also" this almost always means you should split it
into more than one patch.
-- PMM
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [Qemu-trivial] [PATCH] Add object_property_get_child().
2012-02-16 17:39 [Qemu-trivial] [PATCH] Add object_property_get_child() Alexander Barabash
2012-02-16 18:16 ` [Qemu-trivial] [Qemu-devel] " Peter Maydell
@ 2012-02-17 10:17 ` Paolo Bonzini
1 sibling, 0 replies; 3+ messages in thread
From: Paolo Bonzini @ 2012-02-17 10:17 UTC (permalink / raw)
To: Alexander Barabash; +Cc: qemu-trivial, qemu-devel
Besides the non-triviality of the patch, how is this different from
object_property_get_link? Perhaps we should just rename that one to
object_property_get_obj, or add a function that is just a synonym.
> + */
> +Object *object_property_get_child(Object *obj, const char *name,
> + struct Error **errp);
> +
> +/**
> * object_property_set:
> * @obj: the object
> * @v: the visitor that will be used to write the property value. This
> should
> diff --git a/qom/object.c b/qom/object.c
> index 2de6eaf..61e775b 100644
> --- a/qom/object.c
> +++ b/qom/object.c
> @@ -297,12 +297,86 @@ static void object_property_del_all(Object *obj)
> }
> }
>
> +/*
> + * To ensure correct format checking,
> + * this function should be used only via REPORT_OBJECT_ERROR() macro.
> + *
> + * The first argument after 'obj' should be of type 'const char *'.
> + * It is ignored, and replaced by the canonical path of 'obj'.
> + */
> +static void report_object_error(Error **errp, const char *fmt, Object
> *obj, ...)
> + GCC_FMT_ATTR(2, 4);
> +static void report_object_error(Error **errp, const char *fmt, Object
> *obj, ...)
> +{
> + gchar *path;
> + va_list ap;
> +
> + if (errp != NULL) {
> + path = object_get_canonical_path(obj);
> + va_start(ap, obj);
> + va_arg(ap, const char *); /* Ignore the dummy string. */
Why do you need it at all?
> + error_set(errp, fmt, path, &ap);
> + va_end(ap);
> + g_free(path);
> + }
> +}
> +#define REPORT_OBJECT_ERROR(errp, fmt, obj, ...) \
> + do { \
> + report_object_error(errp, fmt, obj, "", ## __VA_ARGS__); \
> + } while (0)
> +#define CHILD_PROPERTY_TYPE_PREFIX "child<"
> +#define CHILD_PROPERTY_TYPE_SUFFIX ">"
> +#define LINK_PROPERTY_TYPE_PREFIX "link<"
> +#define LINK_PROPERTY_TYPE_SUFFIX ">"
> +
> +static bool object_property_is_child(ObjectProperty *prop)
> +{
> + return (strstart(prop->type, CHILD_PROPERTY_TYPE_PREFIX, NULL) != 0);
> +}
> +
> +static bool object_property_is_link(ObjectProperty *prop)
> +{
> + return (strstart(prop->type, LINK_PROPERTY_TYPE_PREFIX, NULL) != 0);
> +}
> +
> +/* Go from LINK_PROPERTY_TYPE_PREFIX FOO LINK_PROPERTY_TYPE_SUFFIX to
> FOO. */
> +static gchar *link_type_to_type(const gchar *type)
> +{
> + return g_strndup(&type[sizeof(LINK_PROPERTY_TYPE_PREFIX) - 1],
> + strlen(type)
> + - (sizeof(LINK_PROPERTY_TYPE_PREFIX) - 1)
> + - (sizeof(LINK_PROPERTY_TYPE_SUFFIX) - 1));
> +}
> +
> +static Object *object_property_extract_child(ObjectProperty *prop,
> + bool *p_is_invalid_type)
> +{
> + if (p_is_invalid_type != NULL) {
> + *p_is_invalid_type = false;
> + }
> + if (object_property_is_child(prop)) {
> + return (Object *)prop->opaque;
> + } else if (object_property_is_link(prop)) {
> + if (prop->opaque != NULL) {
> + return *(Object **)prop->opaque;
> + } else {
> + return NULL;
> + }
> + } else {
> + if (p_is_invalid_type != NULL) {
> + *p_is_invalid_type = true;
> + }
> + return NULL;
> + }
> +}
> +
object_property_get_child should never be on a fast path. We should
avoid as much as possible peeking in the opaque. Instead, you should
just use a visitor like object_property_get_link does.
Everything starting here should be a separate patch. But if you remove
object_property_extract_child, I doubt it makes as much sense to
refactor this.
> static void object_property_del_child(Object *obj, Object *child, Error
> **errp)
> {
> ObjectProperty *prop;
>
> QTAILQ_FOREACH(prop, &obj->properties, node) {
> - if (!strstart(prop->type, "child<", NULL)) {
> + if (!object_property_is_child(prop)) {
> continue;
> }
>
> @@ -799,6 +873,27 @@ Object *object_get_root(void)
> return root;
> }
>
> +Object *object_property_get_child(Object *obj, const char *name,
> + struct Error **errp) {
> + Object *result = NULL;
> + ObjectProperty *prop = object_property_find(obj, name);
> + bool is_invalid_type;
> +
> + if (prop == NULL) {
> + REPORT_OBJECT_ERROR(errp, QERR_OBJECT_PROPERTY_NOT_FOUND, obj,
> name);
> + return NULL;
> + }
> +
> + result = object_property_extract_child(prop, &is_invalid_type);
> + if (is_invalid_type) {
> + REPORT_OBJECT_ERROR(errp, QERR_OBJECT_PROPERTY_INVALID_TYPE,
> + obj, name, "child");
> + return NULL;
> + }
> +
> + return result;
> +}
> +
> static void object_get_child_property(Object *obj, Visitor *v, void
> *opaque,
> const char *name, Error **errp)
> {
> @@ -829,7 +924,10 @@ void object_property_add_child(Object *obj, const
> char *name,
> */
> assert(!object_is_type(obj, type_interface));
>
> - type = g_strdup_printf("child<%s>",
> object_get_typename(OBJECT(child)));
> + type = g_strdup_printf(CHILD_PROPERTY_TYPE_PREFIX
> + "%s"
> + CHILD_PROPERTY_TYPE_SUFFIX,
> + object_get_typename(OBJECT(child)));
>
> object_property_add(obj, name, type, object_get_child_property,
> NULL, object_finalize_child_property, child,
> errp);
> @@ -878,8 +976,7 @@ static void object_set_link_property(Object *obj,
> Visitor *v, void *opaque,
> if (strcmp(path, "") != 0) {
> Object *target;
>
> - /* Go from link<FOO> to FOO. */
> - target_type = g_strndup(&type[5], strlen(type) - 6);
> + target_type = link_type_to_type(type);
> target = object_resolve_path_type(path, target_type, &ambiguous);
>
> if (ambiguous) {
> @@ -907,7 +1004,9 @@ void object_property_add_link(Object *obj, const
> char *name,
> {
> gchar *full_type;
>
> - full_type = g_strdup_printf("link<%s>", type);
> + full_type = g_strdup_printf(LINK_PROPERTY_TYPE_PREFIX
> + "%s"
> + LINK_PROPERTY_TYPE_SUFFIX, type);
>
> object_property_add(obj, name, full_type,
> object_get_link_property,
> @@ -932,7 +1031,7 @@ gchar *object_get_canonical_path(Object *obj)
> g_assert(obj->parent != NULL);
>
> QTAILQ_FOREACH(prop, &obj->parent->properties, node) {
> - if (!strstart(prop->type, "child<", NULL)) {
> + if (!object_property_is_child(prop)) {
> continue;
> }
>
> @@ -980,15 +1079,7 @@ static Object *object_resolve_abs_path(Object
> *parent,
> return NULL;
> }
>
> - child = NULL;
> - if (strstart(prop->type, "link<", NULL)) {
> - Object **pchild = prop->opaque;
> - if (*pchild) {
> - child = *pchild;
> - }
> - } else if (strstart(prop->type, "child<", NULL)) {
> - child = prop->opaque;
> - }
> + child = object_property_extract_child(prop, NULL);
>
> if (!child) {
> return NULL;
> @@ -1010,7 +1101,7 @@ static Object *object_resolve_partial_path(Object
> *parent,
> QTAILQ_FOREACH(prop, &parent->properties, node) {
> Object *found;
>
> - if (!strstart(prop->type, "child<", NULL)) {
> + if (!object_property_is_child(prop)) {
> continue;
> }
>
>
>
>
Paolo
^ permalink raw reply [flat|nested] 3+ messages in thread
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2012-02-16 17:39 [Qemu-trivial] [PATCH] Add object_property_get_child() Alexander Barabash
2012-02-16 18:16 ` [Qemu-trivial] [Qemu-devel] " Peter Maydell
2012-02-17 10:17 ` [Qemu-trivial] " Paolo Bonzini
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