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list: add virDomainListAllSnapshots API

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There was an inherent race between virDomainSnapshotNum() and
virDomainSnapshotListNames(), where an additional snapshot could
be created in the meantime, or where a snapshot could be deleted
before converting the name back to a virDomainSnapshotPtr.  It
was also an awkward name: the function operates on domains, not
domain snapshots.  virDomainSnapshotListChildrenNames() suffered
from the same inherent race, although its naming was nicer.

This patch makes things nicer by grabbing a snapshot list
atomically, in the format most useful to the user.

* include/libvirt/libvirt.h.in (virDomainListAllSnapshots)
(virDomainSnapshotListAllChildren): New declarations.
* src/libvirt.c (virDomainSnapshotListNames)
(virDomainSnapshotListChildrenNames): Add cross-references.
(virDomainListAllSnapshots, virDomainSnapshotListAllChildren):
New functions.
* src/libvirt_public.syms (LIBVIRT_0.9.13): Export them.
* src/driver.h (virDrvDomainListAllSnapshots)
(virDrvDomainSnapshotListAllChildren): New callbacks.
* python/generator.py (skip_function): Prepare for later
hand-written versions.
This commit is contained in:
Eric Blake 2012-05-23 10:40:50 -06:00
parent 35ae18f3c6
commit 37bb0447bb
5 changed files with 196 additions and 10 deletions
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13
include/libvirt/libvirt.h.in
View File

@ -3390,7 +3390,8 @@ char *virDomainSnapshotGetXMLDesc(virDomainSnapshotPtr snapshot,
*
* Flags valid for virDomainSnapshotNum(),
* virDomainSnapshotListNames(), virDomainSnapshotNumChildren(), and
* virDomainSnapshotListChildrenNames(). Note that the interpretation
* virDomainSnapshotListChildrenNames(), virDomainListAllSnapshots(),
* and virDomainSnapshotListAllChildren(). Note that the interpretation
* of flag (1<<0) depends on which function it is passed to; but serves
* to toggle the per-call default of whether the listing is shallow or
* recursive. Remaining bits come in groups; if all bits from a group are
@ -3423,6 +3424,11 @@ int virDomainSnapshotNum(virDomainPtr domain, unsigned int flags);
int virDomainSnapshotListNames(virDomainPtr domain, char **names, int nameslen,
unsigned int flags);
/* Get all snapshot objects for this domain */
int virDomainListAllSnapshots(virDomainPtr domain,
virDomainSnapshotPtr **snaps,
unsigned int flags);
/* Return the number of child snapshots for this snapshot */
int virDomainSnapshotNumChildren(virDomainSnapshotPtr snapshot,
unsigned int flags);
@ -3432,6 +3438,11 @@ int virDomainSnapshotListChildrenNames(virDomainSnapshotPtr snapshot,
char **names, int nameslen,
unsigned int flags);
/* Get all snapshot object children for this snapshot */
int virDomainSnapshotListAllChildren(virDomainSnapshotPtr snapshot,
virDomainSnapshotPtr **snaps,
unsigned int flags);
/* Get a handle to a named snapshot */
virDomainSnapshotPtr virDomainSnapshotLookupByName(virDomainPtr domain,
const char *name,

2
python/generator.py
View File

@ -454,6 +454,8 @@ skip_function = (
'virSaveLastError', # We have our own python error wrapper
'virFreeError', # Only needed if we use virSaveLastError
'virConnectListAllDomains', #overridden in virConnect.py
'virDomainListAllSnapshots', # overridden in virDomain.py
'virDomainSnapshotListAllChildren', # overridden in virDomainSnapshot.py
'virStreamRecvAll', # Pure python libvirt-override-virStream.py
'virStreamSendAll', # Pure python libvirt-override-virStream.py

12
src/driver.h
View File

@ -627,6 +627,11 @@ typedef int
int nameslen,
unsigned int flags);
typedef int
(*virDrvDomainListAllSnapshots)(virDomainPtr domain,
virDomainSnapshotPtr **snaps,
unsigned int flags);
typedef int
(*virDrvDomainSnapshotNumChildren)(virDomainSnapshotPtr snapshot,
unsigned int flags);
@ -637,6 +642,11 @@ typedef int
int nameslen,
unsigned int flags);
typedef int
(*virDrvDomainSnapshotListAllChildren)(virDomainSnapshotPtr snapshot,
virDomainSnapshotPtr **snaps,
unsigned int flags);
typedef virDomainSnapshotPtr
(*virDrvDomainSnapshotLookupByName)(virDomainPtr domain,
const char *name,
@ -993,8 +1003,10 @@ struct _virDriver {
virDrvDomainSnapshotGetXMLDesc domainSnapshotGetXMLDesc;
virDrvDomainSnapshotNum domainSnapshotNum;
virDrvDomainSnapshotListNames domainSnapshotListNames;
virDrvDomainListAllSnapshots domainListAllSnapshots;
virDrvDomainSnapshotNumChildren domainSnapshotNumChildren;
virDrvDomainSnapshotListChildrenNames domainSnapshotListChildrenNames;
virDrvDomainSnapshotListAllChildren domainSnapshotListAllChildren;
virDrvDomainSnapshotLookupByName domainSnapshotLookupByName;
virDrvDomainHasCurrentSnapshot domainHasCurrentSnapshot;
virDrvDomainSnapshotGetParent domainSnapshotGetParent;

177
src/libvirt.c
View File

@ -17123,9 +17123,8 @@ error:
* @flags: bitwise-OR of supported virDomainSnapshotListFlags
*
* Collect the list of domain snapshots for the given domain, and store
* their names in @names. Caller is responsible for freeing each member
* of the array. The value to use for @nameslen can be determined by
* virDomainSnapshotNum() with the same @flags.
* their names in @names. The value to use for @nameslen can be determined
* by virDomainSnapshotNum() with the same @flags.
*
* By default, this command covers all snapshots; it is also possible to
* limit things to just snapshots with no parents, when @flags includes
@ -17149,14 +17148,17 @@ error:
* whether they have metadata that would prevent the removal of the last
* reference to a domain.
*
* Returns the number of domain snapshots found or -1 in case of error.
* Note that this command is inherently racy: another connection can
* define a new snapshot between a call to virDomainSnapshotNum() and
* this call. You are only guaranteed that all currently defined
* snapshots were listed if the return is less than @nameslen. Likewise,
* you should be prepared for virDomainSnapshotLookupByName() to fail when
* converting a name from this call into a snapshot object, if another
* connection deletes the snapshot in the meantime.
* connection deletes the snapshot in the meantime. For more control over
* the results, see virDomainListAllSnapshots().
*
* Returns the number of domain snapshots found or -1 in case of error.
* The caller is responsible for freeing each member of the array.
*/
int
virDomainSnapshotListNames(virDomainPtr domain, char **names, int nameslen,
@ -17194,6 +17196,81 @@ error:
return -1;
}
/**
* virDomainListAllSnapshots:
* @domain: a domain object
* @snaps: pointer to variable to store the array containing snapshot objects,
* or NULL if the list is not required (just returns number of
* snapshots)
* @flags: bitwise-OR of supported virDomainSnapshotListFlags
*
* Collect the list of domain snapshots for the given domain, and allocate
* an array to store those objects. This API solves the race inherent in
* virDomainSnapshotListNames().
*
* By default, this command covers all snapshots; it is also possible to
* limit things to just snapshots with no parents, when @flags includes
* VIR_DOMAIN_SNAPSHOT_LIST_ROOTS. Additional filters are provided in
* groups, where each group contains bits that describe mutually exclusive
* attributes of a snapshot, and where all bits within a group describe
* all possible snapshots. Some hypervisors might reject explicit bits
* from a group where the hypervisor cannot make a distinction. For a
* group supported by a given hypervisor, the behavior when no bits of a
* group are set is identical to the behavior when all bits in that group
* are set. When setting bits from more than one group, it is possible to
* select an impossible combination, in that case a hypervisor may return
* either 0 or an error.
*
* The first group of @flags is VIR_DOMAIN_SNAPSHOT_LIST_LEAVES and
* VIR_DOMAIN_SNAPSHOT_LIST_NO_LEAVES, to filter based on snapshots that
* have no further children (a leaf snapshot).
*
* The next group of @flags is VIR_DOMAIN_SNAPSHOT_LIST_METADATA and
* VIR_DOMAIN_SNAPSHOT_LIST_NO_METADATA, for filtering snapshots based on
* whether they have metadata that would prevent the removal of the last
* reference to a domain.
*
* Returns the number of domain snapshots found or -1 and sets @snaps to
* NULL in case of error. On success, the array stored into @snaps is
* guaranteed to have an extra allocated element set to NULL but not included
* in the return count, to make iteration easier. The caller is responsible
* for calling virDomainSnapshotFree() on each array element, then calling
* free() on @snaps.
*/
int
virDomainListAllSnapshots(virDomainPtr domain, virDomainSnapshotPtr **snaps,
unsigned int flags)
{
virConnectPtr conn;
VIR_DOMAIN_DEBUG(domain, "snaps=%p, flags=%x", snaps, flags);
virResetLastError();
if (snaps)
*snaps = NULL;
if (!VIR_IS_CONNECTED_DOMAIN(domain)) {
virLibDomainError(VIR_ERR_INVALID_DOMAIN, __FUNCTION__);
virDispatchError(NULL);
return -1;
}
conn = domain->conn;
if (conn->driver->domainListAllSnapshots) {
int ret = conn->driver->domainListAllSnapshots(domain, snaps, flags);
if (ret < 0)
goto error;
return ret;
}
virLibConnError(VIR_ERR_NO_SUPPORT, __FUNCTION__);
error:
virDispatchError(conn);
return -1;
}
/**
* virDomainSnapshotNumChildren:
* @snapshot: a domain snapshot object
@ -17263,9 +17340,9 @@ error:
* @flags: bitwise-OR of supported virDomainSnapshotListFlags
*
* Collect the list of domain snapshots that are children of the given
* snapshot, and store their names in @names. Caller is responsible for
* freeing each member of the array. The value to use for @nameslen can
* be determined by virDomainSnapshotNumChildren() with the same @flags.
* snapshot, and store their names in @names. The value to use for
* @nameslen can be determined by virDomainSnapshotNumChildren() with
* the same @flags.
*
* By default, this command covers only direct children; it is also possible
* to expand things to cover all descendants, when @flags includes
@ -17296,7 +17373,11 @@ error:
* snapshots were listed if the return is less than @nameslen. Likewise,
* you should be prepared for virDomainSnapshotLookupByName() to fail when
* converting a name from this call into a snapshot object, if another
* connection deletes the snapshot in the meantime.
* connection deletes the snapshot in the meantime. For more control over
* the results, see virDomainSnapshotListAllChildren().
*
* Returns the number of domain snapshots found or -1 in case of error.
* The caller is responsible for freeing each member of the array.
*/
int
virDomainSnapshotListChildrenNames(virDomainSnapshotPtr snapshot,
@ -17338,6 +17419,84 @@ error:
return -1;
}
/**
* virDomainSnapshotListAllChildren:
* @snapshot: a domain snapshot object
* @snaps: pointer to variable to store the array containing snapshot objects,
* or NULL if the list is not required (just returns number of
* snapshots)
* @flags: bitwise-OR of supported virDomainSnapshotListFlags
*
* Collect the list of domain snapshots that are children of the given
* snapshot, and allocate an array to store those objects. This API solves
* the race inherent in virDomainSnapshotListChildrenNames().
*
* By default, this command covers only direct children; it is also possible
* to expand things to cover all descendants, when @flags includes
* VIR_DOMAIN_SNAPSHOT_LIST_DESCENDANTS. Also, some filters are provided in
* groups, where each group contains bits that describe mutually exclusive
* attributes of a snapshot, and where all bits within a group describe
* all possible snapshots. Some hypervisors might reject explicit bits
* from a group where the hypervisor cannot make a distinction. For a
* group supported by a given hypervisor, the behavior when no bits of a
* group are set is identical to the behavior when all bits in that group
* are set. When setting bits from more than one group, it is possible to
* select an impossible combination, in that case a hypervisor may return
* either 0 or an error.
*
* The first group of @flags is VIR_DOMAIN_SNAPSHOT_LIST_LEAVES and
* VIR_DOMAIN_SNAPSHOT_LIST_NO_LEAVES, to filter based on snapshots that
* have no further children (a leaf snapshot).
*
* The next group of @flags is VIR_DOMAIN_SNAPSHOT_LIST_METADATA and
* VIR_DOMAIN_SNAPSHOT_LIST_NO_METADATA, for filtering snapshots based on
* whether they have metadata that would prevent the removal of the last
* reference to a domain.
*
* Returns the number of domain snapshots found or -1 and sets @snaps to
* NULL in case of error. On success, the array stored into @snaps is
* guaranteed to have an extra allocated element set to NULL but not included
* in the return count, to make iteration easier. The caller is responsible
* for calling virDomainSnapshotFree() on each array element, then calling
* free() on @snaps.
*/
int
virDomainSnapshotListAllChildren(virDomainSnapshotPtr snapshot,
virDomainSnapshotPtr **snaps,
unsigned int flags)
{
virConnectPtr conn;
VIR_DEBUG("snapshot=%p, snaps=%p, flags=%x", snapshot, snaps, flags);
virResetLastError();
if (snaps)
*snaps = NULL;
if (!VIR_IS_DOMAIN_SNAPSHOT(snapshot)) {
virLibDomainSnapshotError(VIR_ERR_INVALID_DOMAIN_SNAPSHOT,
__FUNCTION__);
virDispatchError(NULL);
return -1;
}
conn = snapshot->domain->conn;
if (conn->driver->domainSnapshotListAllChildren) {
int ret = conn->driver->domainSnapshotListAllChildren(snapshot, snaps,
flags);
if (ret < 0)
goto error;
return ret;
}
virLibConnError(VIR_ERR_NO_SUPPORT, __FUNCTION__);
error:
virDispatchError(conn);
return -1;
}
/**
* virDomainSnapshotLookupByName:
* @domain: a domain object

2
src/libvirt_public.syms
View File

@ -537,8 +537,10 @@ LIBVIRT_0.9.11 {
LIBVIRT_0.9.13 {
global:
virConnectListAllDomains;
virDomainListAllSnapshots;
virDomainSnapshotHasMetadata;
virDomainSnapshotIsCurrent;
virDomainSnapshotListAllChildren;
virDomainSnapshotRef;
} LIBVIRT_0.9.11;