[libvirt] [PATCH 3/4] snapshot: take advantage of new relations
Eric Blake
eblake at redhat.com
Sat Oct 8 00:05:56 UTC 2011
Among other improvements, virDomainSnapshotForEachDescendant is
changed from iterative O(n^2) to recursive O(n). A bit better
than the O(n^3) implementation in virsh snapshot-list!
* src/conf/domain_conf.c (virDomainSnapshotObjListNum)
(virDomainSnapshotObjListNumFrom)
(virDomainSnapshotObjeListGetNames, virDomainSnapshotForEachChild)
(virDomainSnapshotForEachDescendant): Optimize.
(virDomainSnapshotActOnDescendant): Tweak.
(virDomainSnapshotActOnChild, virDomainSnapshotMarkDescendant):
Delete, now that they are unused.
---
src/conf/domain_conf.c | 148 ++++++++++++++----------------------------------
1 files changed, 43 insertions(+), 105 deletions(-)
diff --git a/src/conf/domain_conf.c b/src/conf/domain_conf.c
index d4e127d..e77257a 100644
--- a/src/conf/domain_conf.c
+++ b/src/conf/domain_conf.c
@@ -12163,10 +12163,21 @@ int virDomainSnapshotObjListGetNames(virDomainSnapshotObjListPtr snapshots,
char **const names, int maxnames,
unsigned int flags)
{
- struct virDomainSnapshotNameData data = { 0, 0, maxnames, names, flags };
+ struct virDomainSnapshotNameData data = { 0, 0, maxnames, names, 0 };
int i;
- virHashForEach(snapshots->objs, virDomainSnapshotObjListCopyNames, &data);
+ data.flags = flags & ~VIR_DOMAIN_SNAPSHOT_LIST_ROOTS;
+
+ if (!(flags & VIR_DOMAIN_SNAPSHOT_LIST_ROOTS)) {
+ virHashForEach(snapshots->objs, virDomainSnapshotObjListCopyNames,
+ &data);
+ } else {
+ virDomainSnapshotObjPtr root = snapshots->first_root;
+ while (root) {
+ virDomainSnapshotObjListCopyNames(root, root->def->name, &data);
+ root = root->sibling;
+ }
+ }
if (data.oom) {
virReportOOMError();
goto cleanup;
@@ -12231,9 +12242,21 @@ static void virDomainSnapshotObjListCount(void *payload,
int virDomainSnapshotObjListNum(virDomainSnapshotObjListPtr snapshots,
unsigned int flags)
{
- struct virDomainSnapshotNumData data = { 0, flags };
+ struct virDomainSnapshotNumData data = { 0, 0 };
- virHashForEach(snapshots->objs, virDomainSnapshotObjListCount, &data);
+ data.flags = flags & ~VIR_DOMAIN_SNAPSHOT_LIST_ROOTS;
+
+ if (!(flags & VIR_DOMAIN_SNAPSHOT_LIST_ROOTS)) {
+ virHashForEach(snapshots->objs, virDomainSnapshotObjListCount, &data);
+ } else if (data.flags) {
+ virDomainSnapshotObjPtr root = snapshots->first_root;
+ while (root) {
+ virDomainSnapshotObjListCount(root, root->def->name, &data);
+ root = root->sibling;
+ }
+ } else {
+ data.count = snapshots->nroots;
+ }
return data.count;
}
@@ -12251,9 +12274,11 @@ virDomainSnapshotObjListNumFrom(virDomainSnapshotObjPtr snapshot,
virDomainSnapshotForEachDescendant(snapshots, snapshot,
virDomainSnapshotObjListCount,
&data);
- else
+ else if (data.flags)
virDomainSnapshotForEachChild(snapshots, snapshot,
virDomainSnapshotObjListCount, &data);
+ else
+ data.count = snapshot->nchildren;
return data.count;
}
@@ -12271,97 +12296,23 @@ void virDomainSnapshotObjListRemove(virDomainSnapshotObjListPtr snapshots,
virHashRemoveEntry(snapshots->objs, snapshot->def->name);
}
-struct snapshot_act_on_child {
- char *parent;
- int number;
- virHashIterator iter;
- void *data;
-};
-
-static void
-virDomainSnapshotActOnChild(void *payload,
- const void *name,
- void *data)
-{
- virDomainSnapshotObjPtr obj = payload;
- struct snapshot_act_on_child *curr = data;
-
- if (obj->def->parent && STREQ(curr->parent, obj->def->parent)) {
- curr->number++;
- if (curr->iter)
- (curr->iter)(payload, name, curr->data);
- }
-}
-
/* Run iter(data) on all direct children of snapshot, while ignoring all
* other entries in snapshots. Return the number of children
* visited. No particular ordering is guaranteed. */
int
-virDomainSnapshotForEachChild(virDomainSnapshotObjListPtr snapshots,
+virDomainSnapshotForEachChild(virDomainSnapshotObjListPtr snapshots ATTRIBUTE_UNUSED,
virDomainSnapshotObjPtr snapshot,
virHashIterator iter,
void *data)
{
- struct snapshot_act_on_child act;
+ virDomainSnapshotObjPtr child = snapshot->first_child;
- act.parent = snapshot->def->name;
- act.number = 0;
- act.iter = iter;
- act.data = data;
- virHashForEach(snapshots->objs, virDomainSnapshotActOnChild, &act);
-
- return act.number;
-}
-typedef enum {
- MARK_NONE, /* No relation determined yet */
- MARK_DESCENDANT, /* Descendant of target */
- MARK_OTHER, /* Not a descendant of target */
-} snapshot_mark;
-
-struct snapshot_mark_descendant {
- const char *name; /* Parent's name on round 1, NULL on other rounds. */
- virDomainSnapshotObjListPtr snapshots;
- bool marked; /* True if descendants were found in this round */
-};
-
-/* To be called in a loop until no more descendants are found.
- * Additionally marking known unrelated snapshots reduces the number
- * of total hash searches needed. */
-static void
-virDomainSnapshotMarkDescendant(void *payload,
- const void *name ATTRIBUTE_UNUSED,
- void *data)
-{
- virDomainSnapshotObjPtr obj = payload;
- struct snapshot_mark_descendant *curr = data;
- virDomainSnapshotObjPtr parent = NULL;
-
- /* Learned on a previous pass. */
- if (obj->mark)
- return;
-
- if (curr->name) {
- /* First round can only find root nodes and direct children. */
- if (!obj->def->parent) {
- obj->mark = MARK_OTHER;
- } else if (STREQ(obj->def->parent, curr->name)) {
- obj->mark = MARK_DESCENDANT;
- curr->marked = true;
- }
- } else {
- /* All remaining rounds propagate marks from parents to children. */
- parent = virDomainSnapshotFindByName(curr->snapshots, obj->def->parent);
- if (!parent) {
- VIR_WARN("snapshot hash table is inconsistent!");
- obj->mark = MARK_OTHER;
- return;
- }
- if (parent->mark) {
- obj->mark = parent->mark;
- if (obj->mark == MARK_DESCENDANT)
- curr->marked = true;
- }
+ while (child) {
+ (iter)(child, child->def->name, data);
+ child = child->sibling;
}
+
+ return snapshot->nchildren;
}
struct snapshot_act_on_descendant {
@@ -12378,40 +12329,27 @@ virDomainSnapshotActOnDescendant(void *payload,
virDomainSnapshotObjPtr obj = payload;
struct snapshot_act_on_descendant *curr = data;
- if (obj->mark == MARK_DESCENDANT) {
- curr->number++;
- (curr->iter)(payload, name, curr->data);
- }
- obj->mark = MARK_NONE;
+ curr->number++;
+ (curr->iter)(payload, name, curr->data);
+ virDomainSnapshotForEachDescendant(NULL, obj, curr->iter, curr->data);
}
/* Run iter(data) on all descendants of snapshot, while ignoring all
* other entries in snapshots. Return the number of descendants
* visited. No particular ordering is guaranteed. */
int
-virDomainSnapshotForEachDescendant(virDomainSnapshotObjListPtr snapshots,
+virDomainSnapshotForEachDescendant(virDomainSnapshotObjListPtr snapshots ATTRIBUTE_UNUSED,
virDomainSnapshotObjPtr snapshot,
virHashIterator iter,
void *data)
{
- struct snapshot_mark_descendant mark;
struct snapshot_act_on_descendant act;
- /* virHashForEach does not support nested traversal, so we must
- * instead iterate until no more snapshots get marked. We
- * guarantee that on exit, all marks have been cleared again. */
- mark.name = snapshot->def->name;
- mark.snapshots = snapshots;
- mark.marked = true;
- while (mark.marked) {
- mark.marked = false;
- virHashForEach(snapshots->objs, virDomainSnapshotMarkDescendant, &mark);
- mark.name = NULL;
- }
act.number = 0;
act.iter = iter;
act.data = data;
- virHashForEach(snapshots->objs, virDomainSnapshotActOnDescendant, &act);
+ virDomainSnapshotForEachChild(NULL, snapshot,
+ virDomainSnapshotActOnDescendant, &act);
return act.number;
}
--
1.7.4.4
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