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snapshot: take advantage of new relations
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.
This commit is contained in:
Eric Blake
parent
9279bdf757
commit
35abced2a8
@ -12163,10 +12163,21 @@ int virDomainSnapshotObjListGetNames(virDomainSnapshotObjListPtr snapshots,
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char **const names, int maxnames,
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unsigned int flags)
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{
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struct virDomainSnapshotNameData data = { 0, 0, maxnames, names, flags };
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struct virDomainSnapshotNameData data = { 0, 0, maxnames, names, 0 };
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int i;
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virHashForEach(snapshots->objs, virDomainSnapshotObjListCopyNames, &data);
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data.flags = flags & ~VIR_DOMAIN_SNAPSHOT_LIST_ROOTS;
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if (!(flags & VIR_DOMAIN_SNAPSHOT_LIST_ROOTS)) {
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virHashForEach(snapshots->objs, virDomainSnapshotObjListCopyNames,
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&data);
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} else {
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virDomainSnapshotObjPtr root = snapshots->first_root;
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while (root) {
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virDomainSnapshotObjListCopyNames(root, root->def->name, &data);
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root = root->sibling;
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}
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}
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if (data.oom) {
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virReportOOMError();
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goto cleanup;
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@ -12231,9 +12242,21 @@ static void virDomainSnapshotObjListCount(void *payload,
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int virDomainSnapshotObjListNum(virDomainSnapshotObjListPtr snapshots,
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unsigned int flags)
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{
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struct virDomainSnapshotNumData data = { 0, flags };
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struct virDomainSnapshotNumData data = { 0, 0 };
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virHashForEach(snapshots->objs, virDomainSnapshotObjListCount, &data);
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data.flags = flags & ~VIR_DOMAIN_SNAPSHOT_LIST_ROOTS;
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if (!(flags & VIR_DOMAIN_SNAPSHOT_LIST_ROOTS)) {
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virHashForEach(snapshots->objs, virDomainSnapshotObjListCount, &data);
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} else if (data.flags) {
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virDomainSnapshotObjPtr root = snapshots->first_root;
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while (root) {
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virDomainSnapshotObjListCount(root, root->def->name, &data);
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root = root->sibling;
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}
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} else {
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data.count = snapshots->nroots;
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}
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return data.count;
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}
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@ -12251,9 +12274,11 @@ virDomainSnapshotObjListNumFrom(virDomainSnapshotObjPtr snapshot,
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virDomainSnapshotForEachDescendant(snapshots, snapshot,
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virDomainSnapshotObjListCount,
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&data);
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else
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else if (data.flags)
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virDomainSnapshotForEachChild(snapshots, snapshot,
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virDomainSnapshotObjListCount, &data);
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else
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data.count = snapshot->nchildren;
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return data.count;
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}
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@ -12271,97 +12296,23 @@ void virDomainSnapshotObjListRemove(virDomainSnapshotObjListPtr snapshots,
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virHashRemoveEntry(snapshots->objs, snapshot->def->name);
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}
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struct snapshot_act_on_child {
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char *parent;
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int number;
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virHashIterator iter;
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void *data;
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};
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static void
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virDomainSnapshotActOnChild(void *payload,
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const void *name,
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void *data)
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{
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virDomainSnapshotObjPtr obj = payload;
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struct snapshot_act_on_child *curr = data;
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if (obj->def->parent && STREQ(curr->parent, obj->def->parent)) {
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curr->number++;
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if (curr->iter)
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(curr->iter)(payload, name, curr->data);
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}
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}
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/* Run iter(data) on all direct children of snapshot, while ignoring all
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* other entries in snapshots. Return the number of children
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* visited. No particular ordering is guaranteed. */
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int
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virDomainSnapshotForEachChild(virDomainSnapshotObjListPtr snapshots,
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virDomainSnapshotForEachChild(virDomainSnapshotObjListPtr snapshots ATTRIBUTE_UNUSED,
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virDomainSnapshotObjPtr snapshot,
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virHashIterator iter,
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void *data)
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{
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struct snapshot_act_on_child act;
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virDomainSnapshotObjPtr child = snapshot->first_child;
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act.parent = snapshot->def->name;
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act.number = 0;
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act.iter = iter;
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act.data = data;
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virHashForEach(snapshots->objs, virDomainSnapshotActOnChild, &act);
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return act.number;
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}
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typedef enum {
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MARK_NONE, /* No relation determined yet */
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MARK_DESCENDANT, /* Descendant of target */
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MARK_OTHER, /* Not a descendant of target */
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} snapshot_mark;
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struct snapshot_mark_descendant {
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const char *name; /* Parent's name on round 1, NULL on other rounds. */
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virDomainSnapshotObjListPtr snapshots;
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bool marked; /* True if descendants were found in this round */
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};
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/* To be called in a loop until no more descendants are found.
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* Additionally marking known unrelated snapshots reduces the number
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* of total hash searches needed. */
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static void
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virDomainSnapshotMarkDescendant(void *payload,
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const void *name ATTRIBUTE_UNUSED,
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void *data)
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{
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virDomainSnapshotObjPtr obj = payload;
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struct snapshot_mark_descendant *curr = data;
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virDomainSnapshotObjPtr parent = NULL;
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/* Learned on a previous pass. */
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if (obj->mark)
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return;
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if (curr->name) {
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/* First round can only find root nodes and direct children. */
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if (!obj->def->parent) {
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obj->mark = MARK_OTHER;
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} else if (STREQ(obj->def->parent, curr->name)) {
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obj->mark = MARK_DESCENDANT;
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curr->marked = true;
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}
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} else {
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/* All remaining rounds propagate marks from parents to children. */
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parent = virDomainSnapshotFindByName(curr->snapshots, obj->def->parent);
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if (!parent) {
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VIR_WARN("snapshot hash table is inconsistent!");
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obj->mark = MARK_OTHER;
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return;
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}
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if (parent->mark) {
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obj->mark = parent->mark;
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if (obj->mark == MARK_DESCENDANT)
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curr->marked = true;
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}
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while (child) {
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(iter)(child, child->def->name, data);
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child = child->sibling;
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}
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return snapshot->nchildren;
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}
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struct snapshot_act_on_descendant {
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@ -12378,40 +12329,28 @@ virDomainSnapshotActOnDescendant(void *payload,
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virDomainSnapshotObjPtr obj = payload;
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struct snapshot_act_on_descendant *curr = data;
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if (obj->mark == MARK_DESCENDANT) {
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curr->number++;
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(curr->iter)(payload, name, curr->data);
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}
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obj->mark = MARK_NONE;
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(curr->iter)(payload, name, curr->data);
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curr->number += 1 + virDomainSnapshotForEachDescendant(NULL, obj,
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curr->iter,
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curr->data);
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}
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/* Run iter(data) on all descendants of snapshot, while ignoring all
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* other entries in snapshots. Return the number of descendants
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* visited. No particular ordering is guaranteed. */
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int
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virDomainSnapshotForEachDescendant(virDomainSnapshotObjListPtr snapshots,
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virDomainSnapshotForEachDescendant(virDomainSnapshotObjListPtr snapshots ATTRIBUTE_UNUSED,
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virDomainSnapshotObjPtr snapshot,
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virHashIterator iter,
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void *data)
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{
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struct snapshot_mark_descendant mark;
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struct snapshot_act_on_descendant act;
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/* virHashForEach does not support nested traversal, so we must
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* instead iterate until no more snapshots get marked. We
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* guarantee that on exit, all marks have been cleared again. */
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mark.name = snapshot->def->name;
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mark.snapshots = snapshots;
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mark.marked = true;
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while (mark.marked) {
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mark.marked = false;
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virHashForEach(snapshots->objs, virDomainSnapshotMarkDescendant, &mark);
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mark.name = NULL;
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}
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act.number = 0;
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act.iter = iter;
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act.data = data;
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virHashForEach(snapshots->objs, virDomainSnapshotActOnDescendant, &act);
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virDomainSnapshotForEachChild(NULL, snapshot,
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virDomainSnapshotActOnDescendant, &act);
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return act.number;
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}
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