Verified Commit 679616d2 authored by Daniel Vrátil's avatar Daniel Vrátil 🤖
Browse files

ETM: fix race condition during Collection population

When populating Collections in ETM we may receive a "Collection added"
notification. If the Collection doesn't belong to an already-populated
subtree the code in ETMPrivate::retrieveAncestors() will try to iterate
through the chain of parent Collections to figure out which Collections
are missing and must be retrieved. However, Collections from the Monitor
notifications have only one parent set (the ancestor chain is not complete)
and so the code would get stuck.

This change makes retrieveAncestors() to handle the situation gracefuly
by fetching the entire ancestor chain from Akonadi recursively.

This got discovered by etmpopulationtest where the monitor likely
received a delayed notification that we sent during the initial
population of Akonadi by Knut resources.
parent aa839a41
......@@ -255,7 +255,7 @@ void EntityTreeModelPrivate::fetchCollections(Akonadi::CollectionFetchJob *job)
q->connect(job, SIGNAL(result(KJob*)),
q, SLOT(collectionFetchJobDone(KJob*)));
qCDebug(DebugETM) << "collection:" << job->collections(); jobTimeTracker[job].start();
void EntityTreeModelPrivate::fetchCollections(const Collection::List &collections, CollectionFetchJob::Type type)
......@@ -613,7 +613,7 @@ void EntityTreeModelPrivate::monitoredResourcesChanged(const QByteArray &resourc
void EntityTreeModelPrivate::retrieveAncestors(const Akonadi::Collection &collection, bool insertBaseCollection)
bool EntityTreeModelPrivate::retrieveAncestors(const Akonadi::Collection &collection, bool insertBaseCollection)
......@@ -629,23 +629,40 @@ void EntityTreeModelPrivate::retrieveAncestors(const Akonadi::Collection &collec
parentCollection = parentCollection.parentCollection();
// If we got here through Collection added notification, the parent chain may be incomplete
// and if the model is still populating or the collection belongs to a yet-unknown subtree
// this will break here
if (!parentCollection.isValid()) {
// if m_rootCollection is Collection::root(), we always have common ancestor and do the retrieval
// if we traversed up to Collection::root() but are looking at a subtree only (m_rootCollection != Collection::root())
// we have no common ancestor, and we don't have to retrieve anything
if (parentCollection == Collection::root() && m_rootCollection != Collection::root()) {
return true;
if (ancestors.isEmpty() && !insertBaseCollection) {
//Nothing to do, avoid emitting insert signals
return true;
if (!ancestors.isEmpty()) {
CollectionFetchJob *job = nullptr;
// We were unable to reach the top of the tree due to an incomplete ancestor chain, we will have
// to retrieve it from the server.
if (!parentCollection.isValid()) {
if (insertBaseCollection) {
job = new CollectionFetchJob(collection, CollectionFetchJob::Recursive, m_session);
} else {
job = new CollectionFetchJob(collection.parentCollection(), CollectionFetchJob::Recursive, m_session);
} else if (!ancestors.isEmpty()) {
// Fetch the real ancestors
CollectionFetchJob *job = new CollectionFetchJob(ancestors, CollectionFetchJob::Base, m_session);
job = new CollectionFetchJob(ancestors, CollectionFetchJob::Base, m_session);
if (job) {
q->connect(job, SIGNAL(collectionsReceived(Akonadi::Collection::List)),
......@@ -654,6 +671,13 @@ void EntityTreeModelPrivate::retrieveAncestors(const Akonadi::Collection &collec
q, SLOT(collectionFetchJobDone(KJob*)));
if (!parentCollection.isValid()) {
// We can't proceed to insert the fake collections to complete the tree because
// we do not have the complete ancestor chain. However, once the fetch job is
// finished the tree will be populated accordingly.
return false;
// Q_ASSERT( parentCollection != m_rootCollection );
const QModelIndex parent = indexForCollection(parentCollection);
......@@ -690,6 +714,8 @@ void EntityTreeModelPrivate::retrieveAncestors(const Akonadi::Collection &collec
return true;
void EntityTreeModelPrivate::ancestorsFetched(const Akonadi::Collection::List &collectionList)
......@@ -830,7 +856,9 @@ void EntityTreeModelPrivate::monitoredCollectionAdded(const Akonadi::Collection
// The collection we're interested in is contained in a collection we're not interested in.
// We download the ancestors of the collection we're interested in to complete the tree.
if (collection != Collection::root()) {
if (!retrieveAncestors(collection)) {
if (m_itemPopulation == EntityTreeModel::ImmediatePopulation) {
......@@ -185,8 +185,11 @@ public:
* Fetch parent collections and insert this @p collection and its parents into the node tree
* Returns whether the ancestor chain was complete and the parent collections were inserted into
* the tree.
void retrieveAncestors(const Akonadi::Collection &collection, bool insertBaseCollection = true);
bool retrieveAncestors(const Akonadi::Collection &collection, bool insertBaseCollection = true);
void ancestorsFetched(const Akonadi::Collection::List &collectionList);
void insertCollection(const Akonadi::Collection &collection, const Akonadi::Collection &parent);
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