From 0a2fb77698143db3e61776484998fada944c610e Mon Sep 17 00:00:00 2001
From: Seth Alves <seth.alves@gmail.com>
Date: Sun, 13 Mar 2016 07:04:50 -0700
Subject: [PATCH] delete child entities when parent is deleted

---
 .../src/entities/EntityServer.cpp             | 12 ++++++++++
 assignment-client/src/entities/EntityServer.h |  2 ++
 assignment-client/src/octree/OctreeServer.h   |  4 ++--
 libraries/entities/src/EntityTree.cpp         | 23 +++++++++++++++++++
 libraries/entities/src/EntityTree.h           | 11 +++++++--
 5 files changed, 48 insertions(+), 4 deletions(-)

diff --git a/assignment-client/src/entities/EntityServer.cpp b/assignment-client/src/entities/EntityServer.cpp
index b177d2a9a0..867412f6c0 100644
--- a/assignment-client/src/entities/EntityServer.cpp
+++ b/assignment-client/src/entities/EntityServer.cpp
@@ -272,6 +272,18 @@ void EntityServer::readAdditionalConfiguration(const QJsonObject& settingsSectio
     tree->setWantTerseEditLogging(wantTerseEditLogging);
 }
 
+void EntityServer::nodeAdded(SharedNodePointer node) {
+    EntityTreePointer tree = std::static_pointer_cast<EntityTree>(_tree);
+    tree->knowAvatarID(node->getUUID());
+    OctreeServer::nodeAdded(node);
+}
+
+void EntityServer::nodeKilled(SharedNodePointer node) {
+    EntityTreePointer tree = std::static_pointer_cast<EntityTree>(_tree);
+    tree->deleteDescendantsOfAvatar(node->getUUID());
+    tree->forgetAvatarID(node->getUUID());
+    OctreeServer::nodeKilled(node);
+}
 
 // FIXME - this stats tracking is somewhat temporary to debug the Whiteboard issues. It's not a bad
 // set of stats to have, but we'd probably want a different data structure if we keep it very long.
diff --git a/assignment-client/src/entities/EntityServer.h b/assignment-client/src/entities/EntityServer.h
index 74057bfa5d..ec58cda6cd 100644
--- a/assignment-client/src/entities/EntityServer.h
+++ b/assignment-client/src/entities/EntityServer.h
@@ -58,6 +58,8 @@ public:
     virtual void trackViewerGone(const QUuid& sessionID) override;
 
 public slots:
+    virtual void nodeAdded(SharedNodePointer node);
+    virtual void nodeKilled(SharedNodePointer node);
     void pruneDeletedEntities();
 
 protected:
diff --git a/assignment-client/src/octree/OctreeServer.h b/assignment-client/src/octree/OctreeServer.h
index 1430715571..c96c4bb5ad 100644
--- a/assignment-client/src/octree/OctreeServer.h
+++ b/assignment-client/src/octree/OctreeServer.h
@@ -127,8 +127,8 @@ public:
 public slots:
     /// runs the octree server assignment
     void run();
-    void nodeAdded(SharedNodePointer node);
-    void nodeKilled(SharedNodePointer node);
+    virtual void nodeAdded(SharedNodePointer node);
+    virtual void nodeKilled(SharedNodePointer node);
     void sendStatsPacket();
 
 private slots:
diff --git a/libraries/entities/src/EntityTree.cpp b/libraries/entities/src/EntityTree.cpp
index 4c3412edd3..416fc5add3 100644
--- a/libraries/entities/src/EntityTree.cpp
+++ b/libraries/entities/src/EntityTree.cpp
@@ -448,6 +448,18 @@ void EntityTree::processRemovedEntities(const DeleteEntityOperator& theOperator)
     const RemovedEntities& entities = theOperator.getEntities();
     foreach(const EntityToDeleteDetails& details, entities) {
         EntityItemPointer theEntity = details.entity;
+
+        qDebug() << "processRemovedEntities on " << theEntity->getID() << theEntity->getName();
+        if (getIsServer()) {
+            QSet<EntityItemID> childrenIDs;
+            theEntity->forEachChild([&](SpatiallyNestablePointer child) {
+                if (child->getNestableType() == NestableType::Entity) {
+                    childrenIDs += child->getID();
+                }
+            });
+            deleteEntities(childrenIDs, true, true);
+        }
+
         theEntity->die();
 
         if (getIsServer()) {
@@ -1000,6 +1012,10 @@ void EntityTree::fixupMissingParents() {
                 moveOperator.addEntityToMoveList(entity, newCube);
                 iter.remove();
                 entity->markAncestorMissing(false);
+            } else if (_avatarIDs.contains(entity->getParentID())) {
+                _childrenOfAvatars[entity->getParentID()] += entity->getEntityItemID();
+                iter.remove();
+                entity->markAncestorMissing(false);
             }
         } else {
             // entity was deleted before we found its parent.
@@ -1014,6 +1030,13 @@ void EntityTree::fixupMissingParents() {
 
 }
 
+void EntityTree::deleteDescendantsOfAvatar(QUuid avatarID) {
+    if (_childrenOfAvatars.contains(avatarID)) {
+        deleteEntities(_childrenOfAvatars[avatarID]);
+        _childrenOfAvatars.remove(avatarID);
+    }
+}
+
 void EntityTree::update() {
     fixupMissingParents();
     if (_simulation) {
diff --git a/libraries/entities/src/EntityTree.h b/libraries/entities/src/EntityTree.h
index 8190f7225b..1c5a696b17 100644
--- a/libraries/entities/src/EntityTree.h
+++ b/libraries/entities/src/EntityTree.h
@@ -241,6 +241,10 @@ public:
     Q_INVOKABLE int getJointIndex(const QUuid& entityID, const QString& name) const;
     Q_INVOKABLE QStringList getJointNames(const QUuid& entityID) const;
 
+    void knowAvatarID(QUuid avatarID) { _avatarIDs += avatarID; }
+    void forgetAvatarID(QUuid avatarID) { _avatarIDs -= avatarID; }
+    void deleteDescendantsOfAvatar(QUuid avatarID);
+
 public slots:
     void callLoader(EntityItemID entityID);
 
@@ -313,8 +317,11 @@ protected:
     quint64 _maxEditDelta = 0;
     quint64 _treeResetTime = 0;
 
-    void fixupMissingParents();
-    QVector<EntityItemWeakPointer> _missingParent;
+    void fixupMissingParents(); // try to hook members of _missingParent to parent instances
+    QVector<EntityItemWeakPointer> _missingParent; // entites with a parentID but no (yet) known parent instance
+    // we maintain a list of avatarIDs to notice when an entity is a child of one.
+    QSet<QUuid> _avatarIDs; // IDs of avatars connected to entity server
+    QHash<QUuid, QSet<EntityItemID>> _childrenOfAvatars;  // which entities are children of which avatars
 };
 
 #endif // hifi_EntityTree_h