From c2f08dfdba2a8b71fc84f154b08b173670fcccf0 Mon Sep 17 00:00:00 2001
From: Ryan Huffman <ryanhuffman@gmail.com>
Date: Wed, 13 Jun 2018 12:07:20 -0700
Subject: [PATCH] Update Octree to atomically persist data

---
 assignment-client/src/octree/OctreeServer.cpp |  4 +--
 libraries/octree/src/Octree.cpp               |  7 +++--
 libraries/octree/src/OctreePersistThread.cpp  | 31 +++----------------
 libraries/octree/src/OctreePersistThread.h    |  2 --
 4 files changed, 12 insertions(+), 32 deletions(-)

diff --git a/assignment-client/src/octree/OctreeServer.cpp b/assignment-client/src/octree/OctreeServer.cpp
index 2b2aaeb3e9..e993bea358 100644
--- a/assignment-client/src/octree/OctreeServer.cpp
+++ b/assignment-client/src/octree/OctreeServer.cpp
@@ -1207,8 +1207,8 @@ void OctreeServer::beginRunning() {
 
     beforeRun(); // after payload has been processed
 
-    connect(nodeList.data(), &NodeList::nodeAdded, &OctreeServer::nodeAdded);
-    connect(nodeList.data(), &NodeList::nodeKilled, &OctreeServer::nodeKilled);
+    connect(nodeList.data(), &NodeList::nodeAdded, this, &OctreeServer::nodeAdded);
+    connect(nodeList.data(), &NodeList::nodeKilled, this, &OctreeServer::nodeKilled);
 
     nodeList->linkedDataCreateCallback = [this](Node* node) {
         auto queryNodeData = createOctreeQueryNode();
diff --git a/libraries/octree/src/Octree.cpp b/libraries/octree/src/Octree.cpp
index 5f943fabf2..d9da06221d 100644
--- a/libraries/octree/src/Octree.cpp
+++ b/libraries/octree/src/Octree.cpp
@@ -30,6 +30,7 @@
 #include <QJsonObject>
 #include <QJsonArray>
 #include <QFileInfo>
+#include <QSaveFile>
 #include <QString>
 #include <QRegularExpression>
 #include <QRegularExpressionMatch>
@@ -972,10 +973,12 @@ bool Octree::writeToJSONFile(const char* fileName, const OctreeElementPointer& e
         return false;
     }
 
-    QFile persistFile(fileName);
+    QSaveFile persistFile(fileName);
     bool success = false;
     if (persistFile.open(QIODevice::WriteOnly)) {
-        success = persistFile.write(jsonDataForFile) != -1;
+        if (persistFile.write(jsonDataForFile) != -1) {
+            success = persistFile.commit();
+        }
     } else {
         qCritical("Could not write to JSON description of entities.");
     }
diff --git a/libraries/octree/src/OctreePersistThread.cpp b/libraries/octree/src/OctreePersistThread.cpp
index d783a1effd..8b1d766418 100644
--- a/libraries/octree/src/OctreePersistThread.cpp
+++ b/libraries/octree/src/OctreePersistThread.cpp
@@ -62,19 +62,6 @@ OctreePersistThread::OctreePersistThread(OctreePointer tree, const QString& file
 void OctreePersistThread::start() {
     cleanupOldReplacementBackups();
 
-    QFile tempFile { getTempFilename() };
-    if (tempFile.exists()) {
-        qWarning(octree) << "Found temporary octree file at" << tempFile.fileName();
-        qDebug(octree) << "Attempting to recover from temporary octree file";
-        QFile::remove(_filename);
-        if (tempFile.rename(_filename)) {
-            qDebug(octree) << "Successfully recovered from temporary octree file";
-        } else {
-            qWarning(octree) << "Failed to recover from temporary octree file";
-            tempFile.remove();
-        }
-    }
-
     auto& packetReceiver = DependencyManager::get<NodeList>()->getPacketReceiver();
     packetReceiver.registerListener(PacketType::OctreeDataFileReply, this, "handleOctreeDataFileReply");
 
@@ -182,7 +169,7 @@ void OctreePersistThread::handleOctreeDataFileReply(QSharedPointer<ReceivedMessa
 
     _initialLoadComplete = true;
 
-    // Since we just loaded the persistent file, we can consider ourselves as having just persist
+    // Since we just loaded the persistent file, we can consider ourselves as having just persisted
     _lastPersistCheck = std::chrono::steady_clock::now();
 
     if (replacementData.isNull()) {
@@ -305,20 +292,12 @@ void OctreePersistThread::persist() {
 
         _tree->incrementPersistDataVersion();
 
-        QString tempFilename = getTempFilename();
-        qCDebug(octree) << "Saving temporary Octree file to:" << tempFilename;
-        if (_tree->writeToFile(tempFilename.toLocal8Bit().constData(), nullptr, _persistAsFileType)) {
-            QFile tempFile { tempFilename };
+        qCDebug(octree) << "Saving Octree data to:" << _filename;
+        if (_tree->writeToFile(_filename.toLocal8Bit().constData(), nullptr, _persistAsFileType)) {
             _tree->clearDirtyBit(); // tree is clean after saving
-            QFile::remove(_filename);
-            if (tempFile.rename(_filename)) {
-                qCDebug(octree) << "DONE moving temporary Octree file to" << _filename;
-            } else {
-                qCWarning(octree) << "Failed to move temporary Octree file to " << _filename;
-                tempFile.remove();
-            }
+            qCDebug(octree) << "DONE persisting Octree data to" << _filename;
         } else {
-            qCWarning(octree) << "Failed to open temp Octree file at" << tempFilename;
+            qCWarning(octree) << "Failed to persist Octree data to" << _filename;
         }
 
         sendLatestEntityDataToDS();
diff --git a/libraries/octree/src/OctreePersistThread.h b/libraries/octree/src/OctreePersistThread.h
index 5bb6e51e5f..0044a8fa5a 100644
--- a/libraries/octree/src/OctreePersistThread.h
+++ b/libraries/octree/src/OctreePersistThread.h
@@ -65,8 +65,6 @@ protected:
     void replaceData(QByteArray data);
     void sendLatestEntityDataToDS();
 
-    QString getTempFilename() const { return _filename + ".temp"; }
-
 private:
     OctreePointer _tree;
     QString _filename;