Update expensify_prod branch

sqlitecluster/SQLiteNode.cpp

@@ -129,6 +129,11 @@ SQLiteNode::SQLiteNode(SQLiteServer& server, shared_ptr<SQLitePool> dbPool, cons
 {
     SASSERT(_originalPriority >= 0);
     onPrepareHandlerEnabled = false;
+
+    // We create a copy of the database handle here so that the sync node can operate on its handle and the plugin gets
+    // its own handle to operate on. This avoids conflicts where the sync thread and the plugin are trying to both run
+    // queries at the same time. This also avoids the need to create any share locking between the two.
+    pluginDB = new SQLite(_db);
     SINFO("[NOTIFY] setting commit count to: " << _db.getCommitCount());
     _localCommitNotifier.notifyThrough(_db.getCommitCount());
 
@@ -149,6 +154,10 @@ SQLiteNode::~SQLiteNode() {
     for (SQLitePeer* peer : _peerList) {
         delete peer;
     }
+
+    if (pluginDB != nullptr) {
+        delete pluginDB;
+    }
 }
 
 void SQLiteNode::_replicate(SQLitePeer* peer, SData command, size_t sqlitePoolIndex, uint64_t threadAttemptStartTimestamp) {
@@ -1815,7 +1824,7 @@ void SQLiteNode::_changeState(SQLiteNodeState newState) {
 
     if (newState != _state) {
         // First, we notify all plugins about the state change
-        _server.notifyStateChangeToPlugins(_db, newState);
+        _server.notifyStateChangeToPlugins(*pluginDB, newState);
 
         // If we were following, and now we're not, we give up an any replications.
         if (_state == SQLiteNodeState::FOLLOWING) {

sqlitecluster/SQLiteNode.h

@@ -356,4 +356,8 @@ class SQLiteNode : public STCPManager {
     // while we're online.
     // In the event that this list becomes longer than half the cluster size, the node kills itself and logs that it's in an unrecoverable state.
     set<string> _forkedFrom;
+
+    // A pointer to a SQLite instance that is passed to plugin's stateChanged function. This prevents plugins from operating on the same handle that
+    // the sync node is when they run queries in stateChanged.
+    SQLite* pluginDB;
 };