Support nested transactions.

schlangster · schlangster · commit a2c3041df5a8 · 2017-11-02T00:21:19.000+01:00
Support node shifting.
diff --git a/include/react/detail/graph_impl.h b/include/react/detail/graph_impl.h
@@ -180,7 +180,7 @@ class ReactGraph
 
     LinkCache linkCache_;
 
-    bool isTransactionActive_ = false;
+    int  transactionLevel_ = 0;
     bool allowLinkedTransactionMerging_ = false;
 };
 
@@ -195,17 +195,17 @@ void ReactGraph::PushInput(NodeId nodeId, F&& inputCallback)
     
     changedInputs_.push_back(nodeId);
 
-    if (!isTransactionActive_)
+    if (transactionLevel_ == 0)
         Propagate();
 }
 
 template <typename F>
 void ReactGraph::DoTransaction(F&& transactionCallback)
 {
     // Transaction callback may add multiple inputs.
-    isTransactionActive_ = true;
+    ++transactionLevel_;
     std::forward<F>(transactionCallback)();
-    isTransactionActive_ = false;
+    --transactionLevel_;
 
     Propagate();
 }
diff --git a/src/detail/graph_impl.cpp b/src/detail/graph_impl.cpp
@@ -72,7 +72,9 @@ void ReactGraph::Propagate()
         auto& node = nodeData_[nodeId];
         auto* nodePtr = node.nodePtr;
 
-        if (nodePtr->Update(0u) == UpdateResult::changed)
+        UpdateResult res = nodePtr->Update(0u);
+
+        if (res == UpdateResult::changed)
         {
             changedNodes_.push_back(nodePtr);
             ScheduleSuccessors(node);
@@ -87,10 +89,12 @@ void ReactGraph::Propagate()
             auto& node = nodeData_[nodeId];
             auto* nodePtr = node.nodePtr;
 
+            // A predecessor of this node has shifted to a lower level?
             if (node.level < node.newLevel)
             {
-                // Re-schedule this node
+                // Re-schedule this node.
                 node.level = node.newLevel;
+
                 RecalculateSuccessorLevels(node);
                 scheduledNodes_.Push(nodeId, node.level);
                 continue;
@@ -103,7 +107,18 @@ void ReactGraph::Propagate()
                 continue;
             }
 
-            if (nodePtr->Update(0u) == UpdateResult::changed)
+            UpdateResult res = nodePtr->Update(0u);
+
+            // Topology changed?
+            if (res == UpdateResult::shifted)
+            {
+                // Re-schedule this node.
+                RecalculateSuccessorLevels(node);
+                scheduledNodes_.Push(nodeId, node.level);
+                continue;
+            }
+            
+            if (res == UpdateResult::changed)
             {
                 changedNodes_.push_back(nodePtr);
                 ScheduleSuccessors(node);
