Phase enum

ConflictSet.cpp

@@ -389,25 +389,27 @@ struct ConflictSet::Impl {
     Node *n;
     Impl *impl;
 
-    int state;
+    enum Phase { Search, Rotate };
+    Phase phase;
 
     StepwiseInsert() {}
     StepwiseInsert(Node **root, const Key &key, int64_t writeVersion,
                    Impl *impl)
         : current(root), parent(nullptr), key(&key), writeVersion(writeVersion),
-          impl(impl), state(0) {}
+          impl(impl), phase(Search) {}
     bool step() {
-      switch (state) {
-        // Search
-      case 0: {
+      switch (phase) {
+      case Search: {
         if (*current == nullptr) {
           auto *newNode = createNode(*key, parent, writeVersion);
           *current = newNode;
+          // We could interleave the iteration in next, but we'd need a careful
+          // analysis for correctness and it's unlikely to be worthwhile.
           auto *prev = ::next(newNode, false);
           assert(prev != nullptr);
           assert(prev->rangeVersion <= writeVersion);
           newNode->rangeVersion = prev->rangeVersion;
-          state = 1;
+          phase = Rotate;
           n = *current;
           return false;
         } else {
@@ -418,7 +420,7 @@ struct ConflictSet::Impl {
           auto c = *key <=> **current;
           if (c == 0) {
             (*current)->pointVersion = writeVersion;
-            state = 1;
+            phase = Rotate;
             n = *current;
             return false;
           }
@@ -427,8 +429,7 @@ struct ConflictSet::Impl {
         }
         return false;
       }
-      // Rotate
-      case 1: {
+      case Rotate: {
         if (n->parent == nullptr) {
           return true;
         }