Change eraseChild to erase

ConflictSet.cpp

@@ -462,6 +462,8 @@ int64_t getChildMaxVersion(Node *self, uint8_t index) {
 // Precondition - an entry for index must exist in the node
 int64_t &maxVersion(Node *n, ConflictSet::Impl *);
 
+Node *&getInTree(Node *n, ConflictSet::Impl *);
+
 Node *getChild(Node *self, uint8_t index) {
   if (self->type <= Type::Node16) {
     auto *self16 = static_cast<Node16 *>(self);
@@ -703,61 +705,6 @@ Node *&getOrCreateChild(Node *&self, uint8_t index,
   }
 }
 
-// Precondition - an entry for index must exist in the node
-void eraseChild(Node *self, uint8_t index, NodeAllocators *allocators) {
-  auto *child = getChildExists(self, index);
-  switch (child->type) {
-  case Type::Node0:
-    allocators->node0.release((Node0 *)child);
-    break;
-  case Type::Node4:
-    allocators->node4.release((Node4 *)child);
-    break;
-  case Type::Node16:
-    allocators->node16.release((Node16 *)child);
-    break;
-  case Type::Node48:
-    allocators->node48.release((Node48 *)child);
-    break;
-  case Type::Node256:
-    allocators->node256.release((Node256 *)child);
-    break;
-  }
-
-  if (self->type <= Type::Node16) {
-    auto *self16 = static_cast<Node16 *>(self);
-    int nodeIndex = getNodeIndex(self16, index);
-    memmove(self16->index + nodeIndex, self16->index + nodeIndex + 1,
-            sizeof(self16->index[0]) * (self->numChildren - (nodeIndex + 1)));
-    memmove(self16->children + nodeIndex, self16->children + nodeIndex + 1,
-            sizeof(self16->children[0]) * // NOLINT
-                (self->numChildren - (nodeIndex + 1)));
-  } else if (self->type == Type::Node48) {
-    auto *self48 = static_cast<Node48 *>(self);
-    self48->bitSet.reset(index);
-    int8_t toRemoveChildrenIndex = std::exchange(self48->index[index], -1);
-    int8_t lastChildrenIndex = --self48->nextFree;
-    assert(toRemoveChildrenIndex >= 0);
-    assert(lastChildrenIndex >= 0);
-    if (toRemoveChildrenIndex != lastChildrenIndex) {
-      self48->children[toRemoveChildrenIndex] =
-          self48->children[lastChildrenIndex];
-      self48
-          ->index[self48->children[toRemoveChildrenIndex].child->parentsIndex] =
-          toRemoveChildrenIndex;
-    }
-  } else {
-    auto *self256 = static_cast<Node256 *>(self);
-    self256->bitSet.reset(index);
-    self256->children[index].child = nullptr;
-  }
-  --self->numChildren;
-  if (self->numChildren == 0 && !self->entryPresent &&
-      self->parent != nullptr) {
-    eraseChild(self->parent, self->parentsIndex, allocators);
-  }
-}
-
 Node *nextPhysical(Node *node) {
   int index = -1;
   for (;;) {
@@ -780,6 +727,74 @@ Node *nextLogical(Node *node) {
   return node;
 }
 
+// Precondition: self is not the root
+Node *erase(Node *self, NodeAllocators *allocators, ConflictSet::Impl *impl) {
+  assert(self->parent != nullptr);
+
+  Node *parent = self->parent;
+  uint8_t parentsIndex = self->parentsIndex;
+
+  auto *result = nextLogical(self);
+  self->entryPresent = false;
+  if (self->numChildren != 0) {
+    return result;
+  }
+
+  switch (self->type) {
+  case Type::Node0:
+    allocators->node0.release((Node0 *)self);
+    break;
+  case Type::Node4:
+    allocators->node4.release((Node4 *)self);
+    break;
+  case Type::Node16:
+    allocators->node16.release((Node16 *)self);
+    break;
+  case Type::Node48:
+    allocators->node48.release((Node48 *)self);
+    break;
+  case Type::Node256:
+    allocators->node256.release((Node256 *)self);
+    break;
+  }
+
+  if (parent->type <= Type::Node16) {
+    auto *parent16 = static_cast<Node16 *>(parent);
+    int nodeIndex = getNodeIndex(parent16, parentsIndex);
+    assert(nodeIndex >= 0);
+    memmove(parent16->index + nodeIndex, parent16->index + nodeIndex + 1,
+            sizeof(parent16->index[0]) *
+                (parent->numChildren - (nodeIndex + 1)));
+    memmove(parent16->children + nodeIndex, parent16->children + nodeIndex + 1,
+            sizeof(parent16->children[0]) *
+                (parent->numChildren - (nodeIndex + 1)));
+  } else if (parent->type == Type::Node48) {
+    auto *parent48 = static_cast<Node48 *>(parent);
+    parent48->bitSet.reset(parentsIndex);
+    int8_t toRemoveChildrenIndex =
+        std::exchange(parent48->index[parentsIndex], -1);
+    int8_t lastChildrenIndex = --parent48->nextFree;
+    assert(toRemoveChildrenIndex >= 0);
+    assert(lastChildrenIndex >= 0);
+    if (toRemoveChildrenIndex != lastChildrenIndex) {
+      parent48->children[toRemoveChildrenIndex] =
+          parent48->children[lastChildrenIndex];
+      parent48->index[parent48->children[toRemoveChildrenIndex]
+                          .child->parentsIndex] = toRemoveChildrenIndex;
+    }
+  } else {
+    auto *parent256 = static_cast<Node256 *>(parent);
+    parent256->bitSet.reset(parentsIndex);
+    parent256->children[parentsIndex].child = nullptr;
+  }
+  --parent->numChildren;
+  if (parent->numChildren == 0 && !parent->entryPresent &&
+      parent->parent != nullptr) {
+    erase(parent, allocators, impl);
+  }
+  return result;
+}
+
 struct Iterator {
   Node *n;
   int cmp;
@@ -1765,13 +1780,8 @@ void addWriteRange(Node *&root, int64_t oldestVersion,
     assert(beginNode->entryPresent);
   }
 
-  for (beginNode = nextLogical(beginNode); beginNode != endNode;) {
+  for (beginNode = nextLogical(beginNode); beginNode != endNode;
-    auto *old = beginNode;
+       beginNode = erase(beginNode, allocators, impl)) {
-    beginNode = nextLogical(beginNode);
-    old->entryPresent = false;
-    if (old->numChildren == 0 && old->parent != nullptr) {
-      eraseChild(old->parent, old->parentsIndex, allocators);
-    }
   }
 }
 
@@ -1881,34 +1891,34 @@ struct __attribute__((visibility("hidden"))) ConflictSet::Impl {
     if (keyUpdates < 100) {
       return;
     }
-    Node *prev = firstGeq(root, removalKey).n;
+    Node *n = firstGeq(root, removalKey).n;
     // There's no way to erase removalKey without introducing a key after it
-    assert(prev != nullptr);
+    assert(n != nullptr);
+    // Don't erase the root
+    if (n == root) {
+      n = nextLogical(n);
+    }
     for (; keyUpdates > 0; --keyUpdates) {
-      Node *n = nextLogical(prev);
       if (n == nullptr) {
         removalKey = {};
         return;
       }
 
-      if (std::max(prev->entry.pointVersion, prev->entry.rangeVersion) <=
+      if (std::max(n->entry.pointVersion, n->entry.rangeVersion) <=
           oldestVersion) {
-        // Any transaction prev would have prevented from committing is
+        // Any transaction n would have prevented from committing is
         // going to fail with TooOld anyway.
 
         // There's no way to insert a range such that range version of the right
         // node is greater than the point version of the left node
         assert(n->entry.rangeVersion <= oldestVersion);
-        prev->entryPresent = false;
+        n = erase(n, &allocators, this);
-        if (prev->numChildren == 0 && prev->parent != nullptr) {
+      } else {
-          eraseChild(prev->parent, prev->parentsIndex, &allocators);
+        n = nextLogical(n);
-        }
       }
-
-      prev = n;
     }
     removalKeyArena = Arena();
-    removalKey = getSearchPath(removalKeyArena, prev);
+    removalKey = getSearchPath(removalKeyArena, n);
   }
 
   explicit Impl(int64_t oldestVersion) : oldestVersion(oldestVersion) {
@@ -1954,6 +1964,11 @@ int64_t &maxVersion(Node *n, ConflictSet::Impl *impl) {
   }
 }
 
+Node *&getInTree(Node *n, ConflictSet::Impl *impl) {
+  return n->parent == nullptr ? impl->root
+                              : getChildExists(n->parent, n->parentsIndex);
+}
+
 // ==================== END IMPLEMENTATION ====================
 
 // GCOVR_EXCL_START