Github user dragonsinth commented on a diff in the pull request:
https://github.com/apache/curator/pull/250#discussion_r167733216
--- Diff:
curator-recipes/src/main/java/org/apache/curator/framework/recipes/cache/TreeCache.java
---
@@ -702,19 +687,18 @@ private TreeNode find(String findPath)
ImmutableMap.Builder<String, ChildData> builder =
ImmutableMap.builder();
for ( Map.Entry<String, TreeNode> entry : map.entrySet() )
{
- TreeNode childNode = entry.getValue();
- ChildData childData = childNode.childData;
- // Double-check liveness after retreiving data.
- if ( childData != null && childNode.nodeState ==
NodeState.LIVE )
+ ChildData childData = entry.getValue().childData;
+ // Double-check liveness after retrieving data.
+ if ( isLive(childData) )
--- End diff --
It's subtle, but the point I'm trying to make is that you have to read
`.childData` exactly once, then check the liveness, then use only that value
going forward. It would be an error to remove the local variable here and
reference `entry.getValue().childData` twice.
It's a "double" check because _generally_ there shouldn't be any non-LIVE
children in the parent `children` map that we're iterating. But due to
volatility we have to "double check" that child nodes read from the map are
still alive after pulling `.childData`
---
