Bug fix

The bottommost node of a finger isn't necessarily the root for an
iterator's version. It could be "end"

VersionedMap.cpp

@@ -406,10 +406,6 @@ struct Finger {
     assert(searchPathSize_ > 0);
     --searchPathSize_;
   }
-  uint32_t root() const {
-    assert(searchPathSize_ > 0);
-    return searchPath[0];
-  }
   uint32_t backNode() const {
     assert(searchPathSize_ > 0);
     return searchPath[searchPathSize_ - 1];
@@ -1241,18 +1237,14 @@ void VersionedMap::Impl::firstGeq(const weaselab::VersionedMap::Key *key,
     weaselab::VersionedMap::Iterator *iterator;
 
     void begin(RootSet::ThreadSafeHandle handle) {
-      uint32_t root;
       if (iterator->impl != nullptr) {
-        root = iterator->impl->version == version
-                   ? iterator->impl->finger.root()
-                   : handle.rootForVersion(version);
         iterator->impl->~Impl();
         new (iterator->impl) Iterator::Impl();
       } else {
-        root = handle.rootForVersion(version);
         iterator->impl =
             new (safe_malloc(sizeof(Iterator::Impl))) Iterator::Impl();
       }
+      uint32_t root = handle.rootForVersion(version);
       Finger &finger = iterator->impl->finger;
       finger.clear();
       bool ignored = false;

include/VersionedMap.h

@@ -152,8 +152,7 @@ struct __attribute__((__visibility__("default"))) VersionedMap {
    * and <= `getVersion()`.
    *
    * Thread-safe as long as a version is not concurrently invalidated by
-   * `setOldestVersion`. There's a performance benefit if you pass iterator[i]
-   * previously obtained at version[i]. */
+   * `setOldestVersion`. */
   void firstGeq(const Key *key, const int64_t *version, Iterator *iterator,
                 int count) const;