+ // Iterate through the update records to find the latest committed version prior to our read version.
+ map_val_t newest_val = map_get(txn->map, key);
+ map_val_t val = newest_val;
+ update_t *update;
+ for ( ; (update = VAL_TO_PTR(val)) != NULL ; val = update->next) {
+
+ // If TAG2 is set in <val> it indicates that <val> is an update record. Otherwise all the following are
+ // true: <val> is a literal value, it is older than any currently active transaction, and it is the most
+ // recently set value for its key. Therefore it is visible to <txn>.
+ if (!IS_TAGGED(val, TAG2)) {
+ TRACE("x1", "txn_map_get: found untagged value; returning %p", val, 0);