Collection iterators and concurrent modifications

Question

mweidner037 opened this issue 2 years ago · comments

Should check whether collection iterators behave rationally in the face of concurrent modification (like built-in Map and Set). If not, add warnings.

CLazyMap in particular is suspect.

mweidner037 · Answer 1 · Wed Mar 29 2023 03:43:50 GMT+0800 (China Standard Time)

Also LocalList (foundation for list CRDTs' iterators).

mweidner037 · Answer 2 · Mon Apr 03 2023 02:19:36 GMT+0800 (China Standard Time)

Addressed in #247:

CValueMap and CSet are probably safe, given that their iterators just iterate over a (built-in) Map , which has nice concurrent-modification behavior. Then the same holds for CMap and CValueSet.
Likewise for CLazyMap. However, there were potential issues if you called an iterator during a modification (e.g., in a child's event handler); I've attempted to fix these.
LocalList iterators (and their derivatives in the list CRDTs) are not safe and would be hard to fix. I've added a note to their class headers, plus some code that throws an error on a best-effort basis if it sees concurrent modification (like Java's ConcurrentModificationException).