[FLINK-10267] [State] Fix arbitrary iterator access on RocksDBMapIterator

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 1.5.3, 1.6.0
• Fix Version/s: 1.5.4, 1.6.1
• Component/s: Runtime / State Backends
• Labels: pull-request-available
• Assignee: Yun Tang
• Reporter: Yun Tang
• Created: 30/Aug/18 17:29
• Updated: 11/Sep/18 13:47
• Resolved: 11/Sep/18 13:47

Description

Currently, RocksDBMapIterator would load 128 entries into local cacheEntries every time if needed. Both RocksDBMapIterator#next() and RocksDBMapIterator#hasNext() action might trigger to load RocksDBEntry into cacheEntries.

However, if the iterator's size larger than 128 and we continue to access the iterator with following order: hasNext() -> next() -> hasNext() -> remove(), we would meet weird exception when we try to remove the 128th element:

java.lang.IllegalStateException: The remove operation must be called after a valid next operation.

Since we could not control user's access on iterator, we should fix this bug to avoid unexpected exception.

Issue Links

• links to: GitHub Pull Request #6638