[don't merge me] - designed to show write lock in merged() is no longer needed after #5701 #5825
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Signed-off-by: Jon Seymour <jon@wildducktheories.com>
Previously, we needed a write lock on the cache because it was the only lock we had available to guard updates to entry.values and entry.needSort. However, now we have a entry-scoped lock for this purpose, we don't need the cache write lock for this purpose. Since merged() doesn't modify the .store or the c.snapshot.sort, there is no need for a write lock on the cache to protect the cache. So, we don't need to escalate here - we simply rely on the entry lock to protect the entries we are iterating over. Signed-off-by: Jon Seymour <jon@wildducktheories.com>
jonseymour
changed the title
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Mmmm. I was expecting the automated CI tests to detect the race. Not sure why they didn't. Here is the evidence from manually invoking it. |
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Closing since #5701 has been merged w/ the write-lock removed. |
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This contains two changes that are in #5701 but does not include the other the changes.
The purpose is to demonstrate that without the other changes in #5701, taking a write lock is necessary to ensure thread safety.
The fact that the test case executes successfully after #5701, shows that the protection offered by taking the cache write lock is no longer necessary because #5701 introduces entry locks that offer the required protection.