kv: latching changes to support shared locks #109633
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nvanbenschoten
approved these changes
Aug 29, 2023
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Reviewed 4 of 4 files at r1, all commit messages.
Reviewable status:complete! 1 of 0 LGTMs obtained (waiting on @arulajmani)
pkg/kv/kvserver/concurrency/testdata/concurrency_manager/shared_locks_latches line 65 at r1 (raw file):
# Ensure non-locking reads do not conflict with shared locks on latches. We # test non-locking reads above, below, and at the timestamps at which shared # locking requests were issues.
"issued"
pkg/kv/kvserver/concurrency/testdata/concurrency_manager/shared_locks_latches line 643 at r1 (raw file):
finish req=req34 ---- [-] finish req34: finishing request
Nice tests!
Reads that acquire shared locks need to be isolated with concurrent write requests. They also need to be isolated with exclusive-locking reads. They can, however, run concurrently with other shared locking reads and non-locking reads. As described in the shared locks RFC, to make these semantics work, shared-locking reads should acquire read latches at `hlc.MaxTimestamp`. This patch makes that change and adds test cases for all these interactions. Closes cockroachdb#102264 Release note: None
arulajmani
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Aug 29, 2023
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TFTR!
bors r=nvanbenschoten
Reviewable status:
pkg/kv/kvserver/concurrency/testdata/concurrency_manager/shared_locks_latches line 643 at r1 (raw file):
Previously, nvanbenschoten (Nathan VanBenschoten) wrote…
Nice tests!
Thanks!
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Reads that acquire shared locks need to be isolated with concurrent write requests. They also need to be isolated with exclusive-locking reads. They can, however, run concurrently with other shared locking reads and non-locking reads.
As described in the shared locks RFC, to make these semantics work, shared-locking reads should acquire read latches at
hlc.MaxTimestamp. This patch makes that change and adds test cases for all these interactions.Closes #102264
Release note: None