*: keep tombstone if revision == compactAtRev

Before this patch, the tombstone can be deleted if its revision is equal compacted revision. It causes that the watch subscriber won't get this DELETE event. Based on Compact API[1], we should keep tombstone revision if it's not less than the compaction revision. > CompactionRequest compacts the key-value store up to a given revision. > All superseded keys with a revision less than the compaction revision > will be removed. [1]: https://etcd.io/docs/latest/dev-guide/api_reference_v3/ Signed-off-by: Wei Fu <[email protected]> (cherry picked from commit bbdc941) Signed-off-by: Wei Fu <[email protected]>
etcd-io · Aug 20, 2024 · 8d98510 · 8d98510
1 parent db701a5
commit 8d98510
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diff --git a/server/mvcc/hash.go b/server/mvcc/hash.go
@@ -62,6 +62,9 @@ func (h *kvHasher) WriteKeyValue(k, v []byte) {
 	if !upper.GreaterThan(kr) {
 		return
 	}
+
+	isTombstoneRev := isTombstone(k)
+
 	lower := revision{main: h.compactRevision + 1}
 	// skip revisions that are scheduled for deletion
 	// due to compacting; don't skip if there isn't one.
@@ -70,6 +73,17 @@ func (h *kvHasher) WriteKeyValue(k, v []byte) {
 			return
 		}
 	}
+
+	// When performing compaction, if the compacted revision is a
+	// tombstone, older versions (<= 3.5.15 or <= 3.4.33) will delete
+	// the tombstone. But newer versions (> 3.5.15 or > 3.4.33) won't
+	// delete it. So we should skip the tombstone in such cases when
+	// computing the hash to ensure that both older and newer versions
+	// can always generate the same hash values.
+	if kr.main == h.compactRevision && isTombstoneRev {
+		return
+	}
+
 	h.hash.Write(k)
 	h.hash.Write(v)
 }