yifan-c commented on a change in pull request #892:
URL: https://github.com/apache/cassandra/pull/892#discussion_r577060773
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File path: src/java/org/apache/cassandra/gms/Gossiper.java
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@@ -158,38 +158,44 @@
private volatile long lastProcessedMessageAt = System.currentTimeMillis();
- //This property and anything that checks it should be removed in 5.0
- private boolean haveMajorVersion3Nodes = true;
+ // This property and anything that checks it should be removed in 5.0
+ /**
+ * This property is initially set to null version which means that we have
no information about the other nodes.
+ * Once we have information about the cluster, it is set to the earliest
version encountered in the cluster.
+ * Once all nodes are on at least this node version, it becomes null,
which means that we are not upgrading from
+ * the previous version (major, minor).
+ */
+ private CassandraVersion upgradeFromVersion = SystemKeyspace.NULL_VERSION;
- final Supplier<ExpiringMemoizingSupplier.ReturnValue<Boolean>>
haveMajorVersion3NodesSupplier = () ->
+ final Supplier<ExpiringMemoizingSupplier.ReturnValue<CassandraVersion>>
upgradeFromVersionSupplier = () ->
Review comment:
The cluster wide version check is a special treatment for specific
versions, i.e. 3.4 and `v < 4`. What if we keep the checker as-is and always
using the `3.4-` behavior during upgrade?
It could be more expensive (by how much? probably not a lot) during that
time period, but the gain is the simplification.
In practice, I think there won't be a case that the upgrading cluster have
nodes in `3.4-`, `3.11` and `4.0`. The upgrading path is most likely either 3.0
-> 4.0, or 3.x -> 4.0. With such assumption, if we want to lower the data size
being queried, we can define a temporarily system property in the 4.0 version
to select the behavior. e.g. `cassandra.upgrading_from_3_0_plus`, according to
the value use the corresponding behavior. The property, the same as
`Gossiper#upgradeFromVersion`, should be removed in 5.0. If we are adding the
property, we need to document it in the `NEWS.txt` too in order to inform the
instructor when upgrading.
(Maybe just using the `3.4-` behavior is the best option, as it add
complexity in operations)
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