madrob commented on a change in pull request #1528:
URL: https://github.com/apache/lucene-solr/pull/1528#discussion_r430596540
##########
File path: solr/core/src/java/org/apache/solr/cloud/ZkController.java
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@@ -491,6 +493,40 @@ public boolean isClosed() {
assert ObjectReleaseTracker.track(this);
}
+ /**
+ * <p>Verifies if /clusterstate.json exists in Zookeepeer, and if it does
and is not empty, refuses to start and outputs
+ * a helpful message regarding collection migration.</p>
+ *
+ * <p>If /clusterstate.json exists and is empty, it is removed.</p>
+ */
+ private void checkNoOldClusterstate(final SolrZkClient zkClient) throws
InterruptedException {
+ try {
+ if (!zkClient.exists(ZkStateReader.UNSUPPORTED_CLUSTER_STATE, true)) {
+ return;
+ }
+
+ final byte[] data =
zkClient.getData(ZkStateReader.UNSUPPORTED_CLUSTER_STATE, null, null, true);
+
+ if (data.length < 5) {
+ // less than 5 chars is empty (it's likely just "{}"). This log will
only occur once.
+ log.warn("{} no longer supported starting with Solr 9. Found empty
file on Zookeeper, deleting it.", ZkStateReader.UNSUPPORTED_CLUSTER_STATE);
+ zkClient.delete(ZkStateReader.UNSUPPORTED_CLUSTER_STATE, -1, true);
+ } else {
+ // /clusterstate.json not empty: refuse to start but do not
automatically delete. A bit of a pain but user shouldn't
+ // have older collections at this stage anyway.
+ String message = ZkStateReader.UNSUPPORTED_CLUSTER_STATE + " no longer
supported starting with Solr 9. "
+ + "It is present and not empty. Cannot start Solr. Please first
migrate collections to stateFormat=2 using an "
+ + "older version of Solr or if you don't care about the data then
delete the file from "
+ + "Zookeeper using a command line tool, for example: bin/solr zk
rm /clusterstate.json -z host:port";
+ log.error(message);
+ throw new SolrException(SolrException.ErrorCode.INVALID_STATE,
message);
+ }
+ } catch (KeeperException e) {
+ log.error("", e);
Review comment:
Makes sense. If we throw anything here it will still propagate up to
SolrDispatchFilter where it will be logged, so we don't need to double up on
that here. We should probably clean that up in the other places where it
happens, but that's out of scope for this PR.
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