SOLR-17231: Don't try buffering updates when there's no update log. (#3880)

Author: sigram

changelog/unreleased/solr-17231.yml

@@ -0,0 +1,10 @@
+# See https://github.com/apache/solr/blob/main/dev-docs/changelog.adoc
+title: Don't buffer updates on replicas without update log (e.g. PULL).
+type: fixed # added, changed, fixed, deprecated, removed, dependency_update, security, other
+authors:
+  - name: Andrzej Bialecki
+links:
+  - name: SOLR-17231
+    url: https://issues.apache.org/jira/browse/SOLR-17231
+issues:
+  - 17231

solr/core/src/java/org/apache/solr/core/SolrCore.java

@@ -85,6 +85,7 @@
 import org.apache.lucene.store.LockObtainFailedException;
 import org.apache.lucene.util.ResourceLoader;
 import org.apache.solr.client.solrj.impl.JavaBinResponseParser;
+import org.apache.solr.cloud.CloudDescriptor;
 import org.apache.solr.cloud.RecoveryStrategy;
 import org.apache.solr.cloud.ZkSolrResourceLoader;
 import org.apache.solr.common.SolrException;
@@ -1269,10 +1270,12 @@ protected void bufferUpdatesIfConstructing(CoreDescriptor coreDescriptor) {
 
       // ZK pre-register would have already happened so we read slice properties now
       final ClusterState clusterState = coreContainer.getZkController().getClusterState();
+      final CloudDescriptor cloudDescriptor = coreDescriptor.getCloudDescriptor();
       final DocCollection collection =
-          clusterState.getCollection(coreDescriptor.getCloudDescriptor().getCollectionName());
-      final Slice slice = collection.getSlice(coreDescriptor.getCloudDescriptor().getShardId());
-      if (slice.getState() == Slice.State.CONSTRUCTION) {
+          clusterState.getCollection(cloudDescriptor.getCollectionName());
+      final Slice slice = collection.getSlice(cloudDescriptor.getShardId());
+      if (slice.getState() == Slice.State.CONSTRUCTION
+          && getUpdateHandler().getUpdateLog() != null) {
         // set update log to buffer before publishing the core
         getUpdateHandler().getUpdateLog().bufferUpdates();
       }

solr/core/src/test/org/apache/solr/cloud/TestPullReplica.java

@@ -430,6 +430,28 @@ public void testKillLeader() throws Exception {
     doTestNoLeader(false);
   }
 
+  @Test
+  public void testNoBufferingInPullIfConstructing() throws Exception {
+    CollectionAdminRequest.createCollection(collectionName, "conf", 1, 1, 0, 0)
+        .process(cluster.getSolrClient());
+    waitForState("Replica not added", collectionName, activeReplicaCount(1, 0, 0));
+
+    setSliceState(collectionName, "shard1", Slice.State.CONSTRUCTION);
+
+    CollectionAdminRequest.addReplicaToShard(collectionName, "shard1", Replica.Type.PULL)
+        .process(cluster.getSolrClient());
+    waitForState("Replica not added", collectionName, activeReplicaCount(1, 0, 1));
+  }
+
+  private void setSliceState(String collectionName, String shardId, Slice.State state)
+      throws Exception {
+    ShardTestUtil.setSliceState(cluster, collectionName, shardId, state);
+    waitForState(
+        "Expected shard " + shardId + " to be in state " + state,
+        collectionName,
+        c -> c.getSlice(shardId).getState() == state);
+  }
+
   @Ignore("Ignore until I figure out a way to reliably record state transitions")
   public void testPullReplicaStates() throws Exception {
     // Validate that pull replicas go through the correct states when starting, stopping,