Merge pull request #61 from johnmbw/jira/solr16165

SOLR-16165: Rare deadlock in SlotAcc initialization (apache#819)

solr/core/src/java/org/apache/solr/search/facet/Constants.java

@@ -0,0 +1,94 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.apache.solr.search.facet;
+
+import java.io.IOException;
+import java.util.function.IntFunction;
+import org.apache.lucene.index.LeafReaderContext;
+import org.apache.solr.common.util.SimpleOrderedMap;
+import org.apache.solr.search.DocSet;
+
+/** constants used in facets package */
+public class Constants {
+  public static final SlotAcc.CountSlotAcc DEV_NULL_SLOT_ACC = new DevNullCountSlotAcc();
+
+  private Constants() {}
+
+  /**
+   * This CountSlotAcc exists as a /dev/null sink for callers of collect(...) and other "write"-type
+   * methods. It should be used in contexts where "read"-type access methods will never be called.
+   */
+  private static class DevNullCountSlotAcc extends SlotAcc.CountSlotAcc {
+
+    public DevNullCountSlotAcc() {
+      super(null);
+    }
+
+    @Override
+    public void resize(Resizer resizer) {
+      // No-op
+    }
+
+    @Override
+    public void reset() throws IOException {
+      // No-op
+    }
+
+    @Override
+    public void collect(int doc, int slot, IntFunction<SlotContext> slotContext)
+        throws IOException {
+      // No-op
+    }
+
+    @Override
+    public void incrementCount(int slot, int count) {
+      // No-op
+    }
+
+    @Override
+    public void setNextReader(LeafReaderContext readerContext) throws IOException {
+      // No-op
+    }
+
+    @Override
+    public int collect(DocSet docs, int slot, IntFunction<SlotContext> slotContext)
+        throws IOException {
+      return docs.size(); // dressed up no-op
+    }
+
+    @Override
+    public Object getValue(int slotNum) throws IOException {
+      throw new UnsupportedOperationException("not supported");
+    }
+
+    @Override
+    public int compare(int slotA, int slotB) {
+      throw new UnsupportedOperationException("not supported");
+    }
+
+    @Override
+    public void setValues(SimpleOrderedMap<Object> bucket, int slotNum) throws IOException {
+      throw new UnsupportedOperationException("not supported");
+    }
+
+    @Override
+    public int getCount(int slot) {
+      throw new UnsupportedOperationException("not supported");
+    }
+  }
+}

solr/core/src/java/org/apache/solr/search/facet/FacetFieldProcessorByArray.java

@@ -118,9 +118,11 @@ private SimpleOrderedMap<Object> calcFacets() throws IOException {
     if (refineResult != null) {
       if (freq.allBuckets) {
         // count is irrelevant, but hardcoded in collect(...), so intercept/mask normal counts.
-        // Set here to prevent createAccs(...) from creating a 1-slot countAcc that will fail with AIOOBE
-        // NOTE: because collectAcc will be null, it is fine/irrelevant to set a countAcc that doesn't support sweeping
-        countAcc = SlotAcc.DEV_NULL_SLOT_ACC;
+        // Set here to prevent createAccs(...) from creating a 1-slot countAcc that will fail with
+        // AIOOBE
+        // NOTE: because collectAcc will be null, it is fine/irrelevant to set a countAcc that
+        // doesn't support sweeping
+        countAcc = Constants.DEV_NULL_SLOT_ACC;
         createAccs(nDocs, 1);
         assert collectAcc == null;
         otherAccs = accs; // accs is created above and set on allBucketsAcc; but during collection, setNextReader is called on otherAccs.

solr/core/src/java/org/apache/solr/search/facet/SlotAcc.java

@@ -823,63 +823,6 @@ public CountSlotAcc(FacetContext fcontext) {
   public abstract int getCount(int slot);
   }
 
-  /**
-   * This CountSlotAcc exists as a /dev/null sink for callers of collect(...) and other "write"-type
-   * methods. It should be used in contexts where "read"-type access methods will never be called.
-   */
-  static final CountSlotAcc DEV_NULL_SLOT_ACC = new CountSlotAcc(null) {
-
-    @Override
-    public void resize(Resizer resizer) {
-      // No-op
-    }
-
-    @Override
-    public void reset() throws IOException {
-      // No-op
-    }
-
-    @Override
-    public void collect(int doc, int slot, IntFunction<SlotContext> slotContext) throws IOException {
-      // No-op
-    }
-
-    @Override
-    public void incrementCount(int slot, int count) {
-      // No-op
-    }
-
-    @Override
-    public void setNextReader(LeafReaderContext readerContext) throws IOException {
-      // No-op
-    }
-
-    @Override
-    public int collect(DocSet docs, int slot, IntFunction<SlotContext> slotContext) throws IOException {
-      return docs.size(); // dressed up no-op
-    }
-
-    @Override
-    public Object getValue(int slotNum) throws IOException {
-      throw new UnsupportedOperationException("not supported");
-    }
-
-    @Override
-    public int compare(int slotA, int slotB) {
-      throw new UnsupportedOperationException("not supported");
-    }
-
-    @Override
-    public void setValues(SimpleOrderedMap<Object> bucket, int slotNum) throws IOException {
-      throw new UnsupportedOperationException("not supported");
-    }
-
-    @Override
-    public int getCount(int slot) {
-      throw new UnsupportedOperationException("not supported");
-    }
-  };
-
   static class CountSlotArrAcc extends CountSlotAcc {
     int[] result;