Cndb 10302

src/java/org/apache/cassandra/config/CassandraRelevantProperties.java

@@ -284,7 +284,10 @@ public enum CassandraRelevantProperties
     /** what class to use for mbean registeration */
     MBEAN_REGISTRATION_CLASS("org.apache.cassandra.mbean_registration_class"),
 
+    /** Size limit for in-memory tries. This determines when the trie will report that it is full to trigger a flush. */
     MEMTABLE_TRIE_SIZE_LIMIT("cassandra.trie_size_limit_mb"),
+    /** To be used for tests: whether trie cursors should be verified for correctness. */
+    TRIE_DEBUG("cassandra.debug_tries"),
 
     /** This property indicates if the code is running under the in-jvm dtest framework */
     DTEST_IS_IN_JVM_DTEST("org.apache.cassandra.dtest.is_in_jvm_dtest"),

src/java/org/apache/cassandra/db/IDataSize.java

@@ -0,0 +1,25 @@
+/*
+ * 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.cassandra.db;
+
+/// Shared interface for providing data size information
+public interface IDataSize
+{
+    int dataSize();
+}

src/java/org/apache/cassandra/db/memtable/MemtableAverageRowSize.java

@@ -18,11 +18,15 @@
 
 package org.apache.cassandra.db.memtable;
 
+import java.util.function.Consumer;
+
 import org.apache.cassandra.db.DataRange;
+import org.apache.cassandra.db.IDataSize;
 import org.apache.cassandra.db.filter.ColumnFilter;
 import org.apache.cassandra.db.rows.Row;
 import org.apache.cassandra.db.rows.Unfiltered;
 import org.apache.cassandra.db.rows.UnfilteredRowIterator;
+import org.apache.cassandra.db.tries.Trie;
 
 class MemtableAverageRowSize
 {
@@ -31,6 +35,35 @@ class MemtableAverageRowSize
     public final long rowSize;
     public final long operations;
 
+    public MemtableAverageRowSize(Memtable memtable, Trie<?> trie)
+    {
+        // If this is a trie-based memtable, get the row sizes from the trie elements. This achieves two things:
+        // - makes sure the size used is the size reflected in the memtable's dataSize
+        //   (which e.g. excludes clustering keys)
+        // - avoids the conversion to Row, which has non-trivial cost
+
+        class SizeCalculator implements Trie.ValueConsumer<Object>
+        {
+            long totalSize = 0;
+            long count = 0;
+
+            @Override
+            public void accept(Object o)
+            {
+                if (o instanceof IDataSize)
+                {
+                    totalSize += ((IDataSize) o).dataSize();
+                    ++count;
+                }
+            }
+        }
+
+        SizeCalculator sizeCalculator = new SizeCalculator();
+        trie.forEachValue(sizeCalculator);
+
+        this.rowSize = sizeCalculator.count > 0 ? sizeCalculator.totalSize / sizeCalculator.count : 0;
+        this.operations = memtable.getOperations();
+    }
 
     public MemtableAverageRowSize(Memtable memtable)
     {