[GitHub] milleruntime commented on a change in pull request #488: fixes #469 made bulk import scan split tolerant

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milleruntime commented on a change in pull request #488: fixes #469 made bulk import scan split tolerant
URL: https://github.com/apache/accumulo/pull/488#discussion_r189049542
 
 

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 File path: core/src/main/java/org/apache/accumulo/core/metadata/schema/MetadataConsistencyCheckIterator.java
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+/*
+ * 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.accumulo.core.metadata.schema;
+
+import static org.apache.accumulo.fate.util.UtilWaitThread.sleepUninterruptibly;
+
+import java.util.Iterator;
+import java.util.concurrent.TimeUnit;
+import java.util.function.Function;
+
+import org.apache.accumulo.core.data.Key;
+import org.apache.accumulo.core.data.PartialKey;
+import org.apache.accumulo.core.data.Range;
+import org.apache.accumulo.core.data.impl.KeyExtent;
+import org.apache.hadoop.io.Text;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import com.google.common.collect.Iterators;
+
+/**
+ * Tablets for a table in the metadata table should form a linked list. This iterator detects when
+ * tablets do not form a linked list and backs up when this happens.
+ *
+ * <p>
+ * The purpose of this is to hide inconsistencies caused by splits and detect anomalies in the
+ * metadata table.
+ *
+ * <p>
+ * If a tablet that was returned by this iterator is subsequently deleted from the metadata table,
+ * then this iterator will throw a TabletDeletedException. This could occur when a table is merged.
+ */
+public class MetadataConsistencyCheckIterator implements Iterator<TabletMetadata> {
+
+  private static final Logger log = LoggerFactory.getLogger(MetadataConsistencyCheckIterator.class);
+
+  private Range range;
+  private Function<Range,Iterator<TabletMetadata>> iteratorFactory;
+  private Iterator<TabletMetadata> source;
+  private TabletMetadata prevTablet = null;
+
+  MetadataConsistencyCheckIterator(Function<Range,Iterator<TabletMetadata>> iteratorFactory,
+      Range range) {
+    this.range = range;
+    this.iteratorFactory = iteratorFactory;
+    source = iteratorFactory.apply(range);
+  }
+
+  @Override
+  public boolean hasNext() {
+    return source.hasNext();
+  }
+
+  static boolean goodTransition(TabletMetadata prev, TabletMetadata curr) {
+    if (!curr.sawPrevEndRow()) {
+      log.warn("Tablet {} had no prev end row.", curr.getExtent());
+      return false;
+    }
+
+    if (!curr.getTableId().equals(prev.getTableId())) {
+      if (prev.getEndRow() != null) {
+        log.debug("Non-null end row for last tablet in table: " + prev.getExtent() + " "
+            + curr.getExtent());
+        return false;
+      }
+
+      if (curr.getPrevEndRow() != null) {
+        log.debug("First tablet for table had prev end row {} {} ", prev.getExtent(),
+            curr.getExtent());
 
 Review comment:
   How do you know you are testing the first tablet here?

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