[HUDI-437] Support user-defined index (#1408)

* [hotfix] set default value for index class config
* class config takes precedence over `hoodie.index.type`

hudi-client/src/main/java/org/apache/hudi/config/HoodieIndexConfig.java

@@ -37,6 +37,9 @@ public class HoodieIndexConfig extends DefaultHoodieConfig {
   public static final String INDEX_TYPE_PROP = "hoodie.index.type";
   public static final String DEFAULT_INDEX_TYPE = HoodieIndex.IndexType.BLOOM.name();
 
+  public static final String INDEX_CLASS_PROP = "hoodie.index.class";
+  public static final String DEFAULT_INDEX_CLASS = "";
+
   // ***** Bloom Index configs *****
   public static final String BLOOM_FILTER_NUM_ENTRIES = "hoodie.index.bloom.num_entries";
   public static final String DEFAULT_BLOOM_FILTER_NUM_ENTRIES = "60000";
@@ -117,6 +120,11 @@ public class HoodieIndexConfig extends DefaultHoodieConfig {
       return this;
     }
 
+    public Builder withIndexClass(String indexClass) {
+      props.setProperty(INDEX_CLASS_PROP, indexClass);
+      return this;
+    }
+
     public Builder withHBaseIndexConfig(HoodieHBaseIndexConfig hBaseIndexConfig) {
       props.putAll(hBaseIndexConfig.getProps());
       return this;
@@ -195,6 +203,7 @@ public class HoodieIndexConfig extends DefaultHoodieConfig {
     public HoodieIndexConfig build() {
       HoodieIndexConfig config = new HoodieIndexConfig(props);
       setDefaultOnCondition(props, !props.containsKey(INDEX_TYPE_PROP), INDEX_TYPE_PROP, DEFAULT_INDEX_TYPE);
+      setDefaultOnCondition(props, !props.containsKey(INDEX_CLASS_PROP), INDEX_CLASS_PROP, DEFAULT_INDEX_CLASS);
       setDefaultOnCondition(props, !props.containsKey(BLOOM_FILTER_NUM_ENTRIES), BLOOM_FILTER_NUM_ENTRIES,
           DEFAULT_BLOOM_FILTER_NUM_ENTRIES);
       setDefaultOnCondition(props, !props.containsKey(BLOOM_FILTER_FPP), BLOOM_FILTER_FPP, DEFAULT_BLOOM_FILTER_FPP);

hudi-client/src/main/java/org/apache/hudi/config/HoodieWriteConfig.java

@@ -309,6 +309,10 @@ public class HoodieWriteConfig extends DefaultHoodieConfig {
     return HoodieIndex.IndexType.valueOf(props.getProperty(HoodieIndexConfig.INDEX_TYPE_PROP));
   }
 
+  public String getIndexClass() {
+    return props.getProperty(HoodieIndexConfig.INDEX_CLASS_PROP);
+  }
+
   public int getBloomFilterNumEntries() {
     return Integer.parseInt(props.getProperty(HoodieIndexConfig.BLOOM_FILTER_NUM_ENTRIES));
   }

hudi-client/src/main/java/org/apache/hudi/index/HoodieIndex.java

@@ -24,6 +24,8 @@ import org.apache.hudi.common.model.HoodieKey;
 import org.apache.hudi.common.model.HoodieRecord;
 import org.apache.hudi.common.model.HoodieRecordPayload;
 import org.apache.hudi.common.util.Option;
+import org.apache.hudi.common.util.ReflectionUtils;
+import org.apache.hudi.common.util.StringUtils;
 import org.apache.hudi.common.util.collection.Pair;
 import org.apache.hudi.config.HoodieWriteConfig;
 import org.apache.hudi.exception.HoodieIndexException;
@@ -51,6 +53,14 @@ public abstract class HoodieIndex<T extends HoodieRecordPayload> implements Seri
 
   public static <T extends HoodieRecordPayload> HoodieIndex<T> createIndex(HoodieWriteConfig config,
       JavaSparkContext jsc) throws HoodieIndexException {
+    // first use index class config to create index.
+    if (!StringUtils.isNullOrEmpty(config.getIndexClass())) {
+      Object instance = ReflectionUtils.loadClass(config.getIndexClass(), config);
+      if (!(instance instanceof HoodieIndex)) {
+        throw new HoodieIndexException(config.getIndexClass() + " is not a subclass of HoodieIndex");
+      }
+      return (HoodieIndex) instance;
+    }
     switch (config.getIndexType()) {
       case HBASE:
         return new HBaseIndex<>(config);

hudi-client/src/test/java/org/apache/hudi/index/TestHoodieIndex.java

@@ -18,20 +18,33 @@
 
 package org.apache.hudi.index;
 
+import org.apache.hudi.client.WriteStatus;
 import org.apache.hudi.common.HoodieClientTestHarness;
+import org.apache.hudi.common.model.HoodieKey;
+import org.apache.hudi.common.model.HoodieRecord;
+import org.apache.hudi.common.model.HoodieRecordPayload;
+import org.apache.hudi.common.util.Option;
+import org.apache.hudi.common.util.collection.Pair;
 import org.apache.hudi.config.HoodieHBaseIndexConfig;
 import org.apache.hudi.config.HoodieIndexConfig;
 import org.apache.hudi.config.HoodieWriteConfig;
+import org.apache.hudi.exception.HoodieException;
+import org.apache.hudi.exception.HoodieIndexException;
 import org.apache.hudi.index.HoodieIndex.IndexType;
 import org.apache.hudi.index.bloom.HoodieBloomIndex;
 import org.apache.hudi.index.bloom.HoodieGlobalBloomIndex;
 import org.apache.hudi.index.hbase.HBaseIndex;
 
+import org.apache.hudi.table.HoodieTable;
+import org.apache.spark.api.java.JavaPairRDD;
+import org.apache.spark.api.java.JavaRDD;
+import org.apache.spark.api.java.JavaSparkContext;
 import org.junit.After;
 import org.junit.Before;
 import org.junit.Test;
 
 import static org.junit.Assert.assertTrue;
+import static org.junit.Assert.fail;
 
 public class TestHoodieIndex extends HoodieClientTestHarness {
 
@@ -67,5 +80,76 @@ public class TestHoodieIndex extends HoodieClientTestHarness {
     config = clientConfigBuilder.withPath(basePath)
         .withIndexConfig(indexConfigBuilder.withIndexType(IndexType.GLOBAL_BLOOM).build()).build();
     assertTrue(HoodieIndex.createIndex(config, jsc) instanceof HoodieGlobalBloomIndex);
+
+    config = clientConfigBuilder.withPath(basePath)
+        .withIndexConfig(indexConfigBuilder.withIndexClass(DummyHoodieIndex.class.getName()).build()).build();
+    assertTrue(HoodieIndex.createIndex(config, jsc) instanceof DummyHoodieIndex);
+
+    config = clientConfigBuilder.withPath(basePath)
+        .withIndexConfig(indexConfigBuilder.withIndexClass(IndexWithConstructor.class.getName()).build()).build();
+    try {
+      HoodieIndex.createIndex(config, jsc);
+      fail("exception is expected");
+    } catch (HoodieIndexException e) {
+      assertTrue(e.getMessage().contains("is not a subclass of HoodieIndex"));
+    }
+
+    config = clientConfigBuilder.withPath(basePath)
+            .withIndexConfig(indexConfigBuilder.withIndexClass(IndexWithoutConstructor.class.getName()).build()).build();
+    try {
+      HoodieIndex.createIndex(config, jsc);
+      fail("exception is expected");
+    } catch (HoodieException e) {
+      assertTrue(e.getMessage().contains("Unable to instantiate class"));
+    }
+  }
+
+  public static class DummyHoodieIndex<T extends HoodieRecordPayload> extends HoodieIndex<T> {
+    public DummyHoodieIndex(HoodieWriteConfig config) {
+      super(config);
+    }
+
+    @Override
+    public JavaPairRDD<HoodieKey, Option<Pair<String, String>>> fetchRecordLocation(JavaRDD<HoodieKey> hoodieKeys, JavaSparkContext jsc, HoodieTable<T> hoodieTable) {
+      return null;
+    }
+
+    @Override
+    public JavaRDD<HoodieRecord<T>> tagLocation(JavaRDD<HoodieRecord<T>> recordRDD, JavaSparkContext jsc, HoodieTable<T> hoodieTable) throws HoodieIndexException {
+      return null;
+    }
+
+    @Override
+    public JavaRDD<WriteStatus> updateLocation(JavaRDD<WriteStatus> writeStatusRDD, JavaSparkContext jsc, HoodieTable<T> hoodieTable) throws HoodieIndexException {
+      return null;
+    }
+
+    @Override
+    public boolean rollbackCommit(String commitTime) {
+      return false;
+    }
+
+    @Override
+    public boolean isGlobal() {
+      return false;
+    }
+
+    @Override
+    public boolean canIndexLogFiles() {
+      return false;
+    }
+
+    @Override
+    public boolean isImplicitWithStorage() {
+      return false;
+    }
+  }
+
+  public static class IndexWithConstructor {
+    public IndexWithConstructor(HoodieWriteConfig config) {}
+  }
+
+  public static class IndexWithoutConstructor {
+
   }
 }