LUCENE-5969: add merge api

git-svn-id: https://svn.apache.org/repos/asf/lucene/dev/branches/lucene5969@1628073 13f79535-47bb-0310-9956-ffa450edef68

lucene/core/src/java/org/apache/lucene/codecs/DocValuesConsumer.java

@@ -24,7 +24,6 @@ import java.util.Iterator;
 import java.util.List;
 import java.util.NoSuchElementException;
 
-import org.apache.lucene.index.LeafReader;
 import org.apache.lucene.index.BinaryDocValues;
 import org.apache.lucene.index.FieldInfo;
 import org.apache.lucene.index.FilteredTermsEnum;
@@ -150,7 +149,6 @@ public abstract class DocValuesConsumer implements Closeable {
             if (docValuesProducer != null) {
               FieldInfo fieldInfo = mergeState.fieldInfos[i].fieldInfo(mergeFieldInfo.name);
               if (fieldInfo != null && fieldInfo.getDocValuesType() == DocValuesType.NUMERIC) {
-                // TODO: use dedicated merge API, so impl can do merge-specific checksumming, and won't cache values in RAM
                 values = docValuesProducer.getNumeric(fieldInfo);
                 bits = docValuesProducer.getDocsWithField(fieldInfo);
               }
@@ -173,7 +171,6 @@ public abstract class DocValuesConsumer implements Closeable {
             if (docValuesProducer != null) {
               FieldInfo fieldInfo = mergeState.fieldInfos[i].fieldInfo(mergeFieldInfo.name);
               if (fieldInfo != null && fieldInfo.getDocValuesType() == DocValuesType.BINARY) {
-                // TODO: use dedicated merge API, so impl can do merge-specific checksumming, and won't cache values in RAM
                 values = docValuesProducer.getBinary(fieldInfo);
                 bits = docValuesProducer.getDocsWithField(fieldInfo);
               }
@@ -194,7 +191,6 @@ public abstract class DocValuesConsumer implements Closeable {
             if (docValuesProducer != null) {
               FieldInfo fieldInfo = mergeState.fieldInfos[i].fieldInfo(mergeFieldInfo.name);
               if (fieldInfo != null && fieldInfo.getDocValuesType() == DocValuesType.SORTED) {
-                // TODO: use dedicated merge API, so impl can do merge-specific checksumming, and won't cache values in RAM
                 values = docValuesProducer.getSorted(fieldInfo);
               }
             }
@@ -212,7 +208,6 @@ public abstract class DocValuesConsumer implements Closeable {
             if (docValuesProducer != null) {
               FieldInfo fieldInfo = mergeState.fieldInfos[i].fieldInfo(mergeFieldInfo.name);
               if (fieldInfo != null && fieldInfo.getDocValuesType() == DocValuesType.SORTED_SET) {
-                // TODO: use dedicated merge API, so impl can do merge-specific checksumming, and won't cache values in RAM
                 values = docValuesProducer.getSortedSet(fieldInfo);
               }
             }
@@ -230,7 +225,6 @@ public abstract class DocValuesConsumer implements Closeable {
             if (docValuesProducer != null) {
               FieldInfo fieldInfo = mergeState.fieldInfos[i].fieldInfo(mergeFieldInfo.name);
               if (fieldInfo != null && fieldInfo.getDocValuesType() == DocValuesType.SORTED_NUMERIC) {
-                // TODO: use dedicated merge API, so impl can do merge-specific checksumming, and won't cache values in RAM
                 values = docValuesProducer.getSortedNumeric(fieldInfo);
               }
             }

lucene/core/src/java/org/apache/lucene/codecs/DocValuesProducer.java

@@ -79,4 +79,12 @@ public abstract class DocValuesProducer implements Closeable, Accountable {
    * @lucene.internal
    */
   public abstract void checkIntegrity() throws IOException;
+  
+  /** 
+   * Returns an instance optimized for merging.
+   * <p>
+   * The default implementation returns {@code this} */
+  public DocValuesProducer getMergeInstance() throws IOException {
+    return this;
+  }
 }

lucene/core/src/java/org/apache/lucene/codecs/FieldsConsumer.java

@@ -22,7 +22,6 @@ import java.io.IOException;
 import java.util.ArrayList;
 import java.util.List;
 
-import org.apache.lucene.index.LeafReader;
 import org.apache.lucene.index.Fields;
 import org.apache.lucene.index.MappedMultiFields;
 import org.apache.lucene.index.MergeState;

lucene/core/src/java/org/apache/lucene/codecs/FieldsProducer.java

@@ -46,4 +46,12 @@ public abstract class FieldsProducer extends Fields implements Closeable, Accoun
    * @lucene.internal
    */
   public abstract void checkIntegrity() throws IOException;
+  
+  /** 
+   * Returns an instance optimized for merging.
+   * <p>
+   * The default implementation returns {@code this} */
+  public FieldsProducer getMergeInstance() throws IOException {
+    return this;
+  }
 }

lucene/core/src/java/org/apache/lucene/codecs/NormsConsumer.java

@@ -26,8 +26,6 @@ import java.util.NoSuchElementException;
 
 import org.apache.lucene.index.DocValues;
 import org.apache.lucene.index.FieldInfo;
-import org.apache.lucene.index.FieldInfos;
-import org.apache.lucene.index.LeafReader;
 import org.apache.lucene.index.MergeState;
 import org.apache.lucene.index.NumericDocValues;
 import org.apache.lucene.index.SegmentWriteState;
@@ -87,7 +85,6 @@ public abstract class NormsConsumer implements Closeable {
           if (normsProducer != null) {
             FieldInfo fieldInfo = mergeState.fieldInfos[i].fieldInfo(mergeFieldInfo.name);
             if (fieldInfo != null && fieldInfo.hasNorms()) {
-              // TODO: use dedicated merge API, so impl can do merge-specific checksumming, and won't cache values in RAM
               norms = normsProducer.getNorms(fieldInfo);
             }
           }

lucene/core/src/java/org/apache/lucene/codecs/NormsProducer.java

@@ -47,4 +47,12 @@ public abstract class NormsProducer implements Closeable, Accountable {
    * @lucene.internal
    */
   public abstract void checkIntegrity() throws IOException;
+  
+  /** 
+   * Returns an instance optimized for merging.
+   * <p>
+   * The default implementation returns {@code this} */
+  public NormsProducer getMergeInstance() throws IOException {
+    return this;
+  }
 }

lucene/core/src/java/org/apache/lucene/codecs/StoredFieldsReader.java

@@ -50,4 +50,12 @@ public abstract class StoredFieldsReader implements Cloneable, Closeable, Accoun
    * @lucene.internal
    */
   public abstract void checkIntegrity() throws IOException;
+  
+  /** 
+   * Returns an instance optimized for merging.
+   * <p>
+   * The default implementation returns {@code this} */
+  public StoredFieldsReader getMergeInstance() throws IOException {
+    return this;
+  }
 }

lucene/core/src/java/org/apache/lucene/codecs/StoredFieldsWriter.java

@@ -22,8 +22,6 @@ import java.io.IOException;
 import org.apache.lucene.document.DocumentStoredFieldVisitor;
 import org.apache.lucene.index.FieldInfo;
 import org.apache.lucene.index.FieldInfos;
-import org.apache.lucene.index.IndexReader;
-import org.apache.lucene.index.LeafReader;
 import org.apache.lucene.index.MergeState;
 import org.apache.lucene.index.StorableField;
 import org.apache.lucene.index.StoredDocument;

lucene/core/src/java/org/apache/lucene/codecs/TermVectorsReader.java

@@ -56,4 +56,12 @@ public abstract class TermVectorsReader implements Cloneable, Closeable, Account
    *  read term vectors. */
   @Override
   public abstract TermVectorsReader clone();
+  
+  /** 
+   * Returns an instance optimized for merging.
+   * <p>
+   * The default implementation returns {@code this} */
+  public TermVectorsReader getMergeInstance() throws IOException {
+    return this;
+  }
 }

lucene/core/src/java/org/apache/lucene/codecs/TermVectorsWriter.java

@@ -25,8 +25,6 @@ import org.apache.lucene.index.DocsAndPositionsEnum;
 import org.apache.lucene.index.FieldInfo;
 import org.apache.lucene.index.FieldInfos;
 import org.apache.lucene.index.Fields;
-import org.apache.lucene.index.IndexReader;
-import org.apache.lucene.index.LeafReader;
 import org.apache.lucene.index.MergeState;
 import org.apache.lucene.index.Terms;
 import org.apache.lucene.index.TermsEnum;

lucene/core/src/java/org/apache/lucene/index/MergeState.java

@@ -116,10 +116,25 @@ public class MergeState {
       if (reader instanceof SegmentReader) {
         SegmentReader segmentReader = (SegmentReader) reader;
         normsProducer = segmentReader.getNormsReader();
+        if (normsProducer != null) {
+          normsProducer = normsProducer.getMergeInstance();
+        }
         docValuesProducer = segmentReader.getDocValuesReader();
+        if (docValuesProducer != null) {
+          docValuesProducer = docValuesProducer.getMergeInstance();
+        }
         storedFieldsReader = segmentReader.getFieldsReader();
+        if (storedFieldsReader != null) {
+          storedFieldsReader = storedFieldsReader.getMergeInstance();
+        }
         termVectorsReader = segmentReader.getTermVectorsReader();
+        if (termVectorsReader != null) {
+          termVectorsReader = termVectorsReader.getMergeInstance();
+        }
         fieldsProducer = segmentReader.fields();
+        if (fieldsProducer != null) {
+          fieldsProducer = fieldsProducer.getMergeInstance();
+        }
       } else {
         // A "foreign" reader
         normsProducer = readerToNormsProducer(reader);