hopefully corrected or at least improved version of skipTo

git-svn-id: https://svn.apache.org/repos/asf/lucene/java/trunk@150296 13f79535-47bb-0310-9956-ffa450edef68

src/java/org/apache/lucene/index/SegmentMerger.java

@@ -234,6 +234,7 @@ final class SegmentMerger {
   private OutputStream freqOutput = null;
   private OutputStream proxOutput = null;
   private TermInfosWriter termInfosWriter = null;
+  private int skipInterval;
   private SegmentMergeQueue queue = null;
 
   private final void mergeTerms() throws IOException {
@@ -242,6 +243,8 @@ final class SegmentMerger {
       proxOutput = directory.createFile(segment + ".prx");
       termInfosWriter =
               new TermInfosWriter(directory, segment, fieldInfos);
+      skipInterval = termInfosWriter.skipInterval;
+      queue = new SegmentMergeQueue(readers.size());
 
       mergeTermInfos();
 
@@ -254,7 +257,6 @@ final class SegmentMerger {
   }
 
   private final void mergeTermInfos() throws IOException {
-    queue = new SegmentMergeQueue(readers.size());
     int base = 0;
     for (int i = 0; i < readers.size(); i++) {
       IndexReader reader = (IndexReader) readers.elementAt(i);
@@ -327,7 +329,6 @@ final class SegmentMerger {
    */
   private final int appendPostings(SegmentMergeInfo[] smis, int n)
           throws IOException {
-    final int skipInterval = termInfosWriter.skipInterval;
     int lastDoc = 0;
     int df = 0;					  // number of docs w/ term
     resetSkip();

src/java/org/apache/lucene/index/SegmentTermDocs.java

@@ -84,6 +84,8 @@ class SegmentTermDocs implements TermDocs {
 
   public void close() throws IOException {
     freqStream.close();
+    if (skipStream != null)
+      skipStream.close();
   }
 
   public final int doc() { return doc; }
@@ -143,7 +145,7 @@ class SegmentTermDocs implements TermDocs {
 
   /** Optimized implementation. */
   public boolean skipTo(int target) throws IOException {
-    if (df > skipInterval) {                      // optimized case
+    if (df >= skipInterval) {                      // optimized case
 
       if (skipStream == null)
         skipStream = (InputStream) freqStream.clone(); // lazily clone

src/java/org/apache/lucene/index/SegmentTermEnum.java

@@ -33,6 +33,7 @@ final class SegmentTermEnum extends TermEnum implements Cloneable {
   long indexPointer = 0;
   int indexInterval;
   int skipInterval;
+  private int formatM1SkipInterval;
   Term prev;
 
   private char[] buffer = {};
@@ -51,7 +52,7 @@ final class SegmentTermEnum extends TermEnum implements Cloneable {
 
       // back-compatible settings
       indexInterval = 128;
-      skipInterval = Integer.MAX_VALUE;
+      skipInterval = Integer.MAX_VALUE; // switch off skipTo optimization
 
     } else {
       // we have a format version number
@@ -62,8 +63,17 @@ final class SegmentTermEnum extends TermEnum implements Cloneable {
         throw new IOException("Unknown format version:" + format);
 
       size = input.readLong();                    // read the size
-
+      
-      if (!isIndex) {
+      if(format == -1){
+        if (!isIndex) {
+          indexInterval = input.readInt();
+          formatM1SkipInterval = input.readInt();
+        }
+        // switch off skipTo optimization for file format prior to 1.4rc2 in order to avoid a bug in 
+        // skipTo implementation of these versions
+        skipInterval = Integer.MAX_VALUE;
+      }
+      else{
         indexInterval = input.readInt();
         skipInterval = input.readInt();
       }
@@ -107,13 +117,21 @@ final class SegmentTermEnum extends TermEnum implements Cloneable {
     termInfo.docFreq = input.readVInt();	  // read doc freq
     termInfo.freqPointer += input.readVLong();	  // read freq pointer
     termInfo.proxPointer += input.readVLong();	  // read prox pointer
-
+    
-    if (!isIndex) {
+    if(format == -1){
-      if (termInfo.docFreq > skipInterval) {
+    //  just read skipOffset in order to increment  file pointer; 
-        termInfo.skipOffset = input.readVInt();
+    // value is never used since skipTo is switched off
+      if (!isIndex) {
+        if (termInfo.docFreq > formatM1SkipInterval) {
+          termInfo.skipOffset = input.readVInt(); 
+        }
       }
     }
-
+    else{
+      if (termInfo.docFreq >= skipInterval) 
+        termInfo.skipOffset = input.readVInt();
+    }
+    
     if (isIndex)
       indexPointer += input.readVLong();	  // read index pointer
 

src/java/org/apache/lucene/index/TermInfosWriter.java

@@ -27,13 +27,13 @@ import org.apache.lucene.util.StringHelper;
 
 final class TermInfosWriter {
   /** The file format version, a negative number. */
-  public static final int FORMAT = -1;
+  public static final int FORMAT = -2;
 
   private FieldInfos fieldInfos;
   private OutputStream output;
   private Term lastTerm = new Term("", "");
   private TermInfo lastTi = new TermInfo();
-  private int size = 0;
+  private long size = 0;
 
   // TODO: the default values for these two parameters should be settable from
   // IndexWriter.  However, once that's done, folks will start setting them to
@@ -80,10 +80,8 @@ final class TermInfosWriter {
     output = directory.createFile(segment + (isIndex ? ".tii" : ".tis"));
     output.writeInt(FORMAT);                      // write format
     output.writeLong(0);                          // leave space for size
-    if (!isIndex) {
+    output.writeInt(indexInterval);             // write indexInterval
-      output.writeInt(indexInterval);             // write indexInterval
+    output.writeInt(skipInterval);              // write skipInterval
-      output.writeInt(skipInterval);              // write skipInterval
-    }
   }
 
   /** Adds a new <Term, TermInfo> pair to the set.
@@ -106,10 +104,8 @@ final class TermInfosWriter {
     output.writeVLong(ti.freqPointer - lastTi.freqPointer); // write pointers
     output.writeVLong(ti.proxPointer - lastTi.proxPointer);
 
-    if (!isIndex) {
+    if (ti.docFreq >= skipInterval) {
-      if (ti.docFreq > skipInterval) {
+      output.writeVInt(ti.skipOffset);
-        output.writeVInt(ti.skipOffset);
-      }
     }
 
     if (isIndex) {