http://forfuture1978.iteye.com/blog/546841

见图：

lucene-6.5.1-src/lucene-6.5.1

$ grep "skiplistwriter" * -ril

core/src/java/org/apache/lucene/codecs/lucene50/Lucene50PostingsFormat.java

core/src/java/org/apache/lucene/codecs/lucene50/Lucene50SkipWriter.java

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

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

 

测试代码位置：

lucene-6.5.1-src/lucene-6.5.1

$ vim core/src/test/org/apache/lucene/codecs/lucene50/TestBlockPostingsFormat3.java

/**   * checks advancing docs   */  public void assertDocsSkipping(int docFreq, PostingsEnum leftDocs, PostingsEnum rightDocs) throws Exception {    if (leftDocs == null) {      assertNull(rightDocs);      return;    }    int docid = -1;    int averageGap = MAXDOC / (1+docFreq);    int skipInterval = 16;    while (true) {      if (random().nextBoolean()) {        // nextDoc()        docid = leftDocs.nextDoc();        assertEquals(docid, rightDocs.nextDoc());      } else {        // advance()        int skip = docid + (int) Math.ceil(Math.abs(skipInterval + random().nextGaussian() * averageGap));        docid = leftDocs.advance(skip);        assertEquals(docid, rightDocs.advance(skip));      }      if (docid == DocIdSetIterator.NO_MORE_DOCS) {        return;      }      // we don't assert freqs, they are allowed to be different    }  }

 

/**   * checks advancing docs + positions   */  public void assertPositionsSkipping(int docFreq, PostingsEnum leftDocs, PostingsEnum rightDocs) throws Exception {    if (leftDocs == null || rightDocs == null) {      assertNull(leftDocs);      assertNull(rightDocs);      return;    }    int docid = -1;    int averageGap = MAXDOC / (1+docFreq);    int skipInterval = 16;    while (true) {      if (random().nextBoolean()) {        // nextDoc()        docid = leftDocs.nextDoc();        assertEquals(docid, rightDocs.nextDoc());      } else {        // advance()        int skip = docid + (int) Math.ceil(Math.abs(skipInterval + random().nextGaussian() * averageGap));        docid = leftDocs.advance(skip);        assertEquals(docid, rightDocs.advance(skip));      }      if (docid == DocIdSetIterator.NO_MORE_DOCS) {        return;      }      int freq = leftDocs.freq();      assertEquals(freq, rightDocs.freq());      for (int i = 0; i < freq; i++) {        assertEquals(leftDocs.nextPosition(), rightDocs.nextPosition());        // we don't compare the payloads, it's allowed that one is empty etc      }    }  }