package org.apache.lucene.index;

/*
 * 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.
 */

import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.PrintStream;
import java.io.Reader;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import java.util.Random;
import java.util.concurrent.atomic.AtomicBoolean;
import java.util.concurrent.atomic.AtomicInteger;

import org.apache.lucene.analysis.*;
import org.apache.lucene.document.Document;
import org.apache.lucene.document.Field;
import org.apache.lucene.document.FieldType;
import org.apache.lucene.document.StringField;
import org.apache.lucene.search.IndexSearcher;
import org.apache.lucene.search.ScoreDoc;
import org.apache.lucene.search.TermQuery;
import org.apache.lucene.store.Directory;
import org.apache.lucene.store.MockDirectoryWrapper;
import org.apache.lucene.store.RAMDirectory;
import org.apache.lucene.util.LuceneTestCase;
import org.apache.lucene.util._TestUtil;

public class TestIndexWriterDelete extends LuceneTestCase {

  // test the simple case
  public void testSimpleCase() throws IOException {
    String[] keywords = { "1", "2" };
    String[] unindexed = { "Netherlands", "Italy" };
    String[] unstored = { "Amsterdam has lots of bridges",
        "Venice has lots of canals" };
    String[] text = { "Amsterdam", "Venice" };

    Directory dir = newDirectory();
    IndexWriter modifier = new IndexWriter(dir, newIndexWriterConfig(
        TEST_VERSION_CURRENT, new MockAnalyzer(random(), MockTokenizer.WHITESPACE, false)).setMaxBufferedDeleteTerms(1));

    FieldType custom1 = new FieldType();
    custom1.setStored(true);
    for (int i = 0; i < keywords.length; i++) {
      Document doc = new Document();
      doc.add(newStringField("id", keywords[i], Field.Store.YES));
      doc.add(newField("country", unindexed[i], custom1));
      doc.add(newTextField("contents", unstored[i], Field.Store.NO));
      doc.add(newTextField("city", text[i], Field.Store.YES));
      modifier.addDocument(doc);
    }
    modifier.forceMerge(1);
    modifier.commit();

    Term term = new Term("city", "Amsterdam");
    int hitCount = getHitCount(dir, term);
    assertEquals(1, hitCount);
    if (VERBOSE) {
      System.out.println("\nTEST: now delete by term=" + term);
    }
    modifier.deleteDocuments(term);
    modifier.commit();

    if (VERBOSE) {
      System.out.println("\nTEST: now getHitCount");
    }
    hitCount = getHitCount(dir, term);
    assertEquals(0, hitCount);

    modifier.close();
    dir.close();
  }

  // test when delete terms only apply to disk segments
  public void testNonRAMDelete() throws IOException {

    Directory dir = newDirectory();
    IndexWriter modifier = new IndexWriter(dir, newIndexWriterConfig(
        TEST_VERSION_CURRENT, new MockAnalyzer(random(), MockTokenizer.WHITESPACE, false)).setMaxBufferedDocs(2)
        .setMaxBufferedDeleteTerms(2));
    int id = 0;
    int value = 100;

    for (int i = 0; i < 7; i++) {
      addDoc(modifier, ++id, value);
    }
    modifier.commit();

    assertEquals(0, modifier.getNumBufferedDocuments());
    assertTrue(0 < modifier.getSegmentCount());

    modifier.commit();

    IndexReader reader = DirectoryReader.open(dir);
    assertEquals(7, reader.numDocs());
    reader.close();

    modifier.deleteDocuments(new Term("value", String.valueOf(value)));

    modifier.commit();

    reader = DirectoryReader.open(dir);
    assertEquals(0, reader.numDocs());
    reader.close();
    modifier.close();
    dir.close();
  }

  public void testMaxBufferedDeletes() throws IOException {
    Directory dir = newDirectory();
    IndexWriter writer = new IndexWriter(dir, newIndexWriterConfig(
        TEST_VERSION_CURRENT, new MockAnalyzer(random(), MockTokenizer.WHITESPACE, false)).setMaxBufferedDeleteTerms(1));

    writer.addDocument(new Document());
    writer.deleteDocuments(new Term("foobar", "1"));
    writer.deleteDocuments(new Term("foobar", "1"));
    writer.deleteDocuments(new Term("foobar", "1"));
    assertEquals(3, writer.getFlushDeletesCount());
    writer.close();
    dir.close();
  }
  
  // test when delete terms only apply to ram segments
  public void testRAMDeletes() throws IOException {
    for(int t=0;t<2;t++) {
      if (VERBOSE) {
        System.out.println("TEST: t=" + t);
      }
      Directory dir = newDirectory();
      IndexWriter modifier = new IndexWriter(dir, newIndexWriterConfig(
          TEST_VERSION_CURRENT, new MockAnalyzer(random(), MockTokenizer.WHITESPACE, false)).setMaxBufferedDocs(4)
          .setMaxBufferedDeleteTerms(4));
      int id = 0;
      int value = 100;

      addDoc(modifier, ++id, value);
      if (0 == t)
        modifier.deleteDocuments(new Term("value", String.valueOf(value)));
      else
        modifier.deleteDocuments(new TermQuery(new Term("value", String.valueOf(value))));
      addDoc(modifier, ++id, value);
      if (0 == t) {
        modifier.deleteDocuments(new Term("value", String.valueOf(value)));
        assertEquals(2, modifier.getNumBufferedDeleteTerms());
        assertEquals(1, modifier.getBufferedDeleteTermsSize());
      }
      else
        modifier.deleteDocuments(new TermQuery(new Term("value", String.valueOf(value))));

      addDoc(modifier, ++id, value);
      assertEquals(0, modifier.getSegmentCount());
      modifier.commit();

      IndexReader reader = DirectoryReader.open(dir);
      assertEquals(1, reader.numDocs());

      int hitCount = getHitCount(dir, new Term("id", String.valueOf(id)));
      assertEquals(1, hitCount);
      reader.close();
      modifier.close();
      dir.close();
    }
  }

  // test when delete terms apply to both disk and ram segments
  public void testBothDeletes() throws IOException {
    Directory dir = newDirectory();
    IndexWriter modifier = new IndexWriter(dir, newIndexWriterConfig(
        TEST_VERSION_CURRENT, new MockAnalyzer(random(), MockTokenizer.WHITESPACE, false)).setMaxBufferedDocs(100)
        .setMaxBufferedDeleteTerms(100));

    int id = 0;
    int value = 100;

    for (int i = 0; i < 5; i++) {
      addDoc(modifier, ++id, value);
    }

    value = 200;
    for (int i = 0; i < 5; i++) {
      addDoc(modifier, ++id, value);
    }
    modifier.commit();

    for (int i = 0; i < 5; i++) {
      addDoc(modifier, ++id, value);
    }
    modifier.deleteDocuments(new Term("value", String.valueOf(value)));

    modifier.commit();

    IndexReader reader = DirectoryReader.open(dir);
    assertEquals(5, reader.numDocs());
    modifier.close();
    reader.close();
    dir.close();
  }

  // test that batched delete terms are flushed together
  public void testBatchDeletes() throws IOException {
    Directory dir = newDirectory();
    IndexWriter modifier = new IndexWriter(dir, newIndexWriterConfig(
        TEST_VERSION_CURRENT, new MockAnalyzer(random(), MockTokenizer.WHITESPACE, false)).setMaxBufferedDocs(2)
        .setMaxBufferedDeleteTerms(2));

    int id = 0;
    int value = 100;

    for (int i = 0; i < 7; i++) {
      addDoc(modifier, ++id, value);
    }
    modifier.commit();

    IndexReader reader = DirectoryReader.open(dir);
    assertEquals(7, reader.numDocs());
    reader.close();

    id = 0;
    modifier.deleteDocuments(new Term("id", String.valueOf(++id)));
    modifier.deleteDocuments(new Term("id", String.valueOf(++id)));

    modifier.commit();

    reader = DirectoryReader.open(dir);
    assertEquals(5, reader.numDocs());
    reader.close();

    Term[] terms = new Term[3];
    for (int i = 0; i < terms.length; i++) {
      terms[i] = new Term("id", String.valueOf(++id));
    }
    modifier.deleteDocuments(terms);
    modifier.commit();
    reader = DirectoryReader.open(dir);
    assertEquals(2, reader.numDocs());
    reader.close();

    modifier.close();
    dir.close();
  }

  // test deleteAll()
  public void testDeleteAll() throws IOException {
    Directory dir = newDirectory();
    IndexWriter modifier = new IndexWriter(dir, newIndexWriterConfig(
        TEST_VERSION_CURRENT, new MockAnalyzer(random(), MockTokenizer.WHITESPACE, false)).setMaxBufferedDocs(2)
        .setMaxBufferedDeleteTerms(2));

    int id = 0;
    int value = 100;

    for (int i = 0; i < 7; i++) {
      addDoc(modifier, ++id, value);
    }
    modifier.commit();

    IndexReader reader = DirectoryReader.open(dir);
    assertEquals(7, reader.numDocs());
    reader.close();

    // Add 1 doc (so we will have something buffered)
    addDoc(modifier, 99, value);

    // Delete all
    modifier.deleteAll();

    // Delete all shouldn't be on disk yet
    reader = DirectoryReader.open(dir);
    assertEquals(7, reader.numDocs());
    reader.close();

    // Add a doc and update a doc (after the deleteAll, before the commit)
    addDoc(modifier, 101, value);
    updateDoc(modifier, 102, value);

    // commit the delete all
    modifier.commit();

    // Validate there are no docs left
    reader = DirectoryReader.open(dir);
    assertEquals(2, reader.numDocs());
    reader.close();

    modifier.close();
    dir.close();
  }

  // test rollback of deleteAll()
  public void testDeleteAllRollback() throws IOException {
    Directory dir = newDirectory();
    IndexWriter modifier = new IndexWriter(dir, newIndexWriterConfig(
        TEST_VERSION_CURRENT, new MockAnalyzer(random(), MockTokenizer.WHITESPACE, false)).setMaxBufferedDocs(2)
        .setMaxBufferedDeleteTerms(2));

    int id = 0;
    int value = 100;

    for (int i = 0; i < 7; i++) {
      addDoc(modifier, ++id, value);
    }
    modifier.commit();

    addDoc(modifier, ++id, value);

    IndexReader reader = DirectoryReader.open(dir);
    assertEquals(7, reader.numDocs());
    reader.close();

    // Delete all
    modifier.deleteAll();

    // Roll it back
    modifier.rollback();
    modifier.close();

    // Validate that the docs are still there
    reader = DirectoryReader.open(dir);
    assertEquals(7, reader.numDocs());
    reader.close();

    dir.close();
  }


  // test deleteAll() w/ near real-time reader
  public void testDeleteAllNRT() throws IOException {
    Directory dir = newDirectory();
    IndexWriter modifier = new IndexWriter(dir, newIndexWriterConfig(
        TEST_VERSION_CURRENT, new MockAnalyzer(random(), MockTokenizer.WHITESPACE, false)).setMaxBufferedDocs(2)
        .setMaxBufferedDeleteTerms(2));

    int id = 0;
    int value = 100;

    for (int i = 0; i < 7; i++) {
      addDoc(modifier, ++id, value);
    }
    modifier.commit();

    IndexReader reader = modifier.getReader();
    assertEquals(7, reader.numDocs());
    reader.close();

    addDoc(modifier, ++id, value);
    addDoc(modifier, ++id, value);

    // Delete all
    modifier.deleteAll();

    reader = modifier.getReader();
    assertEquals(0, reader.numDocs());
    reader.close();


    // Roll it back
    modifier.rollback();
    modifier.close();

    // Validate that the docs are still there
    reader = DirectoryReader.open(dir);
    assertEquals(7, reader.numDocs());
    reader.close();

    dir.close();
  }


  private void updateDoc(IndexWriter modifier, int id, int value)
      throws IOException {
    Document doc = new Document();
    doc.add(newTextField("content", "aaa", Field.Store.NO));
    doc.add(newStringField("id", String.valueOf(id), Field.Store.YES));
    doc.add(newStringField("value", String.valueOf(value), Field.Store.NO));
    modifier.updateDocument(new Term("id", String.valueOf(id)), doc);
  }


  private void addDoc(IndexWriter modifier, int id, int value)
      throws IOException {
    Document doc = new Document();
    doc.add(newTextField("content", "aaa", Field.Store.NO));
    doc.add(newStringField("id", String.valueOf(id), Field.Store.YES));
    doc.add(newStringField("value", String.valueOf(value), Field.Store.NO));
    modifier.addDocument(doc);
  }

  private int getHitCount(Directory dir, Term term) throws IOException {
    IndexReader reader = DirectoryReader.open(dir);
    IndexSearcher searcher = new IndexSearcher(reader);
    int hitCount = searcher.search(new TermQuery(term), null, 1000).totalHits;
    reader.close();
    return hitCount;
  }

  public void testDeletesOnDiskFull() throws IOException {
    doTestOperationsOnDiskFull(false);
  }

  public void testUpdatesOnDiskFull() throws IOException {
    doTestOperationsOnDiskFull(true);
  }

  /**
   * Make sure if modifier tries to commit but hits disk full that modifier
   * remains consistent and usable. Similar to TestIndexReader.testDiskFull().
   */
  private void doTestOperationsOnDiskFull(boolean updates) throws IOException {

    Term searchTerm = new Term("content", "aaa");
    int START_COUNT = 157;
    int END_COUNT = 144;

    // First build up a starting index:
    MockDirectoryWrapper startDir = newMockDirectory();
    // TODO: find the resource leak that only occurs sometimes here.
    startDir.setNoDeleteOpenFile(false);
    IndexWriter writer = new IndexWriter(startDir, newIndexWriterConfig( TEST_VERSION_CURRENT, new MockAnalyzer(random(), MockTokenizer.WHITESPACE, false)));
    for (int i = 0; i < 157; i++) {
      Document d = new Document();
      d.add(newStringField("id", Integer.toString(i), Field.Store.YES));
      d.add(newTextField("content", "aaa " + i, Field.Store.NO));
      writer.addDocument(d);
    }
    writer.close();

    long diskUsage = startDir.sizeInBytes();
    long diskFree = diskUsage + 10;

    IOException err = null;

    boolean done = false;

    // Iterate w/ ever increasing free disk space:
    while (!done) {
      if (VERBOSE) {
        System.out.println("TEST: cycle");
      }
      MockDirectoryWrapper dir = new MockDirectoryWrapper(random(), new RAMDirectory(startDir, newIOContext(random())));
      dir.setPreventDoubleWrite(false);
      IndexWriter modifier = new IndexWriter(dir,
                                             newIndexWriterConfig(
                                                                  TEST_VERSION_CURRENT, new MockAnalyzer(random(), MockTokenizer.WHITESPACE, false))
                                             .setMaxBufferedDocs(1000)
                                             .setMaxBufferedDeleteTerms(1000)
                                             .setMergeScheduler(new ConcurrentMergeScheduler()));
      ((ConcurrentMergeScheduler) modifier.getConfig().getMergeScheduler()).setSuppressExceptions();

      // For each disk size, first try to commit against
      // dir that will hit random IOExceptions & disk
      // full; after, give it infinite disk space & turn
      // off random IOExceptions & retry w/ same reader:
      boolean success = false;

      for (int x = 0; x < 2; x++) {
        if (VERBOSE) {
          System.out.println("TEST: x=" + x);
        }

        double rate = 0.1;
        double diskRatio = ((double)diskFree) / diskUsage;
        long thisDiskFree;
        String testName;

        if (0 == x) {
          thisDiskFree = diskFree;
          if (diskRatio >= 2.0) {
            rate /= 2;
          }
          if (diskRatio >= 4.0) {
            rate /= 2;
          }
          if (diskRatio >= 6.0) {
            rate = 0.0;
          }
          if (VERBOSE) {
            System.out.println("\ncycle: " + diskFree + " bytes");
          }
          testName = "disk full during reader.close() @ " + thisDiskFree
            + " bytes";
        } else {
          thisDiskFree = 0;
          rate = 0.0;
          if (VERBOSE) {
            System.out.println("\ncycle: same writer: unlimited disk space");
          }
          testName = "reader re-use after disk full";
        }

        dir.setMaxSizeInBytes(thisDiskFree);
        dir.setRandomIOExceptionRate(rate);

        try {
          if (0 == x) {
            int docId = 12;
            for (int i = 0; i < 13; i++) {
              if (updates) {
                Document d = new Document();
                d.add(newStringField("id", Integer.toString(i), Field.Store.YES));
                d.add(newTextField("content", "bbb " + i, Field.Store.NO));
                modifier.updateDocument(new Term("id", Integer.toString(docId)), d);
              } else { // deletes
                modifier.deleteDocuments(new Term("id", Integer.toString(docId)));
                // modifier.setNorm(docId, "contents", (float)2.0);
              }
              docId += 12;
            }
          }
          modifier.close();
          success = true;
          if (0 == x) {
            done = true;
          }
        }
        catch (IOException e) {
          if (VERBOSE) {
            System.out.println("  hit IOException: " + e);
            e.printStackTrace(System.out);
          }
          err = e;
          if (1 == x) {
            e.printStackTrace();
            fail(testName + " hit IOException after disk space was freed up");
          }
        }
        // prevent throwing a random exception here!!
        final double randomIOExceptionRate = dir.getRandomIOExceptionRate();
        final long maxSizeInBytes = dir.getMaxSizeInBytes();
        dir.setRandomIOExceptionRate(0.0);
        dir.setMaxSizeInBytes(0);
        if (!success) {
          // Must force the close else the writer can have
          // open files which cause exc in MockRAMDir.close
          if (VERBOSE) {
            System.out.println("TEST: now rollback");
          }
          modifier.rollback();
        }

        // If the close() succeeded, make sure there are
        // no unreferenced files.
        if (success) {
          _TestUtil.checkIndex(dir);
          TestIndexWriter.assertNoUnreferencedFiles(dir, "after writer.close");
        }
        dir.setRandomIOExceptionRate(randomIOExceptionRate);
        dir.setMaxSizeInBytes(maxSizeInBytes);

        // Finally, verify index is not corrupt, and, if
        // we succeeded, we see all docs changed, and if
        // we failed, we see either all docs or no docs
        // changed (transactional semantics):
        IndexReader newReader = null;
        try {
          newReader = DirectoryReader.open(dir);
        }
        catch (IOException e) {
          e.printStackTrace();
          fail(testName
               + ":exception when creating IndexReader after disk full during close: "
               + e);
        }

        IndexSearcher searcher = newSearcher(newReader);
        ScoreDoc[] hits = null;
        try {
          hits = searcher.search(new TermQuery(searchTerm), null, 1000).scoreDocs;
        }
        catch (IOException e) {
          e.printStackTrace();
          fail(testName + ": exception when searching: " + e);
        }
        int result2 = hits.length;
        if (success) {
          if (x == 0 && result2 != END_COUNT) {
            fail(testName
                 + ": method did not throw exception but hits.length for search on term 'aaa' is "
                 + result2 + " instead of expected " + END_COUNT);
          } else if (x == 1 && result2 != START_COUNT && result2 != END_COUNT) {
            // It's possible that the first exception was
            // "recoverable" wrt pending deletes, in which
            // case the pending deletes are retained and
            // then re-flushing (with plenty of disk
            // space) will succeed in flushing the
            // deletes:
            fail(testName
                 + ": method did not throw exception but hits.length for search on term 'aaa' is "
                 + result2 + " instead of expected " + START_COUNT + " or " + END_COUNT);
          }
        } else {
          // On hitting exception we still may have added
          // all docs:
          if (result2 != START_COUNT && result2 != END_COUNT) {
            err.printStackTrace();
            fail(testName
                 + ": method did throw exception but hits.length for search on term 'aaa' is "
                 + result2 + " instead of expected " + START_COUNT + " or " + END_COUNT);
          }
        }
        newReader.close();
        if (result2 == END_COUNT) {
          break;
        }
      }
      dir.close();
      modifier.close();

      // Try again with 10 more bytes of free space:
      diskFree += 10;
    }
    startDir.close();
  }

  // This test tests that buffered deletes are cleared when
  // an Exception is hit during flush.
  public void testErrorAfterApplyDeletes() throws IOException {

    MockDirectoryWrapper.Failure failure = new MockDirectoryWrapper.Failure() {
        boolean sawMaybe = false;
        boolean failed = false;
        Thread thread;
        @Override
        public MockDirectoryWrapper.Failure reset() {
          thread = Thread.currentThread();
          sawMaybe = false;
          failed = false;
          return this;
        }
        @Override
        public void eval(MockDirectoryWrapper dir)  throws IOException {
          if (Thread.currentThread() != thread) {
            // don't fail during merging
            return;
          }
          if (sawMaybe && !failed) {
            boolean seen = false;
            StackTraceElement[] trace = new Exception().getStackTrace();
            for (int i = 0; i < trace.length; i++) {
              if ("applyDeletes".equals(trace[i].getMethodName())) {
                seen = true;
                break;
              }
            }
            if (!seen) {
              // Only fail once we are no longer in applyDeletes
              failed = true;
              if (VERBOSE) {
                System.out.println("TEST: mock failure: now fail");
                new Throwable().printStackTrace(System.out);
              }
              throw new IOException("fail after applyDeletes");
            }
          }
          if (!failed) {
            StackTraceElement[] trace = new Exception().getStackTrace();
            for (int i = 0; i < trace.length; i++) {
              if ("applyDeletes".equals(trace[i].getMethodName())) {
                if (VERBOSE) {
                  System.out.println("TEST: mock failure: saw applyDeletes");
                  new Throwable().printStackTrace(System.out);
                }
                sawMaybe = true;
                break;
              }
            }
          }
        }
      };

    // create a couple of files

    String[] keywords = { "1", "2" };
    String[] unindexed = { "Netherlands", "Italy" };
    String[] unstored = { "Amsterdam has lots of bridges",
        "Venice has lots of canals" };
    String[] text = { "Amsterdam", "Venice" };

    MockDirectoryWrapper dir = newMockDirectory();
    IndexWriter modifier = new IndexWriter(dir, newIndexWriterConfig(
                                                                     TEST_VERSION_CURRENT, new MockAnalyzer(random(), MockTokenizer.WHITESPACE, false)).setMaxBufferedDeleteTerms(2).setReaderPooling(false).setMergePolicy(newLogMergePolicy()));

    LogMergePolicy lmp = (LogMergePolicy) modifier.getConfig().getMergePolicy();
    lmp.setUseCompoundFile(true);

    dir.failOn(failure.reset());

    FieldType custom1 = new FieldType();
    custom1.setStored(true);
    for (int i = 0; i < keywords.length; i++) {
      Document doc = new Document();
      doc.add(newStringField("id", keywords[i], Field.Store.YES));
      doc.add(newField("country", unindexed[i], custom1));
      doc.add(newTextField("contents", unstored[i], Field.Store.NO));
      doc.add(newTextField("city", text[i], Field.Store.YES));
      modifier.addDocument(doc);
    }
    // flush (and commit if ac)

    if (VERBOSE) {
      System.out.println("TEST: now full merge");
    }

    modifier.forceMerge(1);
    if (VERBOSE) {
      System.out.println("TEST: now commit");
    }
    modifier.commit();

    // one of the two files hits

    Term term = new Term("city", "Amsterdam");
    int hitCount = getHitCount(dir, term);
    assertEquals(1, hitCount);

    // open the writer again (closed above)

    // delete the doc
    // max buf del terms is two, so this is buffered

    if (VERBOSE) {
      System.out.println("TEST: delete term=" + term);
    }

    modifier.deleteDocuments(term);

    // add a doc (needed for the !ac case; see below)
    // doc remains buffered

    if (VERBOSE) {
      System.out.println("TEST: add empty doc");
    }
    Document doc = new Document();
    modifier.addDocument(doc);

    // commit the changes, the buffered deletes, and the new doc

    // The failure object will fail on the first write after the del
    // file gets created when processing the buffered delete

    // in the ac case, this will be when writing the new segments
    // files so we really don't need the new doc, but it's harmless

    // a new segments file won't be created but in this
    // case, creation of the cfs file happens next so we
    // need the doc (to test that it's okay that we don't
    // lose deletes if failing while creating the cfs file)
    boolean failed = false;
    try {
      if (VERBOSE) {
        System.out.println("TEST: now commit for failure");
      }
      modifier.commit();
    } catch (IOException ioe) {
      // expected
      failed = true;
    }

    assertTrue(failed);

    // The commit above failed, so we need to retry it (which will
    // succeed, because the failure is a one-shot)

    modifier.commit();

    hitCount = getHitCount(dir, term);

    // Make sure the delete was successfully flushed:
    assertEquals(0, hitCount);

    modifier.close();
    dir.close();
  }

  // This test tests that the files created by the docs writer before
  // a segment is written are cleaned up if there's an i/o error

  public void testErrorInDocsWriterAdd() throws IOException {

    MockDirectoryWrapper.Failure failure = new MockDirectoryWrapper.Failure() {
        boolean failed = false;
        @Override
        public MockDirectoryWrapper.Failure reset() {
          failed = false;
          return this;
        }
        @Override
        public void eval(MockDirectoryWrapper dir)  throws IOException {
          if (!failed) {
            failed = true;
            throw new IOException("fail in add doc");
          }
        }
      };

    // create a couple of files

    String[] keywords = { "1", "2" };
    String[] unindexed = { "Netherlands", "Italy" };
    String[] unstored = { "Amsterdam has lots of bridges",
        "Venice has lots of canals" };
    String[] text = { "Amsterdam", "Venice" };

    MockDirectoryWrapper dir = newMockDirectory();
    IndexWriter modifier = new IndexWriter(dir, newIndexWriterConfig( TEST_VERSION_CURRENT, new MockAnalyzer(random(), MockTokenizer.WHITESPACE, false)));
    modifier.commit();
    dir.failOn(failure.reset());

    FieldType custom1 = new FieldType();
    custom1.setStored(true);
    for (int i = 0; i < keywords.length; i++) {
      Document doc = new Document();
      doc.add(newStringField("id", keywords[i], Field.Store.YES));
      doc.add(newField("country", unindexed[i], custom1));
      doc.add(newTextField("contents", unstored[i], Field.Store.NO));
      doc.add(newTextField("city", text[i], Field.Store.YES));
      try {
        modifier.addDocument(doc);
      } catch (IOException io) {
        if (VERBOSE) {
          System.out.println("TEST: got expected exc:");
          io.printStackTrace(System.out);
        }
        break;
      }
    }

    modifier.close();
    TestIndexWriter.assertNoUnreferencedFiles(dir, "docsWriter.abort() failed to delete unreferenced files");
    dir.close();
  }

  public void testDeleteNullQuery() throws IOException {
    Directory dir = newDirectory();
    IndexWriter modifier = new IndexWriter(dir, new IndexWriterConfig(TEST_VERSION_CURRENT, new MockAnalyzer(random(), MockTokenizer.WHITESPACE, false)));

    for (int i = 0; i < 5; i++) {
      addDoc(modifier, i, 2*i);
    }

    modifier.deleteDocuments(new TermQuery(new Term("nada", "nada")));
    modifier.commit();
    assertEquals(5, modifier.numDocs());
    modifier.close();
    dir.close();
  }
  
  public void testDeleteAllSlowly() throws Exception {
    final Directory dir = newDirectory();
    RandomIndexWriter w = new RandomIndexWriter(random(), dir);
    final int NUM_DOCS = atLeast(1000);
    final List<Integer> ids = new ArrayList<Integer>(NUM_DOCS);
    for(int id=0;id<NUM_DOCS;id++) {
      ids.add(id);
    }
    Collections.shuffle(ids, random());
    for(int id : ids) {
      Document doc = new Document();
      doc.add(newStringField("id", ""+id, Field.Store.NO));
      w.addDocument(doc);
    }
    Collections.shuffle(ids, random());
    int upto = 0;
    while(upto < ids.size()) {
      final int left = ids.size() - upto;
      final int inc = Math.min(left, _TestUtil.nextInt(random(), 1, 20));
      final int limit = upto + inc;
      while(upto < limit) {
        w.deleteDocuments(new Term("id", ""+ids.get(upto++)));
      }
      final IndexReader r = w.getReader();
      assertEquals(NUM_DOCS - upto, r.numDocs());
      r.close();
    }

    w.close();
    dir.close();
  }
  
  public void testIndexingThenDeleting() throws Exception {
    // TODO: move this test to its own class and just @SuppressCodecs?
    // TODO: is it enough to just use newFSDirectory?
    final String fieldFormat = _TestUtil.getPostingsFormat("field");
    assumeFalse("This test cannot run with Memory codec", fieldFormat.equals("Memory"));
    assumeFalse("This test cannot run with SimpleText codec", fieldFormat.equals("SimpleText"));
    assumeFalse("This test cannot run with Direct codec", fieldFormat.equals("Direct"));
    final Random r = random();
    Directory dir = newDirectory();
    // note this test explicitly disables payloads
    final Analyzer analyzer = new Analyzer() {
      @Override
      public TokenStreamComponents createComponents(String fieldName, Reader reader) {
        return new TokenStreamComponents(new MockTokenizer(reader, MockTokenizer.WHITESPACE, true));
      }
    };
    IndexWriter w = new IndexWriter(dir, newIndexWriterConfig( TEST_VERSION_CURRENT, analyzer).setRAMBufferSizeMB(1.0).setMaxBufferedDocs(IndexWriterConfig.DISABLE_AUTO_FLUSH).setMaxBufferedDeleteTerms(IndexWriterConfig.DISABLE_AUTO_FLUSH));
    Document doc = new Document();
    doc.add(newTextField("field", "go 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20", Field.Store.NO));
    int num = atLeast(3);
    for (int iter = 0; iter < num; iter++) {
      int count = 0;

      final boolean doIndexing = r.nextBoolean();
      if (VERBOSE) {
        System.out.println("TEST: iter doIndexing=" + doIndexing);
      }
      if (doIndexing) {
        // Add docs until a flush is triggered
        final int startFlushCount = w.getFlushCount();
        while(w.getFlushCount() == startFlushCount) {
          w.addDocument(doc);
          count++;
        }
      } else {
        // Delete docs until a flush is triggered
        final int startFlushCount = w.getFlushCount();
        while(w.getFlushCount() == startFlushCount) {
          w.deleteDocuments(new Term("foo", ""+count));
          count++;
        }
      }
      assertTrue("flush happened too quickly during " + (doIndexing ? "indexing" : "deleting") + " count=" + count, count > 2500);
    }
    w.close();
    dir.close();
  }

  // LUCENE-3340: make sure deletes that we don't apply
  // during flush (ie are just pushed into the stream) are
  // in fact later flushed due to their RAM usage:
  public void testFlushPushedDeletesByRAM() throws Exception {
    Directory dir = newDirectory();
    // Cannot use RandomIndexWriter because we don't want to
    // ever call commit() for this test:
    // note: tiny rambuffer used, as with a 1MB buffer the test is too slow (flush @ 128,999)
    IndexWriter w = new IndexWriter(dir,
                                    newIndexWriterConfig(TEST_VERSION_CURRENT, new MockAnalyzer(random()))
                                    .setRAMBufferSizeMB(0.1f).setMaxBufferedDocs(1000).setMergePolicy(NoMergePolicy.NO_COMPOUND_FILES).setReaderPooling(false));
    int count = 0;
    while(true) {
      Document doc = new Document();
      doc.add(new StringField("id", count+"", Field.Store.NO));
      final Term delTerm;
      if (count == 1010) {
        // This is the only delete that applies
        delTerm = new Term("id", ""+0);
      } else {
        // These get buffered, taking up RAM, but delete
        // nothing when applied:
        delTerm = new Term("id", "x" + count);
      }
      w.updateDocument(delTerm, doc);
      // Eventually segment 0 should get a del docs:
      // TODO: fix this test
      if (dir.fileExists("_0_1.del") || dir.fileExists("_0_1.liv") ) {
        if (VERBOSE) {
          System.out.println("TEST: deletes created @ count=" + count);
        }
        break;
      }
      count++;

      // Today we applyDeletes @ count=21553; even if we make
      // sizable improvements to RAM efficiency of buffered
      // del term we're unlikely to go over 100K:
      if (count > 100000) {
        fail("delete's were not applied");
      }
    }
    w.close();
    dir.close();
  }

  // LUCENE-3340: make sure deletes that we don't apply
  // during flush (ie are just pushed into the stream) are
  // in fact later flushed due to their RAM usage:
  public void testFlushPushedDeletesByCount() throws Exception {
    Directory dir = newDirectory();
    // Cannot use RandomIndexWriter because we don't want to
    // ever call commit() for this test:
    final int flushAtDelCount = atLeast(1020);
    IndexWriter w = new IndexWriter(dir,
                                    newIndexWriterConfig(TEST_VERSION_CURRENT, new MockAnalyzer(random())).
                                    setMaxBufferedDeleteTerms(flushAtDelCount).setMaxBufferedDocs(1000).setRAMBufferSizeMB(IndexWriterConfig.DISABLE_AUTO_FLUSH).setMergePolicy(NoMergePolicy.NO_COMPOUND_FILES).setReaderPooling(false));
    int count = 0;
    while(true) {
      Document doc = new Document();
      doc.add(new StringField("id", count+"", Field.Store.NO));
      final Term delTerm;
      if (count == 1010) {
        // This is the only delete that applies
        delTerm = new Term("id", ""+0);
      } else {
        // These get buffered, taking up RAM, but delete
        // nothing when applied:
        delTerm = new Term("id", "x" + count);
      }
      w.updateDocument(delTerm, doc);
      // Eventually segment 0 should get a del docs:
      // TODO: fix this test
      if (dir.fileExists("_0_1.del") || dir.fileExists("_0_1.liv")) {
        break;
      }
      count++;
      if (count > flushAtDelCount) {
        fail("delete's were not applied at count=" + flushAtDelCount);
      }
    }
    w.close();
    dir.close();
  }

  // Make sure buffered (pushed) deletes don't use up so
  // much RAM that it forces long tail of tiny segments:
  @Nightly
  public void testApplyDeletesOnFlush() throws Exception {
    Directory dir = newDirectory();
    // Cannot use RandomIndexWriter because we don't want to
    // ever call commit() for this test:
    final AtomicInteger docsInSegment = new AtomicInteger();
    final AtomicBoolean closing = new AtomicBoolean();
    final AtomicBoolean sawAfterFlush = new AtomicBoolean();
    IndexWriter w = new IndexWriter(dir,
                                    newIndexWriterConfig(TEST_VERSION_CURRENT, new MockAnalyzer(random())).
                                    setRAMBufferSizeMB(0.5).setMaxBufferedDocs(-1).setMergePolicy(NoMergePolicy.NO_COMPOUND_FILES).setReaderPooling(false)) {
        @Override
        public void doAfterFlush() {
          assertTrue("only " + docsInSegment.get() + " in segment", closing.get() || docsInSegment.get() >= 7);
          docsInSegment.set(0);
          sawAfterFlush.set(true);
        }
      };
    int id = 0;
    while(true) {
      StringBuilder sb = new StringBuilder();
      for(int termIDX=0;termIDX<100;termIDX++) {
        sb.append(' ').append(_TestUtil.randomRealisticUnicodeString(random()));
      }
      if (id == 500) {
        w.deleteDocuments(new Term("id", "0"));
      }
      Document doc = new Document();
      doc.add(newStringField("id", ""+id, Field.Store.NO));
      doc.add(newTextField("body", sb.toString(), Field.Store.NO));
      w.updateDocument(new Term("id", ""+id), doc);
      docsInSegment.incrementAndGet();
      // TODO: fix this test
      if (dir.fileExists("_0_1.del") || dir.fileExists("_0_1.liv")) {
        if (VERBOSE) {
          System.out.println("TEST: deletes created @ id=" + id);
        }
        break;
      }
      id++;
    }
    closing.set(true);
    assertTrue(sawAfterFlush.get());
    w.close();
    dir.close();
  }

  // LUCENE-4455
  public void testDeletesCheckIndexOutput() throws Exception {
    Directory dir = newDirectory();
    IndexWriterConfig iwc = new IndexWriterConfig(TEST_VERSION_CURRENT, new MockAnalyzer(random()));
    iwc.setMaxBufferedDocs(2);
    IndexWriter w = new IndexWriter(dir, iwc);
    Document doc = new Document();
    doc.add(newField("field", "0", StringField.TYPE_NOT_STORED));
    w.addDocument(doc);

    doc = new Document();
    doc.add(newField("field", "1", StringField.TYPE_NOT_STORED));
    w.addDocument(doc);
    w.commit();
    assertEquals(1, w.getSegmentCount());

    w.deleteDocuments(new Term("field", "0"));
    w.commit();
    assertEquals(1, w.getSegmentCount());
    w.close();

    ByteArrayOutputStream bos = new ByteArrayOutputStream(1024);
    CheckIndex checker = new CheckIndex(dir);
    checker.setInfoStream(new PrintStream(bos, false, "UTF-8"), false);
    CheckIndex.Status indexStatus = checker.checkIndex(null);
    assertTrue(indexStatus.clean);
    String s = bos.toString("UTF-8");

    // Segment should have deletions:
    assertTrue(s.contains("has deletions"));
    w = new IndexWriter(dir, iwc);
    w.forceMerge(1);
    w.close();

    bos = new ByteArrayOutputStream(1024);
    checker.setInfoStream(new PrintStream(bos, false, "UTF-8"), false);
    indexStatus = checker.checkIndex(null);
    assertTrue(indexStatus.clean);
    s = bos.toString("UTF-8");
    assertFalse(s.contains("has deletions"));
    dir.close();
  }
}