From 2ce53791d3205efff5eb12d0d24911b3ea31abe3 Mon Sep 17 00:00:00 2001
From: Simon Willnauer <simonw@apache.org>
Date: Sun, 20 May 2018 14:06:14 +0200
Subject: [PATCH] LUCENE-8324: Checkpoint after fully deletes segment is
 dropped on flush

---
 .../org/apache/lucene/index/IndexWriter.java  |  1 +
 .../apache/lucene/index/TestIndexWriter.java  | 36 +++++++++++++++++++
 2 files changed, 37 insertions(+)

diff --git a/lucene/core/src/java/org/apache/lucene/index/IndexWriter.java b/lucene/core/src/java/org/apache/lucene/index/IndexWriter.java
index af2fd47d2d6..8db29ffca57 100644
--- a/lucene/core/src/java/org/apache/lucene/index/IndexWriter.java
+++ b/lucene/core/src/java/org/apache/lucene/index/IndexWriter.java
@@ -2650,6 +2650,7 @@ public class IndexWriter implements Closeable, TwoPhaseCommit, Accountable {
         try {
           if (isFullyDeleted(rld)) {
             dropDeletedSegment(newSegment);
+            checkpoint();
           }
         } finally {
           release(rld);
diff --git a/lucene/core/src/test/org/apache/lucene/index/TestIndexWriter.java b/lucene/core/src/test/org/apache/lucene/index/TestIndexWriter.java
index 1dd1eb293c7..a36920be31e 100644
--- a/lucene/core/src/test/org/apache/lucene/index/TestIndexWriter.java
+++ b/lucene/core/src/test/org/apache/lucene/index/TestIndexWriter.java
@@ -40,6 +40,7 @@ import java.util.Random;
 import java.util.Set;
 import java.util.concurrent.CountDownLatch;
 import java.util.concurrent.atomic.AtomicBoolean;
+import java.util.stream.Collectors;
 
 import com.carrotsearch.randomizedtesting.generators.RandomPicks;
 import org.apache.lucene.analysis.Analyzer;
@@ -3314,4 +3315,39 @@ public class TestIndexWriter extends LuceneTestCase {
       t.join();
     }
   }
+
+  private static void assertFiles(IndexWriter writer) throws IOException {
+    // remove segment files we don't know if we have committed and what is kept around
+    Set<String> segFiles = new HashSet<>(writer.segmentInfos.files(true)).stream()
+        .filter(f -> f.startsWith("segments") == false).collect(Collectors.toSet());
+    Set<String> dirFiles = new HashSet<>(Arrays.asList(writer.getDirectory().listAll()))
+        .stream().filter(f -> f.startsWith("segments") == false).collect(Collectors.toSet());
+    Set<String> s = new HashSet<>(segFiles);
+    s.removeAll(dirFiles);
+    assertEquals(segFiles.toString() + " vs "+ dirFiles.toString(), segFiles.size(), dirFiles.size());
+  }
+
+  public void testFullyDeletedSegmentsReleaseFiles() throws IOException {
+    Directory dir = newDirectory();
+    IndexWriterConfig config = newIndexWriterConfig();
+    config.setRAMBufferSizeMB(Integer.MAX_VALUE);
+    config.setMaxBufferedDocs(2); // no auto flush
+    IndexWriter writer = new IndexWriter(dir, config);
+    Document d = new Document();
+    d.add(new StringField("id", "doc-0", Field.Store.YES));
+    writer.addDocument(d);
+    writer.flush();
+    d = new Document();
+    d.add(new StringField("id", "doc-1", Field.Store.YES));
+    writer.addDocument(d);
+    writer.deleteDocuments(new Term("id", "doc-1"));
+    assertEquals(1, writer.segmentInfos.asList().size());
+    writer.flush();
+    assertEquals(1, writer.segmentInfos.asList().size());
+    writer.commit();
+    assertFiles(writer);
+    assertEquals(1, writer.segmentInfos.asList().size());
+    IOUtils.close(writer, dir);
+  }
+
 }