HDFS-12730. Verify open files captured in the snapshots across config disable and enable.

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/snapshot/SnapshotManager.java

@@ -35,6 +35,7 @@ import java.util.concurrent.atomic.AtomicInteger;
 
 import javax.management.ObjectName;
 
+import com.google.common.annotations.VisibleForTesting;
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
 import org.apache.hadoop.conf.Configuration;
@@ -75,7 +76,7 @@ public class SnapshotManager implements SnapshotStatsMXBean {
   public static final Log LOG = LogFactory.getLog(SnapshotManager.class);
 
   private final FSDirectory fsdir;
-  private final boolean captureOpenFiles;
+  private boolean captureOpenFiles;
   /**
    * If skipCaptureAccessTimeOnlyChange is set to true, if accessTime
    * of a file changed but there is no other modification made to the file,
@@ -121,6 +122,11 @@ public class SnapshotManager implements SnapshotStatsMXBean {
         + snapshotDiffAllowSnapRootDescendant);
   }
 
+  @VisibleForTesting
+  void setCaptureOpenFiles(boolean captureOpenFiles) {
+    this.captureOpenFiles = captureOpenFiles;
+  }
+
   /**
    * @return skipCaptureAccessTimeOnlyChange
    */

hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/snapshot/TestOpenFilesWithSnapshot.java

@@ -843,6 +843,123 @@ public class TestOpenFilesWithSnapshot {
         hbaseFileCksumBeforeTruncate, hbaseFileCksumS3);
   }
 
+  private Path createSnapshot(Path snapRootDir, String snapName,
+      String fileName) throws Exception {
+    final Path snap1Dir = SnapshotTestHelper.createSnapshot(
+        fs, snapRootDir, snapName);
+    return new Path(snap1Dir, fileName);
+  }
+
+  private void verifyFileSize(long fileSize, Path... filePaths) throws
+      IOException {
+    for (Path filePath : filePaths) {
+      Assert.assertEquals(fileSize, fs.getFileStatus(filePath).getLen());
+    }
+  }
+
+  /**
+   * Verify open files captured in the snapshots across config disable
+   * and enable.
+   */
+  @Test
+  public void testOpenFilesWithMixedConfig() throws Exception {
+    final Path snapRootDir = new Path("/level_0_A");
+    final String flumeFileName = "flume.log";
+    final String snap1Name = "s1";
+    final String snap2Name = "s2";
+    final String snap3Name = "s3";
+    final String snap4Name = "s4";
+    final String snap5Name = "s5";
+
+    // Create files and open streams
+    final Path flumeFile = new Path(snapRootDir, flumeFileName);
+    createFile(flumeFile);
+    FSDataOutputStream flumeOutputStream = fs.append(flumeFile);
+
+    // 1. Disable capture open files
+    cluster.getNameNode().getNamesystem()
+        .getSnapshotManager().setCaptureOpenFiles(false);
+
+    // Create Snapshot S1
+    final Path flumeS1Path = createSnapshot(snapRootDir,
+        snap1Name, flumeFileName);
+
+    // Verify if Snap S1 file length is same as the the current versions
+    verifyFileSize(FILELEN, flumeS1Path);
+
+    // Write more data to files
+    long flumeFileWrittenDataLength = FILELEN;
+    int newWriteLength = (int) (BLOCKSIZE * 1.5);
+    byte[] buf = new byte[newWriteLength];
+    Random random = new Random();
+    random.nextBytes(buf);
+    flumeFileWrittenDataLength += writeToStream(flumeOutputStream, buf);
+
+    // Create Snapshot S2
+    final Path flumeS2Path = createSnapshot(snapRootDir,
+        snap2Name, flumeFileName);
+
+    // Since capture open files was disabled, all snapshots paths
+    // and the current version should have same file lengths.
+    verifyFileSize(flumeFileWrittenDataLength,
+        flumeFile, flumeS2Path, flumeS1Path);
+
+    // 2. Enable capture open files
+    cluster.getNameNode().getNamesystem()
+        .getSnapshotManager() .setCaptureOpenFiles(true);
+
+    // Write more data to files
+    flumeFileWrittenDataLength += writeToStream(flumeOutputStream, buf);
+    long flumeFileLengthAfterS3 = flumeFileWrittenDataLength;
+
+    // Create Snapshot S3
+    final Path flumeS3Path = createSnapshot(snapRootDir,
+        snap3Name, flumeFileName);
+
+    // Since open files captured in the previous snapshots were with config
+    // disabled, their file lengths are now same as the current version.
+    // With the config turned on, any new data written to the open files
+    // will no more reflect in the current version or old snapshot paths.
+    verifyFileSize(flumeFileWrittenDataLength, flumeFile, flumeS3Path,
+        flumeS2Path, flumeS1Path);
+
+    // Write more data to files
+    flumeFileWrittenDataLength += writeToStream(flumeOutputStream, buf);
+
+    // Create Snapshot S4
+    final Path flumeS4Path = createSnapshot(snapRootDir,
+        snap4Name, flumeFileName);
+
+    // Verify S4 has the latest data
+    verifyFileSize(flumeFileWrittenDataLength, flumeFile, flumeS4Path);
+
+    // But, open files captured as of Snapshot S3 and before should
+    // have their old file lengths intact.
+    verifyFileSize(flumeFileLengthAfterS3, flumeS3Path,
+        flumeS2Path, flumeS1Path);
+
+    long flumeFileLengthAfterS4 =  flumeFileWrittenDataLength;
+
+    // 3. Disable capture open files
+    cluster.getNameNode().getNamesystem()
+        .getSnapshotManager() .setCaptureOpenFiles(false);
+
+    // Create Snapshot S5
+    final Path flumeS5Path = createSnapshot(snapRootDir,
+        snap5Name, flumeFileName);
+
+    flumeFileWrittenDataLength += writeToStream(flumeOutputStream, buf);
+
+    // Since capture open files was disabled, any snapshots taken after the
+    // config change and the current version should have same file lengths
+    // for the open files.
+    verifyFileSize(flumeFileWrittenDataLength, flumeFile, flumeS5Path);
+
+    // But, the old snapshots taken before the config disable should
+    // continue to be consistent.
+    verifyFileSize(flumeFileLengthAfterS4, flumeS4Path);
+  }
+
   private void restartNameNode() throws Exception {
     cluster.triggerBlockReports();
     NameNode nameNode = cluster.getNameNode();