HDDS-1981: Datanode should sync db when container is moved to CLOSED or QUASI_CLOSED state (apache#1319)

Author: lokeshj1703

hadoop-hdds/common/src/main/java/org/apache/hadoop/utils/LevelDBStore.java

@@ -240,6 +240,12 @@ public void compactDB() throws IOException {
     }
   }
 
+  @Override
+  public void flushDB(boolean sync) {
+    // TODO: Implement flush for level db
+    // do nothing
+  }
+
   @Override
   public void writeBatch(BatchOperation operation) throws IOException {
     List<BatchOperation.SingleOperation> operations =

hadoop-hdds/common/src/main/java/org/apache/hadoop/utils/MetadataStore.java

@@ -131,6 +131,12 @@ List<Map.Entry<byte[], byte[]>> getSequentialRangeKVs(byte[] startKey,
    */
   void compactDB() throws IOException;
 
+  /**
+   * Flush the outstanding I/O operations of the DB.
+   * @param sync if true will sync the outstanding I/Os to the disk.
+   */
+  void flushDB(boolean sync) throws IOException;
+
   /**
    * Destroy the content of the specified database,
    * a destroyed database will not be able to load again.

hadoop-hdds/common/src/main/java/org/apache/hadoop/utils/RocksDBStore.java

@@ -279,6 +279,19 @@ public void compactDB() throws IOException {
     }
   }
 
+  @Override
+  public void flushDB(boolean sync) throws IOException {
+    if (db != null) {
+      try {
+        // for RocksDB it is sufficient to flush the WAL as entire db can
+        // be reconstructed using it.
+        db.flushWal(sync);
+      } catch (RocksDBException e) {
+        throw toIOException("Failed to flush db", e);
+      }
+    }
+  }
+
   private void deleteQuietly(File fileOrDir) {
     if (fileOrDir != null && fileOrDir.exists()) {
       try {

hadoop-hdds/common/src/main/proto/DatanodeContainerProtocol.proto

@@ -144,6 +144,7 @@ enum Result {
   CONTAINER_NOT_OPEN = 39;
   CONTAINER_MISSING = 40;
   BLOCK_TOKEN_VERIFICATION_FAILED = 41;
+  ERROR_IN_DB_SYNC = 42;
 }
 
 /**

hadoop-hdds/container-service/src/main/java/org/apache/hadoop/ozone/container/keyvalue/KeyValueContainer.java

@@ -68,6 +68,8 @@
     .Result.DISK_OUT_OF_SPACE;
 import static org.apache.hadoop.hdds.protocol.datanode.proto.ContainerProtos
     .Result.ERROR_IN_COMPACT_DB;
+import static org.apache.hadoop.hdds.protocol.datanode.proto.ContainerProtos
+    .Result.ERROR_IN_DB_SYNC;
 import static org.apache.hadoop.hdds.protocol.datanode.proto.ContainerProtos
     .Result.INVALID_CONTAINER_STATE;
 import static org.apache.hadoop.hdds.protocol.datanode.proto.ContainerProtos
@@ -298,8 +300,14 @@ public void markContainerUnhealthy() throws StorageContainerException {
 
   @Override
   public void quasiClose() throws StorageContainerException {
+    // The DB must be synced during close operation
+    flushAndSyncDB();
+
     writeLock();
     try {
+      // Second sync should be a very light operation as sync has already
+      // been done outside the lock.
+      flushAndSyncDB();
       updateContainerData(containerData::quasiCloseContainer);
     } finally {
       writeUnlock();
@@ -308,16 +316,18 @@ public void quasiClose() throws StorageContainerException {
 
   @Override
   public void close() throws StorageContainerException {
+    // The DB must be synced during close operation
+    flushAndSyncDB();
+
     writeLock();
     try {
+      // Second sync should be a very light operation as sync has already
+      // been done outside the lock.
+      flushAndSyncDB();
       updateContainerData(containerData::closeContainer);
     } finally {
       writeUnlock();
     }
-
-    // It is ok if this operation takes a bit of time.
-    // Close container is not expected to be instantaneous.
-    compactDB();
   }
 
   /**
@@ -365,6 +375,22 @@ void compactDB() throws StorageContainerException {
     }
   }
 
+  private void flushAndSyncDB() throws StorageContainerException {
+    try {
+      try (ReferenceCountedDB db = BlockUtils.getDB(containerData, config)) {
+        db.getStore().flushDB(true);
+        LOG.info("Container {} is synced with bcsId {}.",
+            containerData.getContainerID(),
+            containerData.getBlockCommitSequenceId());
+      }
+    } catch (StorageContainerException ex) {
+      throw ex;
+    } catch (IOException ex) {
+      LOG.error("Error in DB sync while closing container", ex);
+      throw new StorageContainerException(ex, ERROR_IN_DB_SYNC);
+    }
+  }
+
   @Override
   public KeyValueContainerData getContainerData()  {
     return containerData;

hadoop-hdds/container-service/src/test/java/org/apache/hadoop/ozone/container/keyvalue/TestKeyValueContainerMarkUnhealthy.java

@@ -155,6 +155,9 @@ public void testMarkClosedContainerAsUnhealthy() throws IOException {
    */
   @Test
   public void testMarkQuasiClosedContainerAsUnhealthy() throws IOException {
+    // We need to create the container so the sync-on-quasi-close operation
+    // does not NPE.
+    keyValueContainer.create(volumeSet, volumeChoosingPolicy, scmId);
     keyValueContainer.quasiClose();
     keyValueContainer.markContainerUnhealthy();
     assertThat(keyValueContainerData.getState(), is(UNHEALTHY));