HBASE-24625 AsyncFSWAL.getLogFileSizeIfBeingWritten does not return the expected synced file length. (#1970)

Signed-off-by: Duo Zhang <[email protected]>

Author: comnetwork

hbase-asyncfs/src/main/java/org/apache/hadoop/hbase/io/asyncfs/AsyncFSOutput.java

@@ -89,4 +89,9 @@ public interface AsyncFSOutput extends Closeable {
    */
   @Override
   void close() throws IOException;
+
+  /**
+   * @return byteSize success synced to underlying filesystem.
+   */
+  long getSyncedLength();
 }

hbase-asyncfs/src/main/java/org/apache/hadoop/hbase/io/asyncfs/FanOutOneBlockAsyncDFSOutput.java

@@ -575,4 +575,9 @@ public void close() throws IOException {
   public boolean isBroken() {
     return state == State.BROKEN;
   }
+
+  @Override
+  public long getSyncedLength() {
+    return this.ackedBlockLength;
+  }
 }

hbase-asyncfs/src/main/java/org/apache/hadoop/hbase/io/asyncfs/WrapperAsyncFSOutput.java

@@ -45,6 +45,8 @@ public class WrapperAsyncFSOutput implements AsyncFSOutput {
 
   private final ExecutorService executor;
 
+  private volatile long syncedLength = 0;
+
   public WrapperAsyncFSOutput(Path file, FSDataOutputStream out) {
     this.out = out;
     this.executor = Executors.newSingleThreadExecutor(new ThreadFactoryBuilder().setDaemon(true)
@@ -91,7 +93,11 @@ private void flush0(CompletableFuture<Long> future, ByteArrayOutputStream buffer
           out.hflush();
         }
       }
-      future.complete(out.getPos());
+      long pos = out.getPos();
+      if(pos > this.syncedLength) {
+        this.syncedLength = pos;
+      }
+      future.complete(pos);
     } catch (IOException e) {
       future.completeExceptionally(e);
       return;
@@ -124,4 +130,9 @@ public void close() throws IOException {
   public boolean isBroken() {
     return false;
   }
+
+  @Override
+  public long getSyncedLength() {
+    return this.syncedLength;
+  }
 }

hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/wal/AbstractFSWAL.java

@@ -1109,7 +1109,7 @@ public OptionalLong getLogFileSizeIfBeingWritten(Path path) {
       Path currentPath = getOldPath();
       if (path.equals(currentPath)) {
         W writer = this.writer;
-        return writer != null ? OptionalLong.of(writer.getLength()) : OptionalLong.empty();
+        return writer != null ? OptionalLong.of(writer.getSyncedLength()) : OptionalLong.empty();
       } else {
         return OptionalLong.empty();
       }

hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/wal/AsyncProtobufLogWriter.java

@@ -231,4 +231,9 @@ protected long writeWALTrailerAndMagic(WALTrailer trailer, byte[] magic) throws
   protected OutputStream getOutputStreamForCellEncoder() {
     return asyncOutputWrapper;
   }
+
+  @Override
+  public long getSyncedLength() {
+    return this.output.getSyncedLength();
+  }
 }

hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/wal/CombinedAsyncWriter.java

@@ -49,6 +49,11 @@ public long getLength() {
     return writers.get(0).getLength();
   }
 
+  @Override
+  public long getSyncedLength() {
+    return writers.get(0).getSyncedLength();
+  }
+
   @Override
   public void close() throws IOException {
     Exception error = null;

hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/wal/ProtobufLogWriter.java

@@ -19,11 +19,14 @@
 
 import java.io.IOException;
 import java.io.OutputStream;
+import java.util.concurrent.atomic.AtomicLong;
+
 import org.apache.hadoop.fs.FSDataOutputStream;
 import org.apache.hadoop.fs.FileSystem;
 import org.apache.hadoop.fs.Path;
 import org.apache.hadoop.fs.StreamCapabilities;
 import org.apache.hadoop.hbase.Cell;
+import org.apache.hadoop.hbase.util.AtomicUtils;
 import org.apache.hadoop.hbase.util.CommonFSUtils;
 import org.apache.hadoop.hbase.util.CommonFSUtils.StreamLacksCapabilityException;
 import org.apache.hadoop.hbase.wal.FSHLogProvider;
@@ -46,6 +49,8 @@ public class ProtobufLogWriter extends AbstractProtobufLogWriter
 
   protected FSDataOutputStream output;
 
+  private final AtomicLong syncedLength = new AtomicLong(0);
+
   @Override
   public void append(Entry entry) throws IOException {
     entry.getKey().getBuilder(compressor).
@@ -85,6 +90,12 @@ public void sync(boolean forceSync) throws IOException {
     } else {
       fsdos.hflush();
     }
+    AtomicUtils.updateMax(this.syncedLength, fsdos.getPos());
+  }
+
+  @Override
+  public long getSyncedLength() {
+    return this.syncedLength.get();
   }
 
   public FSDataOutputStream getStream() {

hbase-server/src/main/java/org/apache/hadoop/hbase/wal/WALProvider.java

@@ -25,6 +25,7 @@
 import java.util.concurrent.CompletableFuture;
 import org.apache.hadoop.conf.Configuration;
 import org.apache.hadoop.hbase.client.RegionInfo;
+import org.apache.hadoop.hbase.regionserver.wal.AsyncFSWAL;
 import org.apache.hadoop.hbase.regionserver.wal.WALActionsListener;
 import org.apache.hadoop.hbase.replication.regionserver.WALFileLengthProvider;
 import org.apache.yetus.audience.InterfaceAudience;
@@ -74,6 +75,22 @@ public interface WALProvider {
 
   interface WriterBase extends Closeable {
     long getLength();
+    /**
+     * NOTE: We add this method for {@link WALFileLengthProvider} used for replication,
+     * considering the case if we use {@link AsyncFSWAL},we write to 3 DNs concurrently,
+     * according to the visibility guarantee of HDFS, the data will be available immediately
+     * when arriving at DN since all the DNs will be considered as the last one in pipeline.
+     * This means replication may read uncommitted data and replicate it to the remote cluster
+     * and cause data inconsistency.
+     * The method {@link WriterBase#getLength} may return length which just in hdfs client
+     * buffer and not successfully synced to HDFS, so we use this method to return the length
+     * successfully synced to HDFS and replication thread could only read writing WAL file
+     * limited by this length.
+     * see also HBASE-14004 and this document for more details:
+     * https://docs.google.com/document/d/11AyWtGhItQs6vsLRIx32PwTxmBY3libXwGXI25obVEY/edit#
+     * @return byteSize successfully synced to underlying filesystem.
+     */
+    long getSyncedLength();
   }
 
   // Writers are used internally. Users outside of the WAL should be relying on the

hbase-server/src/test/java/org/apache/hadoop/hbase/regionserver/TestFailedAppendAndSync.java

@@ -151,6 +151,11 @@ public void append(Entry entry) throws IOException {
         public long getLength() {
           return w.getLength();
         }
+
+        @Override
+        public long getSyncedLength() {
+          return w.getSyncedLength();
+        }
       };
     }
   }

hbase-server/src/test/java/org/apache/hadoop/hbase/regionserver/TestHRegion.java

@@ -1246,6 +1246,11 @@ public void append(Entry entry) throws IOException {
           public long getLength() {
             return w.getLength();
           }
+
+          @Override
+          public long getSyncedLength() {
+            return w.getSyncedLength();
+          }
         };
       }
     }