content: /*
   * 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.
   */
  package org.apache.distributedlog;
  
  import com.google.common.annotations.VisibleForTesting;
  import io.netty.buffer.ByteBuf;
  import io.netty.util.ReferenceCountUtil;
  import java.io.IOException;
  import javax.annotation.concurrent.NotThreadSafe;
  import org.apache.bookkeeper.stats.StatsLogger;
  
  /**
   * Record reader to read records from an enveloped entry buffer.
   */
  @NotThreadSafe
  class EnvelopedEntryReader implements Entry.Reader, RecordStream {
  
      private final long logSegmentSeqNo;
      private final long entryId;
      private final ByteBuf src;
      private final LogRecord.Reader reader;
  
      // slot id
      private long slotId = 0;
      // error lag
      private IOException lastException = null;
      private boolean isExhausted = false;
  
      EnvelopedEntryReader(long logSegmentSeqNo,
                           long entryId,
                           long startSequenceId,
                           ByteBuf in,
                           boolean envelopedEntry,
                           boolean deserializeRecordSet,
                           StatsLogger statsLogger)
              throws IOException {
          this.logSegmentSeqNo = logSegmentSeqNo;
          this.entryId = entryId;
          if (envelopedEntry) {
              this.src = EnvelopedEntry.fromEnvelopedBuf(in, statsLogger);
          } else {
              this.src = in;
          }
          this.reader = new LogRecord.Reader(
                  this,
                  src,
                  startSequenceId,
                  deserializeRecordSet);
      }
  
      @VisibleForTesting
      boolean isExhausted() {
          return isExhausted;
      }
  
      @VisibleForTesting
      ByteBuf getSrcBuf() {
          return src;
      }
  
      private void checkLastException() throws IOException {
          if (null != lastException) {
              throw lastException;
          }
      }
  
      private void releaseBuffer() {
          isExhausted = true;
          ReferenceCountUtil.release(this.src);
      }
  
      @Override
      public long getLSSN() {
          return logSegmentSeqNo;
      }
  
      @Override
      public long getEntryId() {
          return entryId;
      }
  
      @Override
      public LogRecordWithDLSN nextRecord() throws IOException {
          checkLastException();
  
          if (isExhausted) {
              return null;
          }
  
          LogRecordWithDLSN record;
          try {
              record = reader.readOp();
          } catch (IOException ioe) {
              lastException = ioe;
              releaseBuffer();
              throw ioe;
          }
          if (null == record) {
              releaseBuffer();
          }
          return record;
      }
  
      public void release() {
          if (isExhausted) {
              return;
          }
          releaseBuffer();
      }
  
      @Override
      public boolean skipTo(long txId) throws IOException {
          checkLastException();
  
          return reader.skipTo(txId, true);
      }
  
      @Override
      public boolean skipTo(DLSN dlsn) throws IOException {
          checkLastException();
  
          return reader.skipTo(dlsn);
      }
  
      //
      // Record Stream
      //
  
      @Override
      public void advance(int numRecords) {
          slotId += numRecords;
      }
  
      @Override
      public DLSN getCurrentPosition() {
          return new DLSN(logSegmentSeqNo, entryId, slotId);
      }
  
      @Override
      public String getName() {
          return "EnvelopedReader";
      }
  
  }
  