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.impl.logsegment;
  
  import com.google.common.collect.Lists;
  import java.io.IOException;
  import java.util.Enumeration;
  import java.util.List;
  import java.util.concurrent.CompletableFuture;
  import org.apache.bookkeeper.client.AsyncCallback.ReadCallback;
  import org.apache.bookkeeper.client.BKException;
  import org.apache.bookkeeper.client.LedgerEntry;
  import org.apache.bookkeeper.client.LedgerHandle;
  import org.apache.bookkeeper.common.concurrent.FutureUtils;
  import org.apache.distributedlog.DistributedLogConfiguration;
  import org.apache.distributedlog.Entry;
  import org.apache.distributedlog.LogSegmentMetadata;
  import org.apache.distributedlog.exceptions.BKTransmitException;
  import org.apache.distributedlog.logsegment.LogSegmentRandomAccessEntryReader;
  
  /**
   * BookKeeper ledger based random access entry reader.
   */
  class BKLogSegmentRandomAccessEntryReader implements
          LogSegmentRandomAccessEntryReader,
          ReadCallback {
  
      private final long lssn;
      private final long startSequenceId;
      private final boolean envelopeEntries;
      private final boolean deserializeRecordSet;
      // state
      private final LogSegmentMetadata metadata;
      private final LedgerHandle lh;
      private CompletableFuture<Void> closePromise = null;
  
      BKLogSegmentRandomAccessEntryReader(LogSegmentMetadata metadata,
                                          LedgerHandle lh,
                                          DistributedLogConfiguration conf) {
          this.metadata = metadata;
          this.lssn = metadata.getLogSegmentSequenceNumber();
          this.startSequenceId = metadata.getStartSequenceId();
          this.envelopeEntries = metadata.getEnvelopeEntries();
          this.deserializeRecordSet = conf.getDeserializeRecordSetOnReads();
          this.lh = lh;
      }
  
      @Override
      public long getLastAddConfirmed() {
          return lh.getLastAddConfirmed();
      }
  
      @Override
      public CompletableFuture<List<Entry.Reader>> readEntries(long startEntryId, long endEntryId) {
          CompletableFuture<List<Entry.Reader>> promise = new CompletableFuture<List<Entry.Reader>>();
          lh.asyncReadEntries(startEntryId, endEntryId, this, promise);
          return promise;
      }
  
      Entry.Reader processReadEntry(LedgerEntry entry) throws IOException {
          return Entry.newBuilder()
                  .setLogSegmentInfo(lssn, startSequenceId)
                  .setEntryId(entry.getEntryId())
                  .setEnvelopeEntry(envelopeEntries)
                  .deserializeRecordSet(deserializeRecordSet)
                  .setEntry(entry.getEntryBuffer())
                  .buildReader();
      }
  
      @SuppressWarnings("unchecked")
      @Override
      public void readComplete(int rc, LedgerHandle lh, Enumeration<LedgerEntry> entries, Object ctx) {
          CompletableFuture<List<Entry.Reader>> promise = (CompletableFuture<List<Entry.Reader>>) ctx;
          if (BKException.Code.OK == rc) {
              List<Entry.Reader> entryList = Lists.newArrayList();
              while (entries.hasMoreElements()) {
                  LedgerEntry entry = entries.nextElement();
                  try {
                      entryList.add(processReadEntry(entry));
                  } catch (IOException ioe) {
                      // release the buffers
                      while (entries.hasMoreElements()) {
                          LedgerEntry le = entries.nextElement();
                          le.getEntryBuffer().release();
                      }
                      FutureUtils.completeExceptionally(promise, ioe);
                      return;
                  } finally {
                      entry.getEntryBuffer().release();
                  }
              }
              FutureUtils.complete(promise, entryList);
          } else {
              FutureUtils.completeExceptionally(promise,
                      new BKTransmitException("Failed to read entries :", rc));
          }
      }
  
      @Override
      public CompletableFuture<Void> asyncClose() {
          final CompletableFuture<Void> closeFuture;
          synchronized (this) {
              if (null != closePromise) {
                  return closePromise;
              }
              closeFuture = closePromise = new CompletableFuture<Void>();
          }
          FutureUtils.proxyTo(
              BKUtils.closeLedgers(lh),
              closeFuture
          );
          return closeFuture;
      }
  }
  