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.bookkeeper.client;
  
  import com.google.common.annotations.VisibleForTesting;
  import io.netty.buffer.ByteBuf;
  import java.util.List;
  import org.apache.bookkeeper.client.BKException.BKDigestMatchException;
  import org.apache.bookkeeper.net.BookieId;
  import org.apache.bookkeeper.proto.BookieClient;
  import org.apache.bookkeeper.proto.BookieProtocol;
  import org.apache.bookkeeper.proto.BookkeeperInternalCallbacks.ReadEntryCallback;
  import org.apache.bookkeeper.proto.checksum.DigestManager;
  import org.apache.bookkeeper.proto.checksum.DigestManager.RecoveryData;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  /**
   * This class encapsulated the read last confirmed operation.
   *
   */
  class ReadLastConfirmedOp implements ReadEntryCallback {
      static final Logger LOG = LoggerFactory.getLogger(ReadLastConfirmedOp.class);
      private final long ledgerId;
      private final byte[] ledgerKey;
      private final BookieClient bookieClient;
      private final DigestManager digestManager;
      private int numResponsesPending;
      private RecoveryData maxRecoveredData;
      private volatile boolean completed = false;
      private int lastSeenError = BKException.Code.ReadException;
  
      private final LastConfirmedDataCallback cb;
      private final DistributionSchedule.QuorumCoverageSet coverageSet;
      private final List<BookieId> currentEnsemble;
  
      /**
       * Wrapper to get all recovered data from the request.
       */
      interface LastConfirmedDataCallback {
          void readLastConfirmedDataComplete(int rc, RecoveryData data);
      }
  
      public ReadLastConfirmedOp(BookieClient bookieClient,
                                 DistributionSchedule schedule,
                                 DigestManager digestManager,
                                 long ledgerId,
                                 List<BookieId> ensemble,
                                 byte[] ledgerKey,
                                 LastConfirmedDataCallback cb) {
          this.cb = cb;
          this.bookieClient = bookieClient;
          this.maxRecoveredData = new RecoveryData(LedgerHandle.INVALID_ENTRY_ID, 0);
          this.numResponsesPending = ensemble.size();
          this.coverageSet = schedule.getCoverageSet();
          this.currentEnsemble = ensemble;
          this.ledgerId = ledgerId;
          this.ledgerKey = ledgerKey;
          this.digestManager = digestManager;
      }
  
      public void initiate() {
          for (int i = 0; i < currentEnsemble.size(); i++) {
              bookieClient.readEntry(currentEnsemble.get(i),
                                     ledgerId,
                                     BookieProtocol.LAST_ADD_CONFIRMED,
                                     this, i, BookieProtocol.FLAG_NONE);
          }
      }
  
      public void initiateWithFencing() {
          for (int i = 0; i < currentEnsemble.size(); i++) {
              bookieClient.readEntry(currentEnsemble.get(i),
                                     ledgerId,
                                     BookieProtocol.LAST_ADD_CONFIRMED,
                                     this, i, BookieProtocol.FLAG_DO_FENCING,
                                     ledgerKey);
          }
      }
  
      @Override
      public synchronized void readEntryComplete(final int rc, final long ledgerId, final long entryId,
              final ByteBuf buffer, final Object ctx) {
          int bookieIndex = (Integer) ctx;
  
          // add the response to coverage set
          coverageSet.addBookie(bookieIndex, rc);
  
          numResponsesPending--;
          boolean heardValidResponse = false;
          if (rc == BKException.Code.OK) {
              try {
                  RecoveryData recoveryData = digestManager.verifyDigestAndReturnLastConfirmed(buffer);
                  if (recoveryData.getLastAddConfirmed() > maxRecoveredData.getLastAddConfirmed()) {
                      maxRecoveredData = recoveryData;
                  }
                  heardValidResponse = true;
              } catch (BKDigestMatchException e) {
                  // Too bad, this bookie didn't give us a valid answer, we
                  // still might be able to recover though so continue
                  LOG.error("Mac mismatch for ledger: " + ledgerId + ", entry: " + entryId
                            + " while reading last entry from bookie: "
                            + currentEnsemble.get(bookieIndex));
              }
          }
  
          if (rc == BKException.Code.NoSuchLedgerExistsException || rc == BKException.Code.NoSuchEntryException) {
              // this still counts as a valid response, e.g., if the client crashed without writing any entry
              heardValidResponse = true;
          }
  
          if (rc == BKException.Code.UnauthorizedAccessException  && !completed) {
              cb.readLastConfirmedDataComplete(rc, maxRecoveredData);
              completed = true;
          }
  
          if (!heardValidResponse && BKException.Code.OK != rc) {
              lastSeenError = rc;
          }
  
          // other return codes dont count as valid responses
          if (heardValidResponse
              && coverageSet.checkCovered()
              && !completed) {
              completed = true;
              if (LOG.isDebugEnabled()) {
                  LOG.debug("Read Complete with enough validResponses for ledger: {}, entry: {}",
                          ledgerId, entryId);
              }
  
              cb.readLastConfirmedDataComplete(BKException.Code.OK, maxRecoveredData);
              return;
          }
  
          if (numResponsesPending == 0 && !completed) {
              LOG.error("While readLastConfirmed ledger: {} did not hear success responses from all quorums, {}",
                        ledgerId, coverageSet);
              cb.readLastConfirmedDataComplete(lastSeenError, maxRecoveredData);
          }
  
      }
  
      @VisibleForTesting
      synchronized int getNumResponsesPending() {
          return numResponsesPending;
      }
  }
  