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.metadata.etcd;
  
  import static org.apache.bookkeeper.metadata.etcd.EtcdUtils.ioResult;
  
  import io.etcd.jetcd.ByteSequence;
  import io.etcd.jetcd.Client;
  import io.etcd.jetcd.KV;
  import io.etcd.jetcd.kv.DeleteResponse;
  import io.etcd.jetcd.kv.GetResponse;
  import io.etcd.jetcd.kv.TxnResponse;
  import io.etcd.jetcd.op.Cmp;
  import io.etcd.jetcd.op.CmpTarget;
  import io.etcd.jetcd.options.GetOption;
  import io.etcd.jetcd.options.PutOption;
  import java.io.IOException;
  import java.nio.charset.StandardCharsets;
  import lombok.AccessLevel;
  import lombok.Getter;
  import lombok.extern.slf4j.Slf4j;
  import org.apache.bookkeeper.meta.LayoutManager;
  import org.apache.bookkeeper.meta.LedgerLayout;
  
  /**
   * Etcd based layout manager.
   */
  @Slf4j
  @Getter(AccessLevel.PACKAGE)
  class EtcdLayoutManager implements LayoutManager {
  
      private final Client client;
      private final KV kvClient;
      private final String scope;
      private final ByteSequence layoutKey;
  
      EtcdLayoutManager(Client client, String scope) {
          this.client = client;
          this.kvClient = client.getKVClient();
          this.scope = scope;
          this.layoutKey = ByteSequence.from(EtcdUtils.getLayoutKey(scope), StandardCharsets.UTF_8);
      }
  
      @Override
      public LedgerLayout readLedgerLayout() throws IOException {
          GetResponse response = ioResult(kvClient.get(layoutKey, GetOption.DEFAULT));
          if (response.getCount() <= 0) {
              return null;
          } else {
              byte[] layoutData = response.getKvs().get(0).getValue().getBytes();
              return LedgerLayout.parseLayout(layoutData);
          }
      }
  
      @Override
      public void storeLedgerLayout(LedgerLayout layout) throws IOException {
          ByteSequence layoutData = ByteSequence.from(layout.serialize());
          TxnResponse response = ioResult(kvClient.txn()
              .If(new Cmp(layoutKey, Cmp.Op.GREATER, CmpTarget.createRevision(0)))
              .Then(io.etcd.jetcd.op.Op.get(layoutKey, GetOption.DEFAULT))
              .Else(io.etcd.jetcd.op.Op.put(layoutKey, layoutData, PutOption.DEFAULT))
              .commit());
          // key doesn't exist and we created the key
          if (!response.isSucceeded()) {
              return;
          // key exists and we retrieved the key
          } else {
              GetResponse resp = response.getGetResponses().get(0);
              if (resp.getCount() <= 0) {
                  // fail to put key/value but key is not found
                  throw new IOException("Creating layout node '" + layoutKey.toString(StandardCharsets.UTF_8)
                      + "' failed due to it already exists but no layout node is found");
              } else {
                  throw new LedgerLayoutExistsException(
                      "Ledger layout already exists under '" + layoutKey.toString(StandardCharsets.UTF_8) + "'");
              }
          }
      }
  
      @Override
      public void deleteLedgerLayout() throws IOException {
          DeleteResponse response = ioResult(kvClient.delete(layoutKey));
          if (response.getDeleted() > 0) {
              if (log.isDebugEnabled()) {
                  log.debug("Successfully delete layout '{}'", layoutKey.toString(StandardCharsets.UTF_8));
              }
              return;
          } else {
              throw new IOException("No ledger layout is found under '" + layoutKey.toString(StandardCharsets.UTF_8)
                      + "'");
          }
      }
  }
  