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.server.http.service;
  
  import static com.google.common.base.Preconditions.checkNotNull;
  import static java.nio.charset.StandardCharsets.UTF_8;
  
  import com.google.common.collect.Maps;
  import java.util.LinkedHashMap;
  import java.util.Map;
  import java.util.concurrent.CompletableFuture;
  import org.apache.bookkeeper.client.api.LedgerMetadata;
  import org.apache.bookkeeper.common.util.JsonUtil;
  import org.apache.bookkeeper.conf.ServerConfiguration;
  import org.apache.bookkeeper.http.HttpServer;
  import org.apache.bookkeeper.http.service.HttpEndpointService;
  import org.apache.bookkeeper.http.service.HttpServiceRequest;
  import org.apache.bookkeeper.http.service.HttpServiceResponse;
  import org.apache.bookkeeper.meta.LedgerManager;
  import org.apache.bookkeeper.meta.LedgerManagerFactory;
  import org.apache.bookkeeper.meta.LedgerMetadataSerDe;
  import org.apache.bookkeeper.versioning.Versioned;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  /**
   * HttpEndpointService that handle Bookkeeper list ledger related http request.
   *
   * <p>The GET method will list all ledger_ids in this bookkeeper cluster.
   * User can choose print metadata of each ledger or not by set parameter "print_metadata"
   */
  public class ListLedgerService implements HttpEndpointService {
  
      static final Logger LOG = LoggerFactory.getLogger(ListLedgerService.class);
  
      protected ServerConfiguration conf;
      protected LedgerManagerFactory ledgerManagerFactory;
      private final LedgerMetadataSerDe serDe;
  
      public ListLedgerService(ServerConfiguration conf, LedgerManagerFactory ledgerManagerFactory) {
          checkNotNull(conf);
          this.conf = conf;
          this.ledgerManagerFactory = ledgerManagerFactory;
          this.serDe = new LedgerMetadataSerDe();
  
      }
  
      // Number of LedgerMetadata contains in each page
      static final int LIST_LEDGER_BATCH_SIZE = 100;
  
      private void keepLedgerMetadata(long ledgerId, CompletableFuture<Versioned<LedgerMetadata>> future,
                                      LinkedHashMap<String, Object> output, boolean decodeMeta)
              throws Exception {
          LedgerMetadata md = future.get().getValue();
          if (decodeMeta) {
              output.put(Long.valueOf(ledgerId).toString(), md);
          } else {
              output.put(Long.valueOf(ledgerId).toString(), new String(serDe.serialize(md), UTF_8));
          }
      }
  
      @Override
      public HttpServiceResponse handle(HttpServiceRequest request) throws Exception {
          HttpServiceResponse response = new HttpServiceResponse();
          // GET
          // parameter could be like: print_metadata=true&page=PageIndex
          if (HttpServer.Method.GET == request.getMethod()) {
              Map<String, String> params = request.getParams();
              // default not print metadata
              boolean printMeta = (params != null)
                && params.containsKey("print_metadata")
                && params.get("print_metadata").equals("true");
  
              // do not decode meta by default for backward compatibility
              boolean decodeMeta = (params != null)
                      && params.getOrDefault("decode_meta", "false").equals("true");
  
              // Page index should start from 1;
              int pageIndex = (printMeta && params.containsKey("page"))
                  ? Integer.parseInt(params.get("page")) : -1;
  
              LedgerManager manager = ledgerManagerFactory.newLedgerManager();
              LedgerManager.LedgerRangeIterator iter = manager.getLedgerRanges(0);
  
              // output <ledgerId: ledgerMetadata>
              LinkedHashMap<String, Object> output = Maps.newLinkedHashMap();
              // futures for readLedgerMetadata for each page.
              Map<Long, CompletableFuture<Versioned<LedgerMetadata>>> futures =
                  new LinkedHashMap<>(LIST_LEDGER_BATCH_SIZE);
  
              if (printMeta) {
                  int ledgerIndex = 0;
  
                  // start and end ledger index for wanted page.
                  int startLedgerIndex = 0;
                  int endLedgerIndex = 0;
                  if (pageIndex > 0) {
                      startLedgerIndex = (pageIndex - 1) * LIST_LEDGER_BATCH_SIZE;
                      endLedgerIndex = startLedgerIndex + LIST_LEDGER_BATCH_SIZE - 1;
                  }
  
                  // get metadata
                  while (iter.hasNext()) {
                      LedgerManager.LedgerRange r = iter.next();
                      for (Long lid : r.getLedgers()) {
                          ledgerIndex++;
                          if (endLedgerIndex == 0       // no actual page parameter provided
                                  || (ledgerIndex >= startLedgerIndex && ledgerIndex <= endLedgerIndex)) {
                              futures.put(lid, manager.readLedgerMetadata(lid));
                          }
                      }
                      if (futures.size() >= LIST_LEDGER_BATCH_SIZE) {
                          for (Map.Entry<Long, CompletableFuture<Versioned<LedgerMetadata>> > e : futures.entrySet()) {
                              keepLedgerMetadata(e.getKey(), e.getValue(), output, decodeMeta);
                          }
                          futures.clear();
                      }
                  }
                  for (Map.Entry<Long, CompletableFuture<Versioned<LedgerMetadata>> > e : futures.entrySet()) {
                      keepLedgerMetadata(e.getKey(), e.getValue(), output, decodeMeta);
                  }
                  futures.clear();
              } else {
                  while (iter.hasNext()) {
                      LedgerManager.LedgerRange r = iter.next();
                      for (Long lid : r.getLedgers()) {
                          output.put(lid.toString(), null);
                      }
                  }
              }
  
              manager.close();
  
              String jsonResponse = JsonUtil.toJson(output);
              if (LOG.isDebugEnabled()) {
                  LOG.debug("output body:" + jsonResponse);
              }
              response.setBody(jsonResponse);
              response.setCode(HttpServer.StatusCode.OK);
              return response;
          } else {
              response.setCode(HttpServer.StatusCode.NOT_FOUND);
              response.setBody("Not found method. Should be GET method");
              return response;
          }
      }
  }
  