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.cassandra.service.snapshot;
  
  import java.util.ArrayList;
  import java.util.List;
  import java.util.concurrent.Callable;
  import java.util.function.Predicate;
  
  public class GetSnapshotsTask implements Callable<List<TableSnapshot>>
  {
      private final SnapshotManager snapshotManager;
      private final Predicate<TableSnapshot> predicate;
      private final boolean shouldRemoveIfNotExists;
  
      public GetSnapshotsTask(SnapshotManager snapshotManager,
                              Predicate<TableSnapshot> predicate,
                              boolean shouldRemoveIfNotExists)
      {
          this.snapshotManager = snapshotManager;
          this.predicate = predicate;
          this.shouldRemoveIfNotExists = shouldRemoveIfNotExists;
      }
  
      @Override
      public List<TableSnapshot> call()
      {
          if (shouldRemoveIfNotExists)
              return getWithRemoval();
          else
              return getWithoutRemoval();
      }
  
      private List<TableSnapshot> getWithRemoval()
      {
          List<TableSnapshot> notExistingAnymore = new ArrayList<>();
          List<TableSnapshot> snapshots = new ArrayList<>();
          for (TableSnapshot snapshot : snapshotManager.getSnapshots())
          {
              if (snapshot.isCompleted() && predicate.test(snapshot))
              {
                  if (!snapshot.hasManifest())
                      notExistingAnymore.add(snapshot);
                  else
                      snapshots.add(snapshot);
              }
          }
  
          // we do not want to clear snapshots which do not exist periodically
          // because that would beat the purpose of caching (we would need to go to the disk
          // to see if manifests still exists every time), hence, we will clean on listing,
          // we do not need to have cache clean of non-existing snapshots when nobody is looking
          if (!notExistingAnymore.isEmpty())
          {
              snapshotManager.getSnapshots().removeAll(notExistingAnymore);
          }
  
          return snapshots;
      }
  
      private List<TableSnapshot> getWithoutRemoval()
      {
          List<TableSnapshot> snapshots = new ArrayList<>();
          for (TableSnapshot snapshot : snapshotManager.getSnapshots())
          {
              if (snapshot.isCompleted() && predicate.test(snapshot))
              {
                  if (snapshot.hasManifest())
                      snapshots.add(snapshot);
              }
          }
  
          return snapshots;
      }
  
      @Override
      public String toString()
      {
          return "GetSnapshotsTask{" +
                 "shouldRemoveIfNotExists=" + shouldRemoveIfNotExists +
                 '}';
      }
  }
  