/**
    * 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.hadoop.hbase.regionserver;
  
  import java.io.IOException;
  import java.util.ArrayList;
  import java.util.List;
  
  import org.apache.commons.logging.Log;
  import org.apache.commons.logging.LogFactory;
  import org.apache.hadoop.hbase.classification.InterfaceAudience;
  import org.apache.hadoop.conf.Configuration;
  import org.apache.hadoop.fs.Path;
  import org.apache.hadoop.hbase.HBaseInterfaceAudience;
  import org.apache.hadoop.hbase.KeyValue.KVComparator;
  import org.apache.hadoop.hbase.regionserver.compactions.CompactionContext;
  import org.apache.hadoop.hbase.regionserver.compactions.CompactionRequest;
  import org.apache.hadoop.hbase.regionserver.compactions.StripeCompactionPolicy;
  import org.apache.hadoop.hbase.regionserver.compactions.StripeCompactor;
  import org.apache.hadoop.hbase.regionserver.compactions.CompactionThroughputController;
  import org.apache.hadoop.hbase.security.User;
  
  import com.google.common.base.Preconditions;
  
  /**
   * The storage engine that implements the stripe-based store/compaction scheme.
   */
  @InterfaceAudience.LimitedPrivate(HBaseInterfaceAudience.CONFIG)
  public class StripeStoreEngine extends StoreEngine<StripeStoreFlusher,
    StripeCompactionPolicy, StripeCompactor, StripeStoreFileManager> {
    private static final Log LOG = LogFactory.getLog(StripeStoreEngine.class);
    private StripeStoreConfig config;
  
    @Override
    public boolean needsCompaction(List<StoreFile> filesCompacting) {
      return this.compactionPolicy.needsCompactions(this.storeFileManager, filesCompacting);
    }
  
    @Override
    public CompactionContext createCompaction() {
      return new StripeCompaction();
    }
  
    @Override
    protected void createComponents(
        Configuration conf, Store store, KVComparator comparator) throws IOException {
      this.config = new StripeStoreConfig(conf, store);
      this.compactionPolicy = new StripeCompactionPolicy(conf, store, config);
      this.storeFileManager = new StripeStoreFileManager(comparator, conf, this.config);
      this.storeFlusher = new StripeStoreFlusher(
        conf, store, this.compactionPolicy, this.storeFileManager);
      this.compactor = new StripeCompactor(conf, store);
    }
  
    /**
     * Represents one instance of stripe compaction, with the necessary context and flow.
     */
    private class StripeCompaction extends CompactionContext {
      private StripeCompactionPolicy.StripeCompactionRequest stripeRequest = null;
  
      @Override
      public List<StoreFile> preSelect(List<StoreFile> filesCompacting) {
        return compactionPolicy.preSelectFilesForCoprocessor(storeFileManager, filesCompacting);
      }
  
      @Override
      public boolean select(List<StoreFile> filesCompacting, boolean isUserCompaction,
          boolean mayUseOffPeak, boolean forceMajor) throws IOException {
        this.stripeRequest = compactionPolicy.selectCompaction(
            storeFileManager, filesCompacting, mayUseOffPeak);
        this.request = (this.stripeRequest == null)
            ? new CompactionRequest(new ArrayList<StoreFile>()) : this.stripeRequest.getRequest();
        return this.stripeRequest != null;
      }
  
      @Override
      public void forceSelect(CompactionRequest request) {
        super.forceSelect(request);
        if (this.stripeRequest != null) {
          this.stripeRequest.setRequest(this.request);
        } else {
          LOG.warn("Stripe store is forced to take an arbitrary file list and compact it.");
          this.stripeRequest = compactionPolicy.createEmptyRequest(storeFileManager, this.request);
        }
     }
 
     @Override
     public List<Path> compact(CompactionThroughputController throughputController)
         throws IOException {
       Preconditions.checkArgument(this.stripeRequest != null, "Cannot compact without selection");
       return this.stripeRequest.execute(compactor, throughputController, null);
     }
 
     @Override
     public List<Path> compact(CompactionThroughputController throughputController, User user)
         throws IOException {
       Preconditions.checkArgument(this.stripeRequest != null, "Cannot compact without selection");
       return this.stripeRequest.execute(compactor, throughputController, user);
     }
   }
 }