/*
    * 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.omid.tso;
  
  import com.google.inject.AbstractModule;
  import com.google.inject.Provides;
  import org.apache.commons.pool2.ObjectPool;
  import org.apache.commons.pool2.impl.GenericObjectPool;
  import org.apache.commons.pool2.impl.GenericObjectPoolConfig;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  import javax.inject.Singleton;
  import java.util.ArrayList;
  import java.util.List;
  
  public class BatchPoolModule extends AbstractModule {
  
      private static final Logger LOG = LoggerFactory.getLogger(BatchPoolModule.class);
  
      private final TSOServerConfig config;
  
      public BatchPoolModule(TSOServerConfig config) {
          this.config = config;
      }
  
      @Override
      protected void configure() {
      }
  
      @Provides
      @Singleton
      ObjectPool<Batch> getBatchPool() throws Exception {
  
          int poolSize = config.getNumConcurrentCTWriters();
          int batchSize = config.getBatchSizePerCTWriter();
  
          LOG.info("Pool Size (# of Batches) {}; Batch Size {}", poolSize, batchSize);
          LOG.info("Total Batch Size (Pool size * Batch Size): {}", poolSize * batchSize);
          // Setup ObjectPool behaviour
          GenericObjectPoolConfig config = new GenericObjectPoolConfig();
          config.setMaxTotal(poolSize);
          config.setMaxIdle(poolSize + 1); // This avoids GenericObjectPool to destroy the batches when returned to
                                           // the pool during the pre-creation below
          config.setBlockWhenExhausted(true);
          GenericObjectPool<Batch> batchPool = new GenericObjectPool<>(new Batch.BatchFactory(batchSize), config);
          LOG.info("Pre-creating objects in the pool...");
          // TODO There should be a better way to do the pre-creation below avoiding the two loops
          List<Batch> batches = new ArrayList<>(poolSize);
          for (int i = 0; i < poolSize; i++) {
              batches.add(batchPool.borrowObject());
          }
          for (Batch batch : batches) {
              batchPool.returnObject(batch);
          }
          return batchPool;
  
      }
  
  }