content: /*
   * Copyright 1999-2018 Alibaba Group Holding Ltd.
   *
   * Licensed 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 com.alibaba.csp.sentinel.slots;
  
  import com.alibaba.csp.sentinel.log.RecordLog;
  import com.alibaba.csp.sentinel.slotchain.AbstractLinkedProcessorSlot;
  import com.alibaba.csp.sentinel.slotchain.DefaultProcessorSlotChain;
  import com.alibaba.csp.sentinel.slotchain.ProcessorSlot;
  import com.alibaba.csp.sentinel.slotchain.ProcessorSlotChain;
  import com.alibaba.csp.sentinel.slotchain.SlotChainBuilder;
  import com.alibaba.csp.sentinel.spi.Spi;
  import com.alibaba.csp.sentinel.spi.SpiLoader;
  
  import java.util.List;
  
  /**
   * Builder for a default {@link ProcessorSlotChain}.
   *
   * @author qinan.qn
   * @author leyou
   */
  @Spi(isDefault = true)
  public class DefaultSlotChainBuilder implements SlotChainBuilder {
  
      @Override
      public ProcessorSlotChain build() {
          ProcessorSlotChain chain = new DefaultProcessorSlotChain();
  
          List<ProcessorSlot> sortedSlotList = SpiLoader.of(ProcessorSlot.class).loadInstanceListSorted();
          for (ProcessorSlot slot : sortedSlotList) {
              if (!(slot instanceof AbstractLinkedProcessorSlot)) {
                  RecordLog.warn("The ProcessorSlot(" + slot.getClass().getCanonicalName() + ") is not an instance of AbstractLinkedProcessorSlot, can't be added into ProcessorSlotChain");
                  continue;
              }
  
              chain.addLast((AbstractLinkedProcessorSlot<?>) slot);
          }
  
          return chain;
      }
  }
  