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 com.datastax.oss.driver.internal.core.session;
  
  import com.datastax.oss.driver.api.core.session.Request;
  import com.datastax.oss.driver.api.core.type.reflect.GenericType;
  import com.datastax.oss.driver.shaded.guava.common.collect.ImmutableList;
  import net.jcip.annotations.ThreadSafe;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  @ThreadSafe
  public class RequestProcessorRegistry {
  
    private static final Logger LOG = LoggerFactory.getLogger(RequestProcessorRegistry.class);
  
    private final String logPrefix;
    // Effectively immutable: the contents are never modified after construction
    private final RequestProcessor<?, ?>[] processors;
  
    public RequestProcessorRegistry(String logPrefix, RequestProcessor<?, ?>... processors) {
      this.logPrefix = logPrefix;
      this.processors = processors;
    }
  
    public <RequestT extends Request, ResultT> RequestProcessor<RequestT, ResultT> processorFor(
        RequestT request, GenericType<ResultT> resultType) {
  
      for (RequestProcessor<?, ?> processor : processors) {
        if (processor.canProcess(request, resultType)) {
          LOG.trace("[{}] Using {} to process {}", logPrefix, processor, request);
          // The cast is safe provided that the processor implements canProcess correctly
          @SuppressWarnings("unchecked")
          RequestProcessor<RequestT, ResultT> result =
              (RequestProcessor<RequestT, ResultT>) processor;
          return result;
        } else {
          LOG.trace("[{}] {} cannot process {}, trying next", logPrefix, processor, request);
        }
      }
      throw new IllegalArgumentException("No request processor found for " + request);
    }
  
    /** This creates a defensive copy on every call, do not overuse. */
    public Iterable<RequestProcessor<?, ?>> getProcessors() {
      return ImmutableList.copyOf(processors);
    }
  }
  