text: /*
   *
   * Copyright 2018 gRPC authors.
   *
   * 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.
   *
   */
  
  #ifndef GRPC_CORE_EXT_FILTERS_CLIENT_CHANNEL_LOCAL_SUBCHANNEL_POOL_H
  #define GRPC_CORE_EXT_FILTERS_CLIENT_CHANNEL_LOCAL_SUBCHANNEL_POOL_H
  
  #include <grpc/support/port_platform.h>
  
  #include "src/core/ext/filters/client_channel/subchannel_pool_interface.h"
  
  namespace grpc_core {
  
  // The local subchannel pool that is owned by a single channel. It doesn't
  // support subchannel sharing with other channels by nature. Nor does it support
  // subchannel retention when a subchannel is not used. The only real purpose of
  // using this subchannel pool is to allow subchannel reuse within the channel
  // when an incoming resolver update contains some addresses for which the
  // channel has already created subchannels.
  // Thread-unsafe.
  class LocalSubchannelPool final : public SubchannelPoolInterface {
   public:
    LocalSubchannelPool();
    ~LocalSubchannelPool() override;
  
    // Implements interface methods.
    // Thread-unsafe. Intended to be invoked within the client_channel combiner.
    Subchannel* RegisterSubchannel(SubchannelKey* key,
                                   Subchannel* constructed) override;
    void UnregisterSubchannel(SubchannelKey* key) override;
    Subchannel* FindSubchannel(SubchannelKey* key) override;
  
   private:
    // The vtable for subchannel operations in an AVL tree.
    static const grpc_avl_vtable subchannel_avl_vtable_;
    // A map from subchannel key to subchannel.
    grpc_avl subchannel_map_;
  };
  
  }  // namespace grpc_core
  
  #endif /* GRPC_CORE_EXT_FILTERS_CLIENT_CHANNEL_LOCAL_SUBCHANNEL_POOL_H */
  