text: /*
   *
   * Copyright 2015, Google Inc.
   * All rights reserved.
   *
   * Redistribution and use in source and binary forms, with or without
   * modification, are permitted provided that the following conditions are
   * met:
   *
   *     * Redistributions of source code must retain the above copyright
   * notice, this list of conditions and the following disclaimer.
   *     * Redistributions in binary form must reproduce the above
   * copyright notice, this list of conditions and the following disclaimer
   * in the documentation and/or other materials provided with the
   * distribution.
   *     * Neither the name of Google Inc. nor the names of its
   * contributors may be used to endorse or promote products derived from
   * this software without specific prior written permission.
   *
   * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
   * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
   * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
   * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
   * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
   * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
   * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
   * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
   * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
   * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
   * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
   *
   */
  
  #ifndef GRPC_INTERNAL_CORE_CLIENT_CONFIG_SUBCHANNEL_H
  #define GRPC_INTERNAL_CORE_CLIENT_CONFIG_SUBCHANNEL_H
  
  #include "src/core/channel/channel_stack.h"
  #include "src/core/client_config/connector.h"
  
  /** A (sub-)channel that knows how to connect to exactly one target
      address. Provides a target for load balancing. */
  typedef struct grpc_subchannel grpc_subchannel;
  typedef struct grpc_subchannel_call grpc_subchannel_call;
  typedef struct grpc_subchannel_args grpc_subchannel_args;
  
  #ifdef GRPC_SUBCHANNEL_REFCOUNT_DEBUG
  #define GRPC_SUBCHANNEL_REF(p, r) \
    grpc_subchannel_ref((p), __FILE__, __LINE__, (r))
  #define GRPC_SUBCHANNEL_UNREF(p, r) \
    grpc_subchannel_unref((p), __FILE__, __LINE__, (r))
  #define GRPC_SUBCHANNEL_CALL_REF(p, r) \
    grpc_subchannel_call_ref((p), __FILE__, __LINE__, (r))
  #define GRPC_SUBCHANNEL_CALL_UNREF(p, r) \
    grpc_subchannel_call_unref((p), __FILE__, __LINE__, (r))
  #define GRPC_SUBCHANNEL_REF_EXTRA_ARGS \
    , const char *file, int line, const char *reason
  #else
  #define GRPC_SUBCHANNEL_REF(p, r) grpc_subchannel_ref((p))
  #define GRPC_SUBCHANNEL_UNREF(p, r) grpc_subchannel_unref((p))
  #define GRPC_SUBCHANNEL_CALL_REF(p, r) grpc_subchannel_call_ref((p))
  #define GRPC_SUBCHANNEL_CALL_UNREF(p, r) grpc_subchannel_call_unref((p))
  #define GRPC_SUBCHANNEL_REF_EXTRA_ARGS
  #endif
  
  void grpc_subchannel_ref(
      grpc_subchannel *channel GRPC_SUBCHANNEL_REF_EXTRA_ARGS);
  void grpc_subchannel_unref(
      grpc_subchannel *channel GRPC_SUBCHANNEL_REF_EXTRA_ARGS);
  void grpc_subchannel_call_ref(
      grpc_subchannel_call *call GRPC_SUBCHANNEL_REF_EXTRA_ARGS);
  void grpc_subchannel_call_unref(
      grpc_subchannel_call *call GRPC_SUBCHANNEL_REF_EXTRA_ARGS);
  
  /** construct a call (possibly asynchronously) */
  void grpc_subchannel_create_call(grpc_subchannel *subchannel,
                                   grpc_pollset *pollset,
                                   grpc_subchannel_call **target,
                                   grpc_iomgr_closure *notify);
  
  /** process a transport level op */
  void grpc_subchannel_process_transport_op(grpc_subchannel *subchannel,
                                            grpc_transport_op *op);
  
  /** poll the current connectivity state of a channel */
  grpc_connectivity_state grpc_subchannel_check_connectivity(
      grpc_subchannel *channel);
  
  /** call notify when the connectivity state of a channel changes from *state.
      Updates *state with the new state of the channel */
  void grpc_subchannel_notify_on_state_change(grpc_subchannel *channel,
                                              grpc_connectivity_state *state,
                                              grpc_iomgr_closure *notify);
  
  void grpc_subchannel_add_interested_party(grpc_subchannel *channel,
                                            grpc_pollset *pollset);
  void grpc_subchannel_del_interested_party(grpc_subchannel *channel,
                                            grpc_pollset *pollset);
  
  /** continue processing a transport op */
  void grpc_subchannel_call_process_op(grpc_subchannel_call *subchannel_call,
                                       grpc_transport_stream_op *op);
  
  /** continue querying for peer */
  char *grpc_subchannel_call_get_peer(grpc_subchannel_call *subchannel_call);
  
  struct grpc_subchannel_args {
    /** Channel filters for this channel - wrapped factories will likely
        want to mutate this */
    const grpc_channel_filter **filters;
    /** The number of filters in the above array */
    size_t filter_count;
    /** Channel arguments to be supplied to the newly created channel */
    const grpc_channel_args *args;
    /** Address to connect to */
    struct sockaddr *addr;
    size_t addr_len;
    /** metadata context to use */
    grpc_mdctx *mdctx;
    /** master channel */
    grpc_channel *master;
  };
  
  /** create a subchannel given a connector */
  grpc_subchannel *grpc_subchannel_create(grpc_connector *connector,
                                          grpc_subchannel_args *args);
  
  #endif /* GRPC_INTERNAL_CORE_CLIENT_CONFIG_SUBCHANNEL_H */
  