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.
   *
   */
  
  #include <limits.h>
  
  #include <grpc/census.h>
  
  #include "src/core/ext/census/grpc_filter.h"
  #include "src/core/lib/channel/channel_stack_builder.h"
  #include "src/core/lib/surface/channel_init.h"
  
  static bool maybe_add_census_filter(grpc_channel_stack_builder *builder,
                                      void *arg_must_be_null) {
    const grpc_channel_args *args =
        grpc_channel_stack_builder_get_channel_arguments(builder);
    if (grpc_channel_args_is_census_enabled(args)) {
      return grpc_channel_stack_builder_prepend_filter(
          builder, &grpc_client_census_filter, NULL, NULL);
    }
    return true;
  }
  
  void census_grpc_plugin_init(void) {
    /* Only initialize census if no one else has and some features are
     * available. */
    if (census_enabled() == CENSUS_FEATURE_NONE &&
        census_supported() != CENSUS_FEATURE_NONE) {
      if (census_initialize(census_supported())) { /* enable all features. */
        gpr_log(GPR_ERROR, "Could not initialize census.");
      }
    }
    grpc_channel_init_register_stage(GRPC_CLIENT_CHANNEL, INT_MAX,
                                     maybe_add_census_filter, NULL);
    grpc_channel_init_register_stage(GRPC_SERVER_CHANNEL, INT_MAX,
                                     maybe_add_census_filter, NULL);
  }
  
  void census_grpc_plugin_shutdown(void) { census_shutdown(); }
  