일반적인 작업

/* Don't try to compile this file on its own. It's meant to be #included
   by example code */
/* Insert some sample data */
// start-common-insert
bool
insert_data (mongoc_collection_t *collection)
{
   mongoc_bulk_operation_t *bulk;
   enum N { ndocs = 4 };
   bson_t *docs[ndocs];
   bson_error_t error;
   int i = 0;
   bool ret;
   bulk = mongoc_collection_create_bulk_operation_with_opts (collection, NULL);
   docs[0] = BCON_NEW ("x", BCON_DOUBLE (1.0), "tags", "[", "dog", "cat", "]");
   docs[1] = BCON_NEW ("x", BCON_DOUBLE (2.0), "tags", "[", "cat", "]");
   docs[2] = BCON_NEW ("x", BCON_DOUBLE (2.0), "tags", "[", "mouse", "cat", "dog", "]");
   docs[3] = BCON_NEW ("x", BCON_DOUBLE (3.0), "tags", "[", "]");
   for (i = 0; i < ndocs; i++) {
      mongoc_bulk_operation_insert (bulk, docs[i]);
      bson_destroy (docs[i]);
      docs[i] = NULL;
   }
   ret = mongoc_bulk_operation_execute (bulk, NULL, &error);
   if (!ret) {
      fprintf (stderr, "Error inserting data: %s\n", error.message);
   }
   mongoc_bulk_operation_destroy (bulk);
   return ret;
}
/* A helper which we'll use a lot later on */
void
print_res (const bson_t *reply)
{
   char *str;
   BSON_ASSERT (reply);
   str = bson_as_canonical_extended_json (reply, NULL);
   printf ("%s\n", str);
   bson_free (str);
}
// end-common-insert

bool
explain (mongoc_collection_t *collection)
{
   bson_t *command;
   bson_t reply;
   bson_error_t error;
   bool res;
   command =
      BCON_NEW ("explain", "{", "find", BCON_UTF8 (COLLECTION_NAME), "filter", "{", "x", BCON_INT32 (1), "}", "}");
   res = mongoc_collection_command_simple (collection, command, NULL, &reply, &error);
   if (!res) {
      fprintf (stderr, "Error with explain: %s\n", error.message);
      goto cleanup;
   }
   /* Do something with the reply */
   print_res (&reply);
cleanup:
   bson_destroy (&reply);
   bson_destroy (command);
   return res;
}

/*
 * Copyright 2009-present MongoDB, Inc.
 *
 * 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.
 */
#include <mongoc/mongoc.h>
#include <stdio.h>
const char *COLLECTION_NAME = "things";
#include "../doc-common-insert.c"
#include "explain.c"
int
main (int argc, char *argv[])
{
   mongoc_database_t *database = NULL;
   mongoc_client_t *client = NULL;
   mongoc_collection_t *collection = NULL;
   mongoc_uri_t *uri = NULL;
   bson_error_t error;
   char *host_and_port;
   int res = 0;
   if (argc < 2 || argc > 3) {
      fprintf (stderr,
               "usage: %s MONGOD-1-CONNECTION-STRING "
               "[MONGOD-2-HOST-NAME:MONGOD-2-PORT]\n",
               argv[0]);
      fprintf (stderr,
               "MONGOD-1-CONNECTION-STRING can be "
               "of the following forms:\n");
      fprintf (stderr, "localhost\t\t\t\tlocal machine\n");
      fprintf (stderr, "localhost:27018\t\t\t\tlocal machine on port 27018\n");
      fprintf (stderr,
               "mongodb://user:pass@localhost:27017\t"
               "local machine on port 27017, and authenticate with username "
               "user and password pass\n");
      return EXIT_FAILURE;
   }
   mongoc_init ();
   if (strncmp (argv[1], "mongodb://", 10) == 0) {
      host_and_port = bson_strdup (argv[1]);
   } else {
      host_and_port = bson_strdup_printf ("mongodb://%s", argv[1]);
   }
   uri = mongoc_uri_new_with_error (host_and_port, &error);
   if (!uri) {
      fprintf (stderr,
               "failed to parse URI: %s\n"
               "error message:       %s\n",
               host_and_port,
               error.message);
      res = EXIT_FAILURE;
      goto cleanup;
   }
   client = mongoc_client_new_from_uri (uri);
   if (!client) {
      res = EXIT_FAILURE;
      goto cleanup;
   }
   mongoc_client_set_error_api (client, 2);
   database = mongoc_client_get_database (client, "test");
   collection = mongoc_database_get_collection (database, COLLECTION_NAME);
   printf ("Inserting data\n");
   if (!insert_data (collection)) {
      res = EXIT_FAILURE;
      goto cleanup;
   }
   printf ("explain\n");
   if (!explain (collection)) {
      res = EXIT_FAILURE;
      goto cleanup;
   }
cleanup:
   if (collection) {
      mongoc_collection_destroy (collection);
   }
   if (database) {
      mongoc_database_destroy (database);
   }
   if (client) {
      mongoc_client_destroy (client);
   }
   if (uri) {
      mongoc_uri_destroy (uri);
   }
   bson_free (host_and_port);
   mongoc_cleanup ();
   return res;
}