text: #include <mongoc.h>
  #include <stdio.h>
  #include <stdlib.h>
  
  static bool gExpectingFailure;
  static bool gShutdown;
  
  static void
  query_collection (mongoc_collection_t *col)
  {
     mongoc_cursor_t *cursor;
     const bson_t *doc;
     bson_error_t error;
     bson_t q;
  
     mongoc_init ();
  
     bson_init(&q);
     bson_append_utf8(&q, "hello", -1, "world", -1);
  
     cursor = mongoc_collection_find(col,
                                     MONGOC_QUERY_NONE,
                                     0,
                                     0,
                                     0,
                                     &q,
                                     NULL,
                                     NULL);
  
     while (mongoc_cursor_next(cursor, &doc)) {
        char *str;
  
        str = bson_as_json(doc, NULL);
        fprintf(stderr, "%s\n", str);
        bson_free(str);
     }
  
     if (mongoc_cursor_error(cursor, &error)) {
        if (gExpectingFailure) {
           if ((error.domain != MONGOC_ERROR_STREAM) ||
               (error.code != MONGOC_ERROR_STREAM_SOCKET)) {
              abort();
           }
           gExpectingFailure = false;
        } else {
           MONGOC_WARNING("%s", error.message);
           abort();
        }
     }
  
     bson_destroy(&q);
  }
  
  static void
  test_secondary (mongoc_client_t *client)
  {
     mongoc_collection_t *col;
  
     col = mongoc_client_get_collection(client, "test", "test");
  
     while (!gShutdown) {
        query_collection(col);
     }
  
     mongoc_collection_destroy(col);
  }
  
  int
  main (int   argc,
        char *argv[])
  {
     mongoc_read_prefs_t *read_prefs;
     mongoc_client_t *client;
     mongoc_uri_t *uri;
  
     if (argc < 2) {
        fprintf(stderr, "usage: %s mongodb://...\n", argv[0]);
        return EXIT_FAILURE;
     }
  
     uri = mongoc_uri_new(argv[1]);
     if (!uri) {
        fprintf(stderr, "Invalid URI: \"%s\"\n", argv[1]);
        return EXIT_FAILURE;
     }
  
     client = mongoc_client_new_from_uri(uri);
  
     read_prefs = mongoc_read_prefs_new(MONGOC_READ_SECONDARY);
     mongoc_client_set_read_prefs(client, read_prefs);
     mongoc_read_prefs_destroy(read_prefs);
  
     test_secondary(client);
  
     mongoc_client_destroy(client);
     mongoc_uri_destroy(uri);
  
     return EXIT_SUCCESS;
  }
  