int mysql_library_init(int argc, char **argv, char **groups)

Description

This function should be called to initialize the MySQL library before you call any other MySQL function. If your application uses the embedded server, this call starts the server and initializes any subsystems (mysys, InnoDB, and so forth) that the server uses.

In a non-multi-threaded environment, the call to mysql_library_init() may be omitted, because mysql_init() will invoke it automatically as necessary. However, mysql_library_init() is not thread-safe in a multi-threaded environment, and thus neither is mysql_init(), which calls mysql_library_init(). You must either call mysql_library_init() prior to spawning any threads, or else use a mutex to protect the call, whether you invoke mysql_library_init() or indirectly via mysql_init(). This should be done prior to any other client library call.

After your application is done using the MySQL library, call mysql_library_end() to clean up. See Section 26.2.3.39, “mysql_library_end()”.

The argc and argv arguments are analogous to the arguments to main(). The first element of argv is ignored (it typically contains the program name). For convenience, argc may be 0 (zero) if there are no command-line arguments for the server. mysql_library_init() makes a copy of the arguments so it is safe to destroy argv or groups after the call.

If you want to connect to an external server without starting the embedded server, you have to specify a negative value for argc.

The groups argument should be an array of strings that indicate the groups in option files from which options should be read. See Section 4.2.3.2, “Using Option Files”. The final entry in the array should be NULL. For convenience, if the groups argument itself is NULL, the [server] and [embedded] groups are used by default.

See Section 26.2.2, “C API Function Overview”, for additional usage information.

mysql_library_init() was added in MySQL 5.0.3. For older versions of MySQL, call mysql_server_init() instead.

Example

#include <mysql.h>
#include <stdlib.h>

static char *server_args[] = {
  "this_program",       /* this string is not used */
  "--datadir=.",
  "--key_buffer_size=32M"
};
static char *server_groups[] = {
  "embedded",
  "server",
  "this_program_SERVER",
  (char *)NULL
};

int main(void) {
  if (mysql_library_init(sizeof(server_args) / sizeof(char *),
                        server_args, server_groups)) {
    fprintf(stderr, "could not initialize MySQL library\n");
    exit(1);
  }

  /* Use any MySQL API functions here */

  mysql_library_end();

  return EXIT_SUCCESS;
}

Return Values

Zero if successful. Non-zero if an error occurred.