Begin an async connection to a MySQL instance

public static function connect(
  string $host,
  int $port,
  string $dbname,
  string $user,
  string $password,
  int $timeout_micros = -1,
  ?MySSLContextProvider $ssl_provider = NULL,
  int $tcp_timeout_micros = 0,
  string $sni_server_name = '',
  string $server_cert_extensions = '',
  string $server_cert_values = '',
): Awaitable<AsyncMysqlConnection>;

Use this to asynchronously connect to a MySQL instance.

Normally you would use this to make one asynchronous connection to the MySQL client.

If you want to be able to pool up a bunch of connections, you would call setPoolsConnectionLimit(), create a default pool of connections with AsyncMysqlConnectionPool()::__construct(), which now has that limit set, and then call AsyncMysqlConnectionPool()::connect().


  • string $host - The hostname to connect to.
  • int $port - The port to connect to.
  • string $dbname - The initial database to use when connecting.
  • string $user - The user to connect as.
  • string $password - The password to connect with.
  • int $timeout_micros = -1 - Timeout, in microseconds, for the connect; -1 for default, 0 for no timeout.
  • ?MySSLContextProvider $ssl_provider = NULL
  • int $tcp_timeout_micros = 0 - Timeout, in microseconds, for the tcp phase of connect operation; Default: 0 for no timeout.
  • string $sni_server_name = '' - SNI hostname to use when connecting via SSL.
  • string $server_cert_extensions = '' - collection of name of TLS cert extension names used to validate server cert
  • string $server_cert_values = '' - collection of accepted values in server cert for "server_cert_extension" extension



The following example shows how to use AsyncMysqlClient::connect() to connect to a database asynchronously and get a result from that connection. Notice a couple of things:

  • The parameters to connect() are very similar to that of a normal mysqli connection.
  • With AsyncMysqlClient, we are able to take full advantage of async to perform other DB connection or I/O operations while waiting for this connection to return.
use \Hack\UserDocumentation\API\Examples\AsyncMysql\ConnectionInfo as CI;

async function do_connect(): Awaitable<\AsyncMysqlQueryResult> {
  // Cast because the array from get_connection_info() is a mixed
  $conn = await \AsyncMysqlClient::connect(
  return await $conn->query('SELECT * FROM test_table');

async function run_it(): Awaitable<void> {
  $res = await do_connect();
  \var_dump($res->numRows()); // The number of rows from the SELECT statement
await \Hack\UserDocumentation\API\Examples\AsyncMysql\skipif_async();