mysqli::ping
mysqli_ping
(PHP 5, PHP 7, PHP 8)
mysqli::ping -- mysqli_ping — ping 一个连接，或者如果连接处于断开状态，重新连接
说明
面向对象风格
mysqli::ping(): bool
过程化风格
检查到服务器的连接是否还正常。 在启用 mysqli.reconnect 选项的前提下， 如果连接已经断开， ping 操作会尝试重新建立连接。
注意: mysqlnd 驱动会忽略 php.ini 中的 mysqli.reconnect 选项， 所以它不会自动重连。
客户端建立连接之后，长时间处于闲置状态， 可以用此函数来检查服务器是否关闭了这个连接， 如有必要，将会自动重新建立到服务器的连接。
返回值
成功时返回 true， 或者在失败时返回 false。
范例
示例 #1 mysqli::ping() 例程
面向对象风格
<?php
$mysqli = new mysqli("localhost", "my_user", "my_password", "world");
/* 检查连接 */
if ($mysqli->connect_errno) {
printf("Connect failed: %s\n", $mysqli->connect_error);
exit();
}
/* 检查连接是否还活跃 */
if ($mysqli->ping()) {
printf ("Our connection is ok!\n");
} else {
printf ("Error: %s\n", $mysqli->error);
}
/* 关闭连接 */
$mysqli->close();
?>
过程化风格
<?php
$link = mysqli_connect("localhost", "my_user", "my_password", "world");
/* 检查连接 */
if (mysqli_connect_errno()) {
printf("Connect failed: %s\n", mysqli_connect_error());
exit();
}
/* 检查连接是否还活跃 */
if (mysqli_ping($link)) {
printf ("Our connection is ok!\n");
} else {
printf ("Error: %s\n", mysqli_error($link));
}
/* 关闭连接 */
mysqli_close($link);
?>
以上例程会输出：
Our connection is ok!
add a note
User Contributed Notes 3 notes
jay at grooveshark dot com ¶
7 years ago
This does not work with mysqlnd and is marked as wontfix: https://bugs.php.net/bug.php?id=52561
snooops84 at googlemail dot com ¶
7 years ago
The behaviour about the option mysqli.reconnect is default set to Off at Debian PHP Packages. So i would recommend to update the first line description about the recommendation at the option mysqli.reconnect. (practice note ;))
root at jusme dot org ¶
6 years ago
As jay at grooveshark dot com very helpfully pointed out, the mysqlnd driver which is becoming pretty standard does not obey reconnect commands. If you have a DB wrapper class (which hopefully you do) you can implement your own version of ping() such as:
<?php
class db extends mysqli
{
private $db_host;
private $db_user;
private $db_pass;
private $db_name;
private $persistent;
public function __construct($db_host, $db_user, $db_pass, $db_name, $persistent = true)
{
$this->db_host = $db_host;
$this->db_user = $db_user;
$this->db_pass = $db_pass;
$this->db_name = $db_name;
$this->persistent = $persistent;
parent::init();
parent::options(MYSQLI_OPT_CONNECT_TIMEOUT, 1);
@parent::real_connect(($this->persistent ? 'p:' : '') . $this->db_host, $this->db_user, $this->db_pass, $this->db_name);
if ($this->connect_errno)
die("All DB servers down!\n");
}
public function ping()
{
@parent::query('SELECT LAST_INSERT_ID()');
if ($this->errno == 2006)
$this->__construct($this->db_host, $this->db_user, $this->db_pass, $this->db_name, $this->persistent);
}
...
}
$db = new db(DB_HOST, DB_USER, DB_PASS, DB_NAME);
// Some code that potentially takes a really long time to execute goes here
// Ping for safety to try to gracefully reconnect
$db->ping();
// Now we should be able to run queries again
$db->query('SELECT LAST_INSERT_ID()');
?>
If you wanted you could even put "$this->ping();" at the top of db::query() to avoid any explicit reconnection calls but I wouldn't recommend it due to the (slight) overhead of running the cheap "SELECT LAST_INSERT_ID()" query every time prior to running your real intended query. There are probably even cheaper queries to run in favor of "SELECT LAST_INSERT_ID()" but it was the first that came to mind and is cheap enough for most purposes since you shouldn't be calling ping() a whole bunch anyway.