PHP - Manual: mysqli::ping

2024-11-14

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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

mysqli_ping(mysqli $link): bool

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。

参数

mysql: 仅以过程化样式：由mysqli_connect() 或 mysqli_init() 返回的 mysqli 对象。

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!

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User Contributed Notes 3 notes

down

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

down

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 ;))

down

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.

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官方地址：https://www.php.net/manual/en/mysqli.ping.php

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mysqli::ping

mysqli_ping

说明

参数

返回值

范例

User Contributed Notes 3 notes