MySQL has gone away解决办法

MySQL has gone away解决办法

时间：2008-03-16 21:22:26 类别：wordpress 访问：6 viewsRSS 2.0评论

最近写的一个采集系统在wordpress上面老是mysql has gone away
原因是mysql连接丢失

在一些耗时的地方, 使用mysql_ping来重新获得连接

下面给出我改进的wp-db.php类, 加入了

$wpdb -> check_conn () ;

方法检查,如果连接丢失,自动重新连接

我非常讨厌在new一个类的时候还带上参数

$wpdb = new wpdb ( DB_USER , DB_PASSWORD , DB_NAME , DB_HOST ) ;

这个写法我是非常讨厌的,也顺便修了它

<?php
// WordPress DB Class
// ========================
// fix by 21Andy.com at 2008-03-16
// Andy Tse ( [email protected] )
// http://www.21andy.com
// ========================
// ORIGINAL CODE FROM:
// Justin Vincent ( [email protected] )
// http://php.justinvincent.com

define ( ' EZSQL_VERSION ' , ' WP1.25 ' ) ;
define ( ' OBJECT ' , ' OBJECT ' , true ) ;
define ( ' ARRAY_A ' , ' ARRAY_A ' , false ) ;
define ( ' ARRAY_N ' , ' ARRAY_N ' , false ) ;

if ( ! defined ( ' SAVEQUERIES ' ))
define ( ' SAVEQUERIES ' , false ) ;

class wpdb {

var $show_errors = false ;
var $num_queries = 0 ;
var $last_query ;
var $col_info ;
var $queries ;
var $ready = false ;

// Our tables
var $posts ;
var $users ;
var $categories ;
var $post2cat ;
var $comments ;
var $links ;
var $options ;
var $optiontypes ;
var $optionvalues ;
var $optiongroups ;
var $optiongroup_options ;
var $postmeta ;
var $usermeta ;
var $terms ;
var $term_taxonomy ;
var $term_relationships ;

var $charset ;
var $collate ;

/**
* Connects to the database server and selects a database
* @param string $dbuser
* @param string $dbpassword
* @param string $dbname
* @param string $dbhost
*/
function wpdb () {
return $this -> __construct () ;
}

function __construct () {
register_shutdown_function ( array ( & $this , " __destruct " )) ;

if ( defined ( ' WP_DEBUG ' ) and WP_DEBUG == true )
$this -> show_errors () ;

if ( defined ( ' DB_CHARSET ' ) )
$this -> charset = DB_CHARSET ;

if ( defined ( ' DB_COLLATE ' ) )
$this -> collate = DB_COLLATE ;

if ( ! defined ( ' DB_USER ' ) ||
! defined ( ' DB_PASSWORD ' ) ||
! defined ( ' DB_NAME ' ) ||
! defined ( ' DB_HOST ' ) )
exit ( ' please config DB setting!!! ' ) ;

$this -> dbuser = DB_USER ;
$this -> dbpassword = DB_PASSWORD ;
$this -> dbname = DB_NAME ;
$this -> dbhost = DB_HOST ;
$this -> connect () ;
}

function connect () {
$this -> dbh = @ mysql_connect ( $this -> dbhost , $this -> dbuser , $this -> dbpassword ) ;
if ( ! $this -> dbh ) {
$this -> bail ( "
<h1>Error establishing a database connection</h1>
<p>This either means that the username and password information in your <code>wp-config.php</code> file is incorrect or we can't contact the database server at <code> $dbhost </code>. This could mean your host's database server is down.</p>
<ul>
<li>Are you sure you have the correct username and password?</li>
<li>Are you sure that you have typed the correct hostname?</li>
<li>Are you sure that the database server is running?</li>
</ul>
<p>If you're unsure what these terms mean you should probably contact your host. If you still need help you can always visit the <a href='http://wordpress.org/support/'>WordPress Support Forums</a>.</p>
" ) ;
return ;
}

$this -> ready = true ;

if ( ! empty ( $this -> charset ) && version_compare ( mysql_get_server_info () , ' 4.1.0 ' , ' >= ' ) )
$this -> query ( " SET NAMES ' $this ->charset' " ) ;

$this -> select ( $this -> dbname ) ;
}

function check_conn () {
if ( ! mysql_ping ( $this -> dbh )) {
//here is the major trick, you have to close the connection (even though its not currently working) for it to recreate properly.
mysql_close ( $this -> dbh ) ;
$this -> connect () ;
}
}

function __destruct () {
return true ;
}

/**
* Selects a database using the current class's $this->dbh
* @param string $db name
*/
function select ( $db ) {
if ( !@ mysql_select_db ( $db , $this -> dbh )) {
$this -> ready = false ;
$this -> bail ( "
<h1>Can&#8217;t select database</h1>
<p>We were able to connect to the database server (which means your username and password is okay) but not able to select the <code> $db </code> database.</p>
<ul>
<li>Are you sure it exists?</li>
<li>Does the user <code> " . DB_USER . " </code> have permission to use the <code> $db </code> database?</li>
<li>On some systems the name of your database is prefixed with your username, so it would be like username_wordpress. Could that be the problem?</li>
</ul>
<p>If you don't know how to setup a database you should <strong>contact your host</strong>. If all else fails you may find help at the <a href='http://wordpress.org/support/'>WordPress Support Forums</a>.</p> " ) ;
return ;
}
}

/**
* Escapes content for insertion into the database, for security
*
* @param string $string
* @return string query safe string
*/
function escape ( $string ) {
return addslashes ( $string ) ; // Disable rest for now, causing problems
if ( ! $this -> dbh || version_compare ( phpversion () , ' 4.3.0 ' ) == ' -1 ' )
return mysql_escape_string ( $string ) ;
else
return mysql_real_escape_string ( $string , $this -> dbh ) ;
}

/**
* Escapes content by reference for insertion into the database, for security
* @param string $s
*/
function escape_by_ref ( & $s ) {
$s = $this -> escape ( $s ) ;
}

/**
* Prepares a SQL query for safe use, using sprintf() syntax
*/
function prepare ( $args = NULL ) {
if ( NULL === $args )
return ;
$args = func_get_args () ;
$query = array_shift ( $args ) ;
$query = str_replace ( " '%s' " , ' %s ' , $query ) ; // in case someone mistakenly already singlequoted it
$query = str_replace ( ' "%s" ' , ' %s ' , $query ) ; // doublequote unquoting
$query = str_replace ( ' %s ' , " '%s' " , $query ) ; // quote the strings
array_walk ( $args , array ( & $this , ' escape_by_ref ' )) ;
return @ vsprintf ( $query , $args ) ;
}

// ==================================================================
// Print SQL/DB error.

function print_error ( $str = '' ) {
global $EZSQL_ERROR ;
if ( ! $str ) $str = mysql_error ( $this -> dbh ) ;
$EZSQL_ERROR [] =
array ( ' query ' => $this -> last_query , ' error_str ' => $str ) ;

$error_str = " WordPress database error $str for query $this ->last_query " ;
error_log ( $error_str , 0 ) ;

// Is error output turned on or not..
if ( ! $this -> show_errors )
return false ;

$str = htmlspecialchars ( $str , ENT_QUOTES ) ;
$query = htmlspecialchars ( $this -> last_query , ENT_QUOTES ) ;

// If there is an error then take note of it
print " <div id='error'>
<p class='wpdberror'><strong>WordPress database error:</strong> [ $str ]<br />
<code> $query </code></p>
</div> " ;
}

// ==================================================================
// Turn error handling on or off..

function show_errors ( $show = true ) {
$errors = $this -> show_errors ;
$this -> show_errors = $show ;
return $errors ;
}

function hide_errors () {
$show = $this -> show_errors ;
$this -> show_errors = false ;
return $show ;
}

// ==================================================================
// Kill cached query results

function flush () {
$this -> last_result = array () ;
$this -> col_info = null ;
$this -> last_query = null ;
}

// ==================================================================
// Basic Query - see docs for more detail

function query ( $query ) {
if ( ! $this -> ready )
return false ;

// filter the query, if filters are available
// NOTE: some queries are made before the plugins have been loaded, and thus cannot be filtered with this method
if ( function_exists ( ' apply_filters ' ) )
$query = apply_filters ( ' query ' , $query ) ;

// initialise return
$return_val = 0 ;
$this -> flush () ;

// Log how the function was called
$this -> func_call = " \$ db->query( \" $query \" ) " ;

// Keep track of the last query for debug..
$this -> last_query = $query ;

// Perform the query via std mysql_query function..
if ( SAVEQUERIES )
$this -> timer_start () ;

$this -> result = @ mysql_query ( $query , $this -> dbh ) ;
++ $this -> num_queries ;

if ( SAVEQUERIES )
$this -> queries [] = array ( $query , $this -> timer_stop () ) ;

// If there is an error then take note of it..
if ( mysql_error ( $this -> dbh ) ) {
$this -> print_error () ;
return false ;
}

if ( preg_match ( " /^ \\ s*(insert|delete|update|replace) /i " , $query ) ) {
$this -> rows_affected = mysql_affected_rows ( $this -> dbh ) ;
// Take note of the insert_id
if ( preg_match ( " /^ \\ s*(insert|replace) /i " , $query ) ) {
$this -> insert_id = mysql_insert_id ( $this -> dbh ) ;
}
// Return number of rows affected
$return_val = $this -> rows_affected ;
} else {
$i = 0 ;
while ( $i < @ mysql_num_fields ( $this -> result )) {
$this -> col_info [ $i ] = @ mysql_fetch_field ( $this -> result ) ;
$i ++;
}
$num_rows = 0 ;
while ( $row = @ mysql_fetch_object ( $this -> result ) ) {
$this -> last_result [ $num_rows ] = $row ;
$num_rows ++;
}

@ mysql_free_result ( $this -> result ) ;

// Log number of rows the query returned
$this -> num_rows = $num_rows ;

// Return number of rows selected
$return_val = $this -> num_rows ;
}

return $return_val ;
}

/**
* Get one variable from the database
* @param string $query (can be null as well, for caching, see codex)
* @param int $x = 0 row num to return
* @param int $y = 0 col num to return
* @return mixed results
*/
function get_var ( $query = null , $x = 0 , $y = 0 ) {
$this -> func_call = " \$ db->get_var( \" $query \" , $x , $y ) " ;
if ( $query )
$this -> query ( $query ) ;

// Extract var out of cached results based x,y vals
if ( $this -> last_result [ $y ] ) {
$values = array_values ( get_object_vars ( $this -> last_result [ $y ])) ;
}

// If there is a value return it else return null
return ( isset ( $values [ $x ]) && $values [ $x ] !== '' ) ? $values [ $x ] : null ;
}

/**
* Get one row from the database
* @param string $query
* @param string $output ARRAY_A | ARRAY_N | OBJECT
* @param int $y row num to return
* @return mixed results
*/
function get_row ( $query = null , $output = OBJECT , $y = 0 ) {
$this -> func_call = " \$ db->get_row( \" $query \" , $output , $y ) " ;
if ( $query )
$this -> query ( $query ) ;
else
return null ;

if ( ! isset ( $this -> last_result [ $y ]) )
return null ;

if ( $output == OBJECT ) {
return $this -> last_result [ $y ] ? $this -> last_result [ $y ] : null ;
} elseif ( $output == ARRAY_A ) {
return $this -> last_result [ $y ] ? get_object_vars ( $this -> last_result [ $y ]) : null ;
} elseif ( $output == ARRAY_N ) {
return $this -> last_result [ $y ] ? array_values ( get_object_vars ( $this -> last_result [ $y ])) : null ;
} else {
$this -> print_error ( " \$ db->get_row(string query, output type, int offset) -- Output type must be one of: OBJECT, ARRAY_A, ARRAY_N " ) ;
}
}

/**
* Gets one column from the database
* @param string $query (can be null as well, for caching, see codex)
* @param int $x col num to return
* @return array results
*/
function get_col ( $query = null , $x = 0 ) {
if ( $query )
$this -> query ( $query ) ;

$new_array = array () ;
// Extract the column values
for ( $i = 0 ; $i < count ( $this -> last_result ) ; $i ++ ) {
$new_array [ $i ] = $this -> get_var ( null , $x , $i ) ;
}
return $new_array ;
}

/**
* Return an entire result set from the database
* @param string $query (can also be null to pull from the cache)
* @param string $output ARRAY_A | ARRAY_N | OBJECT
* @return mixed results
*/
function get_results ( $query = null , $output = OBJECT ) {
$this -> func_call = " \$ db->get_results( \" $query \" , $output ) " ;

if ( $query )
$this -> query ( $query ) ;
else
return null ;

// Send back array of objects. Each row is an object
if ( $output == OBJECT ) {
return $this -> last_result ;
} elseif ( $output == ARRAY_A || $output == ARRAY_N ) {
if ( $this -> last_result ) {
$i = 0 ;
foreach ( $this -> last_result as $row ) {
$new_array [ $i ] = ( array ) $row ;
if ( $output == ARRAY_N ) {
$new_array [ $i ] = array_values ( $new_array [ $i ]) ;
}
$i ++;
}
return $new_array ;
} else {
return null ;
}
}
}

/**
* Grabs column metadata from the last query
* @param string $info_type one of name, table, def, max_length, not_null, primary_key, multiple_key, unique_key, numeric, blob, type, unsigned, zerofill
* @param int $col_offset 0: col name. 1: which table the col's in. 2: col's max length. 3: if the col is numeric. 4: col's type
* @return mixed results
*/
function get_col_info ( $info_type = ' name ' , $col_offset = - 1 ) {
if ( $this -> col_info ) {
if ( $col_offset == - 1 ) {
$i = 0 ;
foreach ( $this -> col_info as $col ) {
$new_array [ $i ] = $col -> { $info_type } ;
$i ++;
}
return $new_array ;
} else {
return $this -> col_info [ $col_offset ] -> { $info_type } ;
}
}
}

/**
* Starts the timer, for debugging purposes
*/
function timer_start () {
$mtime = microtime () ;
$mtime = explode ( ' ' , $mtime ) ;
$this -> time_start = $mtime [ 1 ] + $mtime [ 0 ] ;
return true ;
}

/**
* Stops the debugging timer
* @return int total time spent on the query, in milliseconds
*/
function timer_stop () {
$mtime = microtime () ;
$mtime = explode ( ' ' , $mtime ) ;
$time_end = $mtime [ 1 ] + $mtime [ 0 ] ;
$time_total = $time_end - $this -> time_start ;
return $time_total ;
}

/**
* Wraps fatal errors in a nice header and footer and dies.
* @param string $message
*/
function bail ( $message ) { // Just wraps errors in a nice header and footer
if ( ! $this -> show_errors ) {
if ( class_exists ( ' WP_Error ' ) )
$this -> error = new WP_Error ( ' 500 ' , $message ) ;
else
$this -> error = $message ;
return false ;
}
wp_die ( $message ) ;
}
}

if ( ! isset ( $wpdb ) )
$wpdb = new wpdb ;
?>

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