PHP实现MySQL读写分离-php手册-php.cn

本代码是从uchome的代码修改的，是因为要解决uchome的效率而处理的。PHP实现的Mysql读写分离

本代码是从uchome的代码修改的，是因为要解决uchome的效率而处理的。

PHP实现的Mysql读写分离

主要特性：

简单的读写分离
一个主数据库，可以添加更多的只读数据库
读写分离但不用担心某些特性不支持
缺点：同时连接两个数据库
英文比较烂，也写几个字吧

php code for mysql read/write split
feature:
simply rw split
one master,can add more slaves
support all mysql feature
link to the master and slave at the same time

PHP代码：

mysql_rw_php.class.php

/****************************************
*** mysql-rw-php version 0.1 @ 2009-4-16
*** code by hqlulu#gmail.com
*** http://www.aslibra.com
*** http://code.google.com/p/mysql-rw-php/
*** code modify from class_mysql.php (uchome)
****************************************/
class mysql_rw_php {
//查询个数
var $querynum = 0;
//当前操作的数据库连接
var $link = null;
//字符集
var $charset;
//当前数据库
var $cur_db = '';
//是否存在有效的只读数据库连接
var $ro_exist = false;
//只读数据库连接
var $link_ro = null;
//读写数据库连接
var $link_rw = null;
function mysql_rw_php(){
}
function connect($dbhost, $dbuser, $dbpw, $dbname = '', $pconnect = 0, $halt = TRUE) {
    if($pconnect) {
      if(!$this->link = @mysql_pconnect($dbhost, $dbuser, $dbpw)) {
        $halt && $this->halt('Can not connect to MySQL server');
      }
    } else {
      if(!$this->link = @mysql_connect($dbhost, $dbuser, $dbpw)) {
        $halt && $this->halt('Can not connect to MySQL server');
      }
    }

    //只读连接失败
    if(!$this->link && !$halt) return false;

    //未初始化rw时，第一个连接作为rw
    if($this->link_rw == null)
      $this->link_rw = $this->link;
    if($this->version() > '4.1') {
      if($this->charset) {
        @mysql_query("SET character_set_connection=$this->charset, character_set_results=$this->charset, character_set_client=binary", $this->link);
      }
      if($this->version() > '5.0.1') {
        @mysql_query("SET sql_mode=''", $this->link);
      }
    }
    if($dbname) {
      $this->select_db($dbname);
    }
}
//连接一个只读的mysql数据库
function connect_ro($dbhost, $dbuser, $dbpw, $dbname = '', $pconnect = 0){
    if($this->link_rw == null)
      $this->link_rw = $this->link;
    $this->link = null;
    //不产生halt错误
    $this->connect($dbhost, $dbuser, $dbpw, $dbname, $pconnect, false);
    if($this->link){
      //连接成功
      //echo "link ro sussess!
";
      $this->ro_exist = true;
      $this->link_ro = $this->link;
      if($this->cur_db){
        //如果已经选择过数据库则需要操作一次
        @mysql_select_db($this->cur_db, $this->link_ro);
      }
    }else{
      //连接失败
      //echo "link ro failed!
";
      $this->link = &$this->link_rw;
    }
}
//设置一系列只读数据库并且连接其中一个
function set_ro_list($ro_list){
    if(is_array($ro_list)){
      //随机选择其中一个
      $link_ro = $ro_list[array_rand($ro_list)];
      $this->connect_ro($link_ro['dbhost'], $link_ro['dbuser'], $link_ro['dbpw']);
    }
}
function select_db($dbname) {
    //同时操作两个数据库连接
    $this->cur_db = $dbname;
    if($this->ro_exist){
      @mysql_select_db($dbname, $this->link_ro);
    }
    return @mysql_select_db($dbname, $this->link_rw);
}
function fetch_array($query, $result_type = MYSQL_ASSOC) {
    return mysql_fetch_array($query, $result_type);
}
function fetch_one_array($sql, $type = '') {
    $qr = $this->query($sql, $type);
    return $this->fetch_array($qr);
}
function query($sql, $type = '') {
    $this->link = &$this->link_rw;
    //判断是否select语句
    if($this->ro_exist && preg_match ("/^(\s*)select/i", $sql)){
      $this->link = &$this->link_ro;
    }
    $func = $type == 'UNBUFFERED' && @function_exists('mysql_unbuffered_query') ?
      'mysql_unbuffered_query' : 'mysql_query';
    if(!($query = $func($sql, $this->link)) && $type != 'SILENT') {
      $this->halt('MySQL Query Error', $sql);
    }
    $this->querynum++;
    return $query;
}
function affected_rows() {
    return mysql_affected_rows($this->link);
}
function error() {
    return (($this->link) ? mysql_error($this->link) : mysql_error());
}
function errno() {
    return intval(($this->link) ? mysql_errno($this->link) : mysql_errno());
}
function result($query, $row) {
    $query = @mysql_result($query, $row);
    return $query;
}
function num_rows($query) {
    $query = mysql_num_rows($query);
    return $query;
}
function num_fields($query) {
    return mysql_num_fields($query);
}
function free_result($query) {
    return mysql_free_result($query);
}
function insert_id() {
    return ($id = mysql_insert_id($this->link)) >= 0 ? $id : $this->result($this->query("SELECT last_insert_id()"), 0);
}
function fetch_row($query) {
    $query = mysql_fetch_row($query);
    return $query;
}
function fetch_fields($query) {
    return mysql_fetch_field($query);
}
function version() {
    return mysql_get_server_info($this->link);
}
function close() {
    return mysql_close($this->link);
}
function halt($message = '', $sql = '') {
    $dberror = $this->error();
    $dberrno = $this->errno();
    echo "

        MySQL Error

        Message: $message

        SQL: $sql

        Error: $dberror

        Errno.: $dberrno

";
exit();
}
}
?>

example.php