php----stream_select函数用法

http://blog.csdn.net/tongnianhani/article/details/73695314在这篇文章中我们已经简单介绍了stream_socket_pair函 数的简单用法，如果你还不熟悉他的用法，可以点击进去先看下这个函数的用法，因为我们接下来要介绍的stream_select函数的用法时会用到这个函数； 

简单说stream_select 函数就是返回参数$read，$write已经可读或者可写状态的的数量，如果基本可读也不可写则超时时间过后就会返回0，从文档介绍中可以看到

int stream_select ( array&$read ,array &$write ,array &$except , int $tv_sec [, int $tv_usec = 0 ] ) 前三个参数都是引用，所以如果不可读则$read返回的是空数组，$write也是同理，举例说明

<?php$sockets  =  stream_socket_pair ( STREAM_PF_UNIX ,  STREAM_SOCK_STREAM ,  STREAM_IPPROTO_IP );$pid      =  pcntl_fork ();$timeout = 2;if ( $pid  == - 1 ) {die( 'could not fork' );} else if ( $pid ) {/* parent */fclose ( $sockets [ 0 ]);fwrite ( $sockets [ 1 ],  "child PID:  $pid \n" );fwrite ( $sockets [ 0 ],  "message from child\n" );$str = stream_select($sockets,$w=null,$e=null,$timeout);var_dump($str);var_dump($sockets);echo  'main-'.fgets ( $sockets [ 1 ]);//echo  'child-'.fgets ( $sockets [ 0 ]);fclose ( $sockets [ 1 ]);} else {/* child */fclose ( $sockets [ 1 ]);fwrite ( $sockets [ 0 ],  "message from child\n" );echo  'child-'.fgets ( $sockets [ 0 ]);$str = stream_select($sockets,$w=null,$e=null,$timeout);var_dump($str);var_dump($sockets);fclose ( $sockets [ 0 ]);}

上面的例子返回的结果为：

child-child PID:  2510 
int(1)
array(1) {
  [1] =>
  resource(5) of type (stream)
}
main-message from child
int(1)
array(1) {
  [0] =>
  resource(4) of type (stream)
}

如果没有可读内容，则返回空数组，代码如下

<?php$sockets  =  stream_socket_pair ( STREAM_PF_UNIX ,  STREAM_SOCK_STREAM ,  STREAM_IPPROTO_IP );$pid      =  pcntl_fork ();$timeout = 2;$str = stream_select($sockets,$w=null,$e=null,$timeout);var_dump($str);var_dump($sockets);

输出结果：

int(0)
array(0) {
}