缘由

下午看业务代码的时候发现系统在输出json格式的数据的时候，使用了exit：

<?php
// bla bla bla ...
class Demo {
    protected function showSucc($errno = 0, $errmsg = '',$data=NULL,$flag=FALSE)
    {
        header('Content-Type:application/json');
        $out['errno'] = $errno;
        $out['errmsg'] = !empty($errmsg)?$errmsg:'SUCCESS';
        $out['data'] = $data;

        echo json_encode($out);

        if($flag)
        {
            $commonLog = $this->CommonLogModel->getLog();
            $commonLog['in'] = $commonLog['request'] = $_REQUEST;
            $commonLog['out'] = $commonLog['return'] = $out;
            $commonLog['errno'] = $out['errno'];
            $commonLog['msg'] = $out['errmsg'];
            $commonLog['errmsg'] = 'REQUEST_INFO';

            $filter = isset($commonLog['filter']) ? $commonLog['filter'] : array('company_id'=>'', 'out_order_id'=>'', 'order_id'=>'', 'phone'=>'');
            if(!empty($this->memberInfo))
            {
                $filter['company_id'] = $this->memberInfo['company_id'];
                $filter['phone']      = $this->memberInfo['phone'];
            }
            log_notice('showSucc', $commonLog, $filter);
//            log_monitor('showSucc', $commonLog, $filter);
        }

        exit;
    }
}

在exit之前，有一个记录日志的方法log_monitor，根据之前看的这套框架，系统的日志代码最终的save方法是注册在register_shutdown_function里面的，即程序退出时执行．

那么这个日志会不会上报上去呢？

Find out

俗话说，外事不决问狗狗．但是，PHP的问题呢，我们看manual就足够了．

打开关于exit的页面，一句话赫然入目：

Terminates execution of the script. Shutdown functions and 
object destructors will always be executed even if exit is called.

A-ao，原来exit是会调用注册的shutdown functions的，同时呢，也会调用各种对象的__destruct方法．

其实，exit就是一个平滑的退出过程吧，register_shutdown_function里面有一个Note:

Shutdown functions will not be executed if the process 
is killed with a SIGTERM or SIGKILL signal. While you cannot 
intercept a SIGKILL, you can use pcntl_signal() to install 
a handler for a SIGTERM which uses exit() to end cleanly.

大概意思是，当你使用信号SIGKILL和SIGTERM进行关闭的时候，注册的shutdown function不会被执行，当然SIGTERM可以用可以使用信号绑定到exit上面进行平滑的关闭．

其他想法

Manual上面一般都是关于正常情况的讨论，那么异常情况呢？

比如出现了Fatal Error呢？

于是有了下面这个栗子：

<?php

function foo()
{
    var_dump(microtime(true));
}

register_shutdown_function("foo");

var_dump(microtime(true));

baz();

exit;

显然，上面的栗子中baz()这个函数是不存在的，那么这一行就会出现Fatal Error．

这种情况下，其实shutdown function也生效了，是不是很惊讶. ToT

Jiao's LAB

PHP - exit and shutdown function

缘由

Find out

其他想法