研究RabbitMQ消费脚本注册信号时候，发现的问题

执行了 sleep(2)，发起ctrl + c信号，发现获取系统时间没有 +2s。

构建测试代码

<?php

namespace App\Console\Commands;

use Illuminate\Console\Command;

class TestSignal extends Command
{
    protected $signature = 'test:signal';

    public function handle()
    {
        pcntl_async_signals(true);

        $interrupted = false;
        pcntl_signal(SIGINT, function ($signal) use (&$interrupted) {
            $interrupted = true;
            echo (sprintf('got signal[%d]', $signal)) . "\n";
        });

        while (!$interrupted) {
            echo "sleep 3s\n";
            sleep(3);
            echo "current time: " .date('Y-m-d H:i:s') . "\n";
        }
    }
}

验证效果

使用 phptrace -p pid 查看运行时的函数调用信息

...

> sleep(3)
< sleep(3) = 0
> date("Y-m-d H:i:s")
< date("Y-m-d H:i:s") = "2018-12-13 18:04:05"
> sleep(3)
< sleep(3) = 0
> date("Y-m-d H:i:s")
< date("Y-m-d H:i:s") = "2018-12-13 18:04:08"
> sleep(3)
< sleep(3) = 3
> App\Console\Commands\TestSignal->App\Console\Commands\{closure}(2, array(3))
    > sprintf("got signal[%d]", 2)
    < sprintf("got signal[%d]", 2) = "got signal[2]"
< App\Console\Commands\TestSignal->App\Console\Commands\{closure}(2, array(3)) = NULL
> date("Y-m-d H:i:s")
< date("Y-m-d H:i:s") = "2018-12-13 18:04:08"

...

当执行ctrl + c时，sleep(3) 会直接返回，所以获取当前时间又是 2018-12-13 18:04:08。

官网解释

If the call was interrupted by a signal, sleep() returns a non-zero value. 
On Windows, this value will always be 192 (the value of the WAIT_IO_COMPLETION constant within the Windows API).
On other platforms, the return value will be the number of seconds left to sleep.