PHP进程信号处理

<?php
while (1) {
    echo "I am doing something important\n";
    echo "If i am interruptted, the data will be corrupted\n";
    echo "Be careful\n";
    echo "\n\n";
    sleep(5);
}

假设现在有以上这么一个PHP脚本，我们想要脚本在收到SIGINT、SIGTERM等进程信号时，输出一段信息并结束脚本，该如何实现呢？

使用pcntl_signal和pcntl_signal_dispatch函数即可（注意PHP需要安装pcntl扩展才能使用这两个函数），见代码：

<?php

/**
 * 信号ID和信号名称对应关系，没注释掉的信号都是可以通过pcntl_signal函数注册的
 */
$GLOBALS['G_SIG_MAP'] = array(
    1 => 'SIGHUP',
    2 => 'SIGINT',
    3 => 'SIGQUIT',
    4 => 'SIGILL',
    5 => 'SIGTRAP',
    6 => 'SIGABRT',
    7 => 'SIGEMT',
    8 => 'SIGFPE',
    //9 => 'SIGKILL',
    10 => 'SIGBUS',
    11 => 'SIGSEGV',
    12 => 'SIGSYS',
    13 => 'SIGPIPE',
    14 => 'SIGALRM',
    15 => 'SIGTERM',
    16 => 'SIGURG',
    //17 => 'SIGSTOP',
    18 => 'SIGTSTP',
    19 => 'SIGCONT',
    20 => 'SIGCHLD',
    21 => 'SIGTTIN',
    22 => 'SIGTTOU',
    23 => 'SIGIO',
    24 => 'SIGXCPU',
    25 => 'SIGXFSZ',
    26 => 'SIGVTALRM',
    27 => 'SIGPROF',
    28 => 'SIGWINCH',
    29 => 'SIGINFO',
    30 => 'SIGUSR1',
    31 => 'SIGUSR2',
);

/**
 * 进程信号处理函数
 * @param int $signo 信号ID
 */
function signalHandler($signo) {
    if (isset($GLOBALS['G_SIG_MAP'][$signo])) {
        echo "Caught signal {$GLOBALS['G_SIG_MAP'][$signo]}, exit\n";
    } else {
        echo "Caught unknown signal:$signo";
    }
    exit();
}

foreach ($GLOBALS['G_SIG_MAP'] as $id => $name) {
    pcntl_signal($id, 'signalHandler');
}

while (1) {
    echo "I am doing something important\n";
    echo "If i am interruptted, the data will be corrupted\n";
    echo "Be careful\n";
    echo "\n\n";
    pcntl_signal_dispatch(); // 此函数调用必须放在循环体内
    sleep(5);
}

在linux shell中执行该脚本，然后使用kill -2 脚本进程ID命令向进程发送信号，脚本正常输出信息并退出。