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    pcntl_signal_dispatch

    (PHP 5 >= 5.3.0, PHP 7, PHP 8)

    pcntl_signal_dispatch — ペンディングシグナル用のハンドラをコールする

    説明

    pcntl_signal_dispatch(): bool

    pcntl_signal_dispatch() 関数は、 pcntl_signal() がインストールしたシグナルハンドラを 各ペンディングシグナルに対してコールします。

    パラメータ

    この関数にはパラメータはありません。

    戻り値

    成功した場合に true を、失敗した場合に false を返します。

    例

    例1 pcntl_signal_dispatch() の例

    <?php
    echo "Installing signal handler...\n";
    pcntl_signal(SIGHUP, function($signo) {
    echo     "signal handler called\n";
    });

    echo     "Generating signal SIGHUP to self...\n";
    posix_kill(posix_getpid(), SIGHUP);

    echo     "Dispatching...\n";
    pcntl_signal_dispatch();

    echo     "Done\n";

    ?>

    上の例の出力は、 たとえば以下のようになります。

    Installing signal handler...
Generating signal SIGHUP to self...
Dispatching...
signal handler called
Done

    参考

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    User Contributed Notes 4 notes

    up
    41
    webmaster at ajeux dot com
    15 years ago
    If you are running PHP as CLI and as a "daemon" (i.e. in a loop), this function must be called in each loop to check if new signals are waiting dispatching.
    up
    9
    me at subsonic dot cz
    10 years ago
    Note that calling pcntl_signal_dispatch() from within a signal handler invoked by a previous pcntl_signal_dispatch() will not trigger handlers for any new pending signals. This means that if you write a CLI daemon which forks off child processes in response to a signal, then those child processes won't be able to respond to signals. This gave me a headache for a while as pcntl_signal_dispatch() doesn't raise any errors when this occurs. One solution is to set a flag within the signal handler and react upon it (by forking off the needed child processes) elsewhere in the parent process's main loop.
    up
    0
    stefanis
    10 years ago
    As noted by "me at subsonic dot net" calling pcntl_signal_dispatch() from within a signal handler invoked by a previous pcntl_signal_dispatch() will not trigger handlers for any new pending signals. This seems to be true even if you pcntl_exec() a new PHP processor to execute an entirely different script.

    The solution seems to be to explicitly call pcntl_signal_dispatch()inside a ticks_handler() . And use sig_handler(int) as a push function to a queue. Immediately following the call to dispatch in the ticks_handler, pop your queue doing what you would have done in the signal_handler until the queue is empty.
    up
    -2
    stefanis
    10 years ago
    Well I misspoke before. It is not enough to process signals outside of the signal handler. They must be processed outside of the tick handler (explicit or implied). So...

    Register a tick handler that calls pcntl_signal_dispatch();
    In the signal handler, enqueue your signal;
    In the main loop of your script, process your signals;

    <?php
    declare(ticks=1);
    global     $sig_queue;
    global     $use_queue;
    $sig_queue = array();
    $use_queue = true; // set to false to do it the old way

    function tick_handler()
    {
    pcntl_signal_dispatch();
    }

    function     sig_handler($sig)
    {
    global     $sig_queue;
    global     $use_queue;

    if(isset(    $use_queue) && $use_queue)
    {
    $sig_queue[] = $sig;
    }
    else
    {
    sig_helper($sig);
    }
    }

    function     sig_helper($sig)
    {
    switch(    $sig)
    {
    case     SIGHUP:
    $pid = pcntl_fork();
    if(    $pid) print("forked $pid\n");
    break;

    default:
    print(    "unhandled sig: $sig\n");
    }
    }

    pcntl_signal(SIGHUP, "sig_handler");

    while(    true)
    {
    if(    $use_queue) foreach($sig_queue as $idx=>$sig)
    {
    sig_helper($sig);
    unset(    $sig_queue[$idx]);
    }
    sleep(1);
    }
    ?>
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