Process->push

投递数据到消息队列中。

bool Process->push(string $data);

• $data要投递的数据，长度受限与操作系统内核参数的限制。默认为8192，最大不超过65536
• 操作失败会返回false，成功返回true
• 默认模式下（阻塞模式），如果队列已满，push方法会阻塞等待
• 非阻塞模式下，如果队列已满，push方法会立即返回false
  示例

$workers = [];
$worker_num = 2;
for($i = 0; $i < $worker_num; $i++)
{
    $process = new swoole_process('callback_function', false, false);
    $process->useQueue();
    $pid = $process->start();
    $workers[$pid] = $process;
    //echo "Master: new worker, PID=".$pid."\n";
}
function callback_function(swoole_process $worker)
{
    //echo "Worker: start. PID=".$worker->pid."\n";
    //recv data from master
    $recv = $worker->pop();
    echo "From Master: $recv\n";
    sleep(2);
    $worker->exit(0);
}
foreach($workers as $pid => $process)
{
    $process->push("hello worker[$pid]\n");
}
for($i = 0; $i < $worker_num; $i++)
{
    $ret = swoole_process::wait();
    $pid = $ret['pid'];
    unset($workers[$pid]);
    echo "Worker Exit, PID=".$pid.PHP_EOL;
}