<?php

fork_process(
    $start = 1,
    $end = 10,
    $function_name = 'run',
    $block_size = 1,
    $processes = 4
);

function fork_process($start, $end, $function_name, $block_size, $processes) {
    $from = $start;
    $to = $block_size;

    $block = ceil((($end - $start)) / $block_size);

    $sockets = array();
    if (socket_create_pair(AF_UNIX, SOCK_STREAM, 0, $sockets) === false) {
        echo socket_strerror(socket_last_error())."\n";
        exit(0);
    }

    $index = 0;

    $parent = true;
    $children = array();
    for ($i = 0; $i < min($processes, $block) && $parent; $i++) {
        $pid = pcntl_fork();
        if ($pid == 0) {
            $parent = false;
            $index = $i;
            sleep(1);
        } else if ($pid != -1) {
            $children[] = $pid;
        }
    }

    if ($parent) {
        process_parent($sockets, $children, $block, $block_size, $function_name, $end, $start, $processes);
    } else {
        $from = $start + ($block_size * $index);
        $to = $start + ($block_size * ($index + 1)) - 1;
        if ($end <= $to) {
            $to = $end;
        }

        process_child($sockets, $index, $from, $to, $function_name);
        posix_kill(getmypid(), 9);
    }
}

function process_parent(&$sockets, &$children, $block, $blockSize, $functionName, $maxId, $start, $processNum) {
    $parent = true;

    $status = null;
    while (count($children)) {
        pcntl_wait($status);
        array_pop($children);
        socket_set_nonblock($sockets[0]);
        $output = socket_read($sockets[0], 100000, PHP_BINARY_READ);
        if ($output === false) {
            echo socket_strerror(socket_last_error($sockets[0]))."\n";
            continue;
        } else {
            // process output from children
        }
    }
    socket_close($sockets[0]);
}

function process_child(&$sockets, $index, $from, $to, $functionName) {
    socket_close($sockets[0]);
    $data = call_user_func_array($functionName, array($from, $to));
    if (socket_write($sockets[1], $data) === false) {
        echo socket_strerror(socket_last_error($sockets[1]))."\n";
    }
    socket_close($sockets[1]);
}

function run() {
    return true;
}