Einhorn PHP Example

server.php

<?php

declare(ticks = 1);

# Einhorn sends a "USR2" signal to our server process
# in case the server shuts down.
pcntl_signal(SIGUSR2, function() {
    fwrite(STDERR, "Worker shutting down...\n");
    exit(0);
});

# Einhorn passes the file descriptor number as first argument
# to the script.
$fd = $argv[1];

# The "php://fd" stream is a hidden gem, and can be used
# to connect to an already open file descriptor by its number.
$server = fopen("php://fd/$fd", "rb");

if (false === $server) {
    exit(1);
}

stream_set_blocking($server, 0);

for (;;) {
    $read = array($server);
    $write = null;
    $except = array($server);

    $ready = stream_select($read, $write, $except, 0, 5E5);

    if ($ready > 0) {
        if ($read) {
            handleConnection($read[0]);
        }

        if ($except) {
            exit(1);
        }
    }
}

function handleConnection($server)
{
    $client = stream_socket_accept($server);

    if (false === $client) {
        return;
    }

    $body = "Hello World!\n";

    $headers = array(
        "Content-Type: text/html",
        "Content-Length: " . strlen($body),
        "Connection: close"
    );

    fwrite($client, "HTTP/1.1 200 OK\r\n");
    fwrite($client, join("\r\n", $headers));
    fwrite($client, "\r\n\r\n");
    fwrite($client, $body);

    fclose($client);
}

start_server.sh

#!/usr/bin/env bash

# Launches 4 instances of our server script, opens 
# a socket on 127.0.0.1:1337 and passes the number
# of the file descriptor to our "server.php" as first argument.
einhorn -n 4 php server.php srv:127.0.0.1:1337