How to use blocking coroutines before Swoole\Server::start() ?

[ValiDrv]

Question

• How can coroutines be used before the HTTP server starts? without the error Swoole\Server::start(): eventLoop has already been created, unable to start Swoole\Http\Server

Example:

# Blocking function to pre-load/refresh some cache in static variables (faster than the table/have the ram).
function cacheData() {
  $wg = new Swoole\Coroutine\WaitGroup();
  # async  IO
  go(function () use ($wg) { $wg->add(1); IO::code(); $wg->done(); });
  go(function () use ($wg) { $wg->add(1); IO::code(); $wg->done(); });
  go(function () use ($wg) { $wg->add(1); IO::code(); $wg->done(); });
  go(function () use ($wg) { $wg->add(1); IO::code(); $wg->done(); });
  # wait for all of them
  $wg->wait();
}

...
cacheData(); # Load the data before the server start

$http = new Server($listen_ip, $listen_port);
# Refresh the data inside each worker at a set interval.
$http->on('workerStart', function(Server $server, int $worker_id) {
   Timer::tick(1000, function () { cacheData(); });  
});
...
$http->start(); # << error: Swoole\Server::start(): eventLoop has already been created, unable to start Swoole\Http\Server

[huanghantao]

You need to use theSwoole\Coroutine\run method and then use the coroutine inside:

<?php

use Swoole\Http\Server;

use function Swoole\Coroutine\run;

run(function () {
        $wg = new Swoole\Coroutine\WaitGroup();
  # async  IO
  go(function () use ($wg) { $wg->add(1); IO::code(); $wg->done(); });
  go(function () use ($wg) { $wg->add(1); IO::code(); $wg->done(); });
  go(function () use ($wg) { $wg->add(1); IO::code(); $wg->done(); });
  go(function () use ($wg) { $wg->add(1); IO::code(); $wg->done(); });
  # wait for all of them
  $wg->wait();
});

$http = new Server("0.0.0.0", 49501);

$http->on('request', function ($request, $response) {
    $response->end("<h1>Hello World. #".rand(1000, 9999)."</h1>");
});
$http->start();

[ValiDrv]

Awesome, thank you, makes sense now.

The Chinese documentation (wiki.swoole.com) seems very good and logical, but once passed through google translate, it can lose some info/semantics, so some terms become confusing/not so clear.