DefaultConnectionFactory example

$proxySocket = new SocketAddress($proxyUrl['host'], $proxyUrl['port']);
            $proxyHeaders = $options['proxy']['auth'] ? ['Proxy-Authorization' => $options['proxy']['auth']] : [];

            if ('ssl' === $proxyUrl['scheme']) {
                $connector = new Https1TunnelConnector($proxySocket, $context->getTlsContext(), $proxyHeaders, $connector);
            } else {
                $connector = new Http1TunnelConnector($proxySocket, $proxyHeaders, $connector);
            }
        }

        $maxHostConnections = 0 < $this->maxHostConnections ? $this->maxHostConnections : \PHP_INT_MAX;
        $pool = new DefaultConnectionFactory($connector, $context);
        $pool = ConnectionLimitingPool::byAuthority($maxHostConnections, $pool);

        return $this->clients[$key] = [($this->clientConfigurator)(new PooledHttpClient($pool)), $handleConnector];
    }

    private function handlePush(Request $request, Promise $response, array $options): Promise
    {
        $deferred = new Deferred();
        $authority = $request->getUri()->getAuthority();

        if ($this->maxPendingPushes <= \count($this->pushedResponses[$authority] ?? [])) {