Experimental curl-based Service driver

Probably it's not yet functional

README.md

@@ -11,7 +11,7 @@ Arsse has the following requirements:
 - A Web server; example configuration currently exists for:
     - nginx
     - Apache 2
-- PHP 7.0 or newer with the following extensions:
+- PHP 7.0.7 or newer with the following extensions:
     - [intl](http://php.net/manual/en/book.intl.php)
     - [json](http://php.net/manual/en/book.json.php)
     - [hash](http://php.net/manual/en/book.hash.php)

lib/Service/Curl/Driver.php

@@ -0,0 +1,72 @@
+<?php
+declare(strict_types=1);
+namespace JKingWeb\Arsse\Service\Curl;
+use JKingWeb\Arsse\Data;
+
+class Driver implements \JKingWeb\Arsse\Service\Driver {
+    protected $options = [];
+    protected $queue;
+    protected $handles = [];
+    
+    static function driverName(): string {
+        return Data::$lang->msg("Driver.Service.Curl.Name");
+    }
+
+    static function requirementsMet(): bool {
+        return extension_loaded("curl");
+    }
+
+    function __construct() {
+        //default curl options for individual requests
+        $this->options = [
+            \CURLOPT_URL => Data::$serviceCurlBase."index.php/apps/news/api/v1-2/feeds/update",
+            \CURLOPT_CUSTOMREQUEST => "GET",
+            \CURLOPT_FAILONERROR => false,
+            \CURLOPT_FOLLOWLOCATION => false,
+            \CURLOPT_FORBID_REUSE => false,
+            \CURLOPT_CONNECTTIMEOUT => 20,
+            \CURLOPT_DNS_CACHE_TIMEOUT => 360, // FIXME: this should probably be twice the update-check interval so that the DNS cache is always in memory
+            \CURLOPT_PROTOCOLS => \CURLPROTO_HTTP | \CURLPROTO_HTTPS,
+            \CURLOPT_DEFAULT_PROTOCOL => "https",
+            \CURLOPT_USERAGENT => Data::$conf->fetchUserAgentString,
+            \CURLMOPT_MAX_HOST_CONNECTIONS => Data::$conf->serviceQueueWidth,
+            \CURLOPT_HTTPHEADER => [
+                'Accept: application/json',
+                'Content-Type: application/json',
+            ],
+            \CURLOPT_HEADER => false,
+        ];
+        // start an async session
+        $this->queue = curl_multi_init();
+        // enable pipelining
+        curl_multi_setopt($this->queue, \CURLMOPT_PIPELINING, 1);
+    }
+
+    function qeueue(int ...$feeds): int {
+        foreach($feeds as $id) {
+            $h = curl_init();
+            curl_setopt($h, \CURLOPT_POSTFIELDS, json_encode(['userId' => "", 'feedId' => $id]));
+            $this->handles[] = $h;
+            curl_multi_add_handle($this->queue, $h);
+        }
+        return sizeof($this->handles);
+    }
+
+    function exec(): int {
+        $active = 0;
+        do {
+            curl_multi_exec($this->queue, $active);
+            curl_multi_select($this->queue);
+        } while ($active > 0);
+        return Data::$conf->serviceQueueWidth - $active;
+    }
+
+    function clean(): bool {
+        foreach($this->handles as $h) {
+            curl_multi_remove_handle($this->queue, $h);
+            curl_close($h);
+        }
+        $this->handles = [];
+        return true;
+    }
+}