Add support for Expires and Cache-Control headers

ChangeLog

@@ -13,6 +13,7 @@ Version 1.2.0 (unreleased)
 * Add support for Wallabag service
 * Show last parsing error message in user interface
 * Disable automatically a feed after too many failures
+* Add support for Expires and Cache-Control headers (HTTP cache)
 * Add unit tests
 
 Migration procedure from 1.1.x to 1.2.0:

app/handlers/feed.php

@@ -71,6 +71,7 @@ function create_feed($user_id, $url, $download_content = false, $rtl = false, $c
             $feed,
             $resource->getEtag(),
             $resource->getLastModified(),
+            $resource->getExpiration()->getTimestamp(),
             $rtl,
             $download_content,
             $cloak_referrer
@@ -120,6 +121,7 @@ function update_feed($user_id, $feed_id)
             'etag'                  => $resource->getEtag(),
             'last_modified'         => $resource->getLastModified(),
             'last_checked'          => time(),
+            'expiration'            => $resource->getExpiration()->getTimestamp(),
             'parsing_error'         => 0,
             'parsing_error_message' => '',
         ));
@@ -135,7 +137,7 @@ function update_feed($user_id, $feed_id)
 
 function update_feeds($user_id, $limit = null)
 {
-    foreach (Model\Feed\get_feed_ids($user_id, $limit) as $feed_id) {
+    foreach (Model\Feed\get_feed_ids_to_refresh($user_id, $limit) as $feed_id) {
         update_feed($user_id, $feed_id);
     }
 }

app/models/feed.php

@@ -6,13 +6,14 @@ use Miniflux\Model\Favicon;
 use Miniflux\Model\Item;
 use Miniflux\Model\Group;
 use PicoDb\Database;
+use PicoDb\SQLException;
 use PicoFeed\Parser\Feed;
 
 const STATUS_ACTIVE   = 1;
 const STATUS_INACTIVE = 0;
 const TABLE           = 'feeds';
 
-function create($user_id, Feed $feed, $etag, $last_modified, $rtl = false, $scraper = false, $cloak_referrer = false)
+function create($user_id, Feed $feed, $etag, $last_modified, $expiration = 0, $rtl = false, $scraper = false, $cloak_referrer = false)
 {
     $db = Database::getInstance('db');
 
@@ -32,6 +33,7 @@ function create($user_id, Feed $feed, $etag, $last_modified, $rtl = false, $scra
             'etag'             => $etag,
             'last_modified'    => $last_modified,
             'last_checked'     => time(),
+            'expiration'       => $expiration,
             'cloak_referrer'   => $cloak_referrer ? 1 : 0,
         ));
 
@@ -85,12 +87,17 @@ function get_feeds_with_items_count($user_id)
     return $feeds;
 }
 
-function get_feed_ids($user_id, $limit = null)
+function get_feed_ids_to_refresh($user_id, $limit = null, $expiration = 0)
 {
+    if ($expiration === 0) {
+        $expiration = time();
+    }
+
     $query = Database::getInstance('db')
         ->table(TABLE)
         ->eq('user_id', $user_id)
         ->eq('enabled', STATUS_ACTIVE)
+        ->lte('expiration', $expiration)
         ->asc('last_checked')
         ->asc('id');
 
@@ -113,29 +120,33 @@ function get_feed($user_id, $feed_id)
 function update_feed($user_id, $feed_id, array $values)
 {
     $db = Database::getInstance('db');
-    $db->startTransaction();
 
-    $feed = $values;
+    try {
-    unset($feed['id']);
+        $db->startTransaction();
-    unset($feed['group_name']);
-    unset($feed['feed_group_ids']);
 
-    $result = Database::getInstance('db')
+        $feed = $values;
-            ->table('feeds')
+        unset($feed['id']);
-            ->eq('user_id', $user_id)
+        unset($feed['group_name']);
-            ->eq('id', $feed_id)
+        unset($feed['feed_group_ids']);
-            ->save($feed);
 
-    if ($result) {
+        $result = Database::getInstance('db')
-        if (isset($values['feed_group_ids']) && isset($values['group_name']) &&
+                ->table('feeds')
-            ! Group\update_feed_groups($user_id, $values['id'], $values['feed_group_ids'], $values['group_name'])) {
+                ->eq('user_id', $user_id)
-            $db->cancelTransaction();
+                ->eq('id', $feed_id)
-            return false;
+                ->update($feed);
+
+        if ($result) {
+            if (isset($values['feed_group_ids']) && isset($values['group_name']) &&
+                ! Group\update_feed_groups($user_id, $values['id'], $values['feed_group_ids'], $values['group_name'])) {
+                $db->cancelTransaction();
+                return false;
+            }
+
+            $db->closeTransaction();
+            return true;
         }
 
-        $db->closeTransaction();
+    } catch (SQLException $e) {}
-        return true;
-    }
 
     $db->cancelTransaction();
     return false;

app/schemas/postgres.php

@@ -5,7 +5,12 @@ namespace Miniflux\Schema;
 use PDO;
 use Miniflux\Helper;
 
-const VERSION = 2;
+const VERSION = 3;
+
+function version_3(PDO $pdo)
+{
+    $pdo->exec('ALTER TABLE feeds ADD COLUMN expiration BIGINT DEFAULT 0');
+}
 
 function version_2(PDO $pdo)
 {

app/schemas/sqlite.php

@@ -5,7 +5,12 @@ namespace Miniflux\Schema;
 use PDO;
 use Miniflux\Helper;
 
-const VERSION = 2;
+const VERSION = 3;
+
+function version_3(PDO $pdo)
+{
+    $pdo->exec('ALTER TABLE feeds ADD COLUMN expiration INTEGER DEFAULT 0');
+}
 
 function version_2(PDO $pdo)
 {

composer.json

@@ -15,7 +15,7 @@
         "fguillot/simple-validator": "v1.0.0",
         "fguillot/json-rpc": "v1.2.3",
         "fguillot/picodb": "v1.0.14 ",
-        "fguillot/picofeed": "v0.1.27",
+        "fguillot/picofeed": "v0.1.28",
         "pda/pheanstalk": "v3.1.0",
         "ircmaxell/password-compat": "^1.0.4"
     },

producer.php

@@ -17,7 +17,7 @@ $limit = get_cli_option('limit', $options);
 $connection = new Pheanstalk(BEANSTALKD_HOST);
 
 foreach (Model\User\get_all_users() as $user) {
-    foreach (Model\Feed\get_feed_ids($user['id'], $limit) as $feed_id) {
+    foreach (Model\Feed\get_feed_ids_to_refresh($user['id'], $limit) as $feed_id) {
         $payload = serialize(array(
             'feed_id' => $feed_id,
             'user_id' => $user['id'],

tests/unit/FeedModelTest.php

@@ -64,13 +64,22 @@ class FeedModelTest extends BaseTest
         $feed->setTitle('Some feed');
         $feed->setFeedUrl('another feed url');
         $feed->setSiteUrl('site url');
-        $this->assertEquals(2, Model\Feed\create(1, $feed, 'etag', 'last modified'));
+        $this->assertEquals(2, Model\Feed\create(1, $feed, 'etag', 'last modified', time()));
 
-        $feed_ids = Model\Feed\get_feed_ids(1);
+        $feed = new Feed();
-        $this->assertEquals(array(1, 2), $feed_ids);
+        $feed->setTitle('Some feed');
+        $feed->setFeedUrl('some other feed url');
+        $feed->setSiteUrl('site url');
+        $this->assertEquals(3, Model\Feed\create(1, $feed, 'etag', 'last modified', strtotime('-1 week')));
 
-        $feed_ids = Model\Feed\get_feed_ids(1, 1);
+        $feed_ids = Model\Feed\get_feed_ids_to_refresh(1);
+        $this->assertEquals(array(1, 2, 3), $feed_ids);
+
+        $feed_ids = Model\Feed\get_feed_ids_to_refresh(1, 1);
         $this->assertEquals(array(1), $feed_ids);
+
+        $feed_ids = Model\Feed\get_feed_ids_to_refresh(1, null, strtotime('-2 days'));
+        $this->assertEquals(array(1, 3), $feed_ids);
     }
 
     public function testGetFeedWithItemsCount()

vendor/autoload.php

@@ -4,4 +4,4 @@
 
 require_once __DIR__ . '/composer' . '/autoload_real.php';
 
-return ComposerAutoloaderInitfd7e8d436e1dc450edc3153ac8bc31b4::getLoader();
+return ComposerAutoloaderInitfc88bf644a3dc0d30b5792ad2fec7895::getLoader();

vendor/composer/autoload_real.php

@@ -2,7 +2,7 @@
 
 // autoload_real.php @generated by Composer
 
-class ComposerAutoloaderInitfd7e8d436e1dc450edc3153ac8bc31b4
+class ComposerAutoloaderInitfc88bf644a3dc0d30b5792ad2fec7895
 {
     private static $loader;
 
@@ -19,15 +19,15 @@ class ComposerAutoloaderInitfd7e8d436e1dc450edc3153ac8bc31b4
             return self::$loader;
         }
 
-        spl_autoload_register(array('ComposerAutoloaderInitfd7e8d436e1dc450edc3153ac8bc31b4', 'loadClassLoader'), true, true);
+        spl_autoload_register(array('ComposerAutoloaderInitfc88bf644a3dc0d30b5792ad2fec7895', 'loadClassLoader'), true, true);
         self::$loader = $loader = new \Composer\Autoload\ClassLoader();
-        spl_autoload_unregister(array('ComposerAutoloaderInitfd7e8d436e1dc450edc3153ac8bc31b4', 'loadClassLoader'));
+        spl_autoload_unregister(array('ComposerAutoloaderInitfc88bf644a3dc0d30b5792ad2fec7895', 'loadClassLoader'));
 
         $useStaticLoader = PHP_VERSION_ID >= 50600 && !defined('HHVM_VERSION');
         if ($useStaticLoader) {
             require_once __DIR__ . '/autoload_static.php';
 
-            call_user_func(\Composer\Autoload\ComposerStaticInitfd7e8d436e1dc450edc3153ac8bc31b4::getInitializer($loader));
+            call_user_func(\Composer\Autoload\ComposerStaticInitfc88bf644a3dc0d30b5792ad2fec7895::getInitializer($loader));
         } else {
             $map = require __DIR__ . '/autoload_namespaces.php';
             foreach ($map as $namespace => $path) {
@@ -48,19 +48,19 @@ class ComposerAutoloaderInitfd7e8d436e1dc450edc3153ac8bc31b4
         $loader->register(true);
 
         if ($useStaticLoader) {
-            $includeFiles = Composer\Autoload\ComposerStaticInitfd7e8d436e1dc450edc3153ac8bc31b4::$files;
+            $includeFiles = Composer\Autoload\ComposerStaticInitfc88bf644a3dc0d30b5792ad2fec7895::$files;
         } else {
             $includeFiles = require __DIR__ . '/autoload_files.php';
         }
         foreach ($includeFiles as $fileIdentifier => $file) {
-            composerRequirefd7e8d436e1dc450edc3153ac8bc31b4($fileIdentifier, $file);
+            composerRequirefc88bf644a3dc0d30b5792ad2fec7895($fileIdentifier, $file);
         }
 
         return $loader;
     }
 }
 
-function composerRequirefd7e8d436e1dc450edc3153ac8bc31b4($fileIdentifier, $file)
+function composerRequirefc88bf644a3dc0d30b5792ad2fec7895($fileIdentifier, $file)
 {
     if (empty($GLOBALS['__composer_autoload_files'][$fileIdentifier])) {
         require $file;

vendor/composer/autoload_static.php

@@ -4,7 +4,7 @@
 
 namespace Composer\Autoload;
 
-class ComposerStaticInitfd7e8d436e1dc450edc3153ac8bc31b4
+class ComposerStaticInitfc88bf644a3dc0d30b5792ad2fec7895
 {
     public static $files = array (
         'e40631d46120a9c38ea139981f8dab26' => __DIR__ . '/..' . '/ircmaxell/password-compat/lib/password.php',
@@ -277,10 +277,10 @@ class ComposerStaticInitfd7e8d436e1dc450edc3153ac8bc31b4
     public static function getInitializer(ClassLoader $loader)
     {
         return \Closure::bind(function () use ($loader) {
-            $loader->prefixLengthsPsr4 = ComposerStaticInitfd7e8d436e1dc450edc3153ac8bc31b4::$prefixLengthsPsr4;
+            $loader->prefixLengthsPsr4 = ComposerStaticInitfc88bf644a3dc0d30b5792ad2fec7895::$prefixLengthsPsr4;
-            $loader->prefixDirsPsr4 = ComposerStaticInitfd7e8d436e1dc450edc3153ac8bc31b4::$prefixDirsPsr4;
+            $loader->prefixDirsPsr4 = ComposerStaticInitfc88bf644a3dc0d30b5792ad2fec7895::$prefixDirsPsr4;
-            $loader->prefixesPsr0 = ComposerStaticInitfd7e8d436e1dc450edc3153ac8bc31b4::$prefixesPsr0;
+            $loader->prefixesPsr0 = ComposerStaticInitfc88bf644a3dc0d30b5792ad2fec7895::$prefixesPsr0;
-            $loader->classMap = ComposerStaticInitfd7e8d436e1dc450edc3153ac8bc31b4::$classMap;
+            $loader->classMap = ComposerStaticInitfc88bf644a3dc0d30b5792ad2fec7895::$classMap;
 
         }, null, ClassLoader::class);
     }

vendor/composer/installed.json

@@ -37,6 +37,89 @@
         "description": "Simple validator library",
         "homepage": "https://github.com/fguillot/simpleValidator"
     },
+    {
+        "name": "fguillot/json-rpc",
+        "version": "v1.2.3",
+        "version_normalized": "1.2.3.0",
+        "source": {
+            "type": "git",
+            "url": "https://github.com/fguillot/JsonRPC.git",
+            "reference": "86dd3cf0724bc495cb31882122e9a3a77b9a2ffc"
+        },
+        "dist": {
+            "type": "zip",
+            "url": "https://api.github.com/repos/fguillot/JsonRPC/zipball/86dd3cf0724bc495cb31882122e9a3a77b9a2ffc",
+            "reference": "86dd3cf0724bc495cb31882122e9a3a77b9a2ffc",
+            "shasum": ""
+        },
+        "require": {
+            "php": ">=5.3.4"
+        },
+        "require-dev": {
+            "phpunit/phpunit": "4.8.*"
+        },
+        "time": "2016-12-15 03:00:30",
+        "type": "library",
+        "installation-source": "dist",
+        "autoload": {
+            "psr-0": {
+                "JsonRPC": "src/"
+            }
+        },
+        "notification-url": "https://packagist.org/downloads/",
+        "license": [
+            "MIT"
+        ],
+        "authors": [
+            {
+                "name": "Frédéric Guillot"
+            }
+        ],
+        "description": "Simple Json-RPC client/server library that just works",
+        "homepage": "https://github.com/fguillot/JsonRPC"
+    },
+    {
+        "name": "fguillot/picodb",
+        "version": "v1.0.14",
+        "version_normalized": "1.0.14.0",
+        "source": {
+            "type": "git",
+            "url": "https://github.com/fguillot/picoDb.git",
+            "reference": "86a831302ab10af800c83dbe4b3b01c88d5433f1"
+        },
+        "dist": {
+            "type": "zip",
+            "url": "https://api.github.com/repos/fguillot/picoDb/zipball/86a831302ab10af800c83dbe4b3b01c88d5433f1",
+            "reference": "86a831302ab10af800c83dbe4b3b01c88d5433f1",
+            "shasum": ""
+        },
+        "require": {
+            "php": ">=5.3.0"
+        },
+        "require-dev": {
+            "phpunit/phpunit": "4.8.*"
+        },
+        "time": "2016-07-16 22:59:59",
+        "type": "library",
+        "installation-source": "dist",
+        "autoload": {
+            "psr-0": {
+                "PicoDb": "lib/"
+            }
+        },
+        "notification-url": "https://packagist.org/downloads/",
+        "license": [
+            "MIT"
+        ],
+        "authors": [
+            {
+                "name": "Frédéric Guillot",
+                "homepage": "https://github.com/fguillot/"
+            }
+        ],
+        "description": "Minimalist database query builder",
+        "homepage": "https://github.com/fguillot/picoDb"
+    },
     {
         "name": "zendframework/zendxml",
         "version": "1.0.2",
@@ -84,6 +167,61 @@
             "zf2"
         ]
     },
+    {
+        "name": "fguillot/picofeed",
+        "version": "v0.1.28",
+        "version_normalized": "0.1.28.0",
+        "source": {
+            "type": "git",
+            "url": "https://github.com/fguillot/picoFeed.git",
+            "reference": "9da506c308bcb40b6fc630f9123466028c03170b"
+        },
+        "dist": {
+            "type": "zip",
+            "url": "https://api.github.com/repos/fguillot/picoFeed/zipball/9da506c308bcb40b6fc630f9123466028c03170b",
+            "reference": "9da506c308bcb40b6fc630f9123466028c03170b",
+            "shasum": ""
+        },
+        "require": {
+            "ext-dom": "*",
+            "ext-iconv": "*",
+            "ext-libxml": "*",
+            "ext-simplexml": "*",
+            "ext-xml": "*",
+            "php": ">=5.3.0",
+            "zendframework/zendxml": "^1.0"
+        },
+        "require-dev": {
+            "phpdocumentor/reflection-docblock": "2.0.4",
+            "phpunit/phpunit": "4.8.26",
+            "symfony/yaml": "2.8.7"
+        },
+        "suggest": {
+            "ext-curl": "PicoFeed will use cURL if present"
+        },
+        "time": "2016-12-29 00:06:41",
+        "bin": [
+            "picofeed"
+        ],
+        "type": "library",
+        "installation-source": "dist",
+        "autoload": {
+            "psr-0": {
+                "PicoFeed": "lib/"
+            }
+        },
+        "notification-url": "https://packagist.org/downloads/",
+        "license": [
+            "MIT"
+        ],
+        "authors": [
+            {
+                "name": "Frédéric Guillot"
+            }
+        ],
+        "description": "Modern library to handle RSS/Atom feeds",
+        "homepage": "https://github.com/fguillot/picoFeed"
+    },
     {
         "name": "pda/pheanstalk",
         "version": "v3.1.0",
@@ -136,48 +274,6 @@
             "beanstalkd"
         ]
     },
-    {
-        "name": "fguillot/picodb",
-        "version": "v1.0.14",
-        "version_normalized": "1.0.14.0",
-        "source": {
-            "type": "git",
-            "url": "https://github.com/fguillot/picoDb.git",
-            "reference": "86a831302ab10af800c83dbe4b3b01c88d5433f1"
-        },
-        "dist": {
-            "type": "zip",
-            "url": "https://api.github.com/repos/fguillot/picoDb/zipball/86a831302ab10af800c83dbe4b3b01c88d5433f1",
-            "reference": "86a831302ab10af800c83dbe4b3b01c88d5433f1",
-            "shasum": ""
-        },
-        "require": {
-            "php": ">=5.3.0"
-        },
-        "require-dev": {
-            "phpunit/phpunit": "4.8.*"
-        },
-        "time": "2016-07-16 22:59:59",
-        "type": "library",
-        "installation-source": "dist",
-        "autoload": {
-            "psr-0": {
-                "PicoDb": "lib/"
-            }
-        },
-        "notification-url": "https://packagist.org/downloads/",
-        "license": [
-            "MIT"
-        ],
-        "authors": [
-            {
-                "name": "Frédéric Guillot",
-                "homepage": "https://github.com/fguillot/"
-            }
-        ],
-        "description": "Minimalist database query builder",
-        "homepage": "https://github.com/fguillot/picoDb"
-    },
     {
         "name": "ircmaxell/password-compat",
         "version": "v1.0.4",
@@ -221,101 +317,5 @@
             "hashing",
             "password"
         ]
-    },
-    {
-        "name": "fguillot/json-rpc",
-        "version": "v1.2.3",
-        "version_normalized": "1.2.3.0",
-        "source": {
-            "type": "git",
-            "url": "https://github.com/fguillot/JsonRPC.git",
-            "reference": "86dd3cf0724bc495cb31882122e9a3a77b9a2ffc"
-        },
-        "dist": {
-            "type": "zip",
-            "url": "https://api.github.com/repos/fguillot/JsonRPC/zipball/86dd3cf0724bc495cb31882122e9a3a77b9a2ffc",
-            "reference": "86dd3cf0724bc495cb31882122e9a3a77b9a2ffc",
-            "shasum": ""
-        },
-        "require": {
-            "php": ">=5.3.4"
-        },
-        "require-dev": {
-            "phpunit/phpunit": "4.8.*"
-        },
-        "time": "2016-12-15 03:00:30",
-        "type": "library",
-        "installation-source": "dist",
-        "autoload": {
-            "psr-0": {
-                "JsonRPC": "src/"
-            }
-        },
-        "notification-url": "https://packagist.org/downloads/",
-        "license": [
-            "MIT"
-        ],
-        "authors": [
-            {
-                "name": "Frédéric Guillot"
-            }
-        ],
-        "description": "Simple Json-RPC client/server library that just works",
-        "homepage": "https://github.com/fguillot/JsonRPC"
-    },
-    {
-        "name": "fguillot/picofeed",
-        "version": "v0.1.27",
-        "version_normalized": "0.1.27.0",
-        "source": {
-            "type": "git",
-            "url": "https://github.com/fguillot/picoFeed.git",
-            "reference": "41924841d3cd0480364ca9bcb90abe095d744457"
-        },
-        "dist": {
-            "type": "zip",
-            "url": "https://api.github.com/repos/fguillot/picoFeed/zipball/41924841d3cd0480364ca9bcb90abe095d744457",
-            "reference": "41924841d3cd0480364ca9bcb90abe095d744457",
-            "shasum": ""
-        },
-        "require": {
-            "ext-dom": "*",
-            "ext-iconv": "*",
-            "ext-libxml": "*",
-            "ext-simplexml": "*",
-            "ext-xml": "*",
-            "php": ">=5.3.0",
-            "zendframework/zendxml": "^1.0"
-        },
-        "require-dev": {
-            "phpdocumentor/reflection-docblock": "2.0.4",
-            "phpunit/phpunit": "4.8.26",
-            "symfony/yaml": "2.8.7"
-        },
-        "suggest": {
-            "ext-curl": "PicoFeed will use cURL if present"
-        },
-        "time": "2016-12-26 22:25:33",
-        "bin": [
-            "picofeed"
-        ],
-        "type": "library",
-        "installation-source": "dist",
-        "autoload": {
-            "psr-0": {
-                "PicoFeed": "lib/"
-            }
-        },
-        "notification-url": "https://packagist.org/downloads/",
-        "license": [
-            "MIT"
-        ],
-        "authors": [
-            {
-                "name": "Frédéric Guillot"
-            }
-        ],
-        "description": "Modern library to handle RSS/Atom feeds",
-        "homepage": "https://github.com/fguillot/picoFeed"
     }
 ]

vendor/fguillot/picofeed/lib/PicoFeed/Client/Client.php

@@ -2,6 +2,7 @@
 
 namespace PicoFeed\Client;
 
+use DateTime;
 use LogicException;
 use PicoFeed\Logging\Logger;
 use PicoFeed\Config\Config;
@@ -55,6 +56,13 @@ abstract class Client
      */
     protected $last_modified = '';
 
+    /**
+     * Expiration DateTime
+     *
+     * @var DateTime
+     */
+    protected $expiration = null;
+
     /**
      * Proxy hostname.
      *
@@ -214,6 +222,9 @@ abstract class Client
         $this->handleErrorResponse($response);
         $this->handleNormalResponse($response);
 
+        $this->expiration = $this->parseExpiration($response['headers']);
+        Logger::setMessage(get_called_class().' Expiration: '.$this->expiration->format(DATE_ISO8601));
+
         return $this;
     }
 
@@ -241,6 +252,9 @@ abstract class Client
      * Handle Http Error codes
      *
      * @param array $response Client response
+     * @throws ForbiddenException
+     * @throws InvalidUrlException
+     * @throws UnauthorizedException
      */
     protected function handleErrorResponse(array $response)
     {
@@ -402,13 +416,12 @@ abstract class Client
     /**
      * Set the url.
      *
+     * @param  $url
      * @return string
-     * @return \PicoFeed\Client\Client
      */
     public function setUrl($url)
     {
         $this->url = $url;
-
         return $this;
     }
 
@@ -670,4 +683,31 @@ abstract class Client
     {
         return $code == 301 || $code == 302 || $code == 303 || $code == 307;
     }
+
+    public function parseExpiration(HttpHeaders $headers)
+    {
+        if (isset($headers['Cache-Control'])) {
+            if (preg_match('/s-maxage=(\d+)/', $headers['Cache-Control'], $matches)) {
+                return new DateTime('+' . $matches[1] . ' seconds');
+            } else if (preg_match('/max-age=(\d+)/', $headers['Cache-Control'], $matches)) {
+                return new DateTime('+' . $matches[1] . ' seconds');
+            }
+        }
+
+        if (! empty($headers['Expires'])) {
+            return new DateTime($headers['Expires']);
+        }
+
+        return new DateTime();
+    }
+
+    /**
+     * Get expiration date time from "Expires" or "Cache-Control" headers
+     *
+     * @return DateTime
+     */
+    public function getExpiration()
+    {
+        return $this->expiration ?: new DateTime();
+    }
 }