Improve handling of deprecated apis

docs/en/04_Changelogs/4.2.0.md

@@ -236,6 +236,18 @@ that the response should be considered not cacheable.
 See [Developer Guide: Performance > HTTP Cache Headers](/developer_guide/performance/http_cache_headers)
 for details on the new API.
 
+#### Disabling legacy cache headers
+
+In order to forcibly disable all deprecated HTTP APIs you can set the below config:
+
+```yaml
+SilverStripe\Control\HTTP:
+  ignoreDeprecatedCaching: true
+```
+
+This will ensure that any code paths that use the old API will not interefere with upgraded code
+that interferes with the new behaviour.
+
 #### Example Usage
 
 ##### Global opt-in for page content 

src/Control/HTTP.php

@@ -53,6 +53,13 @@ class HTTP
      */
     private static $disable_http_cache = false;
 
+    /**
+     * Set to true to disable all deprecated HTTP Cache settings
+     *
+     * @var bool
+     */
+    private static $ignoreDeprecatedCaching = false;
+
     /**
      * Mapping of extension to mime types
      *
@@ -424,6 +431,11 @@ class HTTP
     {
         Deprecation::notice('5.0', 'Headers are added automatically by HTTPCacheControlMiddleware instead.');
 
+        // Skip if deprecated API is disabled
+        if (Config::inst()->get(HTTP::class, 'ignoreDeprecatedCaching')) {
+            return;
+        }
+
         // Ensure a valid response object is provided
         if (!$response instanceof HTTPResponse) {
             user_error("HTTP::add_cache_headers() must be passed an HTTPResponse object", E_USER_WARNING);
@@ -449,11 +461,30 @@ class HTTP
         /** @var HTTPRequest $request */
         $request = Injector::inst()->get(HTTPRequest::class);
 
-        $config = Config::forClass(__CLASS__);
+        // Run middleware
+        ChangeDetectionMiddleware::singleton()->process($request, function (HTTPRequest $request) use ($response) {
+            return HTTPCacheControlMiddleware::singleton()->process($request, function (HTTPRequest $request) use ($response) {
+                return $response;
+            });
+        });
+    }
+
+    /**
+     * Ensure that all deprecated HTTP cache settings are respected
+     *
+     * @deprecated 4.2..5.0 Use HTTPCacheControlMiddleware instead
+     * @param HTTPRequest $request
+     * @param HTTPResponse $response
+     */
+    public static function augmentState(HTTPRequest $request, HTTPResponse $response)
+    {
+        // Skip if deprecated API is disabled
+        $config = Config::forClass(HTTP::class);
+        if ($config->get('ignoreDeprecatedCaching')) {
+            return;
+        }
 
-        // Get current cache control state
         $cacheControlMiddleware = HTTPCacheControlMiddleware::singleton();
-        $changeDetectionMiddleware = ChangeDetectionMiddleware::singleton();
 
         // if http caching is disabled by config, disable it - used on dev environments due to frequently changing
         // templates and other data. will be overridden by forced publicCache(true) or privateCache(true) calls
@@ -489,13 +520,6 @@ class HTTP
             Deprecation::notice('5.0', 'Etag should not be set explicitly');
             $response->addHeader('ETag', self::$etag);
         }
-
-        // Run middleware
-        $changeDetectionMiddleware->process($request, function (HTTPRequest $request) use ($cacheControlMiddleware, $response) {
-            return $cacheControlMiddleware->process($request, function (HTTPRequest $request) use ($response) {
-                return $response;
-            });
-        });
     }
 
     /**

src/Control/Middleware/HTTPCacheControlMiddleware.php

@@ -3,6 +3,7 @@
 namespace SilverStripe\Control\Middleware;
 
 use InvalidArgumentException;
+use SilverStripe\Control\HTTP;
 use SilverStripe\Control\HTTPRequest;
 use SilverStripe\Control\HTTPResponse;
 use SilverStripe\Control\HTTPResponse_Exception;
@@ -49,6 +50,9 @@ class HTTPCacheControlMiddleware implements HTTPMiddleware, Resettable
         // Update state based on current request and response objects
         $this->augmentState($request, $response);
 
+        // Update state based on deprecated HTTP settings
+        HTTP::augmentState($request, $response);
+
         // Add all headers to this response object
         $this->applyToResponse($response);
 

src/Control/RSS/RSSFeed.php

@@ -2,6 +2,7 @@
 
 namespace SilverStripe\Control\RSS;
 
+use SilverStripe\Control\Middleware\HTTPCacheControlMiddleware;
 use SilverStripe\ORM\SS_List;
 use SilverStripe\ORM\ArrayList;
 use SilverStripe\ORM\FieldType\DBHTMLText;
@@ -226,11 +227,11 @@ class RSSFeed extends ViewableData
         $response = Controller::curr()->getResponse();
 
         if (is_int($this->lastModified)) {
-            HTTP::register_modification_timestamp($this->lastModified);
+            HTTPCacheControlMiddleware::singleton()->registerModificationDate($this->lastModified);
             $response->addHeader("Last-Modified", gmdate("D, d M Y H:i:s", $this->lastModified) . ' GMT');
         }
         if (!empty($this->etag)) {
-            HTTP::register_etag($this->etag);
+            $response->addHeader('ETag', "\"{$this->etag}\"");
         }
 
         $response->addHeader("Content-Type", "application/rss+xml; charset=utf-8");

src/ORM/DataObject.php

@@ -380,13 +380,6 @@ class DataObject extends ViewableData implements DataObjectInterface, i18nEntity
 
         $this->original = $this->record;
 
-        // Keep track of the modification date of all the data sourced to make this page
-        // From this we create a Last-Modified HTTP header
-        if (isset($record['LastEdited'])) {
-            HTTPCacheControlMiddleware::singleton()
-                ->registerModificationDate($record['LastEdited']);
-        }
-
         // Must be called after parent constructor
         if (!$isSingleton && (!isset($this->record['ID']) || !$this->record['ID'])) {
             $this->populateDefaults();