Issue #2044583 by jlindsey15, Gábor Hojtsy, Wim Leers, Berdir: Add...

Issue #2044583 by jlindsey15, Gábor Hojtsy, Wim Leers, Berdir: Add EntityChangedInterface to allow entities with 'changed' field to be properly cached.

core/lib/Drupal/Core/Entity/EntityChangedInterface.php

+<?php
+
+/**
+ * @file
+ * Contains \Drupal\Core\Entity\EntityChangedInterface.
+ */
+
+namespace Drupal\Core\Entity;
+
+/**
+ * Defines a common interface for entity change timestamp tracking.
+ *
+ * This data may be useful for more precise cache invalidation (especially
+ * on the client side) and concurrent editing locking.
+ */
+interface EntityChangedInterface {
+
+  /**
+   * Returns the timestamp of the last entity change.
+   *
+   * @return int
+   *   The timestamp of the last entity save operation.
+   */
+  public function getChangedTime();
+
+}

core/modules/comment/lib/Drupal/comment/CommentInterface.php

@@ -8,11 +8,12 @@
 namespace Drupal\comment;
 
 use Drupal\Core\Entity\ContentEntityInterface;
+use Drupal\Core\Entity\EntityChangedInterface;
 
 /**
  * Provides an interface defining a comment entity.
  */
-interface CommentInterface extends ContentEntityInterface {
+interface CommentInterface extends ContentEntityInterface, EntityChangedInterface {
 
   /**
    * Returns the permalink URL for this comment.

core/modules/comment/lib/Drupal/comment/Entity/Comment.php

@@ -460,4 +460,12 @@ public static function baseFieldDefinitions($entity_type) {
     );
     return $properties;
   }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getChangedTime() {
+    return $this->changed->value;
+  }
+
 }

core/modules/file/lib/Drupal/file/FileInterface.php

@@ -8,12 +8,13 @@
 namespace Drupal\file;
 
 use Drupal\Core\Entity\ContentEntityInterface;
+use Drupal\Core\Entity\EntityChangedInterface;
 use Drupal\user\UserInterface;
 
 /**
  * Defines getter and setter methods for file entity base fields.
  */
-interface FileInterface extends ContentEntityInterface {
+interface FileInterface extends ContentEntityInterface, EntityChangedInterface {
 
   /**
    * Returns the name of the file.
@@ -110,14 +111,6 @@ public function setPermanent();
    */
   public function setTemporary();
 
-  /**
-   * Returns the timestamp when the file was created.
-   *
-   * @return int
-   *   Creation timestamp of the file.
-   */
-  public function getChangedTime();
-
   /**
    * Returns the user that owns this file.
    *

core/modules/node/lib/Drupal/node/NodeInterface.php

@@ -7,13 +7,14 @@
 
 namespace Drupal\node;
 
+use Drupal\Core\Entity\EntityChangedInterface;
 use Drupal\Core\Entity\ContentEntityInterface;
 use Drupal\user\UserInterface;
 
 /**
  * Provides an interface defining a node entity.
  */
-interface NodeInterface extends ContentEntityInterface {
+interface NodeInterface extends ContentEntityInterface, EntityChangedInterface {
 
   /**
    * Returns the node type.
@@ -62,14 +63,6 @@ public function getCreatedTime();
    */
   public function setCreatedTime($timestamp);
 
-  /**
-   * Returns the node modification timestamp.
-   *
-   * @return int
-   *   Node creation timestamp.
-   */
-  public function getChangedTime();
-
   /**
    * Returns the node promotion status.
    *