diff --git a/core/lib/Drupal/Component/PhpStorage/FileReadOnlyStorage.php b/core/lib/Drupal/Component/PhpStorage/FileReadOnlyStorage.php
index 92924a1..1a460ad 100644
--- a/core/lib/Drupal/Component/PhpStorage/FileReadOnlyStorage.php
+++ b/core/lib/Drupal/Component/PhpStorage/FileReadOnlyStorage.php
@@ -64,9 +64,9 @@ public function delete($name) {
   }
 
   /**
-   * Returns the full path where the file is or should be stored.
+   * {@inheritdoc}
    */
-  protected function getFullPath($name) {
+  public function getFullPath($name) {
     return $this->directory . '/' . $name;
   }
 
@@ -87,13 +87,6 @@ public function deleteAll() {
   /**
    * {@inheritdoc}
    */
-  public function getPath($name) {
-    return $this->getFullPath($name);
-  }
-
-  /**
-   * {@inheritdoc}
-   */
   public function listAll() {
     $names = array();
     if (file_exists($this->directory)) {
diff --git a/core/lib/Drupal/Component/PhpStorage/FileStorage.php b/core/lib/Drupal/Component/PhpStorage/FileStorage.php
index 0eb2502..78f1222 100644
--- a/core/lib/Drupal/Component/PhpStorage/FileStorage.php
+++ b/core/lib/Drupal/Component/PhpStorage/FileStorage.php
@@ -195,17 +195,10 @@ public function delete($name) {
   }
 
   /**
-   * Returns the full path where the file is or should be stored.
-   */
-  protected function getFullPath($name) {
-    return $this->directory . '/' . $name;
-  }
-
-  /**
    * {@inheritdoc}
    */
-  public function getPath($name) {
-    return $this->getFullPath($name);
+  public function getFullPath($name) {
+    return $this->directory . '/' . $name;
   }
 
   /**
diff --git a/core/lib/Drupal/Component/PhpStorage/PhpStorageInterface.php b/core/lib/Drupal/Component/PhpStorage/PhpStorageInterface.php
index e1b0649..1f6a682 100644
--- a/core/lib/Drupal/Component/PhpStorage/PhpStorageInterface.php
+++ b/core/lib/Drupal/Component/PhpStorage/PhpStorageInterface.php
@@ -89,7 +89,7 @@ public function deleteAll();
    *   The full file path for the provided name. Return FALSE if the
    *   implementation needs to prevent access to the file.
    */
-  public function getPath($name);
+  public function getFullPath($name);
 
   /**
    * Lists all the files in the storage.
diff --git a/core/lib/Drupal/Core/Cache/PhpBackend.php b/core/lib/Drupal/Core/Cache/PhpBackend.php
index 71349c0..23ed324 100644
--- a/core/lib/Drupal/Core/Cache/PhpBackend.php
+++ b/core/lib/Drupal/Core/Cache/PhpBackend.php
@@ -2,7 +2,7 @@
 
 /**
  * @file
- * Definition of Drupal\Core\Cache\PhpBackend.
+ * Contains \Drupal\Core\Cache\PhpBackend.
  */
 
 namespace Drupal\Core\Cache;
@@ -16,6 +16,11 @@
  * Stores cache items in a PHP file using a storage that implements
  * Drupal\Component\PhpStorage\PhpStorageInterface.
  *
+ * This is fast because of PHP's opcode caching mechanism. Once a file's
+ * content is stored in PHP's opcode cache, including it doesn't require
+ * reading the contents from a filesystem. Instead, PHP will use the already
+ * compiled opcodes stored in memory.
+ *
  * @ingroup cache
  */
 class PhpBackend implements CacheBackendInterface {
@@ -44,7 +49,7 @@ public function __construct($bin) {
    * {@inheritdoc}
    */
   public function get($cid, $allow_invalid = FALSE) {
-    if ($file = $this->storage()->getPath($cid)) {
+    if ($file = $this->storage()->getFullPath($cid)) {
       $cache = @include $file;
     }
     if (isset($cache)) {
@@ -87,6 +92,8 @@ public function getMultiple(&$cids, $allow_invalid = FALSE) {
    *
    * @param object $cache
    *   An item loaded from cache_get() or cache_get_multiple().
+   * @param bool $allow_invalid
+   *   If FALSE, the method returns FALSE if the cache item is not valid.
    *
    * @return mixed
    *   The item with data as appropriate or FALSE if there is no
diff --git a/core/modules/system/lib/Drupal/system/Tests/Cache/PhpBackendUnitTest.php b/core/modules/system/lib/Drupal/system/Tests/Cache/PhpBackendUnitTest.php
index 6258550..82c877c 100644
--- a/core/modules/system/lib/Drupal/system/Tests/Cache/PhpBackendUnitTest.php
+++ b/core/modules/system/lib/Drupal/system/Tests/Cache/PhpBackendUnitTest.php
@@ -2,7 +2,7 @@
 
 /**
  * @file
- * Definition of Drupal\system\Tests\Cache\PhpBackendUnitTest.
+ * Contains \Drupal\system\Tests\Cache\PhpBackendUnitTest.
  */
 
 namespace Drupal\system\Tests\Cache;