feature #19507 [FrameworkBundle] Introduce a cache warmer for Serializer based on PhpArrayAdapter (tgalopin)

This PR was merged into the 3.2-dev branch.

Discussion
----------

[FrameworkBundle] Introduce a cache warmer for Serializer based on PhpArrayAdapter

| Q             | A
| ------------- | ---
| Branch?       | master
| Bug fix?      | no
| New feature?  | yes
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | -
| License       | MIT
| Doc PR        | -

Following the cache warmer for annotations (#18533) and for the validator (#19485), this PR introduces a cache warmer for the Serializer YAML and XML metadata configuration (mainly groups).

Based on the PhpArrayAdapter, it uses the naming conventions (Resources/config/serialization) to find the files and compile them into a single PHP file stored in the cache directory. This file uses shared memory on PHP 7.

The benefit of this PR are the same than the ones of the previous PR:

- serialization metadata cache can be warmed up offline
- on PHP 7, there is no need for user extension to get maximum performances (ie. if you use this PR and the other one, you probably won't need to enable APCu to have great performances)
- on PHP 7 again, we are not sensitive to APCu memory fragmentation
last but not least, global performance is slightly better (I get 30us per class gain in Blackfire)

As previous work on the Serializer cache system introduced issues (see symfony/symfony@96e418a), it would be interesting to pay careful attention to the backward compatibility during the review (ping @Ener-Getick).

Commits
-------

810f469 [FrameworkBundle] Introduce a cache warmer for Serializer based on PhpArrayAdapter

Author: fabpot

Mapping/Loader/XmlFileLoader.php

@@ -36,12 +36,11 @@ class XmlFileLoader extends FileLoader
     public function loadClassMetadata(ClassMetadataInterface $classMetadata)
     {
         if (null === $this->classes) {
-            $this->classes = array();
-            $xml = $this->parseFile($this->file);
+            $this->classes = $this->getClassesFromXml();
+        }
 
-            foreach ($xml->class as $class) {
-                $this->classes[(string) $class['name']] = $class;
-            }
+        if (!$this->classes) {
+            return false;
         }
 
         $attributesMetadata = $classMetadata->getAttributesMetadata();
@@ -74,6 +73,20 @@ public function loadClassMetadata(ClassMetadataInterface $classMetadata)
         return false;
     }
 
+    /**
+     * Return the names of the classes mapped in this file.
+     *
+     * @return string[] The classes names
+     */
+    public function getMappedClasses()
+    {
+        if (null === $this->classes) {
+            $this->classes = $this->getClassesFromXml();
+        }
+
+        return array_keys($this->classes);
+    }
+
     /**
      * Parses a XML File.
      *
@@ -93,4 +106,16 @@ private function parseFile($file)
 
         return simplexml_import_dom($dom);
     }
+
+    private function getClassesFromXml()
+    {
+        $xml = $this->parseFile($this->file);
+        $classes = array();
+
+        foreach ($xml->class as $class) {
+            $classes[(string) $class['name']] = $class;
+        }
+
+        return $classes;
+    }
 }

Mapping/Loader/YamlFileLoader.php

@@ -38,26 +38,11 @@ class YamlFileLoader extends FileLoader
     public function loadClassMetadata(ClassMetadataInterface $classMetadata)
     {
         if (null === $this->classes) {
-            if (!stream_is_local($this->file)) {
-                throw new MappingException(sprintf('This is not a local file "%s".', $this->file));
-            }
-
-            if (null === $this->yamlParser) {
-                $this->yamlParser = new Parser();
-            }
-
-            $classes = $this->yamlParser->parse(file_get_contents($this->file));
-
-            if (empty($classes)) {
-                return false;
-            }
-
-            // not an array
-            if (!is_array($classes)) {
-                throw new MappingException(sprintf('The file "%s" must contain a YAML array.', $this->file));
-            }
+            $this->classes = $this->getClassesFromYaml();
+        }
 
-            $this->classes = $classes;
+        if (!$this->classes) {
+            return false;
         }
 
         if (isset($this->classes[$classMetadata->getName()])) {
@@ -103,4 +88,41 @@ public function loadClassMetadata(ClassMetadataInterface $classMetadata)
 
         return false;
     }
+
+    /**
+     * Return the names of the classes mapped in this file.
+     *
+     * @return string[] The classes names
+     */
+    public function getMappedClasses()
+    {
+        if (null === $this->classes) {
+            $this->classes = $this->getClassesFromYaml();
+        }
+
+        return array_keys($this->classes);
+    }
+
+    private function getClassesFromYaml()
+    {
+        if (!stream_is_local($this->file)) {
+            throw new MappingException(sprintf('This is not a local file "%s".', $this->file));
+        }
+
+        if (null === $this->yamlParser) {
+            $this->yamlParser = new Parser();
+        }
+
+        $classes = $this->yamlParser->parse(file_get_contents($this->file));
+
+        if (empty($classes)) {
+            return array();
+        }
+
+        if (!is_array($classes)) {
+            throw new MappingException(sprintf('The file "%s" must contain a YAML array.', $this->file));
+        }
+
+        return $classes;
+    }
 }