bug symfony#23413 [VarDumper] Reduce size of serialized Data objects (nicolas-grekas)

This PR was merged into the 3.3 branch.

Discussion
----------

[VarDumper] Reduce size of serialized Data objects

| Q             | A
| ------------- | ---
| Branch?       | 3.3
| Bug fix?      | yes
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | no
| Fixed tickets | symfony#23233
| License       | MIT
| Doc PR        | -

By using `Stub` objects a lot, especially for arrays, `Data` objects generate heavy serialized strings.
By implemeting `Serializable` on `Data`, this PR removes most of the boilerplate.

This PR also removes duplicate data in `LoggerDataCollector`, and reduces the backtrace of silenced errors to their 3 last items - which should be enough - and is otherwise responsible for a significant portion of the serialized payloads.

This is not the last possible step towards shrinking serialized profiles, but the next one is more complex -and maybe this one is good enough? Please give feedback if you can.

Commits
-------

70bd2bc [VarDumper] Reduce size of serialized Data objects

Author: fabpot

src/Symfony/Component/Debug/ErrorHandler.php

@@ -414,7 +414,7 @@ public function handleError($type, $message, $file, $line)
                 $errorAsException = self::$silencedErrorCache[$message];
                 ++$errorAsException->count;
             } else {
-                $lightTrace = $this->tracedErrors & $type ? $this->cleanTrace(debug_backtrace(DEBUG_BACKTRACE_IGNORE_ARGS), $type, $file, $line, false) : array();
+                $lightTrace = $this->tracedErrors & $type ? $this->cleanTrace(debug_backtrace(DEBUG_BACKTRACE_IGNORE_ARGS, 3), $type, $file, $line, false) : array();
                 $errorAsException = new SilencedErrorContext($type, $file, $line, $lightTrace);
             }
 

src/Symfony/Component/HttpKernel/DataCollector/LoggerDataCollector.php

@@ -120,6 +120,7 @@ private function getContainerDeprecationLogs()
             $log['priorityName'] = 'DEBUG';
             $log['channel'] = '-';
             $log['scream'] = false;
+            unset($log['type'], $log['file'], $log['line'], $log['trace'], $log['trace'], $log['count']);
             $logs[] = $log;
         }
 
@@ -251,7 +252,7 @@ private function computeErrorsCount(array $containerDeprecationLogs)
         }
 
         foreach ($containerDeprecationLogs as $deprecationLog) {
-            $count['deprecation_count'] += $deprecationLog['count'];
+            $count['deprecation_count'] += $deprecationLog['context']['exception']->count;
         }
 
         ksort($count['priorities']);

src/Symfony/Component/HttpKernel/Kernel.php

@@ -551,7 +551,7 @@ protected function initializeContainer()
                         return;
                     }
 
-                    $backtrace = debug_backtrace(DEBUG_BACKTRACE_IGNORE_ARGS);
+                    $backtrace = debug_backtrace(DEBUG_BACKTRACE_IGNORE_ARGS, 3);
                     // Clean the trace by removing first frames added by the error handler itself.
                     for ($i = 0; isset($backtrace[$i]); ++$i) {
                         if (isset($backtrace[$i]['file'], $backtrace[$i]['line']) && $backtrace[$i]['line'] === $line && $backtrace[$i]['file'] === $file) {

src/Symfony/Component/HttpKernel/Tests/DataCollector/DumpDataCollectorTest.php

@@ -50,7 +50,7 @@ public function testDump()
         );
         $this->assertEquals($xDump, $dump);
 
-        $this->assertStringMatchesFormat('a:3:{i:0;a:5:{s:4:"data";O:39:"Symfony\Component\VarDumper\Cloner\Data":%a', $collector->serialize());
+        $this->assertStringMatchesFormat('a:3:{i:0;a:5:{s:4:"data";%c:39:"Symfony\Component\VarDumper\Cloner\Data":%a', $collector->serialize());
         $this->assertSame(0, $collector->getDumpsCount());
         $this->assertSame('a:2:{i:0;b:0;i:1;s:5:"UTF-8";}', $collector->serialize());
     }

src/Symfony/Component/VarDumper/Cloner/Data.php

@@ -16,7 +16,7 @@
 /**
  * @author Nicolas Grekas <p@tchwork.com>
  */
-class Data implements \ArrayAccess, \Countable, \IteratorAggregate
+class Data implements \ArrayAccess, \Countable, \IteratorAggregate, \Serializable
 {
     private $data;
     private $position = 0;
@@ -278,6 +278,57 @@ public function dump(DumperInterface $dumper)
         $this->dumpItem($dumper, new Cursor(), $refs, $this->data[$this->position][$this->key]);
     }
 
+    /**
+     * @internal
+     */
+    public function serialize()
+    {
+        $data = $this->data;
+
+        foreach ($data as $i => $values) {
+            foreach ($values as $k => $v) {
+                if ($v instanceof Stub) {
+                    if (Stub::TYPE_ARRAY === $v->type) {
+                        $v = self::mapStubConsts($v, false);
+                        $data[$i][$k] = array($v->class, $v->position, $v->cut);
+                    } else {
+                        $v = self::mapStubConsts($v, false);
+                        $data[$i][$k] = array($v->class, $v->position, $v->cut, $v->type, $v->value, $v->handle, $v->refCount, $v->attr);
+                    }
+                }
+            }
+        }
+
+        return serialize(array($data, $this->position, $this->key, $this->maxDepth, $this->maxItemsPerDepth, $this->useRefHandles));
+    }
+
+    /**
+     * @internal
+     */
+    public function unserialize($serialized)
+    {
+        list($data, $this->position, $this->key, $this->maxDepth, $this->maxItemsPerDepth, $this->useRefHandles) = unserialize($serialized);
+
+        foreach ($data as $i => $values) {
+            foreach ($values as $k => $v) {
+                if ($v && is_array($v)) {
+                    $s = new Stub();
+                    if (3 === count($v)) {
+                        $s->type = Stub::TYPE_ARRAY;
+                        $s = self::mapStubConsts($s, false);
+                        list($s->class, $s->position, $s->cut) = $v;
+                        $s->value = $s->cut + count($data[$s->position]);
+                    } else {
+                        list($s->class, $s->position, $s->cut, $s->type, $s->value, $s->handle, $s->refCount, $s->attr) = $v;
+                    }
+                    $data[$i][$k] = self::mapStubConsts($s, true);
+                }
+            }
+        }
+
+        $this->data = $data;
+    }
+
     /**
      * Depth-first dumping of items.
      *
@@ -406,4 +457,23 @@ private function dumpChildren($dumper, $parentCursor, &$refs, $children, $hashCu
 
         return $hashCut;
     }
+
+    private static function mapStubConsts(Stub $stub, $resolve)
+    {
+        static $stubConstIndexes, $stubConstValues;
+
+        if (null === $stubConstIndexes) {
+            $r = new \ReflectionClass(Stub::class);
+            $stubConstIndexes = array_flip(array_values($r->getConstants()));
+            $stubConstValues = array_flip($stubConstIndexes);
+        }
+
+        $map = $resolve ? $stubConstValues : $stubConstIndexes;
+
+        $stub = clone $stub;
+        $stub->type = $map[$stub->type];
+        $stub->class = isset($map[$stub->class]) ? $map[$stub->class] : $stub->class;
+
+        return $stub;
+    }
 }