BitOne · oliverde8 · Jan 6, 2018
diff --git a/README.md b/README.md
@@ -200,6 +200,42 @@ Path from 0x7f94a1856260
 +---------------------------+
 ```
 
+## Comparing two memory dumps
+Will allow you to see which objects counts and size have changed. 
+
+```bash
+$ bin/analyzer   diff [options] [--] <first-file> <second-file>
+
+Arguments:
+    first-file            PHP Meminfo Dump File in JSON format
+    second-file           PHP Meminfo Dump File in JSON format to compare first file with
+
+Options:
+    -s, --sort[=SORT]     Define sorting order when displaying diff. Available options are :
+                           - c : Sort by count
+                           - s : Sort by size
+                           - dc : Sort by the count differene
+                           - ds : Sort by the size difference
+```
+
+### Exemple 
+
+Fallowing exemple displays the diff sorting them by difference in size.
+
+```bash
+$ bin/analyzer diff eXpansion-mem-dump-2018-01-06T11\:37\:38+0000.json eXpansion-mem-dump-2018-01-06T12\:04\:23+0000.json  -sds
++-------------------------------------------------------------+-----------------------+-----------------------------------+-----------------------+--------------------------+
+| Type                                                        | First Instances Count | First Cumulated Self Size (bytes) | Second Instances Diff | Second Size Diff (bytes) |
++-------------------------------------------------------------+-----------------------+-----------------------------------+-----------------------+--------------------------+
+| string                                                      | 7495                  | 436324                            | +372                  | +23447                   |
+| array                                                       | 2097                  | 150984                            | +28                   | +2016                    |
+| integer                                                     | 769                   | 12304                             | +61                   | +976                     |
+| DateTime                                                    | 10                    | 720                               | +8                    | +576                     |
+| boolean                                                     | 795                   | 12720                             | +15                   | +240                     |
+| eXpansion\Bundle\LocalRecords\Model\Record                  | 2                     | 144                               | +2                    | +144                     |
+| eXpansion\Framework\Core\Listener\BaseStorageUpdateListener | 3                     | 216                               | +1                    | +72                      |
+```
+
 A worflow to find and understand memory leak by using PHP Meminfo
 -----------------------------------------------------------------
 

diff --git a/analyzer/src/BitOne/PhpMemInfo/Console/Application.php b/analyzer/src/BitOne/PhpMemInfo/Console/Application.php
@@ -5,6 +5,7 @@
 use BitOne\PhpMemInfo\Console\Command\QueryCommand;
 use BitOne\PhpMemInfo\Console\Command\ReferencePathCommand;
 use BitOne\PhpMemInfo\Console\Command\SummaryCommand;
+use BitOne\PhpMemInfo\Console\Command\DiffCommand;
 use Symfony\Component\Console\Application as BaseApplication;
 
 /**
@@ -21,5 +22,6 @@ public function __construct()
         $this->add(new QueryCommand());
         $this->add(new ReferencePathCommand());
         $this->add(new SummaryCommand());
+        $this->add(new DiffCommand());
     }
 }
diff --git a/analyzer/src/BitOne/PhpMemInfo/Console/Command/DiffCommand.php b/analyzer/src/BitOne/PhpMemInfo/Console/Command/DiffCommand.php
@@ -0,0 +1,172 @@
+<?php
+
+namespace BitOne\PhpMemInfo\Console\Command;
+
+use BitOne\PhpMemInfo\Loader;
+use BitOne\PhpMemInfo\Analyzer\SummaryCreator;
+use Symfony\Component\Console\Command\Command;
+use Symfony\Component\Console\Exception\InvalidArgumentException;
+use Symfony\Component\Console\Helper\Table;
+use Symfony\Component\Console\Input\InputArgument;
+use Symfony\Component\Console\Input\InputInterface;
+use Symfony\Component\Console\Input\InputOption;
+use Symfony\Component\Console\Output\OutputInterface;
+
+
+/**
+ * Class DiffCommand
+ *
+ * @author  oliver de Cramer <oliverde8@gmail.com>
+ * @license   http://opensource.org/licenses/MIT MIT
+ */
+class DiffCommand extends Command
+{
+    const SORT_COUNT = 'c';
+    const SORT_SIZE = 's';
+    const SORT_DIFF_COUNT = 'dc';
+    const SORT_DIFF_SIZE = 'ds';
+
+    /** @var array List of available sorts and the keys to use for the sorting. */
+    protected $sorts = [
+        self::SORT_COUNT => 1,
+        self::SORT_SIZE => 2,
+        self::SORT_DIFF_COUNT => 3,
+        self::SORT_DIFF_SIZE => 4,
+    ];
+
+    /**
+     * {@inheritedDoc}.
+     */
+    protected function configure()
+    {
+        $sortDescription = "Define sorting order when displaying diff. Available options are : \n";
+        $sortDescription .= "- c : Sort by count\n";
+        $sortDescription .= "- s : Sort by size\n";
+        $sortDescription .= "- dc : Sort by the count differene\n";
+        $sortDescription .= "- ds : Sort by the size difference\n";
+
+        $this
+            ->setName('diff')
+            ->setDescription('Compare 2 dump files')
+            ->addArgument(
+                'first-file',
+                InputArgument::REQUIRED,
+                'PHP Meminfo Dump File in JSON format'
+            )
+            ->addArgument(
+                'second-file',
+                InputArgument::REQUIRED,
+                'PHP Meminfo Dump File in JSON format to compare first file with'
+            )
+            ->addOption(
+                'sort',
+                's',
+                InputOption::VALUE_OPTIONAL,
+                $sortDescription,
+                self::SORT_DIFF_COUNT
+            );
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    protected function execute(InputInterface $input, OutputInterface $output)
+    {
+        $firstFilename = $input->getArgument('first-file');
+        $secondFilename = $input->getArgument('second-file');
+        $sort = $input->getOption('sort');
+
+        $loader = new Loader();
+
+        $firstItems = $loader->load($firstFilename);
+        $secondItems = $loader->load($secondFilename);
+
+        $firstSummary = new SummaryCreator($firstItems);
+        $secondSummary = new SummaryCreator($secondItems);
+
+        $firstSummary = $firstSummary->createSummary();
+        $secondSummary = $secondSummary->createSummary();
+
+        $table = new Table($output);
+        $this->formatTable($firstSummary, $secondSummary, $table, $sort);
+
+        $table->render();
+
+        return 0;
+    }
+
+    /**
+     * Format data into a detailed table.
+     *
+     * @param array  $firstSummary
+     * @param array  $secondSummary
+     * @param Table  $table
+     * @param string $sort
+     */
+    protected function formatTable(array $firstSummary, array $secondSummary, Table $table, $sort)
+    {
+        $table->setHeaders(['Type', 'First Instances Count', 'First Cumulated Self Size (bytes)', 'Second Instances Diff', 'Second Size Diff (bytes)']);
+
+        $rows = [];
+        foreach($secondSummary as $type => $stats) {
+            $countDiff = $stats['count'];
+            $sizeDiff = $stats['self_size'];
+
+            if (isset($firstSummary[$type])) {
+                $countDiff = $stats['count'] - $firstSummary[$type]['count'];
+                $sizeDiff = $stats['self_size'] - $firstSummary[$type]['self_size'];
+            }
+
+            $rows[] = [$type, $stats['count'], $stats['self_size'], $this->formatDiffValue($countDiff), $this->formatDiffValue($sizeDiff)];
+        }
+
+        // Let's not forget all elements completely removed from memory.
+        foreach ($firstSummary as $type => $stats) {
+            if (!isset($secondSummary[$type])) {
+                $countDiff = -$stats['count'];
+                $sizeDiff = -$stats['self_size'];
+                $rows[] = [$type, $stats['count'], $stats['self_size'], $this->formatDiffValue($countDiff), $this->formatDiffValue($sizeDiff)];
+            }
+        }
+
+        $this->sortTable($rows, $sort);
+        $table->setRows($rows);
+    }
+
+    /**
+     * Sort data for display.
+     *
+     * @param array $rows
+     * @param       $sort
+     */
+    protected function sortTable(array &$rows, $sort)
+    {
+        if (!isset($this->sorts[$sort])) {
+            throw new InvalidArgumentException("'$sort' is not a know sort parameter, see help for possible sort options");
+        }
+
+        if ($this->sorts[$sort] < 0) {
+            return;
+        }
+
+        $sortIndex = $this->sorts[$sort];
+
+        usort($rows, function($item1, $item2) use ($sortIndex) {
+            return abs(str_replace('+', '', $item1[$sortIndex])) <= abs(str_replace('+', '', $item2[$sortIndex]));
+        });
+    }
+
+    /**
+     * Format diff value for display
+     *
+     * @param int $value
+     *
+     * @return string
+     */
+    protected function formatDiffValue($value)
+    {
+        if ($value > 0) {
+            return '+' . $value;
+        }
+    }
+}