feature #4171 Introduce ChainCache and ReadOnlyFilesystemCache (Okhoshi)

This PR was merged into the 3.x branch.

Discussion
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Introduce ChainCache and ReadOnlyFilesystemCache

Following the feedback in symfony/symfony#54384, I’m proposing the two new Cache implementations in Twig directly.

Commits
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0dbe1d9 Introduce ChainCache and ReadOnlyFilesystemCache

src/Cache/ChainCache.php

@@ -0,0 +1,81 @@
+<?php
+
+/*
+ * This file is part of Twig.
+ *
+ * (c) Fabien Potencier
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Twig\Cache;
+
+/**
+ * Chains several caches together.
+ *
+ * Cached items are fetched from the first cache having them in its data store.
+ * They are saved and deleted in all adapters at once.
+ *
+ * @author Quentin Devos <[email protected]>
+ */
+final class ChainCache implements CacheInterface
+{
+    private $caches;
+
+    /**
+     * @param iterable<CacheInterface> $caches The ordered list of caches used to store and fetch cached items
+     */
+    public function __construct(iterable $caches)
+    {
+        $this->caches = $caches;
+    }
+
+    public function generateKey(string $name, string $className): string
+    {
+        return $className.'#'.$name;
+    }
+
+    public function write(string $key, string $content): void
+    {
+        $splitKey = $this->splitKey($key);
+
+        foreach ($this->caches as $cache) {
+            $cache->write($cache->generateKey(...$splitKey), $content);
+        }
+    }
+
+    public function load(string $key): void
+    {
+        [$name, $className] = $this->splitKey($key);
+
+        foreach ($this->caches as $cache) {
+            $cache->load($cache->generateKey($name, $className));
+
+            if (class_exists($className, false)) {
+                break;
+            }
+        }
+    }
+
+    public function getTimestamp(string $key): int
+    {
+        $splitKey = $this->splitKey($key);
+
+        foreach ($this->caches as $cache) {
+            if (0 < $timestamp = $cache->getTimestamp($cache->generateKey(...$splitKey))) {
+                return $timestamp;
+            }
+        }
+
+        return 0;
+    }
+
+    /**
+     * @return string[]
+     */
+    private function splitKey(string $key): array
+    {
+        return array_reverse(explode('#', $key, 2));
+    }
+}

src/Cache/ReadOnlyFilesystemCache.php

@@ -0,0 +1,25 @@
+<?php
+
+/*
+ * This file is part of Twig.
+ *
+ * (c) Fabien Potencier
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Twig\Cache;
+
+/**
+ * Implements a cache on the filesystem that can only be read, not written to.
+ *
+ * @author Quentin Devos <[email protected]>
+ */
+class ReadOnlyFilesystemCache extends FilesystemCache
+{
+    public function write(string $key, string $content): void
+    {
+        // Do nothing with the content, it's a read-only filesystem.
+    }
+}

tests/Cache/ChainTest.php

@@ -0,0 +1,231 @@
+<?php
+
+namespace Twig\Tests\Cache;
+
+/*
+ * This file is part of Twig.
+ *
+ * (c) Fabien Potencier
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+use PHPUnit\Framework\TestCase;
+use Twig\Cache\ChainCache;
+use Twig\Cache\FilesystemCache;
+use Twig\Tests\FilesystemHelper;
+
+class ChainTest extends TestCase
+{
+    private $classname;
+    private $directory;
+    private $cache;
+    private $key;
+
+    protected function setUp(): void
+    {
+        $nonce = hash(\PHP_VERSION_ID < 80100 ? 'sha256' : 'xxh128', random_bytes(32));
+        $this->classname = '__Twig_Tests_Cache_ChainTest_Template_'.$nonce;
+        $this->directory = sys_get_temp_dir().'/twig-test';
+        $this->cache = new ChainCache([
+            new FilesystemCache($this->directory.'/A'),
+            new FilesystemCache($this->directory.'/B'),
+        ]);
+        $this->key = $this->cache->generateKey('_test_', $this->classname);
+    }
+
+    protected function tearDown(): void
+    {
+        if (file_exists($this->directory)) {
+            FilesystemHelper::removeDir($this->directory);
+        }
+    }
+
+    public function testLoadInA()
+    {
+        $cache = new FilesystemCache($this->directory.'/A');
+        $key = $cache->generateKey('_test_', $this->classname);
+
+        $dir = \dirname($key);
+        @mkdir($dir, 0777, true);
+        $this->assertDirectoryExists($dir);
+        $this->assertFalse(class_exists($this->classname, false));
+
+        $content = $this->generateSource();
+        file_put_contents($key, $content);
+        var_dump($key);
+
+        $this->cache->load($this->key);
+
+        $this->assertTrue(class_exists($this->classname, false));
+    }
+
+    public function testLoadInB()
+    {
+        $cache = new FilesystemCache($this->directory.'/B');
+        $key = $cache->generateKey('_test_', $this->classname);
+
+        $dir = \dirname($key);
+        @mkdir($dir, 0777, true);
+        $this->assertDirectoryExists($dir);
+        $this->assertFalse(class_exists($this->classname, false));
+
+        $content = $this->generateSource();
+        file_put_contents($key, $content);
+        var_dump($key);
+
+        $this->cache->load($this->key);
+
+        $this->assertTrue(class_exists($this->classname, false));
+    }
+
+    public function testLoadInBoth()
+    {
+        $cache = new FilesystemCache($this->directory.'/A');
+        $key = $cache->generateKey('_test_', $this->classname);
+
+        $dir = \dirname($key);
+        @mkdir($dir, 0777, true);
+        $this->assertDirectoryExists($dir);
+        $this->assertFalse(class_exists($this->classname, false));
+
+        $content = $this->generateSource();
+        file_put_contents($key, $content);
+
+        $cache = new FilesystemCache($this->directory.'/B');
+        $key = $cache->generateKey('_test_', $this->classname);
+
+        $dir = \dirname($key);
+        @mkdir($dir, 0777, true);
+        $this->assertDirectoryExists($dir);
+        $this->assertFalse(class_exists($this->classname, false));
+
+        $content = $this->generateSource();
+        file_put_contents($key, $content);
+
+        $this->cache->load($this->key);
+
+        $this->assertTrue(class_exists($this->classname, false));
+    }
+
+    public function testLoadMissing()
+    {
+        $this->assertFalse(class_exists($this->classname, false));
+
+        $this->cache->load($this->key);
+
+        $this->assertFalse(class_exists($this->classname, false));
+    }
+
+    public function testWrite()
+    {
+        $content = $this->generateSource();
+
+        $cacheA = new FilesystemCache($this->directory.'/A');
+        $keyA = $cacheA->generateKey('_test_', $this->classname);
+
+        $this->assertFileDoesNotExist($keyA);
+        $this->assertFileDoesNotExist($this->directory.'/A');
+
+        $cacheB = new FilesystemCache($this->directory.'/B');
+        $keyB = $cacheB->generateKey('_test_', $this->classname);
+
+        $this->assertFileDoesNotExist($keyB);
+        $this->assertFileDoesNotExist($this->directory.'/B');
+
+        $this->cache->write($this->key, $content);
+
+        $this->assertFileExists($this->directory.'/A');
+        $this->assertFileExists($keyA);
+        $this->assertSame(file_get_contents($keyA), $content);
+
+        $this->assertFileExists($this->directory.'/B');
+        $this->assertFileExists($keyB);
+        $this->assertSame(file_get_contents($keyB), $content);
+    }
+
+    public function testGetTimestampInA()
+    {
+        $cache = new FilesystemCache($this->directory.'/A');
+        $key = $cache->generateKey('_test_', $this->classname);
+
+        $dir = \dirname($key);
+        @mkdir($dir, 0777, true);
+        $this->assertDirectoryExists($dir);
+
+        // Create the file with a specific modification time.
+        touch($key, 1234567890);
+
+        $this->assertSame(1234567890, $this->cache->getTimestamp($this->key));
+    }
+
+    public function testGetTimestampInB()
+    {
+        $cache = new FilesystemCache($this->directory.'/B');
+        $key = $cache->generateKey('_test_', $this->classname);
+
+        $dir = \dirname($key);
+        @mkdir($dir, 0777, true);
+        $this->assertDirectoryExists($dir);
+
+        // Create the file with a specific modification time.
+        touch($key, 1234567890);
+
+        $this->assertSame(1234567890, $this->cache->getTimestamp($this->key));
+    }
+
+    public function testGetTimestampInBoth()
+    {
+        $cacheA = new FilesystemCache($this->directory.'/A');
+        $keyA = $cacheA->generateKey('_test_', $this->classname);
+
+        $dir = \dirname($keyA);
+        @mkdir($dir, 0777, true);
+        $this->assertDirectoryExists($dir);
+
+        // Create the file with a specific modification time.
+        touch($keyA, 1234567890);
+
+        $cacheB = new FilesystemCache($this->directory.'/B');
+        $keyB = $cacheB->generateKey('_test_', $this->classname);
+
+        $dir = \dirname($keyB);
+        @mkdir($dir, 0777, true);
+        $this->assertDirectoryExists($dir);
+
+        // Create the file with a specific modification time.
+        touch($keyB, 1234567891);
+
+        $this->assertSame(1234567890, $this->cache->getTimestamp($this->key));
+    }
+
+    public function testGetTimestampMissingFile()
+    {
+        $this->assertSame(0, $this->cache->getTimestamp($this->key));
+    }
+
+    /**
+     * @dataProvider provideInput
+     */
+    public function testGenerateKey($expected, $input)
+    {
+        $cache = new ChainCache([]);
+        $this->assertSame($expected, $cache->generateKey($input, static::class));
+    }
+
+    public static function provideInput()
+    {
+        return [
+            ['Twig\Tests\Cache\ChainTest#_test_', '_test_'],
+            ['Twig\Tests\Cache\ChainTest#_test#with#hashtag_', '_test#with#hashtag_'],
+        ];
+    }
+
+    private function generateSource()
+    {
+        return strtr('<?php class {{classname}} {}', [
+            '{{classname}}' => $this->classname,
+        ]);
+    }
+}