Reuse cache entries for identical file contents

src/Cache.php

@@ -25,6 +25,7 @@
 
 use function class_exists;
 use function get_debug_type;
+use function is_readable;
 use function is_string;
 use function md5_file;
 use function sprintf;
@@ -113,15 +114,16 @@ public function clear(string $prefix = ''): bool
      */
     public function isHit(string $filename): bool
     {
+        $currentFingerprint = $this->getFingerprint($filename);
+
         // Try to fetch item from cache
-        $item = $this->getItem($filename);
+        $item = $this->pool->getItem($this->getKey($filename, $currentFingerprint));
         if (!$item->isHit()) {
             ++$this->misses;
             return false;
         }
 
         $fingerprintSaved = $item->get();
-        $currentFingerprint = md5_file($filename);
 
         if ($currentFingerprint !== $fingerprintSaved) {
             ++$this->misses;
@@ -151,11 +153,27 @@ public function __debugInfo(): array
         ];
     }
 
-    private function getKey(string $filename): string
+    private function getKey(string $filename, ?string $fingerprint = null): string
     {
+        $fingerprint ??= $this->getFingerprint($filename);
+        if (null !== $fingerprint) {
+            return $fingerprint;
+        }
+
         return str_replace(str_split(ItemInterface::RESERVED_CHARACTERS), '_', $filename);
     }
 
+    private function getFingerprint(string $filename): ?string
+    {
+        if (!is_readable($filename)) {
+            return null;
+        }
+
+        $fingerprint = md5_file($filename);
+
+        return is_string($fingerprint) ? $fingerprint : null;
+    }
+
     /**
      * @since Release 9.6.0
      */

tests/Cache/CacheTest.php

@@ -21,6 +21,7 @@
 use Symfony\Component\Cache\CacheItem;
 
 use function dirname;
+use function is_readable;
 use function md5_file;
 use function sha1_file;
 use function str_replace;
@@ -141,10 +142,32 @@ public function testFilenameHasReservedCharacters(): void
         $this->assertEquals($fingerprint, self::$cache->getItem($filename)->get());
     }
 
+    public function testSameContentsShareCacheItem(): void
+    {
+        $firstFilename = __DIR__ . '/Fixtures/releases/3118/test.fixture';
+        $secondFilename = __DIR__ . '/Fixtures/releases/3119/test.fixture';
+        $fingerprint = md5_file($firstFilename);
+
+        $firstCacheItem = self::$cache->getItem($firstFilename);
+        $secondCacheItem = self::$cache->getItem($secondFilename);
+
+        $this->assertSame($firstCacheItem->getKey(), $secondCacheItem->getKey());
+
+        $firstCacheItem->set($fingerprint);
+        $saved = self::$cache->saveItem($firstCacheItem);
+
+        $this->assertTrue($saved);
+        $this->assertTrue(self::$cache->isHit($secondFilename));
+    }
+
     private function generateItems(array $values): Generator
     {
         foreach ($values as $filename => $processor) {
-            $key = str_replace('/', '_', $filename);
+            if (is_readable($filename)) {
+                $key = md5_file($filename);
+            } else {
+                $key = str_replace('/', '_', $filename);
+            }
             $value = $processor ? $processor($filename) : null;
             $isHit = (null !== $value);
             yield $key => (self::$createCacheItem)($key, $value, $isHit);

tests/Cache/Fixtures/releases/3118/test.fixture

@@ -0,0 +1 @@
+same release contents

tests/Cache/Fixtures/releases/3119/test.fixture

@@ -0,0 +1 @@
+same release contents