Handle key being larger than 2048 bytes (#20)

Author: RikudouSage

src/DynamoDbCache.php

@@ -8,6 +8,7 @@
 use AsyncAws\DynamoDb\ValueObject\AttributeValue;
 use AsyncAws\DynamoDb\ValueObject\KeysAndAttributes;
 use DateInterval;
+use LogicException;
 use Psr\Cache\CacheItemInterface;
 use Psr\Cache\CacheItemPoolInterface;
 use Psr\SimpleCache\CacheInterface;
@@ -23,6 +24,7 @@
 final class DynamoDbCache implements CacheItemPoolInterface, CacheInterface
 {
     private const RESERVED_CHARACTERS = '{}()/\@:';
+    private const MAX_KEY_LENGTH = 2048;
 
     /**
      * @var string
@@ -107,6 +109,11 @@ public function __construct(
             );
         }
         $this->converter = $converter;
+        if ($prefix !== null && strlen($prefix) >= self::MAX_KEY_LENGTH) {
+            throw new LogicException(
+                sprintf('The prefix cannot be longer or equal to the maximum length: %d bytes', self::MAX_KEY_LENGTH)
+            );
+        }
         $this->prefix = $prefix;
     }
 
@@ -123,8 +130,13 @@ public function getItem($key)
             throw $exception;
         }
 
+        $finalKey = $this->getKey($key);
+        if (strlen($finalKey) > self::MAX_KEY_LENGTH) {
+            $finalKey = $this->generateCompliantKey($key);
+        }
+
         try {
-            $item = $this->getRawItem($this->getKey($key));
+            $item = $this->getRawItem($finalKey);
             if (!isset($item[$this->valueField])) {
                 throw new CacheItemNotFoundException();
             }
@@ -133,7 +145,7 @@ public function getItem($key)
             assert(method_exists($this->clock->now(), 'setTimestamp'));
 
             return new DynamoCacheItem(
-                $this->getKey($key),
+                $finalKey,
                 $data !== null,
                 $data !== null ? $this->encoder->decode($data) : null,
                 isset($item[$this->ttlField]) && $item[$this->ttlField]->getN() !== null
@@ -144,7 +156,7 @@ public function getItem($key)
             );
         } catch (CacheItemNotFoundException $e) {
             return new DynamoCacheItem(
-                $this->getKey($key),
+                $finalKey,
                 false,
                 null,
                 null,
@@ -575,4 +587,16 @@ private function getRawItem(string $key): array
 
         return $item->getItem();
     }
+
+    private function generateCompliantKey(string $key): string
+    {
+        $key = $this->getKey($key);
+        $suffix = '_trunc_' . md5($key);
+
+        return substr(
+            $this->getKey($key),
+            0,
+            self::MAX_KEY_LENGTH - strlen($suffix)
+        ) . $suffix;
+    }
 }

tests/DynamoDbCacheTest.php

@@ -18,6 +18,7 @@
 use DateInterval;
 use DateTime;
 use DateTimeImmutable;
+use LogicException;
 use PHPUnit\Framework\TestCase;
 use Psr\Cache\CacheItemInterface;
 use Psr\Log\NullLogger;
@@ -287,6 +288,44 @@ public function testGetItemsDefaultFields()
         }
     }
 
+    /**
+     * @see https://github.com/RikudouSage/DynamoDbCachePsr6/issues/19
+     */
+    public function testGetItemKeyTooLong()
+    {
+        $key = bin2hex(random_bytes(1025));
+
+        $item = $this->instance->getItem($key);
+        self::assertNotEquals($key, $item->getKey());
+        self::assertLessThanOrEqual(2048, strlen($item->getKey()));
+
+        $item = $this->instancePrefixed->getItem($key);
+        self::assertNotEquals($key, $item->getKey());
+        self::assertNotEquals($this->prefix . $key, $item->getKey());
+        self::assertStringStartsWith($this->prefix, $item->getKey());
+        self::assertLessThanOrEqual(2048, strlen($item->getKey()));
+
+        $key = bin2hex(random_bytes(1023));
+
+        $item = $this->instance->getItem($key);
+        self::assertEquals($key, $item->getKey());
+        $item = $this->instancePrefixed->getItem($key);
+        self::assertNotEquals($key, $item->getKey());
+
+        $this->expectException(LogicException::class);
+        new DynamoDbCache(
+            'test',
+            $this->getFakeClient($this->itemPoolPrefixed),
+            'id',
+            'ttl',
+            'value',
+            null,
+            null,
+            null,
+            bin2hex(random_bytes(1024)),
+        );
+    }
+
     public function testGetItemsPrefixed()
     {
         $result = $this->instancePrefixed->getItems([