Implement multibucket shift for ObjectStore

Signed-off-by: John Molakvoæ <skjnldsv@protonmail.com>

Author: skjnldsv

lib/private/Files/Mount/ObjectHomeMountProvider.php

@@ -121,7 +121,7 @@ private function getMultiBucketObjectStoreConfig(IUser $user) {
 			if (!isset($config['arguments']['bucket'])) {
 				$config['arguments']['bucket'] = '';
 			}
-			$mapper = new \OC\Files\ObjectStore\Mapper($user);
+			$mapper = new \OC\Files\ObjectStore\Mapper($user, $this->config);
 			$numBuckets = isset($config['arguments']['num_buckets']) ? $config['arguments']['num_buckets'] : 64;
 			$config['arguments']['bucket'] .= $mapper->getBucket($numBuckets);
 

lib/private/Files/ObjectStore/Mapper.php

@@ -22,6 +22,7 @@
  */
 namespace OC\Files\ObjectStore;
 
+use OCP\IConfig;
 use OCP\IUser;
 
 /**
@@ -35,22 +36,34 @@ class Mapper {
 	/** @var IUser */
 	private $user;
 
+	/** @var IConfig */
+	private $config;
+
 	/**
 	 * Mapper constructor.
 	 *
 	 * @param IUser $user
+	 * @param IConfig $config
 	 */
-	public function __construct(IUser $user) {
+	public function __construct(IUser $user, IConfig $config) {
 		$this->user = $user;
+		$this->config = $config;
 	}
 
 	/**
 	 * @param int $numBuckets
 	 * @return string
 	 */
 	public function getBucket($numBuckets = 64) {
+		// Get the bucket config and shift if provided.
+		// Allow us to prevent writing in old filled buckets
+		$config = $this->config->getSystemValue('objectstore_multibucket');
+		$bucketShift = is_array($config) && isset($config['arguments']['bucket_shift'])
+			? (int)$config['arguments']['bucket_shift']
+			: 0;
+
 		$hash = md5($this->user->getUID());
 		$num = hexdec(substr($hash, 0, 4));
-		return (string)($num % $numBuckets);
+		return (string)(($num % $numBuckets) + $bucketShift);
 	}
 }

tests/lib/Files/Mount/ObjectHomeMountProviderTest.php

@@ -54,7 +54,7 @@ public function testSingleBucket() {
 	}
 
 	public function testMultiBucket() {
-		$this->config->expects($this->once())
+		$this->config->expects($this->exactly(2))
 			->method('getSystemValue')
 			->with($this->equalTo('objectstore_multibucket'), '')
 			->willReturn([
@@ -98,9 +98,9 @@ public function testMultiBucket() {
 	}
 
 	public function testMultiBucketWithPrefix() {
-		$this->config->expects($this->once())
+		$this->config->expects($this->exactly(2))
 			->method('getSystemValue')
-			->with($this->equalTo('objectstore_multibucket'), '')
+			->with('objectstore_multibucket')
 			->willReturn([
 				'class' => 'Test\Files\Mount\FakeObjectStore',
 				'arguments' => [
@@ -147,7 +147,7 @@ public function testMultiBucketWithPrefix() {
 	public function testMultiBucketBucketAlreadySet() {
 		$this->config->expects($this->once())
 			->method('getSystemValue')
-			->with($this->equalTo('objectstore_multibucket'), '')
+			->with('objectstore_multibucket')
 			->willReturn([
 				'class' => 'Test\Files\Mount\FakeObjectStore',
 				'arguments' => [
@@ -185,9 +185,9 @@ public function testMultiBucketBucketAlreadySet() {
 	}
 
 	public function testMultiBucketConfigFirst() {
-		$this->config->expects($this->once())
+		$this->config->expects($this->exactly(2))
 			->method('getSystemValue')
-			->with($this->equalTo('objectstore_multibucket'))
+			->with('objectstore_multibucket')
 			->willReturn([
 				'class' => 'Test\Files\Mount\FakeObjectStore',
 			]);

tests/lib/Files/ObjectStore/MapperTest.php

@@ -22,17 +22,37 @@
 namespace Test\Files\ObjectStore;
 
 use OC\Files\ObjectStore\Mapper;
+use OCP\IConfig;
 use OCP\IUser;
 
 class MapperTest extends \Test\TestCase {
+
+	/** @var IUser|\PHPUnit\Framework\MockObject\MockObject */
+	private $user;
+
+	/** @var IConfig|\PHPUnit\Framework\MockObject\MockObject */
+	private $config;
+
+	/** @var Mapper */
+	private $mapper;
+
+	protected function setUp(): void {
+		parent::setUp();
+
+		$this->user = $this->createMock(IUser::class);
+		$this->config = $this->createMock(IConfig::class);
+		$this->mapper = new Mapper($this->user, $this->config);
+	}
+
 	public function dataGetBucket() {
 		return [
-			['user', 64, '17'],
-			['USER', 64, '0'],
-			['bc0e8b52-a66c-1035-90c6-d9663bda9e3f', 64, '56'],
-			['user', 8, '1'],
-			['user', 2, '1'],
-			['USER', 2, '0'],
+			['user', 64, 0, '17'],
+			['USER', 64, 0, '0'],
+			['bc0e8b52-a66c-1035-90c6-d9663bda9e3f', 64, 0, '56'],
+			['user', 8, 0, '1'],
+			['user', 2, 0, '1'],
+			['USER', 2, 0, '0'],
+			['user', 64, 64, '81'],
 		];
 	}
 
@@ -42,13 +62,17 @@ public function dataGetBucket() {
 	 * @param int $numBuckets
 	 * @param string $expectedBucket
 	 */
-	public function testGetBucket($username, $numBuckets, $expectedBucket) {
-		$user = $this->createMock(IUser::class);
-		$user->method('getUID')
+	public function testGetBucket($username, $numBuckets, $bucketShift, $expectedBucket) {
+		$this->user->expects($this->once())
+			->method('getUID')
 			->willReturn($username);
 
-		$mapper = new Mapper($user);
+		$this->config->expects($this->once())
+			->method('getSystemValue')
+			->with('objectstore_multibucket')
+			->willReturn(['arguments' => ['bucket_shift' => $bucketShift]]);
 
-		$this->assertSame($expectedBucket, $mapper->getBucket($numBuckets));
+		$result = $this->mapper->getBucket($numBuckets);
+		$this->assertEquals($expectedBucket, $result);
 	}
 }