Distribute preview folders in appdata in multibucket setup to multiple buckets

* introduces a new IRootMountProvider to register mount points inside the root storage
* adds a AppdataPreviewObjectStoreStorage to handle the split between preview folders and bucket number

Ref #22033

Signed-off-by: Morris Jobke <hey@morrisjobke.de>

1 files changed, 102 insertions, 0 deletions

diff --git a/lib/private/Files/Mount/ObjectStorePreviewCacheMountProvider.php b/lib/private/Files/Mount/ObjectStorePreviewCacheMountProvider.php
new file mode 100644
index 00000000000..a4acdb6bb0f
--- /dev/null
+++ b/lib/private/Files/Mount/ObjectStorePreviewCacheMountProvider.php
@@ -0,0 +1,102 @@
+<?php
+
+declare(strict_types=1);
+/**
+ * @copyright Copyright (c) 2020, Morris Jobke <hey@morrisjobke.de>
+ *
+ * @author Morris Jobke <hey@morrisjobke.de>
+ *
+ * @license GNU AGPL version 3 or any later version
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as
+ * published by the Free Software Foundation, either version 3 of the
+ * License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+namespace OC\Files\Mount;
+
+use OC\Files\ObjectStore\AppdataPreviewObjectStoreStorage;
+use OCP\Files\Config\IRootMountProvider;
+use OCP\Files\Storage\IStorageFactory;
+use OCP\IConfig;
+use OCP\ILogger;
+
+/**
+ * Mount provider for object store app data folder for previews
+ */
+class ObjectStorePreviewCacheMountProvider implements IRootMountProvider {
+	/** @var ILogger */
+	private $logger;
+	/** @var IConfig */
+	private $config;
+
+	public function __construct(ILogger $logger, IConfig $config) {
+		$this->logger = $logger;
+		$this->config = $config;
+	}
+
+	public function getRootMounts(IStorageFactory $loader): array {
+		if (!is_array($this->config->getSystemValue('objectstore_multibucket'))) {
+			return [];
+		}
+
+		$instanceId = $this->config->getSystemValueString('instanceid', '');
+		$mountPoints = [];
+		$directoryRange = ['0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'a', 'b', 'c', 'd', 'e', 'f'];
+		$i = 0;
+		foreach ($directoryRange as $parent) {
+			foreach ($directoryRange as $child) {
+				$mountPoints[] = new MountPoint(
+					AppdataPreviewObjectStoreStorage::class,
+					'/appdata_' . $instanceId . '/preview/' . $parent . '/' . $child,
+					$this->getMultiBucketObjectStore($i),
+					$loader
+				);
+				$i++;
+			}
+		}
+		return $mountPoints;
+	}
+
+	/**
+	 * @return array
+	 */
+	protected function getMultiBucketObjectStore(int $number): array {
+		$config = $this->config->getSystemValue('objectstore_multibucket');
+
+		// sanity checks
+		if (empty($config['class'])) {
+			$this->logger->error('No class given for objectstore', ['app' => 'files']);
+		}
+		if (!isset($config['arguments'])) {
+			$config['arguments'] = [];
+		}
+
+		/*
+		 * Use any provided bucket argument as prefix
+		 * and add the mapping from parent/child => bucket
+		 */
+		if (!isset($config['arguments']['bucket'])) {
+			$config['arguments']['bucket'] = '';
+		}
+		$numBuckets = isset($config['arguments']['num_buckets']) ? $config['arguments']['num_buckets'] : 64;
+		$config['arguments']['bucket'] .= (string)($number % $numBuckets);
+
+		// instantiate object store implementation
+		$config['arguments']['objectstore'] = new $config['class']($config['arguments']);
+
+		$config['arguments']['internal-id'] = $number;
+
+		return $config['arguments'];
+	}
+}