1 files changed, 94 insertions, 0 deletions
diff --git a/lib/private/DB/AdapterSqlite.php b/lib/private/DB/AdapterSqlite.php
new file mode 100644
index 00000000000..aeadf55ecf7
--- /dev/null
+++ b/lib/private/DB/AdapterSqlite.php
@@ -0,0 +1,94 @@
+<?php
+
+/**
+ * SPDX-FileCopyrightText: 2016-2024 Nextcloud GmbH and Nextcloud contributors
+ * SPDX-FileCopyrightText: 2016 ownCloud, Inc.
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+namespace OC\DB;
+
+use Doctrine\DBAL\Exception\UniqueConstraintViolationException;
+
+class AdapterSqlite extends Adapter {
+	/**
+	 * @param string $tableName
+	 */
+	public function lockTable($tableName) {
+		$this->conn->executeUpdate('BEGIN EXCLUSIVE TRANSACTION');
+	}
+
+	public function unlockTable() {
+		$this->conn->executeUpdate('COMMIT TRANSACTION');
+	}
+
+	public function fixupStatement($statement) {
+		$statement = preg_replace('/`(\w+)` ILIKE \?/', 'LOWER($1) LIKE LOWER(?)', $statement);
+		$statement = str_replace('`', '"', $statement);
+		$statement = str_ireplace('NOW()', 'datetime(\'now\')', $statement);
+		$statement = str_ireplace('GREATEST(', 'MAX(', $statement);
+		$statement = str_ireplace('UNIX_TIMESTAMP()', 'strftime(\'%s\',\'now\')', $statement);
+		return $statement;
+	}
+
+	/**
+	 * Insert a row if the matching row does not exists. To accomplish proper race condition avoidance
+	 * it is needed that there is also a unique constraint on the values. Then this method will
+	 * catch the exception and return 0.
+	 *
+	 * @param string $table The table name (will replace *PREFIX* with the actual prefix)
+	 * @param array $input data that should be inserted into the table  (column name => value)
+	 * @param array|null $compare List of values that should be checked for "if not exists"
+	 *                            If this is null or an empty array, all keys of $input will be compared
+	 *                            Please note: text fields (clob) must not be used in the compare array
+	 * @return int number of inserted rows
+	 * @throws \Doctrine\DBAL\Exception
+	 * @deprecated 15.0.0 - use unique index and "try { $db->insert() } catch (UniqueConstraintViolationException $e) {}" instead, because it is more reliable and does not have the risk for deadlocks - see https://github.com/nextcloud/server/pull/12371
+	 */
+	public function insertIfNotExist($table, $input, ?array $compare = null) {
+		if (empty($compare)) {
+			$compare = array_keys($input);
+		}
+		$fieldList = '`' . implode('`,`', array_keys($input)) . '`';
+		$query = "INSERT INTO `$table` ($fieldList) SELECT "
+			. str_repeat('?,', count($input) - 1) . '? '
+			. " WHERE NOT EXISTS (SELECT 1 FROM `$table` WHERE ";
+
+		$inserts = array_values($input);
+		foreach ($compare as $key) {
+			$query .= '`' . $key . '`';
+			if (is_null($input[$key])) {
+				$query .= ' IS NULL AND ';
+			} else {
+				$inserts[] = $input[$key];
+				$query .= ' = ? AND ';
+			}
+		}
+		$query = substr($query, 0, -5);
+		$query .= ')';
+
+		try {
+			return $this->conn->executeUpdate($query, $inserts);
+		} catch (UniqueConstraintViolationException $e) {
+			// if this is thrown then a concurrent insert happened between the insert and the sub-select in the insert, that should have avoided it
+			// it's fine to ignore this then
+			//
+			// more discussions about this can be found at https://github.com/nextcloud/server/pull/12315
+			return 0;
+		}
+	}
+
+	public function insertIgnoreConflict(string $table, array $values): int {
+		$builder = $this->conn->getQueryBuilder();
+		$builder->insert($table);
+		$updates = [];
+		foreach ($values as $key => $value) {
+			$builder->setValue($key, $builder->createNamedParameter($value));
+		}
+
+		return $this->conn->executeStatement(
+			$builder->getSQL() . ' ON CONFLICT DO NOTHING',
+			$builder->getParameters(),
+			$builder->getParameterTypes()
+		);
+	}
+}