--- /dev/null
+<?php
+
+/**
+ * This file deals with database interface functions
+ * and query specifics/optimisations.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 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 General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ * http://www.gnu.org/copyleft/gpl.html
+ *
+ * @file
+ * @ingroup Database
+ */
+namespace Wikimedia\Rdbms;
+
+use Exception;
+use RuntimeException;
+
+/**
+ * Advanced database interface for IDatabase handles that include maintenance methods
+ *
+ * This is useful for type-hints used by installer, upgrader, and background scripts
+ * that will make use of lower-level and longer-running queries, including schema changes.
+ *
+ * @ingroup Database
+ * @since 1.28
+ */
+interface IMaintainableDatabase extends IDatabase {
+ /**
+ * Format a table name ready for use in constructing an SQL query
+ *
+ * This does two important things: it quotes the table names to clean them up,
+ * and it adds a table prefix if only given a table name with no quotes.
+ *
+ * All functions of this object which require a table name call this function
+ * themselves. Pass the canonical name to such functions. This is only needed
+ * when calling query() directly.
+ *
+ * @note This function does not sanitize user input. It is not safe to use
+ * this function to escape user input.
+ * @param string $name Database table name
+ * @param string $format One of:
+ * quoted - Automatically pass the table name through addIdentifierQuotes()
+ * so that it can be used in a query.
+ * raw - Do not add identifier quotes to the table name
+ * @return string Full database name
+ */
+ public function tableName( $name, $format = 'quoted' );
+
+ /**
+ * Fetch a number of table names into an array
+ * This is handy when you need to construct SQL for joins
+ *
+ * Example:
+ * extract( $dbr->tableNames( 'user', 'watchlist' ) );
+ * $sql = "SELECT wl_namespace,wl_title FROM $watchlist,$user
+ * WHERE wl_user=user_id AND wl_user=$nameWithQuotes";
+ *
+ * @return array
+ */
+ public function tableNames();
+
+ /**
+ * Fetch a number of table names into an zero-indexed numerical array
+ * This is handy when you need to construct SQL for joins
+ *
+ * Example:
+ * list( $user, $watchlist ) = $dbr->tableNamesN( 'user', 'watchlist' );
+ * $sql = "SELECT wl_namespace,wl_title FROM $watchlist,$user
+ * WHERE wl_user=user_id AND wl_user=$nameWithQuotes";
+ *
+ * @return array
+ */
+ public function tableNamesN();
+
+ /**
+ * Returns the size of a text field, or -1 for "unlimited"
+ *
+ * @param string $table
+ * @param string $field
+ * @return int
+ */
+ public function textFieldSize( $table, $field );
+
+ /**
+ * Read and execute SQL commands from a file.
+ *
+ * Returns true on success, error string or exception on failure (depending
+ * on object's error ignore settings).
+ *
+ * @param string $filename File name to open
+ * @param callable|null $lineCallback Optional function called before reading each line
+ * @param callable|null $resultCallback Optional function called for each MySQL result
+ * @param bool|string $fname Calling function name or false if name should be
+ * generated dynamically using $filename
+ * @param callable|null $inputCallback Optional function called for each
+ * complete line sent
+ * @return bool|string
+ * @throws Exception
+ */
+ public function sourceFile(
+ $filename,
+ callable $lineCallback = null,
+ callable $resultCallback = null,
+ $fname = false,
+ callable $inputCallback = null
+ );
+
+ /**
+ * Read and execute commands from an open file handle.
+ *
+ * Returns true on success, error string or exception on failure (depending
+ * on object's error ignore settings).
+ *
+ * @param resource $fp File handle
+ * @param callable|null $lineCallback Optional function called before reading each query
+ * @param callable|null $resultCallback Optional function called for each MySQL result
+ * @param string $fname Calling function name
+ * @param callable|null $inputCallback Optional function called for each complete query sent
+ * @return bool|string
+ */
+ public function sourceStream(
+ $fp,
+ callable $lineCallback = null,
+ callable $resultCallback = null,
+ $fname = __METHOD__,
+ callable $inputCallback = null
+ );
+
+ /**
+ * Called by sourceStream() to check if we've reached a statement end
+ *
+ * @param string &$sql SQL assembled so far
+ * @param string &$newLine New line about to be added to $sql
+ * @return bool Whether $newLine contains end of the statement
+ */
+ public function streamStatementEnd( &$sql, &$newLine );
+
+ /**
+ * Delete a table
+ * @param string $tableName
+ * @param string $fName
+ * @return bool|ResultWrapper
+ */
+ public function dropTable( $tableName, $fName = __METHOD__ );
+
+ /**
+ * Perform a deadlock-prone transaction.
+ *
+ * This function invokes a callback function to perform a set of write
+ * queries. If a deadlock occurs during the processing, the transaction
+ * will be rolled back and the callback function will be called again.
+ *
+ * Avoid using this method outside of Job or Maintenance classes.
+ *
+ * Usage:
+ * $dbw->deadlockLoop( callback, ... );
+ *
+ * Extra arguments are passed through to the specified callback function.
+ * This method requires that no transactions are already active to avoid
+ * causing premature commits or exceptions.
+ *
+ * Returns whatever the callback function returned on its successful,
+ * iteration, or false on error, for example if the retry limit was
+ * reached.
+ *
+ * @return mixed
+ * @throws DBUnexpectedError
+ * @throws Exception
+ */
+ public function deadlockLoop();
+
+ /**
+ * Lists all the VIEWs in the database
+ *
+ * @param string $prefix Only show VIEWs with this prefix, eg. unit_test_
+ * @param string $fname Name of calling function
+ * @throws RuntimeException
+ * @return array
+ */
+ public function listViews( $prefix = null, $fname = __METHOD__ );
+
+ /**
+ * Creates a new table with structure copied from existing table
+ *
+ * Note that unlike most database abstraction functions, this function does not
+ * automatically append database prefix, because it works at a lower abstraction level.
+ * The table names passed to this function shall not be quoted (this function calls
+ * addIdentifierQuotes() when needed).
+ *
+ * @param string $oldName Name of table whose structure should be copied
+ * @param string $newName Name of table to be created
+ * @param bool $temporary Whether the new table should be temporary
+ * @param string $fname Calling function name
+ * @return bool True if operation was successful
+ * @throws RuntimeException
+ */
+ public function duplicateTableStructure(
+ $oldName, $newName, $temporary = false, $fname = __METHOD__
+ );
+
+ /**
+ * Checks if table locks acquired by lockTables() are transaction-bound in their scope
+ *
+ * Transaction-bound table locks will be released when the current transaction terminates.
+ * Table locks that are not bound to a transaction are not effected by BEGIN/COMMIT/ROLLBACK
+ * and will last until either lockTables()/unlockTables() is called or the TCP connection to
+ * the database is closed.
+ *
+ * @return bool
+ * @since 1.29
+ */
+ public function tableLocksHaveTransactionScope();
+
+ /**
+ * Lock specific tables
+ *
+ * Any pending transaction should be resolved before calling this method, since:
+ * a) Doing so resets any REPEATABLE-READ snapshot of the data to a fresh one.
+ * b) Previous row and table locks from the transaction or session may be released
+ * by LOCK TABLES, which may be unsafe for the changes in such a transaction.
+ * c) The main use case of lockTables() is to avoid deadlocks and timeouts by locking
+ * entire tables in order to do long-running, batched, and lag-aware, updates. Batching
+ * and replication lag checks do not work when all the updates happen in a transaction.
+ *
+ * Always get all relevant table locks up-front in one call, since LOCK TABLES might release
+ * any prior table locks on some RDBMes (e.g MySQL).
+ *
+ * For compatibility, callers should check tableLocksHaveTransactionScope() before using
+ * this method. If locks are scoped specifically to transactions then caller must either:
+ * - a) Start a new transaction and acquire table locks for the scope of that transaction,
+ * doing all row updates within that transaction. It will not be possible to update
+ * rows in batches; this might result in high replication lag.
+ * - b) Forgo table locks entirely and avoid calling this method. Careful use of hints like
+ * LOCK IN SHARE MODE and FOR UPDATE and the use of query batching may be preferrable
+ * to using table locks with a potentially large transaction. Use of MySQL and Postges
+ * style REPEATABLE-READ (Snapshot Isolation with or without First-Committer-Rule) can
+ * also be considered for certain tasks that require a consistent view of entire tables.
+ *
+ * If session scoped locks are not supported, then calling lockTables() will trigger
+ * startAtomic(), with unlockTables() triggering endAtomic(). This will automatically
+ * start a transaction if one is not already present and cause the locks to be released
+ * when the transaction finishes (normally during the unlockTables() call).
+ *
+ * In any case, avoid using begin()/commit() in code that runs while such table locks are
+ * acquired, as that breaks in case when a transaction is needed. The startAtomic() and
+ * endAtomic() methods are safe, however, since they will join any existing transaction.
+ *
+ * @param array $read Array of tables to lock for read access
+ * @param array $write Array of tables to lock for write access
+ * @param string $method Name of caller
+ * @return bool
+ * @since 1.29
+ */
+ public function lockTables( array $read, array $write, $method );
+
+ /**
+ * Unlock all tables locked via lockTables()
+ *
+ * If table locks are scoped to transactions, then locks might not be released until the
+ * transaction ends, which could happen after this method is called.
+ *
+ * @param string $method The caller
+ * @return bool
+ * @since 1.29
+ */
+ public function unlockTables( $method );
+}
+
+class_alias( IMaintainableDatabase::class, 'IMaintainableDatabase' );
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