Merge ".mailmap: Correct two contributor names"

[mediawiki.git] / includes / libs / rdbms / database / IDatabase.php

<?php
/**
 * 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
 */
namespace Wikimedia\Rdbms;

use Exception;
use Wikimedia\ScopedCallback;

/**
 * @defgroup Database Database
 * This group deals with database interface functions
 * and query specifics/optimisations.
 */

/**
 * Interface to a relational database
 *
 * This is used for both primary databases and replicas, and used for both concrete
 * connections, as well as wrappers around shared connections, like DBConnRef.
 *
 * As such, callers should not assume that the object represents a live connection
 * (when using DBConnRef, the object may lazily defer the connection to the first query),
 * and should not assume that they have complete control over the connection
 * (when using DBConnRef, multiple objects may automatically share and reuse the same
 * underlying connection).
 *
 * @ingroup Database
 */
interface IDatabase extends IReadableDatabase {
        /** Callback triggered immediately due to no active transaction */
        public const TRIGGER_IDLE = 1;
        /** Callback triggered by COMMIT */
        public const TRIGGER_COMMIT = 2;
        /** Callback triggered by ROLLBACK */
        public const TRIGGER_ROLLBACK = 3;
        /** Callback triggered by atomic section cancel (ROLLBACK TO SAVEPOINT) */
        public const TRIGGER_CANCEL = 4;

        /** Transaction is requested by regular caller outside of the DB layer */
        public const TRANSACTION_EXPLICIT = '';
        /** Transaction is requested internally via DBO_TRX/startAtomic() */
        public const TRANSACTION_INTERNAL = 'implicit';

        /** Atomic section is not cancelable */
        public const ATOMIC_NOT_CANCELABLE = '';
        /** Atomic section is cancelable */
        public const ATOMIC_CANCELABLE = 'cancelable';

        /** Commit/rollback is from outside the IDatabase handle and connection manager */
        public const FLUSHING_ONE = '';
        /**
         * Commit/rollback is from the owning connection manager for the IDatabase handle
         * @internal Only for use within the rdbms library
         */
        public const FLUSHING_ALL_PEERS = 'flush';
        /**
         * Commit/rollback is from the IDatabase handle internally
         * @internal Only for use within the rdbms library
         */
        public const FLUSHING_INTERNAL = 'flush-internal';

        /** Estimate total time (RTT, scanning, waiting on locks, applying) */
        public const ESTIMATE_TOTAL = 'total';
        /** Estimate time to apply (scanning, applying) */
        public const ESTIMATE_DB_APPLY = 'apply';

        /** Flag to return the lock acquisition timestamp (null if not acquired) */
        public const LOCK_TIMESTAMP = 1;

        /**
         * Field for getLBInfo()/setLBInfo(); relevant transaction round level (1 or 0)
         * @internal For use in the rdbms library only
         */
        public const LB_TRX_ROUND_LEVEL = 'trxRoundLevel';
        /**
         * Field for getLBInfo()/setLBInfo(); relevant transaction round owner name or null
         * @internal For use in the rdbms library only
         */
        public const LB_TRX_ROUND_FNAME = 'trxRoundOwner';
        /**
         * Field for getLBInfo()/setLBInfo(); configured read-only mode explanation or false
         * @internal For use in the rdbms library only
         */
        public const LB_READ_ONLY_REASON = 'readOnlyReason';
        /**
         * Alias to LB_TRX_ROUND_FNAME
         * @deprecated Since 1.44
         */
        public const LB_TRX_ROUND_ID = self::LB_TRX_ROUND_FNAME;

        /** Primary server than can stream writes to replica servers */
        public const ROLE_STREAMING_MASTER = 'streaming-master';
        /** Replica server that receives writes from a primary server */
        public const ROLE_STREAMING_REPLICA = 'streaming-replica';
        /** Replica server within a static dataset */
        public const ROLE_STATIC_CLONE = 'static-clone';
        /** Server with unknown topology role */
        public const ROLE_UNKNOWN = 'unknown';

        /**
         * Gets the current transaction level.
         *
         * Historically, transactions were allowed to be "nested". This is no
         * longer supported, so this function really only returns a boolean.
         *
         * @return int The previous value
         */
        public function trxLevel();

        /**
         * Get the UNIX timestamp of the time that the transaction was established
         *
         * This can be used to reason about the staleness of SELECT data in REPEATABLE-READ
         * transaction isolation level. Callers can assume that if a view-snapshot isolation
         * is used, then the data read by SQL queries is *at least* up to date to that point
         * (possibly more up-to-date since the first SELECT defines the snapshot).
         *
         * @return float|null Returns null if there is not active transaction
         * @since 1.25
         */
        public function trxTimestamp();

        /**
         * Check whether there is a transaction open at the specific request of a caller
         *
         * Explicit transactions are spawned by begin(), startAtomic(), and doAtomicSection().
         * Note that explicit transactions should not be confused with explicit transaction rounds.
         *
         * @return bool
         * @since 1.28
         */
        public function explicitTrxActive();

        /**
         * Get properties passed down from the server info array of the load balancer
         *
         * @internal should not be called outside of rdbms library.
         *
         * @param string|null $name The entry of the info array to get, or null to get the whole array
         * @return array|mixed|null
         */
        public function getLBInfo( $name = null );

        /**
         * Get the sequence-based ID assigned by the last query method call
         *
         * This method should only be called when all the following hold true:
         *   - (a) A method call was made to insert(), upsert(), replace(), or insertSelect()
         *   - (b) The method call attempts to insert exactly one row
         *   - (c) The method call omits the value of exactly one auto-increment column
         *   - (d) The method call succeeded
         *   - (e) No subsequent method calls were made, with the exception of affectedRows(),
         *         lastErrno(), lastError(), and getType()
         *
         * In all other cases, the return value is unspecified.
         *
         * When the query method is either insert() with "IGNORE", upsert(), or insertSelect(),
         * callers should first check affectedRows() before calling this method, making sure that
         * the query method actually created a row. Otherwise, an ID from a previous insert might
         * be incorrectly assumed to belong to last insert.
         *
         * @return int
         */
        public function insertId();

        /**
         * Get the number of rows affected by the last query method call
         *
         * This method should only be called when all the following hold true:
         *   - (a) A method call was made to insert(), upsert(), replace(), update(), delete(),
         *         insertSelect(), query() with a non-SELECT statement, or queryMulti() with a
         *         non-SELECT terminal statement
         *   - (b) The method call succeeded
         *   - (c) No subsequent method calls were made, with the exception of affectedRows(),
         *         lastErrno(), lastError(), and getType()
         *
         * In all other cases, the return value is unspecified.
         *
         * UPDATE queries consider rows affected even when all their new column values match
         * the previous values. Such rows can be excluded from the count by changing the WHERE
         * clause to filter them out.
         *
         * If the last query method call was to query() or queryMulti(), then the results
         * are based on the (last) statement provided to that call and are driver-specific.
         *
         * @return int
         */
        public function affectedRows();

        /**
         * Run an SQL query statement and return the result
         *
         * If a connection loss is detected, then an attempt to reconnect will be made.
         * For queries that involve no larger transactions or locks, they will be re-issued
         * for convenience, provided the connection was re-established.
         *
         * In new code, the query wrappers select(), insert(), update(), delete(),
         * etc. should be used where possible, since they give much better DBMS
         * independence and automatically quote or validate user input in a variety
         * of contexts. This function is generally only useful for queries which are
         * explicitly DBMS-dependent and are unsupported by the query wrappers, such
         * as CREATE TABLE.
         *
         * However, the query wrappers themselves should call this function.
         *
         * Callers should avoid the use of statements like BEGIN, COMMIT, and ROLLBACK.
         * Methods like startAtomic(), endAtomic(), and cancelAtomic() can be used instead.
         *
         * @param string|Query $sql Single-statement SQL query
         * @param-taint $sql exec_sql
         * @param string $fname Caller name; used for profiling/SHOW PROCESSLIST comments @phan-mandatory-param
         * @param int $flags Bit field of ISQLPlatform::QUERY_* constants
         * @return bool|IResultWrapper True for a successful write query, IResultWrapper object
         *     for a successful read query, or false on failure if QUERY_SILENCE_ERRORS is set
         * @return-taint tainted
         * @throws DBQueryError If the query is issued, fails, and QUERY_SILENCE_ERRORS is not set
         * @throws DBExpectedError If the query is not, and cannot, be issued yet (non-DBQueryError)
         * @throws DBError If the query is inherently not allowed (non-DBExpectedError)
         */
        public function query( $sql, $fname = __METHOD__, $flags = 0 );

        /**
         * Get an UpdateQueryBuilder bound to this connection. This is overridden by
         * DBConnRef.
         *
         * @note A new query builder must be created per query. Query builders
         *   should not be reused since this uses a fluent interface and the state of
         *   the builder changes during the query which may cause unexpected results.
         *
         * @return UpdateQueryBuilder
         */
        public function newUpdateQueryBuilder(): UpdateQueryBuilder;

        /**
         * Get an DeleteQueryBuilder bound to this connection. This is overridden by
         * DBConnRef.
         *
         * @note A new query builder must be created per query. Query builders
         *   should not be reused since this uses a fluent interface and the state of
         *   the builder changes during the query which may cause unexpected results.
         *
         * @return DeleteQueryBuilder
         */
        public function newDeleteQueryBuilder(): DeleteQueryBuilder;

        /**
         * Get an InsertQueryBuilder bound to this connection. This is overridden by
         * DBConnRef.
         *
         * @note A new query builder must be created per query. Query builders
         *   should not be reused since this uses a fluent interface and the state of
         *   the builder changes during the query which may cause unexpected results.
         *
         * @return InsertQueryBuilder
         */
        public function newInsertQueryBuilder(): InsertQueryBuilder;

        /**
         * Get an ReplaceQueryBuilder bound to this connection. This is overridden by
         * DBConnRef.
         *
         * @note A new query builder must be created per query. Query builders
         *   should not be reused since this uses a fluent interface and the state of
         *   the builder changes during the query which may cause unexpected results.
         *
         * @return ReplaceQueryBuilder
         */
        public function newReplaceQueryBuilder(): ReplaceQueryBuilder;

        /**
         * Lock all rows meeting the given conditions/options FOR UPDATE
         *
         * @param string|string[] $table The unqualified name of table(s) (use an array for a join)
         * @phpcs:ignore Generic.Files.LineLength
         * @param string|IExpression|array<string,?scalar|non-empty-array<int,?scalar>|RawSQLValue>|array<int,string|IExpression> $conds
         *   Condition in the format of IDatabase::select() conditions
         * @param string $fname Function name for profiling @phan-mandatory-param
         * @param array $options Options for select ("FOR UPDATE" is added automatically)
         * @param array $join_conds Join conditions
         * @return int Number of matching rows found (and locked)
         * @throws DBError If an error occurs, {@see query}
         * @since 1.32
         * @deprecated since 1.43; Use SelectQueryBuilder::acquireRowLocks
         */
        public function lockForUpdate(
                $table, $conds = '', $fname = __METHOD__, $options = [], $join_conds = []
        );

        /**
         * Insert row(s) into a table, in the provided order
         *
         * This operation will be seen by affectedRows()/insertId() as one query statement,
         * regardless of how many statements are actually sent by the class implementation.
         *
         * @internal callers outside of rdbms library should use InsertQueryBuilder instead.
         *
         * @param string $table The unqualified name of a table
         * @param array|array[] $rows Row(s) to insert, as either:
         *   - A string-keyed map of (column name => value) defining a new row. Values are
         *     treated as literals and quoted appropriately; null is interpreted as NULL.
         *   - An integer-keyed list of such string-keyed maps, defining a list of new rows.
         *     The keys in each map must be identical to each other and in the same order.
         *     The rows must not collide with each other.
         * @param string $fname Calling function name (use __METHOD__) for logs/profiling @phan-mandatory-param
         * @param string|array $options Combination map/list where each string-keyed entry maps
         *   a non-boolean option to the option parameters and each integer-keyed value is the
         *   name of a boolean option. Supported options are:
         *     - IGNORE: Boolean: skip insertion of rows that would cause unique key conflicts.
         *       IDatabase::affectedRows() can be used to determine how many rows were inserted.
         * @return bool Return true if no exception was thrown (deprecated since 1.33)
         * @throws DBError If an error occurs, {@see query}
         */
        public function insert( $table, $rows, $fname = __METHOD__, $options = [] );

        /**
         * Update all rows in a table that match a given condition
         *
         * This operation will be seen by affectedRows()/insertId() as one query statement,
         * regardless of how many statements are actually sent by the class implementation.
         *
         * @internal callers outside of rdbms library should use UpdateQueryBuilder instead.
         *
         * @param string $table The unqualified name of a table
         * @param-taint $table exec_sql
         * @param array<string,?scalar|RawSQLValue>|array<int,string> $set
         *   Combination map/list where each string-keyed entry maps a column
         *   to a literal assigned value and each integer-keyed value is a SQL expression in the
         *   format of a column assignment within UPDATE...SET. The (column => value) entries are
         *   convenient due to automatic value quoting and conversion of null to NULL. The SQL
         *   assignment format is useful for updates like "column = column + X". All assignments
         *   have no defined execution order, so they should not depend on each other. Do not
         *   modify AUTOINCREMENT or UUID columns in assignments.
         * @param-taint $set exec_sql_numkey
         * @phpcs:ignore Generic.Files.LineLength
         * @param string|IExpression|array<string,?scalar|non-empty-array<int,?scalar>|RawSQLValue>|array<int,string|IExpression> $conds
         *   Condition in the format of IDatabase::select() conditions.
         *   In order to prevent possible performance or replication issues or damaging a data
         *   accidentally, an empty condition for 'update' queries isn't allowed.
         *   IDatabase::ALL_ROWS should be passed explicitly in order to update all rows.
         * @param-taint $conds exec_sql_numkey
         * @param string $fname Calling function name (use __METHOD__) for logs/profiling @phan-mandatory-param
         * @param-taint $fname exec_sql
         * @param string|array $options Combination map/list where each string-keyed entry maps
         *   a non-boolean option to the option parameters and each integer-keyed value is the
         *   name of a boolean option. Supported options are:
         *     - IGNORE: Boolean: skip update of rows that would cause unique key conflicts.
         *       IDatabase::affectedRows() includes all matching rows,
         *       that includes also rows not updated due to key conflict.
         * @param-taint $options none
         * @return bool Return true if no exception was thrown (deprecated since 1.33)
         * @return-taint none
         * @throws DBError If an error occurs, {@see query}
         */
        public function update( $table, $set, $conds, $fname = __METHOD__, $options = [] );

        /**
         * Insert row(s) into a table, in the provided order, while deleting conflicting rows
         *
         * Conflicts are determined by the provided unique indexes. Note that it is possible
         * for the provided rows to conflict even among themselves; it is preferable for the
         * caller to de-duplicate such input beforehand.
         *
         * Note some important implications of the deletion semantics:
         *   - If the table has an AUTOINCREMENT column and $rows omit that column, then any
         *     conflicting existing rows will be replaced with newer having higher values for
         *     that column, even if nothing else changed.
         *   - There might be worse contention than upsert() due to the use of gap-locking.
         *     This does not apply to RDBMS types that use predicate locking nor those that
         *     just lock the whole table or databases anyway.
         *
         * This operation will be seen by affectedRows()/insertId() as one query statement,
         * regardless of how many statements are actually sent by the class implementation.
         *
         * @internal callers outside of rdbms library should use ReplaceQueryBuilder instead.
         *
         * @param string $table The unqualified name of a table
         * @param string|string[]|string[][] $uniqueKeys Column name or non-empty list of column
         *   name lists that define all applicable unique keys on the table. There must only be
         *   one such key. Each unique key on the table is "applicable" unless either:
         *     - It involves an AUTOINCREMENT column for which no values are assigned in $rows
         *     - It involves a UUID column for which newly generated UUIDs are assigned in $rows
         * @param array|array[] $rows Row(s) to insert, in the form of either:
         *   - A string-keyed map of (column name => value) defining a new row. Values are
         *     treated as literals and quoted appropriately; null is interpreted as NULL.
         *     Columns belonging to a key in $uniqueKeys must be defined here and non-null.
         *   - An integer-keyed list of such string-keyed maps, defining a list of new rows.
         *     The keys in each map must be identical to each other and in the same order.
         *     The rows must not collide with each other.
         * @param string $fname Calling function name (use __METHOD__) for logs/profiling @phan-mandatory-param
         * @throws DBError If an error occurs, {@see query}
         */
        public function replace( $table, $uniqueKeys, $rows, $fname = __METHOD__ );

        /**
         * Upsert row(s) into a table, in the provided order, while updating conflicting rows
         *
         * Conflicts are determined by the provided unique indexes. Note that it is possible
         * for the provided rows to conflict even among themselves; it is preferable for the
         * caller to de-duplicate such input beforehand.
         *
         * This operation will be seen by affectedRows()/insertId() as one query statement,
         * regardless of how many statements are actually sent by the class implementation.
         *
         * @internal callers outside of rdbms library should use InsertQueryBuilder instead.
         *
         * @param string $table The unqualified name of a table
         * @param array|array[] $rows Row(s) to insert, in the form of either:
         *   - A string-keyed map of (column name => value) defining a new row. Values are
         *     treated as literals and quoted appropriately; null is interpreted as NULL.
         *     Columns belonging to a key in $uniqueKeys must be defined here and non-null.
         *   - An integer-keyed list of such string-keyed maps, defining a list of new rows.
         *     The keys in each map must be identical to each other and in the same order.
         *     The rows must not collide with each other.
         * @param string|string[]|string[][] $uniqueKeys Column name or non-empty list of column
         *   name lists that define all applicable unique keys on the table. There must only be
         *   one such key. Each unique key on the table is "applicable" unless either:
         *     - It involves an AUTOINCREMENT column for which no values are assigned in $rows
         *     - It involves a UUID column for which newly generated UUIDs are assigned in $rows
         * @param array<string,?scalar|RawSQLValue>|array<int,string> $set
         *   Combination map/list where each string-keyed entry maps a column
         *   to a literal assigned value and each integer-keyed value is a SQL assignment expression
         *   of the form "<unquoted alphanumeric column> = <SQL expression>". The (column => value)
         *   entries are convenient due to automatic value quoting and conversion of null to NULL.
         *   The SQL assignment entries are useful for updates like "column = column + X". All of
         *   the assignments have no defined execution order, so callers should make sure that they
         *   not depend on each other. Do not modify AUTOINCREMENT or UUID columns in assignments,
         *   even if they are just "secondary" unique keys. For multi-row upserts, use
         *   buildExcludedValue() to reference the value of a column from the corresponding row
         *   in $rows that conflicts with the current row.
         * @param string $fname Calling function name (use __METHOD__) for logs/profiling @phan-mandatory-param
         * @throws DBError If an error occurs, {@see query}
         * @since 1.22
         */
        public function upsert(
                $table, array $rows, $uniqueKeys, array $set, $fname = __METHOD__
        );

        /**
         * Delete all rows in a table that match a condition which includes a join
         *
         * For safety, an empty $conds will not delete everything. If you want to
         * delete all rows where the join condition matches, set $conds=IDatabase::ALL_ROWS.
         *
         * DO NOT put the join condition in $conds.
         *
         * This operation will be seen by affectedRows()/insertId() as one query statement,
         * regardless of how many statements are actually sent by the class implementation.
         *
         * @param string $delTable The unqualified name of the table to delete rows from.
         * @param string $joinTable The unqualified name of the reference table to join on.
         * @param string $delVar The variable to join on, in the first table.
         * @param string $joinVar The variable to join on, in the second table.
         * @phpcs:ignore Generic.Files.LineLength
         * @param string|IExpression|array<string,?scalar|non-empty-array<int,?scalar>|RawSQLValue>|array<int,string|IExpression> $conds
         *   Condition array of field names mapped to variables,
         *   ANDed together in the WHERE clause
         * @param string $fname Calling function name (use __METHOD__) for logs/profiling @phan-mandatory-param
         * @throws DBError If an error occurs, {@see query}
         */
        public function deleteJoin(
                $delTable,
                $joinTable,
                $delVar,
                $joinVar,
                $conds,
                $fname = __METHOD__
        );

        /**
         * Delete all rows in a table that match a condition
         *
         * This operation will be seen by affectedRows()/insertId() as one query statement,
         * regardless of how many statements are actually sent by the class implementation.
         *
         * @internal callers outside of rdbms library should use DeleteQueryBuilder instead.
         *
         * @param string $table The unqualified name of a table
         * @param-taint $table exec_sql
         * @phpcs:ignore Generic.Files.LineLength
         * @param string|IExpression|array<string,?scalar|non-empty-array<int,?scalar>|RawSQLValue>|array<int,string|IExpression> $conds
         *   Array of conditions. See $conds in IDatabase::select()
         *   In order to prevent possible performance or replication issues or damaging a data
         *   accidentally, an empty condition for 'delete' queries isn't allowed.
         *   IDatabase::ALL_ROWS should be passed explicitly in order to delete all rows.
         * @param-taint $conds exec_sql_numkey
         * @param string $fname Name of the calling function @phan-mandatory-param
         * @param-taint $fname exec_sql
         * @return bool Return true if no exception was thrown (deprecated since 1.33)
         * @return-taint none
         * @throws DBError If an error occurs, {@see query}
         */
        public function delete( $table, $conds, $fname = __METHOD__ );

        /**
         * INSERT SELECT wrapper
         *
         * @warning If the insert will use an auto-increment or sequence to
         *  determine the value of a column, this may break replication on
         *  databases using statement-based replication if the SELECT is not
         *  deterministically ordered.
         *
         * This operation will be seen by affectedRows()/insertId() as one query statement,
         * regardless of how many statements are actually sent by the class implementation.
         *
         * @param string $destTable Unqualified name of destination table
         * @param string|array $srcTable Unqualified name of source table(s) (use an array for a join)
         * @param array $varMap Must be an associative array of the form
         *    [ 'dest1' => 'source1', ... ]. Source items may be literals
         *    rather than field names, but strings should be quoted with
         *    IDatabase::addQuotes()
         * @phpcs:ignore Generic.Files.LineLength
         * @param string|IExpression|array<string,?scalar|non-empty-array<int,?scalar>|RawSQLValue>|array<int,string|IExpression> $conds
         *    Condition array. See $conds in IDatabase::select() for
         *    the details of the format of condition arrays. May be "*" to copy the
         *    whole table.
         * @param string $fname The function name of the caller, from __METHOD__ @phan-mandatory-param
         * @param array $insertOptions Options for the INSERT part of the query, see
         *    IDatabase::insert() for details. Also, one additional option is
         *    available: pass 'NO_AUTO_COLUMNS' to hint that the query does not use
         *    an auto-increment or sequence to determine any column values.
         * @param array $selectOptions Options for the SELECT part of the query, see
         *    IDatabase::select() for details.
         * @param array $selectJoinConds Join conditions for the SELECT part of the query, see
         *    IDatabase::select() for details.
         * @return bool Return true if no exception was thrown (deprecated since 1.33)
         * @throws DBError If an error occurs, {@see query}
         */
        public function insertSelect(
                $destTable,
                $srcTable,
                $varMap,
                $conds,
                $fname = __METHOD__,
                $insertOptions = [],
                $selectOptions = [],
                $selectJoinConds = []
        );

        /**
         * Run a callback when the current transaction commits or rolls back
         *
         * An error is thrown if no transaction is pending.
         *
         * When transaction round mode (DBO_TRX) is set, the callback will run at the end
         * of the round, just after all peer transactions COMMIT/ROLLBACK.
         *
         * This IDatabase instance will start off in auto-commit mode when the callback starts.
         * The use of other IDatabase handles from the callback should be avoided unless they are
         * known to be in auto-commit mode. Callbacks that create transactions via begin() or
         * startAtomic() must have matching calls to commit()/endAtomic().
         *
         * Use this method only for the following purposes:
         *   - (a) Release of cooperative locks on resources
         *   - (b) Cancellation of in-process deferred tasks
         *
         * The callback takes the following arguments:
         *   - How the current atomic section (if any) or overall transaction (otherwise) ended
         *     (IDatabase::TRIGGER_COMMIT or IDatabase::TRIGGER_ROLLBACK)
         *   - This IDatabase instance (since 1.32)
         *
         * Callbacks will execute in the order they were enqueued.
         *
         * @param callable $callback
         * @param string $fname Caller name @phan-mandatory-param
         * @throws DBError If an error occurs, {@see query}
         * @throws Exception If the callback runs immediately and an error occurs in it
         * @since 1.28
         */
        public function onTransactionResolution( callable $callback, $fname = __METHOD__ );

        /**
         * Run a callback when the current transaction commits or now if there is none
         *
         * If there is a transaction and it is rolled back, then the callback is cancelled.
         *
         * When transaction round mode (DBO_TRX) is set, the callback will run at the end
         * of the round, just after all peer transactions COMMIT. If the transaction round
         * is rolled back, then the callback is cancelled.
         *
         * This IDatabase instance will start off in auto-commit mode when the callback starts.
         * The use of other IDatabase handles from the callback should be avoided unless they are
         * known to be in auto-commit mode. Callbacks that create transactions via begin() or
         * startAtomic() must have matching calls to commit()/endAtomic().
         *
         * Use this method only for the following purposes:
         *   - (a) RDBMS updates, prone to lock timeouts/deadlocks, that do not require
         *         atomicity with respect to the updates in the current transaction (if any)
         *   - (b) Purges to lightweight cache services due to RDBMS updates
         *   - (c) Updates to secondary DBs/stores that must only commit once the updates in
         *         the current transaction (if any) are committed (e.g. insert user account row
         *         to DB1, then, initialize corresponding LDAP account)
         *
         * The callback takes the following arguments:
         *   - How the transaction ended (IDatabase::TRIGGER_COMMIT or IDatabase::TRIGGER_IDLE)
         *   - This IDatabase instance (since 1.32)
         *
         * Callbacks will execute in the order they were enqueued.
         *
         * @param callable $callback
         * @param string $fname Caller name @phan-mandatory-param
         * @throws DBError If an error occurs, {@see query}
         * @throws Exception If the callback runs immediately and an error occurs in it
         * @since 1.32
         */
        public function onTransactionCommitOrIdle( callable $callback, $fname = __METHOD__ );

        /**
         * Run a callback before the current transaction commits or now if there is none
         *
         * If there is a transaction and it is rolled back, then the callback is cancelled.
         *
         * When transaction round mode (DBO_TRX) is set, the callback will run at the end
         * of the round, just after all peer transactions COMMIT. If the transaction round
         * is rolled back, then the callback is cancelled.
         *
         * If there is no current transaction, one will be created to wrap the callback.
         * Callbacks cannot use begin()/commit() to manage transactions. The use of other
         * IDatabase handles from the callback should be avoided.
         *
         * Use this method only for the following purposes:
         *   - a) RDBMS updates, prone to lock timeouts/deadlocks, that require atomicity
         *        with respect to the updates in the current transaction (if any)
         *   - b) Purges to lightweight cache services due to RDBMS updates
         *
         * The callback takes the one argument:
         *   - This IDatabase instance (since 1.32)
         *
         * Callbacks will execute in the order they were enqueued.
         *
         * @param callable $callback
         * @param string $fname Caller name @phan-mandatory-param
         * @throws DBError If an error occurs, {@see query}
         * @throws Exception If the callback runs immediately and an error occurs in it
         * @since 1.22
         */
        public function onTransactionPreCommitOrIdle( callable $callback, $fname = __METHOD__ );

        /**
         * Begin an atomic section of SQL statements
         *
         * Start an implicit transaction if no transaction is already active, set a savepoint
         * (if $cancelable is ATOMIC_CANCELABLE), and track the given section name to enforce
         * that the transaction is not committed prematurely. The end of the section must be
         * signified exactly once, either by endAtomic() or cancelAtomic(). Sections can have
         * have layers of inner sections (sub-sections), but all sections must be ended in order
         * of innermost to outermost. Transactions cannot be started or committed until all
         * atomic sections are closed.
         *
         * ATOMIC_CANCELABLE is useful when the caller needs to handle specific failure cases
         * by discarding the section's writes.  This should not be used for failures when:
         *   - upsert() could easily be used instead
         *   - insert() with IGNORE could easily be used instead
         *   - select() with FOR UPDATE could be checked before issuing writes instead
         *   - The failure is from code that runs after the first write but doesn't need to
         *   - The failures are from contention solvable via onTransactionPreCommitOrIdle()
         *   - The failures are deadlocks; the RDBMs usually discard the whole transaction
         *
         * @note callers must use additional measures for situations involving two or more
         *   (peer) transactions (e.g. updating two database servers at once). The transaction
         *   and savepoint logic of this method only applies to this specific IDatabase instance.
         *
         * Example usage:
         * @code
         *     // Start a transaction if there isn't one already
         *     $dbw->startAtomic( __METHOD__ );
         *     // Serialize these thread table updates
         *     $dbw->select( 'thread', '1', [ 'td_id' => $tid ], __METHOD__, 'FOR UPDATE' );
         *     // Add a new comment for the thread
         *     $dbw->insert( 'comment', $row, __METHOD__ );
         *     $cid = $db->insertId();
         *     // Update thread reference to last comment
         *     $dbw->update( 'thread', [ 'td_latest' => $cid ], [ 'td_id' => $tid ], __METHOD__ );
         *     // Demark the end of this conceptual unit of updates
         *     $dbw->endAtomic( __METHOD__ );
         * @endcode
         *
         * Example usage (atomic changes that might have to be discarded):
         * @code
         *     // Start a transaction if there isn't one already
         *     $sectionId = $dbw->startAtomic( __METHOD__, $dbw::ATOMIC_CANCELABLE );
         *     // Create new record metadata row
         *     $dbw->insert( 'records', $row, __METHOD__ );
         *     // Figure out where to store the data based on the new row's ID
         *     $path = $recordDirectory . '/' . $dbw->insertId();
         *     // Write the record data to the storage system
         *     $status = $fileBackend->create( [ 'dst' => $path, 'content' => $data ] );
         *     if ( $status->isOK() ) {
         *         // Try to cleanup files orphaned by transaction rollback
         *         $dbw->onTransactionResolution(
         *             function ( $type ) use ( $fileBackend, $path ) {
         *                 if ( $type === IDatabase::TRIGGER_ROLLBACK ) {
         *                     $fileBackend->delete( [ 'src' => $path ] );
         *                 }
         *             },
         *             __METHOD__
         *         );
         *         // Demark the end of this conceptual unit of updates
         *         $dbw->endAtomic( __METHOD__ );
         *     } else {
         *         // Discard these writes from the transaction (preserving prior writes)
         *         $dbw->cancelAtomic( __METHOD__, $sectionId );
         *     }
         * @endcode
         *
         * @since 1.23
         * @param string $fname @phan-mandatory-param
         * @param string $cancelable Pass self::ATOMIC_CANCELABLE to use a
         *  savepoint and enable self::cancelAtomic() for this section.
         * @return AtomicSectionIdentifier section ID token
         * @throws DBError If an error occurs, {@see query}
         */
        public function startAtomic( $fname = __METHOD__, $cancelable = self::ATOMIC_NOT_CANCELABLE );

        /**
         * Ends an atomic section of SQL statements
         *
         * Ends the next section of atomic SQL statements and commits the transaction
         * if necessary.
         *
         * @since 1.23
         * @see IDatabase::startAtomic
         * @param string $fname @phan-mandatory-param
         * @throws DBError If an error occurs, {@see query}
         */
        public function endAtomic( $fname = __METHOD__ );

        /**
         * Cancel an atomic section of SQL statements
         *
         * This will roll back only the statements executed since the start of the
         * most recent atomic section, and close that section. If a transaction was
         * open before the corresponding startAtomic() call, any statements before
         * that call are *not* rolled back and the transaction remains open. If the
         * corresponding startAtomic() implicitly started a transaction, that
         * transaction is rolled back.
         *
         * @note callers must use additional measures for situations involving two or more
         *   (peer) transactions (e.g. updating two database servers at once). The transaction
         *   and savepoint logic of startAtomic() are bound to specific IDatabase instances.
         *
         * Note that a call to IDatabase::rollback() will also roll back any open atomic sections.
         *
         * @note As an optimization to save rountrips, this method may only be called
         *   when startAtomic() was called with the ATOMIC_CANCELABLE flag.
         * @since 1.31
         * @see IDatabase::startAtomic
         * @param string $fname @phan-mandatory-param
         * @param AtomicSectionIdentifier|null $sectionId Section ID from startAtomic();
         *   passing this enables cancellation of unclosed nested sections [optional]
         * @throws DBError If an error occurs, {@see query}
         */
        public function cancelAtomic( $fname = __METHOD__, ?AtomicSectionIdentifier $sectionId = null );

        /**
         * Perform an atomic section of reversible SQL statements from a callback
         *
         * The $callback takes the following arguments:
         *   - This database object
         *   - The value of $fname
         *
         * This will execute the callback inside a pair of startAtomic()/endAtomic() calls.
         * If any exception occurs during execution of the callback, it will be handled as follows:
         *   - If $cancelable is ATOMIC_CANCELABLE, cancelAtomic() will be called to back out any
         *     (and only) statements executed during the atomic section. If that succeeds, then the
         *     exception will be re-thrown; if it fails, then a different exception will be thrown
         *     and any further query attempts will fail until rollback() is called.
         *   - If $cancelable is ATOMIC_NOT_CANCELABLE, cancelAtomic() will be called to mark the
         *     end of the section and the error will be re-thrown. Any further query attempts will
         *     fail until rollback() is called.
         *
         * This method is convenient for letting calls to the caller of this method be wrapped
         * in a try/catch blocks for exception types that imply that the caller failed but was
         * able to properly discard the changes it made in the transaction. This method can be
         * an alternative to explicit calls to startAtomic()/endAtomic()/cancelAtomic().
         *
         * Example usage, "RecordStore::save" method:
         * @code
         *     $dbw->doAtomicSection( __METHOD__, function ( $dbw ) use ( $record ) {
         *         // Create new record metadata row
         *         $dbw->insert( 'records', $record->toArray(), __METHOD__ );
         *         // Figure out where to store the data based on the new row's ID
         *         $path = $this->recordDirectory . '/' . $dbw->insertId();
         *         // Write the record data to the storage system;
         *         // blob store throws StoreFailureException on failure
         *         $this->blobStore->create( $path, $record->getJSON() );
         *         // Try to cleanup files orphaned by transaction rollback
         *         $dbw->onTransactionResolution(
         *             function ( $type ) use ( $path ) {
         *                 if ( $type === IDatabase::TRIGGER_ROLLBACK ) {
         *                     $this->blobStore->delete( $path );
         *                 }
         *             },
         *             __METHOD__
         *          );
         *     }, $dbw::ATOMIC_CANCELABLE );
         * @endcode
         *
         * Example usage, caller of the "RecordStore::save" method:
         * @code
         *     $dbw->startAtomic( __METHOD__ );
         *     // ...various SQL writes happen...
         *     try {
         *         $recordStore->save( $record );
         *     } catch ( StoreFailureException $e ) {
         *         // ...various SQL writes happen...
         *     }
         *     // ...various SQL writes happen...
         *     $dbw->endAtomic( __METHOD__ );
         * @endcode
         *
         * @see Database::startAtomic
         * @see Database::endAtomic
         * @see Database::cancelAtomic
         *
         * @param string $fname Caller name (usually __METHOD__) @phan-mandatory-param
         * @param callable $callback Callback that issues write queries
         * @param string $cancelable Pass self::ATOMIC_CANCELABLE to use a
         *  savepoint and enable self::cancelAtomic() for this section.
         * @return mixed Result of the callback (since 1.28)
         * @throws DBError If an error occurs, {@see query}
         * @throws Exception If an error occurs in the callback
         * @since 1.27; prior to 1.31 this did a rollback() instead of
         *  cancelAtomic(), and assumed no callers up the stack would ever try to
         *  catch the exception.
         */
        public function doAtomicSection(
                $fname, callable $callback, $cancelable = self::ATOMIC_NOT_CANCELABLE
        );

        /**
         * Begin a transaction
         *
         * Only call this from code with outer transaction scope.
         * See https://www.mediawiki.org/wiki/Database_transactions for details.
         * Nesting of transactions is not supported.
         *
         * Note that when the DBO_TRX flag is set (which is usually the case for web
         * requests, but not for maintenance scripts), any previous database query
         * will have started a transaction automatically.
         *
         * Nesting of transactions is not supported. Attempts to nest transactions
         * will cause a warning, unless the current transaction was started
         * automatically because of the DBO_TRX flag.
         *
         * @param string $fname Calling function name @phan-mandatory-param
         * @param string $mode A situationally valid IDatabase::TRANSACTION_* constant [optional]
         * @throws DBError If an error occurs, {@see query}
         */
        public function begin( $fname = __METHOD__, $mode = self::TRANSACTION_EXPLICIT );

        /**
         * Commits a transaction previously started using begin()
         *
         * If no transaction is in progress, a warning is issued.
         *
         * Only call this from code with outer transaction scope.
         * See https://www.mediawiki.org/wiki/Database_transactions for details.
         * Nesting of transactions is not supported.
         *
         * @param string $fname @phan-mandatory-param
         * @param string $flush Flush flag, set to situationally valid IDatabase::FLUSHING_*
         *   constant to disable warnings about explicitly committing implicit transactions,
         *   or calling commit when no transaction is in progress.
         *   This will trigger an exception if there is an ongoing explicit transaction.
         *   Only set the flush flag if you are sure that these warnings are not applicable,
         *   and no explicit transactions are open.
         * @throws DBError If an error occurs, {@see query}
         */
        public function commit( $fname = __METHOD__, $flush = self::FLUSHING_ONE );

        /**
         * Rollback a transaction previously started using begin()
         *
         * Only call this from code with outer transaction scope.
         * See https://www.mediawiki.org/wiki/Database_transactions for details.
         * Nesting of transactions is not supported. If a serious unexpected error occurs,
         * throwing an Exception is preferable, using a pre-installed error handler to trigger
         * rollback (in any case, failure to issue COMMIT will cause rollback server-side).
         *
         * Query, connection, and onTransaction* callback errors will be suppressed and logged.
         *
         * @param string $fname Calling function name @phan-mandatory-param
         * @param string $flush Flush flag, set to a situationally valid IDatabase::FLUSHING_*
         *   constant to disable warnings about explicitly rolling back implicit transactions.
         *   This will silently break any ongoing explicit transaction. Only set the flush flag
         *   if you are sure that it is safe to ignore these warnings in your context.
         * @throws DBError If an error occurs, {@see query}
         * @since 1.23 Added $flush parameter
         */
        public function rollback( $fname = __METHOD__, $flush = self::FLUSHING_ONE );

        /**
         * Commit any transaction but error out if writes or callbacks are pending
         *
         * This is intended for clearing out REPEATABLE-READ snapshots so that callers can
         * see a new point-in-time of the database. This is useful when one of many transaction
         * rounds finished and significant time will pass in the script's lifetime. It is also
         * useful to call on a replica server after waiting on replication to catch up to the
         * primary server.
         *
         * @param string $fname Calling function name @phan-mandatory-param
         * @param string $flush Flush flag, set to situationally valid IDatabase::FLUSHING_*
         *   constant to disable warnings about explicitly committing implicit transactions,
         *   or calling commit when no transaction is in progress.
         *   This will trigger an exception if there is an ongoing explicit transaction.
         *   Only set the flush flag if you are sure that these warnings are not applicable,
         *   and no explicit transactions are open.
         * @throws DBError If an error occurs, {@see query}
         * @since 1.28
         * @since 1.34 Added $flush parameter
         */
        public function flushSnapshot( $fname = __METHOD__, $flush = self::FLUSHING_ONE );

        /**
         * Override database's default behavior.
         * Not all options are supported on all database backends;
         * unsupported options are silently ignored.
         *
         * $options include:
         * - 'connTimeout': Set the connection timeout value in seconds.
         *   May be useful for very long batch queries such as full-wiki dumps,
         *   where a single query reads out over hours or days.
         *   Only supported on MySQL and MariaDB.
         * - 'groupConcatMaxLen': Maximum length of a GROUP_CONCAT() result.
         *   Only supported on MySQL and MariaDB.
         *
         * @param array $options
         * @return void
         * @throws DBError If an error occurs, {@see query}
         */
        public function setSessionOptions( array $options );

        /**
         * Check to see if a named lock is not locked by any thread (non-blocking)
         *
         * @param string $lockName Name of lock to poll
         * @param string $method Name of method calling us
         * @return bool
         * @throws DBError If an error occurs, {@see query}
         * @since 1.20
         */
        public function lockIsFree( $lockName, $method );

        /**
         * Acquire a named lock
         *
         * Named locks are not related to transactions
         *
         * @param string $lockName Name of lock to acquire
         * @param string $method Name of the calling method
         * @param int $timeout Acquisition timeout in seconds (0 means non-blocking)
         * @param int $flags Bit field of IDatabase::LOCK_* constants
         * @return bool|float|null Success (bool); acquisition time (float/null) if LOCK_TIMESTAMP
         * @throws DBError If an error occurs, {@see query}
         */
        public function lock( $lockName, $method, $timeout = 5, $flags = 0 );

        /**
         * Release a lock
         *
         * Named locks are not related to transactions
         *
         * @param string $lockName Name of lock to release
         * @param string $method Name of the calling method
         * @return bool Success
         * @throws DBError If an error occurs, {@see query}
         */
        public function unlock( $lockName, $method );

        /**
         * Acquire a named lock, flush any transaction, and return an RAII style unlocker object
         *
         * Only call this from outer transaction scope and when only one DB server will be affected.
         * See https://www.mediawiki.org/wiki/Database_transactions for details.
         *
         * This is suitable for transactions that need to be serialized using cooperative locks,
         * where each transaction can see each others' changes. Any transaction is flushed to clear
         * out stale REPEATABLE-READ snapshot data. Once the returned object falls out of PHP scope,
         * the lock will be released unless a transaction is active. If one is active, then the lock
         * will be released when it either commits or rolls back.
         *
         * If the lock acquisition failed, then no transaction flush happens, and null is returned.
         *
         * @param string $lockKey Name of lock to release
         * @param string $fname Name of the calling method
         * @param int $timeout Acquisition timeout in seconds
         * @return ScopedCallback|null
         * @throws DBError If an error occurs, {@see query}
         * @since 1.27
         */
        public function getScopedLockAndFlush( $lockKey, $fname, $timeout );

        /**
         * Check if this DB server is marked as read-only according to load balancer info
         *
         * @note LoadBalancer checks serverIsReadOnly() when setting the load balancer info array
         *
         * @return bool
         * @since 1.27
         */
        public function isReadOnly();
}