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1 | <?php |
2 | /** |
3 | * This program is free software; you can redistribute it and/or modify |
4 | * it under the terms of the GNU General Public License as published by |
5 | * the Free Software Foundation; either version 2 of the License, or |
6 | * (at your option) any later version. |
7 | * |
8 | * This program is distributed in the hope that it will be useful, |
9 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
10 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
11 | * GNU General Public License for more details. |
12 | * |
13 | * You should have received a copy of the GNU General Public License along |
14 | * with this program; if not, write to the Free Software Foundation, Inc., |
15 | * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. |
16 | * http://www.gnu.org/copyleft/gpl.html |
17 | * |
18 | * @file |
19 | */ |
20 | namespace Wikimedia\Rdbms; |
21 | |
22 | /** |
23 | * This class is a delegate to ILBFactory for a given database cluster |
24 | * |
25 | * ILoadBalancer tracks the database connections and transactions for a given database cluster. |
26 | * A "cluster" is considered to be the set of database servers that manage a given dataset. |
27 | * Within a given cluster, each database server can have one of the following roles: |
28 | * - sole-primary: the server used by this datacenter for writes from the application |
29 | * - co-primary: one of several servers used by this datacenter for writes from the application, |
30 | * relying on asynchronous replication to synchronize their copies of the dataset |
31 | * - replica: a server used only for reads from the application, relying on asynchronous |
32 | * replication to apply writes from the primary server or co-primary servers |
33 | * - static clone: a server that only accepts reads from the application, does not replicate, |
34 | * and has a copy of the final dataset, which must be static (all the servers reject writes) |
35 | * |
36 | * Single-datacenter database clusters consist of either: |
37 | * - A sole-primary server and zero or more replica servers |
38 | * - A set of static clone servers |
39 | * |
40 | * Multi-datacenter database clusters either consist of either: |
41 | * - A sole-primary server and zero or more replica servers in the "primary datacenter" |
42 | * (the one datacenter meant to handle requests/jobs that mutate the database), and zero or |
43 | * more replica servers in each "secondary datacenter" (all the other datacenters) |
44 | * - A co-primary server and zero or more replica servers within each datacenter |
45 | * - A set of static clone servers in each datacenter |
46 | * |
47 | * The term "primary" refers to the server used by this datacenter for handling writes, |
48 | * whether it is a sole-primary or co-primary. |
49 | * |
50 | * The "servers" configuration array contains the list of database servers to use for operations |
51 | * originating from the the local datacenter. The first entry must refer to the server to use for |
52 | * write and read-for-write operations (e.g. the "writer server"): |
53 | * - If there is a primary server, then the first entry must refer to it, even if the primary |
54 | * server resides in a remote datacenter |
55 | * - If there are co-primary servers, then the first entry must refer to the one in the local |
56 | * datacenter |
57 | * - If the servers are static clones, then the first entry can refer to any of them, since the |
58 | * concept of a "writer server" is merely nominal |
59 | * |
60 | * On an infrastructure level, circular replication setups can have more than one database server |
61 | * act as a replication "source" within the same datacenter, provided that no more than one of the |
62 | * servers are writable at any time, namely the "writer server". The other source servers will be |
63 | * treated as replicas by the load balancer, but can be quickly promoted to the "writer server" by |
64 | * the site admin as needed. |
65 | * |
66 | * Likewise, Galera Cluster setups still require the choice of a single "writer server" for each |
67 | * datacenter. Limiting the number of servers that initiate transactions helps reduce the rate of |
68 | * aborted transactions due to wsrep conflicts. |
69 | * |
70 | * By default, each DB server uses DBO_DEFAULT for its 'flags' setting, unless explicitly set |
71 | * otherwise in configuration. DBO_DEFAULT behavior depends on whether 'cliMode' is set: |
72 | * - In CLI mode, the flag has no effect with regards to LoadBalancer. |
73 | * - In non-CLI mode, the flag causes implicit transactions to be used; the first query on |
74 | * a database starts a transaction on that database. The transactions are meant to remain |
75 | * pending until either commitPrimaryChanges() or rollbackPrimaryChanges() is called. The |
76 | * application must have some point where it calls commitPrimaryChanges() near the end of |
77 | * the PHP request. |
78 | * Every iteration of beginPrimaryChanges()/commitPrimaryChanges() is called a "transaction round". |
79 | * Rounds are useful on the primary DB connections because they make single-DB (and by and large |
80 | * multi-DB) updates in web requests all-or-nothing. Also, transactions on replica DBs are useful |
81 | * when REPEATABLE-READ or SERIALIZABLE isolation is used because all foreign keys and constraints |
82 | * hold across separate queries in the DB transaction since the data appears within a consistent |
83 | * point-in-time snapshot. |
84 | * |
85 | * The typical caller will use LoadBalancer::getConnection( DB_* ) to yield a database |
86 | * connection handle. The choice of which DB server to use is based on pre-defined loads for |
87 | * weighted random selection, adjustments thereof by LoadMonitor, and the amount of replication |
88 | * lag on each DB server. Lag checks might cause problems in certain setups, so they should be |
89 | * tuned in the server configuration maps as follows: |
90 | * - Sole-primary + N Replica(s): set 'max lag' to an appropriate threshold for avoiding any |
91 | * replica database lagged by this much or more. If all replicas are this lagged, then the |
92 | * load balancer considers the cluster to be read-only. |
93 | * - Per-datacenter co-primary + N Replica(s): set 'max lag' to an appropriate threshold for |
94 | * avoiding any replica database lagged by this much or more. If all replicas are this |
95 | * lagged, then the load balancer considers the cluster to be read-only. |
96 | * - Read-only archive clones: set 'is static' in the server configuration maps. This will |
97 | * treat all such DBs as having 0 lag. |
98 | * - Externally updated dataset clones: set 'is static' in the server configuration maps. |
99 | * This will treat all such DBs as having 0 lag. |
100 | * - SQL load balancing proxy: any proxy should handle lag checks on its own, so the 'max lag' |
101 | * parameter should probably be set to INF in the server configuration maps. This will make |
102 | * the load balancer ignore whatever it detects as the lag of the logical replica is (which |
103 | * would probably just randomly bounce around). |
104 | * |
105 | * If using a SQL proxy service, it would probably be best to have two proxy hosts for the load |
106 | * balancer to talk to. One would be the 'host' of the "writer server" entry and another for the |
107 | * (logical) replica server entry. The proxy could map the load balancer's "replica" DB to any |
108 | * number of physical replica DBs. |
109 | * |
110 | * @since 1.28 |
111 | * @ingroup Database |
112 | */ |
113 | interface ILoadBalancer { |
114 | /** |
115 | * Request a replica DB connection. Can't be used as a binary flag with bitwise operators! |
116 | */ |
117 | public const DB_REPLICA = -1; |
118 | /** |
119 | * Request a primary, write-enabled DB connection. Can't be used as a binary flag with bitwise |
120 | * operators! |
121 | * @since 1.36 |
122 | */ |
123 | public const DB_PRIMARY = -2; |
124 | |
125 | // phpcs:disable MediaWiki.Usage.DeprecatedConstantUsage.DB_MASTER |
126 | /** |
127 | * Request a primary, write-enabled DB connection |
128 | * @deprecated since 1.36, Use DB_PRIMARY instead |
129 | */ |
130 | public const DB_MASTER = self::DB_PRIMARY; |
131 | // phpcs:enable MediaWiki.Usage.DeprecatedConstantUsage.DB_MASTER |
132 | |
133 | /** Domain specifier when no specific database needs to be selected */ |
134 | public const DOMAIN_ANY = ''; |
135 | /** The generic query group */ |
136 | public const GROUP_GENERIC = ''; |
137 | |
138 | /** Yield an untracked, low-timeout, autocommit-mode handle (to gauge server health) */ |
139 | public const CONN_UNTRACKED_GAUGE = 1; |
140 | /** Yield a tracked autocommit-mode handle (reuse existing ones) */ |
141 | public const CONN_TRX_AUTOCOMMIT = 2; |
142 | /** Yield null on connection failure instead of throwing an exception */ |
143 | public const CONN_SILENCE_ERRORS = 4; |
144 | /** Caller is requesting the primary DB server for possibly writes */ |
145 | public const CONN_INTENT_WRITABLE = 8; |
146 | |
147 | /** |
148 | * Get the name of the overall cluster of database servers managing the dataset |
149 | * |
150 | * Note that the cluster might contain servers in multiple datacenters. |
151 | * The load balancer instance only needs to be aware of the local replica servers, |
152 | * along with either the sole-primary server or the local co-primary server. |
153 | * |
154 | * This is useful for identifying a cluster or replicated dataset, even when: |
155 | * - The primary server is sometimes swapped with another one |
156 | * - The cluster/dataset is replicated among multiple datacenters, with one "primary" |
157 | * datacenter having the writable primary server and the other datacenters having a |
158 | * read-only replica in the "primary" server slot |
159 | * - The dataset is replicated among multiple datacenters, via circular replication, |
160 | * with each datacenter having its own "co-primary" server |
161 | * |
162 | * @return string |
163 | * @since 1.36 |
164 | */ |
165 | public function getClusterName(): string; |
166 | |
167 | /** |
168 | * Get the local (and default) database domain ID of connection handles |
169 | * |
170 | * @see DatabaseDomain |
171 | * @return string Database domain ID; this specifies DB name, schema, and table prefix |
172 | * @since 1.31 |
173 | */ |
174 | public function getLocalDomainID(): string; |
175 | |
176 | /** |
177 | * @param DatabaseDomain|string|false $domain Database domain |
178 | * @return string Value of $domain if it is foreign or the local domain otherwise |
179 | * @since 1.32 |
180 | */ |
181 | public function resolveDomainID( $domain ): string; |
182 | |
183 | /** |
184 | * Indicate whether the tables on this domain are only temporary tables for testing |
185 | * |
186 | * In "temporary tables mode", the CONN_TRX_AUTOCOMMIT flag is ignored |
187 | * |
188 | * @param bool $value |
189 | * @param string $domain |
190 | * @return bool Whether "temporary tables mode" was active |
191 | * @since 1.34 |
192 | */ |
193 | public function setTempTablesOnlyMode( $value, $domain ); |
194 | |
195 | /** |
196 | * Get the specific server index of the reader connection for a given group |
197 | * |
198 | * This takes into account load ratios and lag times. It should return a consistent |
199 | * index during the life time of the load balancer. This initially checks replica DBs |
200 | * for connectivity to avoid returning an unusable server. This means that connections |
201 | * might be attempted by calling this method (usually one at the most but possibly more). |
202 | * Subsequent calls with the same $group will not need to make new connection attempts |
203 | * since the acquired connection for each group is preserved. |
204 | * |
205 | * @param string|false $group Query group or false for the generic group |
206 | * @return int|false Specific server index, or false if no DB handle can be obtained |
207 | */ |
208 | public function getReaderIndex( $group = false ); |
209 | |
210 | /** |
211 | * Get a lazy-connecting database handle for a specific or virtual (DB_PRIMARY/DB_REPLICA) server index |
212 | * |
213 | * The server index, $i, can be one of the following: |
214 | * - DB_REPLICA: a server index will be selected by the load balancer based on read |
215 | * weight, connectivity, and replication lag. Note that the primary server might be |
216 | * configured with read weight. If $groups is empty then it means "the generic group", |
217 | * in which case all servers defined with read weight will be considered. Additional |
218 | * query groups can be configured, having their own list of server indexes and read |
219 | * weights. If a query group list is provided in $groups, then each recognized group |
220 | * will be tried, left-to-right, until server index selection succeeds or all groups |
221 | * have been tried, in which case the generic group will be tried. |
222 | * - DB_PRIMARY: the primary server index will be used; the same as getWriterIndex(). |
223 | * The value of $groups should be [] when using this server index. |
224 | * - Specific server index: a positive integer can be provided to use the server with |
225 | * that index. An error will be thrown in no such server index is recognized. This |
226 | * server selection method is usually only useful for internal load balancing logic. |
227 | * The value of $groups should be [] when using a specific server index. |
228 | * |
229 | * Handle sharing is very useful when callers get DB_PRIMARY handles that are transaction |
230 | * round aware (the default). All such callers will operate within a single transaction as |
231 | * a consequence. The same applies to DB_REPLICA that are samely query grouped (the default) |
232 | * and transaction round aware (the default). |
233 | * |
234 | * Use CONN_TRX_AUTOCOMMIT to use a separate pool of only autocommit handles. This flag is |
235 | * ignored for databases with ATTR_DB_LEVEL_LOCKING (e.g. sqlite) in order to avoid deadlocks. |
236 | * getServerAttributes() can be used to check this attribute beforehand. Avoid using begin() |
237 | * and commit() on such handles. If handle methods like startAtomic() and endAtomic() must be |
238 | * used on the handles, callers should at least make sure that the atomic sections are closed |
239 | * on failure via try/catch and cancelAtomic(). |
240 | * |
241 | * Use CONN_UNTRACKED_GAUGE to get a new, untracked, handle, that uses a low connection timeout, a low |
242 | * read timeout, and autocommit mode. This flag is intended for use only be internal callers. |
243 | * |
244 | * CONN_UNTRACKED_GAUGE and CONN_TRX_AUTOCOMMIT are incompatible. |
245 | * |
246 | * @see ILoadBalancer::getServerAttributes() |
247 | * |
248 | * @param int $i Specific (overrides $groups) or virtual (DB_PRIMARY/DB_REPLICA) server index |
249 | * @param string[]|string $groups Query group(s) in preference order; [] for the default group |
250 | * @param string|false $domain DB domain ID or false for the local domain |
251 | * @param int $flags Bitfield of CONN_* class constants |
252 | * @return IDatabase|false This returns false on failure if CONN_SILENCE_ERRORS is set |
253 | */ |
254 | public function getConnection( $i, $groups = [], $domain = false, $flags = 0 ); |
255 | |
256 | /** |
257 | * Get a DB handle for a specific server index |
258 | * |
259 | * This is an internal utility method for methods like LoadBalancer::getConnectionInternal() |
260 | * and DBConnRef to create the underlying connection to a concrete server. |
261 | * |
262 | * The following is the responsibility of the caller: |
263 | * |
264 | * - translate any virtual server indexes (DB_PRIMARY/DB_REPLICA) to a real server index. |
265 | * - enforce read-only mode on primary DB handle if there is high replication lag. |
266 | * |
267 | * @see ILoadBalancer::getConnection() |
268 | * |
269 | * @internal Only for use within ILoadBalancer/ILoadMonitor |
270 | * @param int $i Specific server index |
271 | * @param string $domain Resolved DB domain |
272 | * @param int $flags Bitfield of class CONN_* constants |
273 | * @return IDatabase|false This returns false on failure if CONN_SILENCE_ERRORS is set |
274 | * @throws DBError If no DB handle could be obtained and CONN_SILENCE_ERRORS is not set |
275 | */ |
276 | public function getServerConnection( $i, $domain, $flags = 0 ); |
277 | |
278 | /** |
279 | * @deprecated since 1.39 noop |
280 | * @param IDatabase $conn |
281 | */ |
282 | public function reuseConnection( IDatabase $conn ); |
283 | |
284 | /** |
285 | * @deprecated since 1.39, use ILoadBalancer::getConnection() instead. |
286 | * @param int $i Specific or virtual (DB_PRIMARY/DB_REPLICA) server index |
287 | * @param string[]|string $groups Query group(s) in preference order; [] for the default group |
288 | * @param string|false $domain DB domain ID or false for the local domain |
289 | * @param int $flags Bitfield of CONN_* class constants (e.g. CONN_TRX_AUTOCOMMIT) |
290 | * @return DBConnRef |
291 | */ |
292 | public function getConnectionRef( $i, $groups = [], $domain = false, $flags = 0 ): DBConnRef; |
293 | |
294 | /** |
295 | * @internal Only to be used by DBConnRef |
296 | * @param int $i Specific (overrides $groups) or virtual (DB_PRIMARY/DB_REPLICA) server index |
297 | * @param string[]|string $groups Query group(s) in preference order; [] for the default group |
298 | * @param string|false $domain DB domain ID or false for the local domain |
299 | * @param int $flags Bitfield of CONN_* class constants (e.g. CONN_TRX_AUTOCOMMIT) |
300 | * @return IDatabase |
301 | */ |
302 | public function getConnectionInternal( $i, $groups = [], $domain = false, $flags = 0 ): IDatabase; |
303 | |
304 | /** |
305 | * Get a DB handle, suitable for migrations and schema changes, for a server index |
306 | * |
307 | * The DBConnRef methods simply proxy an underlying IDatabase object which |
308 | * takes care of the actual connection and query logic. |
309 | * |
310 | * The CONN_TRX_AUTOCOMMIT flag is ignored for databases with ATTR_DB_LEVEL_LOCKING |
311 | * (e.g. sqlite) in order to avoid deadlocks. getServerAttributes() |
312 | * can be used to check such flags beforehand. Avoid the use of begin() or startAtomic() |
313 | * on any CONN_TRX_AUTOCOMMIT connections. |
314 | * |
315 | * @see ILoadBalancer::getConnection() for parameter information |
316 | * @param int $i Specific or virtual (DB_PRIMARY/DB_REPLICA) server index |
317 | * @param string[]|string $groups Query group(s) in preference order; [] for the default group |
318 | * @param string|false $domain DB domain ID or false for the local domain |
319 | * @param int $flags Bitfield of CONN_* class constants (e.g. CONN_TRX_AUTOCOMMIT) |
320 | * @return DBConnRef |
321 | */ |
322 | public function getMaintenanceConnectionRef( $i, $groups = [], $domain = false, $flags = 0 ): DBConnRef; |
323 | |
324 | /** |
325 | * Get the specific server index of the "writer server" |
326 | * |
327 | * The "writer server" is the server that should be used to source writes and critical reads |
328 | * originating from the local datacenter. The "writer server" will be one of the following: |
329 | * - The primary, for single-primary setups (even if it resides in a remote datacenter) |
330 | * - The "preferred" co-primary relative to the local datacenter, for multi-primary setups |
331 | * - The "preferred" static clone, for static clone server setups (e.g. no replication) |
332 | * |
333 | * @return int Specific server index |
334 | */ |
335 | public function getWriterIndex(); |
336 | |
337 | /** |
338 | * Get the number of servers defined in configuration |
339 | * |
340 | * @return int |
341 | */ |
342 | public function getServerCount(); |
343 | |
344 | /** |
345 | * Whether there are any replica servers configured |
346 | * |
347 | * This scans the list of servers defined in configuration, checking for: |
348 | * - Servers that are listed after the primary and not flagged with "is static"; |
349 | * such servers are assumed to be typical streaming replicas |
350 | * - Servers that are listed after the primary and flagged with "is static"; |
351 | * such servers are assumed to have a clone of the static dataset (matching the primary) |
352 | * |
353 | * @return bool |
354 | * @since 1.34 |
355 | */ |
356 | public function hasReplicaServers(); |
357 | |
358 | /** |
359 | * Whether any replica servers use streaming replication from the primary server |
360 | * |
361 | * This scans the list of servers defined in configuration, checking for: |
362 | * - Servers that are listed after the primary and not flagged with "is static"; |
363 | * such servers are assumed to be typical streaming replicas |
364 | * |
365 | * It is possible for some replicas to be configured with "is static" but not |
366 | * others, though it generally should either be set for all or none of the replicas. |
367 | * |
368 | * If this returns false, this means that there is generally no reason to execute |
369 | * replication wait logic for session consistency and lag reduction. |
370 | * |
371 | * @return bool |
372 | * @since 1.34 |
373 | */ |
374 | public function hasStreamingReplicaServers(); |
375 | |
376 | /** |
377 | * Get the readable name of the server with the specified index |
378 | * |
379 | * @param int $i Specific server index |
380 | * @return string Readable server name, falling back to the hostname or IP address |
381 | */ |
382 | public function getServerName( $i ): string; |
383 | |
384 | /** |
385 | * Return the server configuration map for the server with the specified index |
386 | * |
387 | * @param int $i Specific server index |
388 | * @return array|false Server configuration map; false if the index is invalid |
389 | * @since 1.31 |
390 | */ |
391 | public function getServerInfo( $i ); |
392 | |
393 | /** |
394 | * Get the RDBMS type of the server with the specified index (e.g. "mysql", "sqlite") |
395 | * |
396 | * @param int $i Specific server index |
397 | * @return string One of (mysql,postgres,sqlite,...) or "unknown" for bad indexes |
398 | * @since 1.30 |
399 | */ |
400 | public function getServerType( $i ); |
401 | |
402 | /** |
403 | * Get basic attributes of the server with the specified index without connecting |
404 | * |
405 | * @param int $i Specific server index |
406 | * @return array (Database::ATTRIBUTE_* constant => value) for all such constants |
407 | * @since 1.31 |
408 | */ |
409 | public function getServerAttributes( $i ); |
410 | |
411 | /** |
412 | * Get the current primary replication position |
413 | * |
414 | * @return DBPrimaryPos|false Returns false if not applicable |
415 | * @throws DBError |
416 | * @since 1.37 |
417 | */ |
418 | public function getPrimaryPos(); |
419 | |
420 | /** |
421 | * Whether there are pending changes or callbacks in a transaction by this thread |
422 | * @return bool |
423 | * @since 1.37 |
424 | */ |
425 | public function hasPrimaryChanges(); |
426 | |
427 | /** |
428 | * Determine whether an explicit transaction is active on any open primary |
429 | * connection. |
430 | * @return bool |
431 | * @since 1.39 |
432 | */ |
433 | public function explicitTrxActive(); |
434 | |
435 | /** |
436 | * Check if this load balancer object had any recent or still |
437 | * pending writes issued against it by this PHP thread |
438 | * |
439 | * @param float|null $age How many seconds ago is "recent" [defaults to mWaitTimeout] |
440 | * @return bool |
441 | * @since 1.37 |
442 | */ |
443 | public function hasOrMadeRecentPrimaryChanges( $age = null ); |
444 | |
445 | /** |
446 | * @note This method may trigger a DB connection if not yet done |
447 | * @param string|false $domain DB domain ID or false (unused and deprecated since 1.40) |
448 | * @return string|false Reason the primary is read-only or false if it is not |
449 | */ |
450 | public function getReadOnlyReason( $domain = false ); |
451 | |
452 | /** |
453 | * @return bool |
454 | */ |
455 | public function pingAll(); |
456 | |
457 | /** |
458 | * Get the name and lag time of the most-lagged replica server |
459 | * |
460 | * This is useful for maintenance scripts that need to throttle their updates. |
461 | * May attempt to open connections to replica DBs on the default DB. If there is |
462 | * no lag, the maximum lag will be reported as -1. |
463 | * |
464 | * @return array{0:string,1:float|int|false,2:int} (host, max lag, index of max lagged host) |
465 | */ |
466 | public function getMaxLag(); |
467 | |
468 | /** |
469 | * Get an estimate of replication lag (in seconds) for each server |
470 | * |
471 | * Results are cached for a short time in memcached/process cache |
472 | * |
473 | * Values may be "false" if replication is too broken to estimate |
474 | * |
475 | * @return float[]|int[]|false[] Map of (server index => lag) in order of server index |
476 | */ |
477 | public function getLagTimes(); |
478 | |
479 | /** |
480 | * Wait for a replica DB to reach a specified primary position |
481 | * |
482 | * If $conn is not a replica server connection, then this will return true. |
483 | * Otherwise, if $pos is not provided, this will connect to the primary server |
484 | * to get an accurate position. |
485 | * |
486 | * @param IDatabase $conn Replica DB |
487 | * @return bool Success |
488 | * @since 1.37 |
489 | */ |
490 | public function waitForPrimaryPos( IDatabase $conn ); |
491 | |
492 | /** |
493 | * Set a callback via IDatabase::setTransactionListener() on |
494 | * all current and future primary connections of this load balancer |
495 | * |
496 | * @param string $name Callback name |
497 | * @param callable|null $callback |
498 | */ |
499 | public function setTransactionListener( $name, callable $callback = null ); |
500 | |
501 | /** |
502 | * Make certain table names use their own database, schema, and table prefix |
503 | * when passed into SQL queries pre-escaped and without a qualified database name |
504 | * |
505 | * For example, "user" can be converted to "myschema.mydbname.user" for convenience. |
506 | * Appearances like `user`, somedb.user, somedb.someschema.user will used literally. |
507 | * |
508 | * Calling this twice will completely clear any old table aliases. Also, note that |
509 | * callers are responsible for making sure the schemas and databases actually exist. |
510 | * |
511 | * @param array[] $aliases Map of (table => (dbname, schema, prefix) map) |
512 | */ |
513 | public function setTableAliases( array $aliases ); |
514 | |
515 | /** |
516 | * Convert certain database domains to alternative ones. |
517 | * |
518 | * This can be used for backwards compatibility logic. |
519 | * |
520 | * @param DatabaseDomain[]|string[] $aliases Map of (domain alias => domain) |
521 | * @since 1.35 |
522 | */ |
523 | public function setDomainAliases( array $aliases ); |
524 | } |